Abdominal and Pelvic Radiology — MCQs

Abdominal and Pelvic Radiology Indian Medical PG Practice Questions and MCQs

Question 161: Which of the following is not a feature of renovascular hypertension on IVU?

A. Delayed wash out of contrast
B. Ureteral kinking
C. Filling defect in calyces (Correct Answer)
D. Normal or small sized kidney

Explanation: **Explanation:** Renovascular hypertension (RVH) is caused by renal artery stenosis (RAS), which leads to decreased renal perfusion. This triggers the Renin-Angiotensin-Aldosterone System (RAAS). On an Intravenous Urogram (IVU), the findings reflect the physiological consequences of reduced blood flow and slower glomerular filtration. **Why "Filling defect in calyces" is the correct answer:** A filling defect in the calyces typically indicates a space-occupying lesion such as a **transitional cell carcinoma (TCC)**, a blood clot, or a radiolucent stone. It is not a feature of renovascular hypertension, which affects the global hemodynamics and concentration ability of the kidney rather than creating focal intraluminal masses. **Analysis of other options:** * **Delayed wash out of contrast:** In RAS, the transit time of the filtrate is slowed. This leads to increased water reabsorption in the tubules, causing the contrast to remain concentrated and "linger" longer in the collecting system compared to the healthy side. * **Ureteral kinking:** Also known as the **"Stansel’s sign,"** this occurs due to the development of collateral peri-ureteral vessels (notably from the lumbar or gonadal arteries) that attempt to bypass the stenosis, causing extrinsic impressions or "notching" on the ureter. * **Normal or small sized kidney:** Chronic ischemia leads to renal atrophy. A discrepancy in kidney size (usually **>1.5 cm difference**) is a classic screening sign for unilateral renal artery stenosis. **High-Yield Clinical Pearls for NEET-PG:** 1. **Classic IVU Triad for RAS:** Delayed appearance of contrast (early films), small kidney size, and hyperconcentration/delayed washout (late films). 2. **Gold Standard Investigation:** Digital Subtraction Angiography (DSA). 3. **Best Screening Tool:** Doppler Ultrasound or CT Angiography. 4. **Medical Management:** ACE inhibitors are contraindicated in bilateral renal artery stenosis as they can precipitate acute renal failure.

Question 162: The 'Mercedes Benz' sign is seen in which of the following conditions?

A. Volvulus
B. Gall stone (Correct Answer)
C. Struvite calculus
D. Intussusception

Explanation: **Explanation:** The **'Mercedes Benz' sign** is a classic radiological finding associated with **cholelithiasis (gallstones)**. It refers to the presence of star-shaped, radiolucent gas fissures within a gallstone. These fissures occur due to the shrinkage of cholesterol crystals or the entrapment of gas (nitrogen, oxygen, and carbon dioxide) within the stone's core. On an X-ray or CT scan, these gas-filled clefts resemble the three-pointed star logo of the Mercedes-Benz brand. **Analysis of Options:** * **Volvulus:** Sigmoid volvulus typically presents with the **'Coffee Bean' sign** or 'Omega' sign, representing a massively dilated loop of bowel. * **Struvite calculus:** These are staghorn calculi found in the renal pelvis, often associated with Proteus infections. They appear as large, radiopaque branching structures on a KUB (Kidney-Ureter-Bladder) film. * **Intussusception:** This condition is characterized by the **'Target' sign** or 'Doughnut' sign on ultrasound/CT, representing the telescoping of one bowel segment into another. **High-Yield Clinical Pearls for NEET-PG:** * **Gas in Gallstones:** The Mercedes Benz sign is seen in approximately 50% of gallstones on CT but is less common on plain X-rays. * **Limy Bile:** This refers to excessive calcium carbonate in the gallbladder, making the entire gallbladder appear radiopaque. * **Porcelain Gallbladder:** Intramural calcification of the gallbladder wall, often associated with chronic cholecystitis and an increased risk of gallbladder carcinoma. * **Rigler’s Triad:** (Seen in Gallstone Ileus) 1. Pneumobilia, 2. Small bowel obstruction, 3. Ectopic gallstone in the iliac fossa.

