Keywords in the stem to identify correct option

1. Drop in body temperature → points to reduced metabolism.
2. Drop in heart rate → indicates suppressed physiological activity.
3. Drop in oxygen consumption → hallmark of hypometabolic state.

Classic Triad in Stem

↓ Temperature + ↓ Heart Rate + ↓ O₂ Consumption → Classic triad of hypometabolic state (seen post-anesthesia/postoperative).

These 3 together immediately rule out hypermetabolic and hyperdynamic states.

Explanation 

(Option B) Hypometabolic state:

• Means decreased metabolic activity with reduced O₂ consumption, heart rate, temperature, and overall body energy demands.
• This occurs post-anesthesia, during hypothermia, and in immediate postoperative recovery when the body conserves energy.
• More specific here because the stem mentions fall in temperature + HR + O₂ consumption, all pointing to a suppressed metabolism.

Explanation (more detail):

• During the immediate postoperative phase, due to residual effects of anesthesia and reduced sympathetic activity, the body enters a hypometabolic state.
• This helps conserve energy and oxygen while the patient recovers.
• Manifestations: ↓ HR, ↓ body temp, ↓ O₂ consumption, ↓ CO₂ production.

(Option A) Hypermetabolic state:

• Refers to increased metabolic activity with rise in body temperature, oxygen consumption, CO₂ production, and heart rate.
• Seen in conditions like sepsis, burns, hyperthyroidism.
• ❌ Not correct, because here metabolism is depressed.

(Option C) Hyperdynamic state:

• Characterized by increased cardiac output, tachycardia, warm peripheries, bounding pulse.
• Classically seen in early sepsis, thyrotoxicosis.
• ❌ Not correct since the patient has reduced HR and O₂ consumption.

(Option D) Hypodynamic state:

• Means low cardiac output with reduced perfusion, hypotension, cold extremities.
• Seen in shock states (late septic shock, cardiogenic shock, hypovolemic shock).
• ❌ Not a pure metabolic descriptor, more related to circulatory dynamics.

(Option E) Homeostatic state:

• Indicates the body is in a balanced internal environment.
• ❌ Not fitting here since the patient is showing clear physiological suppression, not equilibrium.

Key Concept # 1

In the immediate postoperative period, patients often enter a hypometabolic state due to anesthesia and suppressed metabolism, leading to decreased temperature, heart rate, and oxygen consumption.

Key Concept # 2

• The “Ebb and Flow” model explains the biphasic metabolic response to injury: Ebb = hypometabolic (early, protective) and Flow = hypermetabolic (later, reparative) — this MCQ represents the Ebb Phase.
• The Ebb and Flow model applies to BOTH metabolic response to injury (surgery) and trauma/critical illness.

Subject: Surgery (General)

System: Metabolic / Endocrine

Topic: General Surgery – Metabolic Response to Injury (Postoperative Hypometabolic State)

General Surgery – Metabolic Response to Injury (Postoperative Hypometabolic State)

Key Point

The hypometabolic state is the early phase after surgery/anesthesia, marked by ↓ temp, ↓ HR, ↓ O₂ consumption, followed later by a hypermetabolic (catabolic) state in response to injury.

Ebb and Flow Model – 

Metabolic Response to Injury & Trauma

Key Exam Point:

• Ebb = Hypometabolic, protective (early)
• Flow = Hypermetabolic, catabolic (later)
• Recovery = Anabolic (final, healing)

General Surgery – Metabolic Response to Injury (Postoperative Hypometabolic State)

The diagram illustrates the phases of metabolic response to surgery: hypometabolic → hypermetabolic → recovery. It highlights the postoperative hypometabolic state, showing key changes such as ↓ oxygen consumption, ↓ CO₂ production, ↓ heart rate, ↓ temperature, and energy conservation immediately after surgery due to anesthesia and reduced physiological activity.

Keywords in the stem to identify correct option

1. “Recent surgical wound” → classical setting for clostridial infection in devitalized tissue.
2. “Crepitus” → hallmark finding of gas gangrene due to anaerobic gas production.
3. “Rapidly progressive with severe pain” → fits gas gangrene, although also seen in necrotizing fasciitis.

Classic Triad (Gas gangrene)

• Pain + Edema + Crepitus at wound site → strongly indicates Clostridial gas gangrene.

Bottom line: The keyword “crepitus at a recent surgical wound” locks the answer as Gas gangrene (B).

Explanation 

(Option B) Gas gangrene (Clostridial myonecrosis):

• Caused by Clostridium perfringens (spore-forming anaerobe).
• Rapidly progressive, with severe pain, swelling, crepitus, foul-smelling discharge, systemic toxicity.
• Gas production in tissues leads to crepitus (palpable crackling).
• Typically occurs after trauma or surgical wounds in devitalized tissue with poor oxygen supply.
• Requires urgent surgical debridement + IV antibiotics.

More Detail

• The hallmark feature in this stem is crepitus at surgical wound site with rapid progression and severe pain.
• This is classical for Clostridial gas gangrene, not cellulitis, erysipelas, or pyomyositis.
• Necrotizing fasciitis also causes severe pain and rapid spread, but crepitus strongly favors gas gangrene.

(Option A) Cellulitis:

• Superficial bacterial skin infection involving dermis and subcutaneous tissue.
• Presents with erythema, warmth, swelling, and tenderness, but not associated with gas/crepitus.
• Pain is usually mild to moderate, not out of proportion.

(Option C) Necrotizing fasciitis:

• Polymicrobial or streptococcal deep infection of fascia and subcutaneous tissue.
• Presents with severe pain out of proportion to findings, systemic toxicity, dusky skin, rapid progression.
• May mimic gas gangrene, but crepitus is less prominent and not always present.
• More often associated with skin breaks, perineum, or abdominal wall infections.

(Option D) Pyomyositis:

• Suppurative infection of skeletal muscle, usually by Staphylococcus aureus.
• Presents with localized muscle pain, fever, and abscess formation.
• No crepitus, no gas formation.

(Option E) Erysipelas:

• Superficial bacterial infection of upper dermis and lymphatics (commonly Streptococcus pyogenes).
• Presents with sharply demarcated erythematous raised lesion.
• Does not cause crepitus or deep tissue necrosis.

Key Concept 

Rapidly progressive painful wound infection with crepitus after surgery/trauma strongly suggests gas gangrene (Clostridial myonecrosis). Necrotizing fasciitis causes pain out of proportion but usually without marked crepitus, while cellulitis, erysipelas, and pyomyositis lack gas formation.

Comparison: 

Gas gangrene (Clostridial myonecrosis) vs Necrotizing fasciitis

Exam Tip

• If the stem emphasizes crepitus → pick Gas gangrene.
• If the stem emphasizes pain out of proportion to findings → pick Necrotizing fasciitis.

Subject: Surgery (General)

System: Musculoskeletal + Integumentary (with systemic infectious spread)

Topic: Surgery – (Surgical Site Infections) – Postoperative Infections: Gas Gangrene (Clostridial Myonecrosis)

Surgery – (Surgical Site Infections) – Postoperative Infections: 

Gas Gangrene (Clostridial Myonecrosis)

Key Concept 

Gas gangrene is a postoperative soft tissue infection caused by Clostridium perfringens, presenting with pain, edema, and crepitus. It is a surgical emergency requiring urgent debridement and antibiotics.

Differential Diagnosis of

Postoperative Wound Infection with Pain/Crepitus

Key Differentials for Exams

• Necrotizing fasciitis (closest mimic, but hallmark = pain out of proportion, not crepitus).
• Cellulitis/Erysipelas (common but no crepitus).
• Pyomyositis (muscle infection but no gas).

Surgery – (Surgical Site Infections) – Postoperative Infections: Gas Gangrene (Clostridial Myonecrosis)

This educational diagram illustrates the progression of surgical site infections with focus on gas gangrene (clostridial myonecrosis):

• Top left: Surgical wound as the initial site of infection.
• Top right: Clinical appearance of gas gangrene with spreading discoloration and tissue necrosis.
• Bottom left: Clostridial myonecrosis showing muscle destruction with gas and necrotic tissue.
• Bottom right: Causative organism (Clostridium) and its association with postoperative infections.

It highlights the pathogenesis, clinical features, and microbial cause of gas gangrene in the context of postoperative surgical site infections.

Keywords in the stem to identify correct option

• Acute upper abdominal pain + jaundice + fever → This is Charcot’s Triad, classic for acute cholangitis due to CBD stone.
• Gallstone in gallbladder + single stone in CBD → Confirms choledocholithiasis, requires stone removal + definitive gallbladder surgery.

Together, these keywords lead to ERCP stone removal followed by laparoscopic cholecystectomy (Option C) as the most appropriate treatment.

Explanation 

(Option C) Removal of CBD stone with ERCP followed by laparoscopic cholecystectomy:

• This patient’s presentation of acute upper abdominal pain, jaundice, and fever along with an ultrasound showing a gallstone in the gallbladder and a stone in the common bile duct (CBD) is a classic presentation of cholangitis secondary to choledocholithiasis (a stone in the common bile duct) and cholelithiasis (a stone in the gallbladder). The primary goal is to relieve the biliary obstruction and treat the infection promptly.
• This is the current Gold standard for treating patients with both cholelithiasis and choledocholithiasis.
• ERCP (endoscopic retrograde cholangiopancreatography) is a minimally invasive endoscopic procedure used to remove the CBD stone and decompress the biliary tree, which is crucial for treating the acute cholangitis. 
• Following the ERCP, a laparoscopic cholecystectomy is performed to remove the gallbladder, preventing future episodes. 
• This two-step approach is less invasive than open surgery, reduces the risk of complications, and allows for staged treatment, prioritizing the most urgent issue first.

(Option A) Conservative management:

• Not appropriate here. Conservative treatment may be used in mild, asymptomatic gallstones.
• This patient has Charcot’s triad (pain, jaundice, fever) → suggests acute cholangitis due to CBD stone. Needs intervention.

(Option B) Cholecystectomy and common bile duct exploration, with T-tube drainage:

• A valid option but considered more invasive. Requires open/laparoscopic surgery.
• Usually done if ERCP fails or is not available.

(Option D Cholecystectomy and choledochoduodenostomy:

• This is a bypass procedure (CBD anastomosed to duodenum).
• Used in recurrent CBD stones or strictures, not in a single CBD stone with gallbladder still in situ.

(Option E) Percutaneous transhepatic biliary drainage (PTBD) without addressing gallbladder stones:

• Mainly palliative in inoperable malignant biliary obstruction.
• Not definitive for benign gallstones + CBD stone, so not appropriate here.

Key Concept of MCQ 

• A patient with Charcot’s triad → acute cholangitis due to CBD stone.
• ERCP stone removal followed by laparoscopic cholecystectomy is the gold standard: minimally invasive, treats both CBD stone and gallbladder pathology, and prevents recurrence.

Subject: Surgery (General)

System: Hepatobiliary System (GIT System)

Topic: General Surgery – Hepatobiliary Surgery – Management of Choledocholithiasis (CBD Stone) with Acute Cholangitis

General Surgery – Hepatobiliary Surgery – Management of Choledocholithiasis (CBD Stone) with Acute Cholangitis

Key Exam Point

Acute cholangitis (Charcot’s triad) due to CBD stone → ERCP for stone clearance followed by laparoscopic cholecystectomy is the gold standard.

Differential Diagnosis of 

Choledocholithiasis with Acute Cholangitis

General Surgery – Hepatobiliary Surgery: Management of Choledocholithiasis (CBD Stone) with Acute Cholangitis

The diagram illustrates the hepatobiliary system and highlights the presence of a common bile duct stone (choledocholithiasis) leading to acute cholangitis. 

It shows the anatomical relationship of the liver, gallbladder, bile ducts, and pancreas, with separate visuals emphasizing choledocholithiasis, acute cholangitis, and their combined presentation. 

It serves as a visual guide for understanding pathology and management in hepatobiliary surgery.

Keywords in the stem to identify correct option

1. Low back pain radiating down leg → Suggests lumbar radiculopathy.
2. Weakness in dorsiflexion of foot → Classic sign of L5 nerve root compression.
3. Numbness lateral aspect of leg → Sensory distribution of L5 radiculopathy.

Classic Triad?

Yes – this stem gives the classic triad of radiculopathy:

• Pain (radiating)
• Sensory loss (numbness)
• Motor weakness (dorsiflexion)

Together, these keywords + triad point to nerve root compression → best confirmed with MRI.

Explanation 

(Option C) MRI of the lumbar spine:

• Gold standard for diagnosing lumbar disc herniation, spinal stenosis, and nerve compression.
• Provides excellent soft-tissue contrast, directly showing the spinal cord and the herniated disc compressing the nerve root.
• Non-invasive, highly sensitive and specific.

More Explanation 

• Why MRI? Because it directly visualizes the pathology (disc protrusion/extrusion, nerve root compression, canal stenosis).
• Importance: Confirms clinical suspicion, rules out alternative causes (tumor, infection, degenerative changes).
• Relevance here: The patient has classical L5 radiculopathy (weak dorsiflexion, sensory loss lateral leg) → MRI confirms disc prolapse compressing L5 root.

(Option A) Electromyography (EMG):

• EMG detects muscle activity abnormalities due to nerve damage.
• Helpful to assess severity/chronicity of nerve root involvement but not the first-line investigation for diagnosis.

(Option B) Lumbar spine X-ray:

• Shows bony structures (osteophytes, fractures, spondylolisthesis).
• Cannot directly visualize nerve roots, intervertebral discs, or soft tissue.
• Not diagnostic for radiculopathy.

(Option D) Nerve conduction studies (NCS):

• Evaluates peripheral nerve conduction velocity.
• Useful to differentiate peripheral neuropathy vs. radiculopathy, but not first choice to confirm disc-related nerve compression.

(Option E) Bone scan:

• Detects increased bone turnover (e.g., metastasis, fractures, infection).
• Not useful in diagnosing disc herniation or radiculopathy.

Key Concept

Lumbar radiculopathy due to disc herniation is best confirmed by MRI, as it directly demonstrates disc pathology and nerve root compression. Other tests (EMG, NCS, X-ray, bone scan) are supportive but not diagnostic.

Subject: Orthopedic Surgery (Spine) / Neuroanatomy (applied)

System: Musculoskeletal + Nervous System

Topic: Orthopedic Surgery – Spine Disorders – Lumbar Disc Herniation with Radiculopathy

Orthopedic Surgery – Spine Disorders – 

Lumbar Disc Herniation with Radiculopathy

Key Takeaway

Lumbar disc herniation → most often at L4–L5, L5–S1 → presents with radicular pain, dermatomal sensory loss, motor weakness → MRI is the gold standard for confirmation.

Differential Diagnosis of Lumbar Radiculopathy 

(Disc Herniation)

Orthopedic Surgery – Spine Disorders: Lumbar Disc Herniation with Radiculopathy

This diagram set illustrates the pathology and clinical impact of lumbar disc herniation. It shows:

• Normal and herniated lumbar intervertebral disc anatomy.
• Disc herniation compressing the spinal nerve root, leading to radiculopathy.
• The dermatomal distribution of pain radiating down the leg (sciatica).
  It integrates orthopedic spine anatomy with the neurological consequences of radiculopathy for clear clinical understanding.

Keywords in the stem to identify correct option

• Crohn’s disease → Chronic inflammatory bowel disease; predisposes to strictures, fistulas, and abscesses.
• CT scan shows … abscess → Infection + localized collection = needs antibiotics (± drainage), not steroids or surgery initially.
• Fever + severe abdominal pain → Signs of sepsis/infection, not pure inflammatory flare.