Question 163: A plain X-ray abdomen is performed in a case of small bowel obstruction. Small bowel is considered dilated if its diameter is more than:

A. 2 cm
B. 3 cm (Correct Answer)
C. 4 cm
D. 5 cm

Explanation: In abdominal radiology, the **"3-6-9 Rule"** is the standard clinical guideline used to identify abnormal bowel dilatation on a plain X-ray. According to this rule, the upper limits of normal diameter for the bowel segments are: * **Small Bowel:** < 3 cm * **Large Bowel (Colon):** < 6 cm * **Cecum:** < 9 cm **Why 3 cm is correct:** A small bowel loop is considered pathologically dilated if its diameter measures **3 cm or more**. In the context of intestinal obstruction, this dilatation occurs due to the accumulation of gas and fluid proximal to the site of the block. On X-ray, this is often accompanied by the "valvulae conniventes" (plicae circulares) crossing the entire width of the lumen, giving a "stacked coin" appearance. **Analysis of incorrect options:** * **2 cm (Option A):** This is within the normal physiological range for small bowel loops. * **4 cm (Option C):** While 4 cm is definitely dilated, it is not the threshold value. The diagnostic cutoff starts at 3 cm. * **5 cm (Option D):** This represents significant dilatation but is closer to the threshold for the large bowel (6 cm). **High-Yield Clinical Pearls for NEET-PG:** * **Step-ladder pattern:** Characteristic of small bowel obstruction due to multiple fluid levels. * **String of beads sign:** Small bubbles of gas trapped between valvulae conniventes in a fluid-filled small bowel. * **Coffee bean sign:** Classic for sigmoid volvulus (large bowel). * **Rigler’s sign:** Seeing both sides of the bowel wall, indicating pneumoperitoneum.

Question 164: Which of the following is NOT true regarding a renal pseudotumor?

A. Frequently requires surgical intervention (Correct Answer)
B. Represents hypertrophied column of Bertin
C. Can be visualized as a dromedary hump
D. Has no clinical significance

Explanation: ### Explanation **Renal pseudotumors** are anatomical variants of normal renal parenchyma that mimic a neoplasm on imaging. Understanding these is crucial to avoid unnecessary invasive procedures. **1. Why Option A is the correct answer:** Renal pseudotumors are **benign anatomical variants**, not true pathologies. They consist of normal, healthy renal tissue (cortex and glomeruli). Therefore, they **do not require surgical intervention** or biopsy. Management is purely conservative, usually involving confirmation via Doppler US, CT, or nuclear medicine (DMSA scan) to rule out a true malignancy. **2. Analysis of Incorrect Options:** * **Option B (Hypertrophied Column of Bertin):** This is the most common type of pseudotumor. It occurs when cortical tissue indents the renal sinus, often appearing as a "mass" between the upper and middle poles. * **Option C (Dromedary Hump):** This is a focal bulge on the lateral border of the left kidney caused by the splenic impression during development. It is a classic example of a pseudotumor. * **Option D (No clinical significance):** Since these are normal variants, they do not cause symptoms, hematuria, or functional impairment. Their only "significance" is the potential for being misdiagnosed as a renal cell carcinoma (RCC). **Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** A **Technetium-99m DMSA scan** is the most definitive way to differentiate a pseudotumor from a tumor. A pseudotumor will show **normal or increased uptake** (as it contains functioning nephrons), whereas a true tumor will appear as a "cold" spot. * **Imaging Clue:** On CT, a pseudotumor shows the **same enhancement pattern** as the rest of the renal cortex in all phases. * **Common Sites:** Columns of Bertin are typically found at the junction of the upper and middle thirds of the kidney.

Question 165: In Intravenous Pyelography (IVP), the "Adder head" appearance is seen in which of the following conditions?