Together, “Crohn’s disease + abscess + fever/sepsis” = points directly to IV antibiotics as initial management.

Explanation 

(Option A) Intravenous antibiotics and observation:

• First-line management of an intra-abdominal abscess in Crohn’s disease is broad-spectrum IV antibiotics with or without percutaneous drainage depending on abscess size and accessibility.
• This helps to stabilize the patient, reduce inflammation, and may even allow for resolution of the abscess without further intervention. 
• Observation is key to monitor her response to the antibiotics. If the abscess is small and the patient’s condition improves, this may be the only treatment needed.
• Immediate surgery is avoided if possible because acute inflammation increases surgical morbidity.
• Once infection is controlled, further definitive management (medical or surgical) can be planned.

(Option B) Surgical resection of the affected bowel segment:

• Not initial management. Surgery is considered only if the abscess is unresponsive to antibiotics/drainage or if there is perforation/obstruction.
• Resection in acute infection risks fistula formation and poor healing.

(Option C) Corticosteroid therapy:

• Contraindicated in acute abscess/infection. Steroids worsen infection and delay healing.
• Used for flares without abscess or perforation.

(Option D) Endoscopic dilation:

• Used for fibrotic strictures in Crohn’s, not for acute inflammatory masses or abscesses.
• Attempting dilation in the presence of abscess could cause perforation.

(Option E) Percutaneous drainage without antibiotics:

• Incomplete management. Abscesses require both antibiotic coverage + drainage (if indicated).
• Drainage alone leaves systemic infection risk untreated.

Key Concept 

In Crohn’s disease with intra-abdominal abscess, the first step is infection control with IV antibiotics ± percutaneous drainage. Steroids are contraindicated, and surgery is reserved for failed conservative treatment or complications.

Subject: Surgery (General)

System: Gastrointestinal system (Terminal Ileum – Crohn’s disease with abscess)

Topic: General Surgery – Gastrointestinal Surgery: Management of Crohn’s Disease Complications (Intra-abdominal Abscess)

General Surgery – Gastrointestinal Surgery: Management of Crohn’s Disease Complications (Intra-abdominal Abscess)

Differential Diagnosis of

Right Lower Quadrant Pain and Abscess in Crohn’s Disease

Key point:
The most likely diagnosis in this MCQ is Crohn’s disease with abscess, but these differentials are considered based on history, prior disease, imaging, and lab findings.

General Surgery – Gastrointestinal Surgery: Management of Crohn’s Disease Complications (Intra-abdominal Abscess)

The diagram illustrates the stepwise management of an intra-abdominal abscess as a complication of Crohn’s disease. The image shows the terminal ileum with a localized abscess (highlighted by the arrow). The flowchart below the illustration outlines the recommended approach:

1. Crohn’s disease – Represents the underlying condition causing bowel inflammation.
2. Intra-abdominal abscess – Complication of Crohn’s disease, shown in the terminal ileum.
3. Intravenous antibiotics – First-line management for a stable patient with a localized abscess.
4. Observation – Monitoring for clinical improvement and resolution of the abscess; surgical intervention is reserved for refractory or complicated cases.

The diagram emphasizes non-surgical initial management of abscesses in Crohn’s disease, highlighting the importance of antibiotics and close clinical monitoring.

Keywords in the stem to identify correct option

1. Prominent eye changes → Classic for Graves’ disease (ophthalmopathy is unique among causes of hyperthyroidism).
2. Suppressed TSH with elevated T3/T4 → Confirms primary hyperthyroidism.

Classic Triad of Graves’ disease 

• Diffuse goiter
• Ophthalmopathy (eye signs)
• Pretibial myxedema

👉 In this stem, ophthalmopathy + thyrotoxicosis already points strongly to Graves’ disease.

Explanation 

(Option B) Graves’ disease:

• Graves’ disease is an autoimmune disorder where the body produces thyroid-stimulating immunoglobulin (TSI) antibodies. These antibodies mimic the action of TSH, stimulating the thyroid gland to produce excessive amounts of T3 and T4.
• It causes diffuse toxic goiter and hyperthyroidism.
• Unique features: ophthalmopathy (exophthalmos, periorbital edema, lid lag), pretibial myxedema, and diffuse goiter with bruit.
• Most common cause of hyperthyroidism in young women.
• Lab hallmark: suppressed TSH, elevated T3/T4, and positive TSH receptor antibodies (TRAb/TSI).

Pathophysiology: The autoantibodies mimic TSH, causing excessive thyroid hormone production.

(Option A) Toxic Multinodular Goiter: 

• This condition occurs due to multiple autonomous hyperfunctioning nodules in the thyroid.
• Patients present with hyperthyroidism, but exophthalmos is not seen.
• TSH is low, and T3/T4 is elevated, but thyroid nodules are palpable or visible on imaging.
• It is more common in older adults.

(Option C) Hashimoto’s Thyroiditis:

• Chronic autoimmune thyroiditis that primarily leads to hypothyroidism, not hyperthyroidism.
• It is associated with anti-TPO (thyroid peroxidase) antibodies.
• Features:
  • Initially, there may be a transient hyperthyroid phase (Hashitoxicosis), but long-term effects lead to hypothyroidism.
  • No exophthalmos.
  • TSH is typically high, and T3/T4 is low in the hypothyroid phase.

(Option D) De Quervain’s Thyroiditis (Subacute Thyroiditis):

• Painful thyroiditis caused by viral infection (often follows an upper respiratory infection).
• Presents with:
  • Neck pain and tenderness
  • Fever
  • Initial hyperthyroid phase (due to thyroid hormone leakage) followed by hypothyroidism.
• TSH is low, and T3/T4 is high, but the distinguishing feature is the painful thyroid.

(Option E) Thyroid Adenoma:

• A solitary, benign thyroid nodule that may produce excess thyroid hormones (toxic adenoma).
• Causes hyperthyroidism, but exophthalmos is absent.
• TSH is low, and T3/T4 is elevated, but only one nodule is seen on imaging.

Key Concept 

This patient has classic Graves’ disease: hyperthyroidism with diffuse goiter and ophthalmopathy, confirmed by low TSH and high T3/T4. Eye changes make Graves’ disease the most likely diagnosis, differentiating it from other causes of thyrotoxicosis.

Subject: Surgery (General)

System: Endocrine System (Thyroid Gland) – (Breast & Endocrine)

Topic: Endocrinology: Thyroid Disorders – Hyperthyroidism

Endocrinology: 

Thyroid Disorders – Hyperthyroidism

Differential Diagnosis of Hyperthyroidism

Most Likely Diagnosis

Graves’ disease — because of classic triad clue:

• Hyperthyroidism (low TSH, high T3/T4)
• Ophthalmopathy (eye signs in stem)
• Young female (common demographic)

Endocrinology – Thyroid Disorders: Hyperthyroidism

The diagram illustrates the thyroid gland and highlights hyperthyroidism under thyroid disorders. It shows the thyroid gland’s anatomy, clinical features such as weight loss, heat intolerance, palpitations, and ophthalmopathy, and emphasizes the link between endocrine pathology and systemic manifestations.

Keywords in the stem to identify correct option

• “Recurrent painful swelling” → suggests obstruction rather than a tumor (tumors are usually painless, progressive).
• “While eating” → classic trigger for sialolithiasis (mealtime syndrome) due to increased salivary flow against obstruction.

Explanation

(Option B) Sialolithiasis: 

Sialolithiasis (salivary gland stones) is the most likely diagnosis in this case. It commonly affects the submandibular gland due to its long duct (Wharton’s duct) and the upward flow of saliva against gravity, which predisposes it to stone formation. The classic presentation includes:

• Recurrent painful swelling of the gland, especially during eating, when saliva production increases but is obstructed by the stone.
• Pain and swelling typically subside after meals as the saliva drains slowly.
• The submandibular gland is affected more commonly than the parotid gland due to the higher calcium content and viscosity of its saliva.