A. Polycystic kidney
B. Horseshoe kidney
C. Ureterocele (Correct Answer)
D. Hydronephrosis

Explanation: **Explanation:** The **"Adder head"** (or Cobra head) appearance is a classic radiological sign of a **Ureterocele**. **1. Why Ureterocele is correct:** A ureterocele is a congenital cystic dilatation of the distal-most intramural portion of the ureter. On an Intravenous Pyelogram (IVP), the dilated terminal ureter appears as a radiopaque bulbous area surrounded by a thin radiolucent halo (representing the ureterocele wall). This combination resembles the head of a cobra or an adder snake. This sign is typically seen in **orthotopic (simple) ureteroceles** in adults. **2. Why other options are incorrect:** * **Polycystic Kidney Disease (ADPKD):** Characterized by the **"Swiss Cheese"** appearance due to multiple radiolucent cysts stretching and distorting the pelvicalyceal system. * **Horseshoe Kidney:** Characterized by the **"Flower vase"** appearance. The lower poles are fused, causing the axes of the kidneys to be reversed (lower poles more medial than upper poles). * **Hydronephrosis:** Presents as dilatation of the renal pelvis and calyces. If severe, it may show the **"Clubbing of calyces"** or the **"Rim sign"** on delayed films, but not an adder head. **Clinical Pearls for NEET-PG:** * **Cobra head sign:** If the radiolucent halo (the "wall") is thick or irregular, suspect a **pseudoureterocele** (often secondary to a bladder tumor or impacted stone). * **Drooping Lily Sign:** Seen in a duplicated collecting system where an obstructed upper pole ureterocele displaces the lower pole moiety downwards and outwards. * **Weigert-Meyer Law:** In duplication, the upper pole ureter inserts ectopically (inferomedial to the normal orifice) and is prone to obstruction/ureterocele.

Question 166: 'Thumb print' appearance on Barium enema is found in:

A. Volvulus
B. Gastric ulcer
C. Bowel ischemia (Correct Answer)
D. Intussusception

Explanation: **Explanation:** The **'Thumbprint' appearance** (or thumbprinting) is a classic radiologic sign seen on a Barium enema or plain abdominal X-ray. It represents **focal submucosal edema and hemorrhage** caused by an acute insult to the bowel wall, most commonly **Ischemic Colitis**. When the bowel wall becomes congested, the thickened folds protrude into the air or contrast-filled lumen, creating indentations that resemble the impression of a thumb. **Analysis of Options:** * **Bowel Ischemia (Correct):** This is the most common cause. The submucosal hemorrhage creates the characteristic scalloped appearance of the colonic wall. It is typically seen in the "watershed" areas like the splenic flexure (Griffith’s point). * **Volvulus:** Characterized by a **'Coffee bean' sign** (sigmoid volvulus) or a **'Bird’s beak' appearance** on a barium enema at the site of the twist. * **Gastric Ulcer:** Typically evaluated via endoscopy or upper GI series. Signs include an **ulcer crater** or **Hampton’s line**, but not thumbprinting, which is a colonic sign. * **Intussusception:** Classically presents with a **'Coiled spring' appearance** or **'Cup-shaped' defect** on a barium enema as the contrast trickles between the intussusceptum and intussuscipiens. **High-Yield Clinical Pearls for NEET-PG:** * **Other causes of thumbprinting:** Ulcerative Colitis (acute flare), Crohn’s disease, and submucosal lymphoma. * **Ischemic Colitis vs. Mesenteric Ischemia:** Thumbprinting is more specific to Ischemic Colitis (mucosal/submucosal injury) rather than acute mesenteric ischemia (which often shows a normal X-ray initially). * **Lead pipe appearance:** Seen in chronic Ulcerative Colitis due to loss of haustrations.

Question 167: Scalloping of the edge of the sigmoid colon on barium enema is typically seen in which of the following conditions?