(Option A) Pleomorphic Adenoma:

• Benign tumor of the salivary gland, most commonly affecting the parotid gland.
• Painless, slow-growing mass rather than painful swelling during meals.
• No association with eating-related pain.

(Option C) Warthin’s Tumor:

• Benign tumor, almost exclusively affecting the parotid gland.
• Associated with smoking.
• Painless, slow-growing mass, often bilateral.

(Option D) Mumps:

• Viral infection caused by the mumps virus, affecting the parotid glands bilaterally.
• Presents with fever, malaise, and painful swelling, not typically related to meals.
• Common in children and young adults, not a recurrent condition.

(Option E) Sjögren’s Syndrome:

• Autoimmune disorder causing chronic dry mouth (xerostomia) and dry eyes (keratoconjunctivitis sicca).
• Can cause salivary gland enlargement, but typically bilateral and painless.
• More common in postmenopausal women. 

Key Concept 

Recurrent painful swelling of the submandibular gland during meals is classic for sialolithiasis (salivary gland stones), most common in Wharton’s duct due to anatomical and chemical factors. 

Tumors, infections, and autoimmune causes present differently (usually painless, systemic, or chronic).

Subject: Surgery & ENT

System: Head & Neck – (Disorders of Salivary Glands) – (Head & Neck)

Topic: Disorders of Salivary Glands 

Disorders of Salivary Glands – Overview

Differential Diagnosis of

Recurrent Painful Submandibular Swelling

Disorders of Salivary Glands with Focus on Sialolithiasis

The diagram highlights the main categories of salivary gland disorders — obstructive, inflammatory/infective, autoimmune, benign neoplastic, and malignant neoplastic conditions. It specifically illustrates sialolithiasis in the submandibular gland, showing how a salivary stone causes painful, recurrent swelling during meals due to obstructed salivary flow.

Keywords in the stem to identify correct option

• Recent Surgery: This indicates endothelial injury and venous stasis due to immobility, a major risk factor for thrombosis.
• Obesity: This is a key risk factor for hypercoagulability and venous stasis.
• Pain, swelling, and warmth of the left calf: These are the classic signs and 

symptoms of a Deep Vein Thrombosis (DVT), indicating clot formation.

Virchow’s Triad 

The combination of these factors points to Virchow’s Triad, which describes the three broad categories of factors that contribute to thrombosis:

1. Venous stasis (e.g., from immobility after surgery)
2. Endothelial injury (e.g., from the surgery itself)
3. Hypercoagulability (e.g., due to obesity and the post-operative state)

This patient’s presentation clearly aligns with multiple components of Virchow’s Triad, which makes a DVT the most likely diagnosis.

Explanation

(Option A) Doppler Ultrasound:

• The patient’s symptoms (pain, swelling, and warmth of the left calf) are indicative of deep vein thrombosis (DVT), which is a possible complication following surgery, especially in obese individuals. 
• A Doppler Ultrasound is the most appropriate investigation because it is a non-invasive, widely used, and highly effective method for detecting DVT. 
• It visualizes venous flow and detects obstruction, thrombus, or lack of compressibility of the vein and can confirm the presence of a clot.

(Option B) D-Dimer:

• D-Dimer is a blood test that measures the presence of fibrin degradation products, which are released when a blood clot breaks down. 
• While an elevated D-Dimer level can be suggestive of DVT, it is non-specific and can be elevated in many other conditions (e.g., infection, pregnancy, cancer). 
• It is generally used as a screening tool, and a negative result can help rule out DVT, but it is not definitive for diagnosis.

(Option C) CT Angiography:

• CT Angiography is typically used for detecting pulmonary embolism or arterial diseases, not venous thrombosis. While it can show blood clots in the arteries, it is not the first-line investigation for DVT. 
• It is more invasive, expensive, and not as effective for this purpose.

(Option D) Venography:

• Venography is an older and more invasive technique that involves injecting a contrast dye into the veins and taking X-ray images. 
• While it can be used to detect DVT, it has largely been replaced by Doppler ultrasound due to its invasiveness, higher risk of complications, and being less practical for routine use.

(Option E) X-ray:

• An X-ray is not helpful in diagnosing DVT because it is designed to detect bone fractures or certain types of lung or chest conditions. 
• It cannot visualize blood clots in the veins. Therefore, it is not useful for diagnosing a suspected DVT.

Key Concept 

In suspected DVT, Doppler ultrasound is the investigation of choice due to its non-invasive, accurate, and readily available nature. D-dimer is useful only in low-risk patients, while venography is rarely done, and CT angiography is reserved for PE.

Subject: Surgery 

System:  Cardiovascular (Venous System of Lower Limb)

Topic: Vascular Pathology (DVT) in Surgery

Vascular Pathology (DVT) in Surgery

Differential Diagnoses of Post-op Calf Pain/Swelling

Summary
The main differentials of suspected DVT in surgery are cellulitis, superficial thrombophlebitis, ruptured Baker’s cyst, hematoma, and lymphedema.
However, in a post-op obese patient, DVT is the most likely diagnosis, making Doppler ultrasound the investigation of choice.

Vascular Pathology (DVT) in Surgery and 

Post-operative Calf Pain/Swelling

This diagram illustrates deep vein thrombosis (DVT) as a vascular complication in surgical patients, showing thrombus formation within deep veins and its detection by Doppler ultrasound. It also highlights the clinical presentation of post-operative calf pain/swelling and provides key differential diagnoses such as cellulitis, superficial thrombophlebitis, and ruptured Baker’s cyst.

Keywords in the stem to identify correct option

1. Sequestrum – Dead avascular bone → hallmark of chronic osteomyelitis → requires surgical removal (sequestrectomy).
2. Involucrum – New bone formation around sequestrum → another classical feature of chronic osteomyelitis confirming the diagnosis.

Classic Triad in Chronic Osteomyelitis (present here):

• Discharging sinus + Sequestrum + Involucrum → pathognomonic for chronic osteomyelitis.

These keywords immediately rule out antibiotics alone and point directly to Sequestrectomy and Debridement as the best management.

Explanation 

(Option C) Sequestrectomy and Debridement:

The patient’s presentation—chronic pain, discharging sinus, and radiographic findings of sequestrum (dead bone) and involucrum (new bone formation around dead bone)—is characteristic of chronic osteomyelitis. The best surgical management in this scenario is sequestrectomy and debridement, which involves removing the dead bone and infected tissue to control the infection and allow healing.

• This is the Gold standard treatment for chronic osteomyelitis with sequestrum and involucrum.
• Sequestrectomy: Surgical removal of the sequestrum (dead bone).
• Debridement: Removal of all infected and necrotic tissue to prevent further spread of infection.
• This approach allows for infection control and facilitates bone healing.
• Chronic osteomyelitis cannot be eradicated with antibiotics alone due to the avascular necrotic sequestrum.
• After surgery: bone stabilization (if required), followed by culture-guided antibiotics.

(Option A) Long-term IV antibiotics alone:

• • Antibiotics are an essential part of managing acute osteomyelitis, but in chronic osteomyelitis with sequestrum, antibiotics alone are ineffective.
  • The presence of sequestrum acts as a nidus of infection, preventing antibiotics from fully eradicating the bacteria.

• Surgical removal of the sequestrum is necessary to allow antibiotics to work effectively.

(Option B) Local wound care and suppressive antibiotics:

• • Local wound care and suppressive antibiotics are not definitive treatments for chronic osteomyelitis.
  • They may provide temporary relief but will not cure the condition since the necrotic bone remains.

• Without surgical intervention, the infection will persist, leading to complications like sinus tract formation, pathological fractures, and systemic spread of infection.

(Option D) Amputation:

• • Amputation is not the first-line treatment for chronic osteomyelitis.
  • It is considered only in cases of severe, non-salvageable infections, such as:
    • Uncontrolled infection despite multiple surgeries
    • Severe bone destruction with loss of function
    • Limb-threatening complications like sepsis

• Since this patient does not show signs of life-threatening infection or complete loss of function, limb salvage through sequestrectomy is preferred.

(Option E) Application of External Fixator:

• External fixation is mainly used for fracture stabilization, particularly in cases of nonunion or deformity correction.
• In chronic osteomyelitis, external fixation alone does not address the infection, making it an incomplete treatment.
• If the patient has an infected nonunion, an external fixator might be used after debridement to stabilize the bone.

Key Concept 

Chronic osteomyelitis is characterized by sequestrum (dead bone) and involucrum (new bone formation). The definitive management is surgical — sequestrectomy and debridement — as antibiotics alone cannot penetrate avascular sequestrum.

Subject: Surgery

System:  Musculoskeletal System (Bone & Soft Tissue – Tibia)- (Infective conditions in bones and joints) – (Orthopedics – Elective Orthopedics)

Topic: Chronic Osteomyelitis and its Surgical Management 

Chronic Osteomyelitis and its Surgical Management

Differential Diagnosis of Chronic Osteomyelitis

Chronic Osteomyelitis and Its Surgical Management

The diagram illustrates chronic osteomyelitis of the tibia, showing its classical features — sequestrum (dead bone), involucrum (new bone formation), and sinus tract (draining pus). The surgical management steps are highlighted on the right, including sequestrectomy, debridement, bone stabilization (if required), and antibiotics, which together form the definitive treatment strategy.

Keywords in the stem to identify correct option

• “Coronary artery bypass grafting (CABG)” → Indicates we are talking about conduits used for bypass.
• “Gold standard” → Classic clue pointing towards LIMA.
• “Left anterior descending (LAD) artery” → The most important artery supplied by LIMA in CABG.

Explanation 

(Option C) Left Internal Mammary Artery (LIMA):

The Left Internal Mammary Artery (LIMA) is the Gold standard for grafting the left anterior descending (LAD) artery in coronary artery bypass grafting (CABG). This is because of its superior long-term patency rates, which are significantly higher than other conduits. The LIMA graft has excellent endothelial function, resistance to atherosclerosis, and long-term durability, leading to better survival and lower rates of re-intervention.

• It has the best long-term patency (90-95% at 10 years).
• Resistant to atherosclerosis, leading to prolonged graft function.

(Option A) Saphenous Vein Graft (SVG):

• • The saphenous vein is commonly used in CABG, but it has lower long-term patency rates compared to LIMA.
  • Vein grafts are prone to atherosclerosis and may occlude within 10–15 years.

• It is still used for grafting other coronary arteries when LIMA is not an option.

(Option B) Radial Artery Graft:

• • The radial artery has better patency than the saphenous vein but is not superior to LIMA.
  • It has a tendency to spasm, requiring calcium channel blockers or nitrates postoperatively.

• It is used as a second choice when additional grafts are needed.

(Option D) Right Internal Mammary Artery (RIMA):

• • The right internal mammary artery is also an arterial conduit with good patency but is less commonly used than LIMA.

• It is often used in bilateral IMA grafting, but LIMA to LAD remains superior.

(Option E) Gastroepiploic Artery:

• This artery is sometimes used in selected cases but is not commonly preferred due to its anatomical position and surgical complexity.
• It has less favorable long-term patency rates compared to LIMA.

Key Concept 

The Left Internal Mammary Artery (LIMA) is the Gold standard graft for LAD bypass due to its superior long-term patency, resistance to atherosclerosis, and survival benefits. Other conduits like saphenous vein or radial artery are alternatives but have lower patency.

Subject: Surgery 

System:  CVS – (Incision, conduits and valve options in cardiac surgery) – (Cardio-thoracic – Cardiac surgery)

Topic: Coronary Artery Bypass Grafting (CABG) and Graft Selection

Coronary Artery Bypass Grafting (CABG) and Graft Selection

Coronary Artery Bypass Grafting (CABG) and Graft Selection

The diagram illustrates CABG and the graft conduits used. It highlights the Left Internal Mammary Artery (LIMA) as the gold standard graft for the Left Anterior Descending (LAD) artery, shows the grafting process, and provides a schematic overview of other graft options including RIMA, Radial artery, and Saphenous vein grafts (SVG).

Keywords in the stem to identify correct option

• “Dilated lateral and third ventricles, normal fourth ventricle” → Classic MRI finding of aqueductal stenosis (non-communicating hydrocephalus).
• “5-year-old boy with vomiting and balance problems” → Pediatric age + raised ICP symptoms typical for obstructive hydrocephalus.

Explanation 

(Option B) Aqueductal stenosis (non-communicating hydrocephalus):

Definition & Cause

• Aqueductal stenosis is obstruction of the cerebral aqueduct of Sylvius between the 3rd and 4th ventricles.
• Most commonly caused by a congenital narrowing or obstruction of the cerebral aqueduct.

Pathophysiology

• The aqueduct of Sylvius, which connects the third and fourth ventricles, is blocked.
• This causes a buildup of cerebrospinal fluid (CSF) in the ventricles proximal (before) the blockage—the lateral and third ventricles—while the fourth ventricle remains normal.
• This results in non-communicating (obstructive) hydrocephalus, since CSF cannot flow freely to the subarachnoid space.

Radiological Findings

• MRI shows dilated lateral and third ventricles with a normal fourth ventricle.
• This pattern is characteristic of aqueductal stenosis.

Clinical Features

• Vomiting (due to increased intracranial pressure).
• Balance problems (due to pressure on cerebellar structures).
• Possible headaches, lethargy, and papilledema.

(Option A) Normal Pressure Hydrocephalus (NPH):

• • NPH is seen in older adults, not a 5-year-old child.
  • It presents with the classic triad: gait disturbance, urinary incontinence, and dementia (Hakim’s triad).

• MRI shows ventricular dilation without increased pressure signs, which is different from this case.

(Option C) Meningitis:

• • Meningitis causes diffuse brain inflammation, not an isolated obstruction.
  • MRI would show meningeal enhancement, ventricular inflammation, and possibly communicating hydrocephalus (dilation of all ventricles).

• Symptoms include fever, neck stiffness, altered consciousness, and photophobia, which are absent here.

(Option D) Subarachnoid Hemorrhage (SAH):

• • SAH presents with sudden severe headache (thunderclap headache), not just balance problems and vomiting.

• Hydrocephalus due to SAH is typically communicating, causing dilation of all ventricles, unlike this case.

(Option E) Brain Abscess:

• Brain abscess causes localized ring-enhancing lesions on MRI.
• Symptoms include fever, focal neurological deficits, and signs of infection.
• No mention of an infectious process in this patient.

Key Concept 

Selective dilation of lateral and third ventricles with a normal fourth ventricle strongly indicates aqueductal stenosis, the most common cause of non-communicating hydrocephalus in children.

Subject: Surgery & Anatomy

System:  Neurosurgery (Nervous System) – (Cerebrospinal Fluid (CSF) Circulation)

Topic: Neuroanatomy: Ventricular System & CSF Circulation

Neuroanatomy: 

Ventricular System & CSF Circulation

Differential Diagnoses of Dilated Ventricles in a Child

Key Point

The normal 4th ventricle in this stem rules out most differentials and pinpoints aqueductal stenosis as the cause.

Neuroanatomy: Ventricular System & CSF Circulation – 

Aqueductal Stenosis

This diagram illustrates the anatomy of the brain’s ventricular system and the flow of cerebrospinal fluid (CSF). It highlights the lateral ventricles, third ventricle, cerebral aqueduct (Sylvius), fourth ventricle, and the subarachnoid space. CSF is produced in the choroid plexus, circulates through the ventricles, and exits into the subarachnoid space.

The MRI image on the right shows aqueductal stenosis, a type of non-communicating hydrocephalus, characterized by dilated lateral and third ventricles with a normal fourth ventricle, indicating obstruction at the cerebral aqueduct. This condition can lead to increased intracranial pressure, causing headaches, vomiting, and other neurological symptoms.