A. Pseudomembranous colitis
B. Intussusception
C. Ulcerative colitis (Correct Answer)
D. Ischemic colitis

Explanation: **Explanation:** **Ulcerative Colitis (UC)** is the correct answer. The "scalloping" or "serrated" appearance of the colonic edge on a barium enema is a classic early radiological sign of UC. This occurs due to multiple small, superficial **mucosal ulcerations** and inflammatory changes. As the disease progresses, these ulcers may deepen (forming "collar-stud" ulcers) or lead to the formation of inflammatory pseudopolyps. In chronic stages, the loss of haustration and bowel shortening leads to the characteristic "lead-pipe" appearance. **Analysis of Incorrect Options:** * **Pseudomembranous Colitis:** Typically shows significant mucosal thickening and "thumbprinting" due to severe edema. On contrast studies, it may show the **"Accordion sign"** (trapped contrast between thickened haustral folds). * **Intussusception:** Characterized by the **"Coiled-spring appearance"** or "Cupola sign," where the barium outlines the intussusceptum within the intussuscipiens. * **Ischemic Colitis:** Classically presents with **"Thumbprinting"** (indentations on the barium column) caused by submucosal hemorrhage and edema, usually at the splenic flexure (Griffith’s point). **High-Yield Pearls for NEET-PG:** * **Lead-pipe Colon:** Feature of chronic Ulcerative Colitis (loss of haustra). * **String Sign of Kantor:** Seen in Crohn’s Disease (terminal ileal narrowing). * **Cobblestone Appearance:** Characteristic of Crohn’s Disease (deep longitudinal and transverse ulcers). * **Double-Duct Sign:** Seen in Periampullary Carcinoma/Carcinoma Head of Pancreas. * **Apple-core Lesion:** Classic for Colorectal Carcinoma.

Question 168: What is the initial imaging modality of choice for suspected pyonephrosis?

A. Ultrasound (USG) (Correct Answer)
B. Contrast-enhanced CT (CECT)
C. Intravenous pyelogram (IVP)
D. Magnetic Resonance Imaging (MRI)

Explanation: **Explanation:** **Pyonephrosis** is a surgical emergency characterized by the presence of infected, purulent material (pus) within an obstructed collecting system. Prompt diagnosis is critical to prevent urosepsis and permanent renal damage. **Why Ultrasound (USG) is the correct answer:** Ultrasound is the **initial imaging modality of choice** because it is rapid, non-invasive, bedside-compatible, and highly sensitive (up to 90%) for detecting both hydronephrosis and the presence of debris. The classic sonographic hallmark of pyonephrosis is the presence of **low-level internal echoes (layering debris)** within a dilated collecting system. It also allows for immediate therapeutic intervention via ultrasound-guided percutaneous nephrostomy (PCN). **Why other options are incorrect:** * **Contrast-enhanced CT (CECT):** While CT is more sensitive for identifying the *cause* of obstruction (e.g., stones) and assessing the renal parenchyma, it is generally considered the second-line or confirmatory investigation. The use of IV contrast may also be risky in patients with potential renal impairment due to obstruction. * **Intravenous Pyelogram (IVP):** This is largely obsolete in acute settings. In pyonephrosis, the affected kidney often shows "delayed or absent excretion," providing little diagnostic information regarding the nature of the fluid. * **MRI:** Though sensitive, MRI is time-consuming, expensive, and not practical for an emergency diagnosis. **High-Yield Clinical Pearls for NEET-PG:** * **Triad of Pyonephrosis:** Fever, flank pain, and hydronephrosis. * **Gold Standard for Diagnosis:** Aspiration of pus from the collecting system (usually during PCN). * **Key USG Finding:** Persistent low-level echoes in the dependent portion of the dilated calyces (fluid-debris level). * **Management:** Emergency drainage (PCN or retrograde stenting) is mandatory; antibiotics alone are insufficient.

Question 169: Which of the following is NOT a cause of pneumoperitoneum?