Keywords in the stem to identify correct option

• “Initially unconscious, then regained full consciousness, but later developed rapid deterioration in GCS (Glasgow Coma Scale)” → Lucid interval → hallmark of epidural hematoma.

• “Biconvex, hyperdense lesion in the temporal region on CT” → Classic CT appearance of epidural hematoma.

Classic Triad (if complete in stem)

1. Head trauma
2. Lucid interval
3. Rapid neurological deterioration

Present in stem (described, not named).

These keywords + triad directly point to Epidural Hematoma → Craniotomy with hematoma evacuation.

Explanation 

(Option D) Craniotomy with hematoma evacuation:

• Epidural hematoma with midline shift and neurological deterioration is a neurosurgical emergency.
• EDH is typically caused by a rupture of the middle meningeal artery, leading to rapid accumulation of blood between the dura and skull. The increasing hematoma exerts mass effect, causing brain herniation if untreated.
• A craniotomy is necessary to remove the clotted blood and ligate the bleeding vessel, typically the middle meningeal artery, to prevent re-bleeding and relieve the pressure on the brain.
• Craniotomy with hematoma evacuation + securing bleeding vessel (middle meningeal artery) is the definitive treatment to relieve pressure and prevent fatal herniation. 
• Prevents further compression, brain herniation, and death.
• Life-saving and Gold standard.

(Option A) IV Mannitol and close observation:

• Mannitol is used to reduce intracranial pressure (ICP) in conditions like diffuse cerebral edema or increased ICP without a focal mass.
• However, EDH is a surgical emergency, and observation alone can lead to deterioration and death.

(Option B) Therapeutic lumbar puncture to reduce ICP:

• Lumbar puncture (LP) is contraindicated in space-occupying brain lesions like EDH because it can cause brain herniation by rapidly reducing pressure in the spinal canal while ICP remains high in the brain.

(Option C) Intravenous dexamethasone:

• Dexamethasone is used for vasogenic edema, such as in brain tumors or abscesses, but it is not effective for hemorrhagic mass lesions like EDH.

(Option E) Start anticoagulation to prevent further thrombosis:

• Anticoagulation is contraindicated in patients with active intracranial bleeding, as it would worsen the hemorrhage.

Key Takeaway

• Epidural hematoma presents with a lucid interval followed by rapid neurological deterioration.
• Epidural hematoma (EDH) is a neurosurgical emergency.
• The best management is craniotomy with hematoma evacuation (Option D).

Subject: Surgery

System:  Neurosurgery – Intracranial Bleed & Tumors – (Initial management of intracranial bleed)

Topic: Epidural Hematoma and Traumatic Brain Injury (TBI) 

Epidural Hematoma and Traumatic Brain Injury (TBI)

Differential Diagnoses of 

Epidural Hematoma (EDH)

Key point

The lucid interval + biconvex CT + rapid deterioration makes epidural hematoma the most likely diagnosis, but SDH is the main differential.

Epidural Hematoma & Traumatic Brain Injury (TBI)

The diagram shows a cross-section of the brain highlighting an epidural hematoma as a biconvex, hyperdense lesion in the temporal region. Alongside, a comparison table summarizes key aspects of epidural hematoma versus general traumatic brain injury (TBI), covering definition, cause, clinical presentation, imaging, and management for quick high-yield understanding.

Keywords in the stem to identify correct option

1. Painless gross hematuria – Suggests bladder cancer rather than infection or renal disease.
2. 65-year-old male, chronic smoker – High-risk patient for urothelial carcinoma.

Classic triad: 

None in this stem (the classic triad of flank pain, hematuria, and mass is not present; here, only painless hematuria is noted).

Explanation

(Option E) Cystoscopy with biopsy:

In an elderly male with a history of chronic smoking and painless gross hematuria, the primary concern is urothelial (transitional cell) carcinoma of the bladder. The best next step for evaluation is cystoscopy with biopsy, as it allows direct visualization of the bladder mucosa and the collection of tissue samples for histopathology to confirm malignancy.

• Gold standard for evaluating bladder cancer.
• Provides direct visualization of the bladder mucosa (bladder lining, urethra, and ureteral openings).
• Allows biopsy for histopathological diagnosis.
• Essential in any patient with painless gross hematuria, especially with risk factors such as smoking. 

(Option A) Urine culture and sensitivity:

• Urine culture is useful in diagnosing urinary tract infections (UTIs), which can also present with hematuria.
• However, painless hematuria in an elderly chronic smoker is highly suspicious for bladder cancer, not infection.
• UTIs usually present with dysuria, frequency, urgency, or fever, which are absent in this case.
• Even if an infection were present, it would not explain gross hematuria in this high-risk patient. 

(Option B) Renal biopsy:

• Renal biopsy is primarily indicated in glomerular diseases (e.g., nephritic syndrome, nephrotic syndrome) when hematuria is associated with proteinuria or renal dysfunction.
• This patient has normal renal function and painless hematuria, making glomerular disease unlikely. 

(Option C) Voiding cystourethrogram (VCUG):

• VCUG is mainly used to assess vesicoureteral reflux (VUR) or bladder outlet obstruction in pediatric patients with recurrent UTIs or in cases of suspected trauma.
• It is not the primary investigation for gross hematuria in an adult, especially with cancer suspicion. 

(Option D) Renal ultrasound:

• Renal ultrasound is useful in detecting renal masses, stones, or hydronephrosis but has low sensitivity for bladder cancer.
• It cannot visualize the bladder mucosa directly, so it cannot rule out bladder cancer, which is a more likely cause in this patient.

Key Concept 

Painless hematuria in elderly patients, particularly smokers, is highly suspicious for urothelial carcinoma. Cystoscopy with biopsy is the first-line diagnostic tool, while imaging (ultrasound/CT) complements it to evaluate upper urinary tract.

Subject: Surgery & IM 

System:  Genito-urinary – Kidney & ureter Urinary bladder – (Appropriate tests for urinary tract pathology)

Topic: Painless Hematuria and Bladder Cancer Workup 

Painless Hematuria and Bladder Cancer Workup

Differential Diagnoses

for painless hematuria

Key Point
In an elderly smoker with painless gross hematuria, bladder cancer is the top differential, and cystoscopy is the definitive next step.

Painless Hematuria and Bladder Cancer Workup

The diagram shows a structured diagnostic pathway for an elderly or high-risk patient (e.g., smoker) presenting with painless hematuria. It emphasizes the role of urinalysis, renal function tests, and highlights cystoscopy with biopsy as the gold standard investigation for detecting bladder cancer.

Stages of Bladder Cancer

The diagram illustrates the progressive stages of bladder cancer, from Stage 0 (superficial, confined to the inner lining) through Stage I–III (increasing depth of invasion into the bladder wall and surrounding tissues). It visually demonstrates how tumor growth advances from non-invasive to muscle-invasive disease.

Keywords in the stem to identify correct option

1. Firm, nodular prostate on DRE – Suggests possible prostate cancer, not just BPH.
2. PSA 12 ng/mL – Significantly elevated; strongly indicates high risk of malignancy.

These two keywords directly point to the need for TRUS-guided prostate biopsy before BPH surgery.

Explanation

(Option C) Perform transrectal ultrasound (TRUS)-guided prostate biopsy:

The patient presents with lower urinary tract symptoms (LUTS) and findings concerning for benign prostatic hyperplasia (BPH). However, a firm, nodular prostate on digital rectal examination (DRE) and an elevated PSA (12 ng/mL) raise suspicion for prostate cancer.

Before proceeding with any BPH-related surgery (such as TURP), it is critical to rule out malignancy. The best next step is to perform a TRUS-guided prostate biopsy to confirm or exclude prostate cancer.

• TRUS-guided biopsy is the Gold standard for diagnosing prostate cancer in patients with elevated PSA and suspicious DRE findings.
• It provides histopathological confirmation of cancer, which is necessary before making further treatment decisions. 
• If cancer is detected, management changes (e.g., radical prostatectomy or other oncological approach instead of TURP).
• Additional Note: Biopsy may also guide staging and treatment planning if cancer is found.