A. Subdiaphragmatic fat
B. Laparoscopy (Correct Answer)
C. Chilaiditi syndrome
D. Subphrenic abscess

Explanation: **Explanation:** This question requires distinguishing between **true pneumoperitoneum** (free air in the peritoneal cavity) and **pseudopneumoperitoneum** (mimics of free air on imaging). **Why the Correct Answer is Laparoscopy:** Actually, there is a technical nuance in the question provided. **Laparoscopy is a well-known cause of true pneumoperitoneum** because CO2 is intentionally insufflated into the cavity. However, in the context of "causes of pneumoperitoneum" in radiology exams, the question often asks to identify a **mimic** (pseudopneumoperitoneum) versus a **true presence of air**. If the question identifies Laparoscopy as the "NOT" cause, it is likely referring to the fact that it is an *expected* iatrogenic finding rather than a *pathological* rupture, or there is a clerical error in the provided key. *Note: In standard radiology, Options A, C, and D are classic mimics (Pseudopneumoperitoneum), whereas Laparoscopy is True Pneumoperitoneum.* **Analysis of Options:** * **Subdiaphragmatic fat (A):** A mimic. Low-density fat between the liver and diaphragm can appear radiolucent, simulating free air. * **Chilaiditi syndrome (C):** A mimic. This is the transposition of a loop of colon (usually hepatic flexure) between the liver and the diaphragm. Haustral markings help distinguish it from free air. * **Subphrenic abscess (D):** A mimic. Gas-forming organisms within an abscess collection under the diaphragm can simulate free air, but the air is contained within the abscess wall. **NEET-PG High-Yield Pearls:** 1. **Most common cause of pneumoperitoneum:** Perforation of a hollow viscus (Peptic ulcer is #1). 2. **Best View:** Erect Chest X-ray (can detect as little as 1–2 ml of air). 3. **Signs on X-ray:** Rigler’s sign (double wall sign), Football sign (large volume air), and Cupola sign (air under central tendon of diaphragm). 4. **Pseudopneumoperitoneum mimics:** Chilaiditi syndrome, subdiaphragmatic fat, basal atelectasis, and irregular diaphragm.

Question 170: What is the primary imaging technique used in a case of suspected acute pancreatitis?

A. MRI abdomen
B. CECT abdomen with pancreatic protocol (Correct Answer)
C. USG abdomen
D. MR enterography

Explanation: **Explanation:** **Contrast-Enhanced Computed Tomography (CECT) of the abdomen with pancreatic protocol** is the gold standard and primary imaging modality for evaluating suspected acute pancreatitis and its complications. The "pancreatic protocol" involves thin-section imaging during the late arterial (pancreatic) phase and portal venous phase. This allows for the precise assessment of pancreatic parenchymal enhancement to identify **necrosis** (non-enhancing areas), peripancreatic fluid collections, and vascular complications like pseudoaneurysms. **Analysis of Options:** * **MRI Abdomen:** While highly sensitive for detecting early pancreatitis and choledocholithiasis (via MRCP), it is not the primary choice due to higher costs, longer scan times, and limited availability in emergency settings. * **USG Abdomen:** This is usually the **initial** screening tool to look for gallstones (the most common etiology), but it is poor at visualizing the pancreas itself due to overlying bowel gas and cannot reliably quantify necrosis. * **MR Enterography:** This is specifically used for evaluating small bowel pathology, such as Crohn’s disease, and has no role in the acute management of pancreatitis. **High-Yield Clinical Pearls for NEET-PG:** * **Timing:** CECT is most accurate when performed **72–96 hours** after symptom onset. Imaging done too early (<48 hours) may underestimate the extent of pancreatic necrosis. * **Balthazar Score:** A CT-based grading system used to assess the severity of acute pancreatitis. * **CT Severity Index (CTSI):** Combines the Balthazar grade with the percentage of pancreatic necrosis to predict patient prognosis and mortality. * **Sentinel Loop Sign:** A dilated loop of proximal jejunum seen on X-ray, indicating localized ileus due to nearby inflammation.

Practice by Chapter

Imaging of Liver

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Biliary Tract Imaging

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Pancreatic Imaging

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Spleen and Lymphatic System

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Gastrointestinal Tract Imaging

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Renal and Urinary Tract Imaging

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Adrenal Imaging

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Female Pelvic Imaging

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Male Pelvic Imaging

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Abdominal Trauma Imaging

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Acute Abdomen Imaging

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Imaging of Peritoneal Cavity and Retroperitoneum

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