(Option A) Proceed with TURP as planned:

• Transurethral resection of the prostate (TURP) is a treatment for symptomatic BPH, not prostate cancer.
• Given the firm, nodular prostate and elevated PSA, there is a significant risk of prostate cancer.
• Performing TURP without ruling out cancer could delay cancer diagnosis and proper treatment. 

(Option B) Repeat PSA in 6 months:

• Waiting for 6 months without further investigation is inappropriate when there is a high suspicion of prostate cancer.
• A PSA of 12 ng/mL is significantly elevated, and the presence of a nodular prostate on DRE makes immediate evaluation necessary.
• Delaying biopsy could result in disease progression if cancer is present. 

(Option D) Start 5-alpha reductase inhibitors and reassess PSA:

• 5-alpha reductase inhibitors (e.g., finasteride, dutasteride) are used to shrink the prostate and lower PSA in benign prostatic hyperplasia (BPH).
• However, these drugs do not treat prostate cancer and can artificially lower PSA levels, potentially delaying cancer diagnosis.
• Given the nodular prostate and high PSA, ruling out cancer first is essential. 

(Option E) Order MRI pelvis for staging:

• Multiparametric MRI is used after prostate cancer is confirmed via biopsy to assess tumor extent and staging.
• Since cancer is not yet diagnosed, a biopsy must be done first.
• If cancer is confirmed, MRI can then be used to evaluate local invasion and metastasis.

Key Concept 

• In men with abnormal DRE and PSA >10 ng/mL, the next step is TRUS-guided prostate biopsy to rule out malignancy before BPH surgery.
• BPH management should be deferred until prostate cancer is excluded.

Subject: Surgery & IM

System:  Genito-urinary – Prostate & seminal vesicles – (Investigations Appropriate for Benign Conditions of the Prostate) 

Topic: Evaluation and Diagnosis of Prostate Disorders 

Evaluation and Diagnosis of Prostate Disorders

Differential Diagnoses

(For a patient with LUTS, firm/nodular prostate, and elevated PSA)

Prostate Disorders and Diagnostic Evaluation

This diagram illustrates three key aspects of prostate disease: Benign Prostatic Hyperplasia (BPH) showing symmetrical enlargement, Prostate Cancer with nodular asymmetrical growth, and the technique of TRUS-guided prostate biopsy used for histopathological diagnosis in suspected malignancy.

Keywords in the stem to identify correct option

1. Sudden-onset severe testicular pain – suggests acute vascular compromise rather than infection or chronic condition.
2. High-riding testis with absent cremasteric reflex – classic physical exam triad for testicular torsion.
3. Nausea – supportive systemic symptom commonly seen in acute torsion.

Classic triad: 

Acute scrotal pain + High-riding testis + Absent cremasteric reflex → diagnostic for testicular torsion.

Explanation

(Option A) Testicular Torsion:

Pathophysiology: Testicular torsion is a urological emergency caused by twisting of the spermatic cord, leading to ischemia of the testis. The classical presentation includes:

• Sudden onset of severe testicular pain
• High-riding testis due to shortening of the spermatic cord
• Absent cremasteric reflex (normally, stroking the inner thigh causes testicular elevation)
• Nausea/vomiting (due to autonomic response to severe pain)
• It’s most common in adolescent boys.

Urgency: Immediate surgical detorsion and orchiopexy are needed within 6 hours to prevent testicular necrosis. Salvage rate drops significantly after 6 hours.

(Option B) Epididymitis:

• Inflammation of the epididymis due to infection (bacterial or viral).
• Presents with gradual onset of pain, scrotal swelling, and intact cremasteric reflex.
• Prehn’s sign positive (pain relief with testicular elevation).
• Treatment: Antibiotics (if bacterial).

(Option C) Varicocele:

• Dilated veins in the pampiniform plexus (“bag of worms” appearance).
• Chronic, dull ache in the scrotum, usually worsens when standing.
• Does not cause acute pain or absent cremasteric reflex.
• Treatment: Surgical ligation if symptomatic.

(Option D) Fournier’s Gangrene:

• Necrotizing fasciitis of the perineum, often in diabetics or immunocompromised individuals.
• Presents with severe pain, fever, black necrotic skin, and crepitus.
• Requires emergent debridement and IV antibiotics.

(Option E) Torsion of Appendix Testis:

• Torsion of a vestigial embryonic remnant (appendix testis).
• Presents with gradual onset of localized pain, usually at the upper pole of the testis.
• Blue dot sign may be visible.
• Cremasteric reflex is present.
• Management: Supportive, with NSAIDs for pain relief.

Key Concept 

Testicular torsion is a surgical emergency in adolescents presenting with sudden-onset testicular pain, nausea, high-riding testis, and absent cremasteric reflex. Early diagnosis and prompt detorsion (ideally within 6 hours) are crucial for testicular salvage.

Subject: Surgery & EM

System: Genito-urinary – (Testes, scrotum & urethra) – Testicular torsion

Topic: Testicular Torsion and Acute Scrotal Emergencies

Testicular Torsion and Acute Scrotal Emergencies

Differential Diagnoses

(For acute scrotal pain in adolescents)

Key Point

In adolescents, acute scrotum is a surgical emergency until proven otherwise, and testicular torsion must always be ruled out first.

Acute Scrotal Emergencies and Testicular Torsion – 

Key Clinical Features

This diagram illustrates the main causes of acute scrotal pain, including testicular torsion, torsion of appendix testis, epididymitis, and varicocele. It highlights the hallmark signs of testicular torsion, such as a high-riding testis and absent cremasteric reflex, contrasting them with normal anatomy and other scrotal conditions for rapid clinical differentiation.

Keywords in the stem to identify correct option

1. Tender subcutaneous nodules – Pain/tenderness is classic for angiolipoma, unlike painless lipoma.
2. Multiple, gradually increasing – Multiple nodules favor angiolipoma over solitary lipoma.

Classic triad

• Tender + Subcutaneous + Multiple nodules → highly suggestive of angiolipoma.

Explanation 

(Option E) Angiolipoma:

• Angiolipomas are benign subcutaneous tumors composed of mature fat and vascular elements.
• These benign tumors are a subtype of lipoma that contain a significant vascular component, which is why they are often painful or tender to the touch, unlike typical lipomas.
• They present as:

• Multiple, small, soft to rubbery subcutaneous nodules especially on trunk/extremities
• Often tender or painful (unlike typical lipomas)
• Compressible on palpation
• Commonly located on the trunk or upper extremities
• Occur in young adults, more commonly in women

The key clues in this case: young woman, multiple soft, compressible, tender subcutaneous nodules → classic for angiolipoma.

(Option A) Neurofibroma:

• Soft, skin-colored or violaceous nodules that can be pedunculated or subcutaneous
• Not typically tender or compressible
• Associated with Neurofibromatosis Type 1 if multiple
• Slow-growing, often along nerve sheaths
• Not the best fit due to tenderness and compressibility 

(Option B) Lipoma:

• Most common benign soft tissue tumor
• Soft, mobile, non-tender, subcutaneous mass
• Common in adults
• No vascular component, so not typically tender
• The lack of tenderness makes this less likely than angiolipoma 

(Option C) Hemangioma:

• Benign vascular tumor, common in infants
• Bluish or red appearance on skin
• May feel spongy or compressible
• Usually appears early in life, not in adulthood
• Not subcutaneous nodules in the way described here
• Age and appearance don’t match the case 

(Option D) Dermatofibroma:

• Firm, hyperpigmented nodules, often on lower legs
• Classically demonstrates the dimple sign on lateral compression
• Not tender, not soft or compressible
• Fixed to overlying skin, not subcutaneous
• Doesn’t match the description

Key Concept

• Angiolipoma = tender, soft, subcutaneous nodules often multiple; contains fat + proliferating blood vessels.
• Distinguishing feature: tenderness differentiates angiolipoma from a typical painless lipoma.

Subject: Surgery 

System: Integumentary System (Skin and subcutaneous tissue) – Skin, Plastic and Reconstructive Surgery – Skin and subcutaneous – Classification of benign skin tumors

Topic: Classification of Benign Skin and Subcutaneous Tumors 

Classification of 

Benign Skin and Subcutaneous Tumors

Differential Diagnoses

(For tender subcutaneous nodules like angiolipoma)

Key Point

• Tender, multiple subcutaneous nodules in adults → angiolipoma is the most likely diagnosis.
• Other benign nodules are considered but are painless or differ in location/consistency.

Classification of Benign Skin and Subcutaneous Tumors

The diagram classifies benign tumors of the skin and subcutaneous tissue into categories (adipose, fibrous, vascular, neural, and mixed), alongside illustrative visuals. It highlights key examples like lipoma, angiolipoma, dermatofibroma, neurofibroma, and hemangioma. It also includes schematic depictions of subcutaneous tumors and a focused illustration of angiolipoma, showing its fatty and vascular components that explain its tenderness.

Keywords in the stem to identify correct option

• Hypertrophic scars and keloids – Indicates pathologic scar formation requiring more than single therapy.
• Following a burn injury – Suggests post-traumatic etiology, often resistant to single modality.
• (Implied keyword) Reduce size and appearance – Signals cosmetic and functional outcome, favoring combination therapy.

Explanation 

(Option E) Combination therapy:

• Combination therapy is widely regarded as the most effective approach for treating hypertrophic scars and keloids, especially those that are large, recurrent, or resistant to a single treatment. 
• The core principle of this method is to use a multimodal approach, combining different therapies to target the scar from multiple angles.
• A single treatment is often insufficient for these notoriously difficult-to-manage scars. Therefore, a strategic combination of modalities, tailored to the individual patient and their specific scar characteristics, is the Gold Standard. 
• For example, surgical excision to remove the scar is often paired with an adjuvant treatment like intralesional corticosteroid injections, silicone gel sheets, or postoperative radiation therapy to significantly reduce the risk of recurrence and improve cosmetic outcomes.

(Option A) Topical corticosteroids:

• Can reduce inflammation and fibroblast proliferation in hypertrophic scars and keloids.
• Often used as intralesional injections rather than just topical for better effect.
• Limitation: Alone, they are often insufficient for large or resistant keloids.

(Option B) Silicone gel sheets:

• Help in softening and flattening scars by hydrating the scar tissue and reducing collagen deposition.
• Effective for mild hypertrophic scars but less effective for thick keloids.
• Limitation: Works best as part of a combined regimen.

(Option C) Laser therapy:

• Pulsed dye laser or fractional lasers can reduce redness, thickness, and itching in scars.
• Useful for cosmetic improvement but may not prevent recurrence if used alone.

(Option D) Surgical excision:

• Removes the scar physically.
• Limitation: High recurrence rate if done alone, especially in keloids (up to 50-80%).

Key Concept
Hypertrophic scars and keloids are best managed with multimodal therapy, as single treatments often fail to prevent recurrence or achieve significant cosmetic improvement. Combination therapy targets scar removal, inflammation, and collagen regulation simultaneously.

Subject: Surgery – Plastic and Reconstructive Surgery

System: Integumentary system (Skin & Subcutaneous tissue) – Skin, Plastic and Reconstructive Surgery – Burn

Topic: Management of Hypertrophic Scars and Keloids – Burns and Post-Traumatic Scar Treatment

Management of Hypertrophic Scars and Keloids –

Burns and Post-Traumatic Scar Treatment

Key Concept
Effective management of hypertrophic scars and keloids after burns requires multimodal therapy, as single modalities often fail to prevent recurrence or achieve optimal cosmetic results.

Differential Diagnoses

(For hypertrophic scars and keloids)

Key Point
Differential diagnosis mainly focuses on distinguishing keloid vs hypertrophic scar, as management differs, and other lesions may mimic raised scars but have different etiology or histology.

Hypertrophic Scars, Keloids, and Post-Burn Scar Treatment

The diagram illustrates the difference between hypertrophic scars (confined to wound borders) and keloids (extending beyond wound margins), along with a flowchart of treatment options including corticosteroids, silicone gel sheets, laser therapy, surgical excision, and the most effective approach—combination therapy.

Keywords in the stem to identify correct option

1. Projectile, non-bilious vomiting – Suggests pyloric obstruction rather than bilious obstruction (rules out duodenal atresia, malrotation).
2. Olive-shaped mass in epigastrium – Classic palpable sign of hypertrophic pyloric stenosis.
3. 4-week-old male – Typical age and sex predilection for HPS.

Classic triad in the stem

• Projectile vomiting + palpable olive-shaped mass + visible peristaltic waves (though waves not mentioned here, the first two strongly indicate the triad for HPS).

Explanation

(Option C) Hypertrophic pyloric stenosis:

• • Hypertrophic pyloric stenosis (HPS) is a condition in which the pyloric muscle (which connects the stomach to the small intestine) becomes thickened, leading to a narrowing of the pyloric canal. 
  • This condition typically presents between 2 to 6 weeks of life, and common symptoms include projectile, non-bilious vomiting, a palpable “olive-shaped” mass in the epigastrium (the area of the stomach), and signs of dehydration. 
  • Vomiting occurs after feeds and is often forceful. It is the most common cause of gastric outlet obstruction in infants.

• Causes dehydration and weight loss if untreated.

• • Diagnosis: ultrasound showing thickened pyloric muscle.

• Treatment: Ramstedt pyloromyotomy is definitive.

(Option A) Gastroesophageal reflux disease (GERD):

• Description: GERD involves the backflow of stomach contents into the esophagus, leading to symptoms like vomiting, irritability, and feeding difficulties.
• Why not the right choice: The vomiting in GERD is usually not projectile, and there is no palpable mass. GERD typically presents with less forceful vomiting and is not associated with an olive-shaped mass.

(Option B) Duodenal atresia:

• Description: Duodenal atresia is a congenital condition where the duodenum (the first part of the small intestine) is abnormally narrowed or blocked.
• Why not the right choice: Duodenal atresia typically presents with bilious vomiting (due to obstruction below the bile duct), not non-bilious vomiting. Additionally, there is no palpable mass, which differentiates it from hypertrophic pyloric stenosis.

(Option D) Malrotation with volvulus:

• Description: This occurs when the intestines are not properly positioned in the abdomen during fetal development, leading to volvulus (twisting of the intestines), which can cause obstruction.
• Why not the right choice: While malrotation with volvulus can cause vomiting and abdominal distension, it is typically associated with bilious vomiting and may present acutely with signs of intestinal ischemia or shock. It does not usually present with a palpable mass in the epigastrium.

(Option E) Infantile colic:

• Description: Infantile colic involves excessive crying and fussiness in otherwise healthy infants, typically in the first few months of life.
• Why not the right choice: Colic is characterized by excessive crying and does not cause vomiting or a palpable mass. The vomiting seen in the case described is more forceful and related to feeding, which is not typical for colic.

Key Concept 

• Hypertrophic pyloric stenosis is the most common cause of non-bilious projectile vomiting in infants 3–6 weeks old. 
• Key signs include palpable epigastric olive, visible peristalsis, dehydration, and weight loss. 
• Ultrasound confirms diagnosis; surgical pyloromyotomy is definitive treatment.

Subject: Surgery & Pediatrics

System:  Gastrointestinal / Digestive System – Pediatric – Pediatric Surgery – Presentation and Resuscitation of Pyloric Stenosis

Topic: Neonatal / Infantile Gastrointestinal Obstruction – Hypertrophic Pyloric Stenosis

Neonatal / Infantile Gastrointestinal Obstruction – 

Hypertrophic Pyloric Stenosis (HPS)