Free Practice Questions for ARDMS AB-Abdomen Exam

Malignant lymph nodes are often round in shape (short axis/long axis ratio approaches 1), while benign lymph nodes are typically oval (short axis/long axis ratio < 0.5). Rounded shape in post-thyroidectomy patients raises suspicion for metastatic disease.

According to AIUM and ACR Thyroid Imaging Guidelines:

“A rounded lymph node shape is suspicious for malignancy, especially in patients with thyroid cancer.”

Urinomas are collections of urine in the retroperitoneum that result from trauma, surgery, or obstruction causing urine leakage. Trauma is a frequent cause of urinoma formation due to disruption of the urinary tract.

According to Rumack’s Diagnostic Ultrasound:

“Urinomas may develop as a complication of trauma, surgery, or obstructive uropathy with urinary extravasation into the retroperitoneum.”

The ultrasound images show a heterogeneous, solid-appearing mass within the right kidney. The patient has a history of hypertension and hematuria—classic clinical features that raise suspicion for renal cell carcinoma (RCC), especially in an adult.

Renal cell carcinoma is the most common primary malignant tumor of the kidney in adults. Common presenting symptoms include:

Hematuria (most frequent symptom)

Flank pain

Palpable abdominal mass

Hypertension (due to increased renin secretion)

Sometimes paraneoplastic syndromes (e.g., polycythemia due to erythropoietin production)

Ultrasound Features of RCC:

Solid renal mass, often with heterogeneous echotexture

May contain cystic components, calcifications, or necrotic areas

May distort the renal contour

Doppler may show internal vascularity

Differentiation from other options:

B. Adenoma: Rare and typically small, benign cortical lesions. They do not typically present with hematuria or hypertension and cannot be reliably distinguished from RCC on ultrasound.

C. Nephroblastoma (Wilms tumor): Pediatric renal tumor seen almost exclusively in children under age 5.

D. Pheochromocytoma: Arises from the adrenal gland (not the kidney); associated with hypertension but not hematuria.

An intimal flap in the aorta is a hallmark ultrasound finding of aortic dissection, which can present with tearing chest/abdominal pain and differential blood pressures between arms. The flap represents separation of the intimal and medial layers of the aortic wall.

According to Rumack’s Diagnostic Ultrasound:

“An intimal flap visualized within the aorta is diagnostic of an aortic dissection.”

The image demonstrates a gallbladder with a possible echogenic focus (likely a gallstone) and posterior acoustic shadowing. This is suggestive of cholelithiasis. To differentiate uncomplicated gallstones from acute cholecystitis, the most effective technique is to assess for a positive sonographic Murphy sign.

A positive sonographic Murphy sign refers to the presence of focal tenderness over the gallbladder when it is directly palpated with the ultrasound transducer. It is a strong indicator of acute cholecystitis when combined with other features such as gallbladder wall thickening, pericholecystic fluid, and gallstones.

Sonographic Murphy sign — key points:

Assessed during real-time scanning

Localized tenderness when pressure is applied over the gallbladder

Highly sensitive for acute cholecystitis (especially in the presence of stones)

Differentiation from other options:

A. Use compound imaging: Improves image quality by reducing artifacts but does not verify tenderness or confirm acute inflammation.

B. Change the patient’s position: Helpful to confirm mobility of gallstones, but not diagnostic of inflammation.

C. Ask patient to perform Valsalva: Used primarily in vascular studies (e.g., assessing for varicocele or venous reflux), not relevant here.

Branchial cleft cysts are congenital epithelial cysts that typically occur laterally in the neck, often anterior to the sternocleidomastoid muscle, and lateral to the thyroid gland. The second branchial cleft cyst is the most common type and is found in the lateral neck region.

Medial (B) would be more consistent with thyroglossal duct cysts.

Anterior (C) or posterior (D) do not specifically describe branchial cyst location relative to the thyroid.

Reference Extracts:

Som PM, Curtin HD. Head and Neck Imaging. 5th ed. Elsevier, 2011.

Rumack CM, Wilson SR, Charboneau JW, Levine D. Diagnostic Ultrasound. 5th ed. Elsevier, 2017.

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The ultrasound image clearly demonstrates a thickened and elongated pyloric muscle with a visible channel, which is characteristic of hypertrophic pyloric stenosis (HPS). This condition is most commonly seen in male infants between 2 and 8 weeks of age who present with non-bilious projectile vomiting, dehydration, and a palpable “olive-like” mass in the right upper quadrant.

Ultrasound is the imaging modality of choice and is highly sensitive and specific for diagnosing pyloric stenosis.

Key sonographic criteria for HPS:

Muscle thickness >3 mm

Pyloric channel length >15–17 mm

“Target sign” or “doughnut sign” on transverse imaging (concentric rings)

“Cervix” or “railroad track sign” on longitudinal imaging (elongated canal with echogenic center)

Differentiation from other options:

A. Intussusception: Also shows a target sign, but it occurs in the right lower quadrant or periumbilical region, not in the gastric antrum.

C. Hydronephrosis: Refers to dilation of the renal pelvis and calyces — not gastrointestinal.

D. Gastritis: May show gastric wall thickening but lacks the distinct elongated, thickened pyloric muscle seen here.

The renal arteries originate from the abdominal aorta just inferior to the superior mesenteric artery (SMA). The SMA arises anteriorly from the abdominal aorta at the level of L1, and just below it, the renal arteries branch laterally. The splenic vein, portal vein, and hepatic artery are located more superiorly in relation to the renal arteries.

According to Moore's Clinically Oriented Anatomy:

"The superior mesenteric artery arises from the anterior surface of the abdominal aorta just above the renal arteries." (Moore KL et al., Clinically Oriented Anatomy, 8th ed.)

The ultrasound image demonstrates a classic example of ascites, shown by the anechoic (dark) fluid located between bowel loops or surrounding abdominal organs. In this case, there appears to be a small fluid collection in the peritoneal cavity.

One of the key maneuvers used to differentiate free fluid (such as ascites) from loculated fluid or other structures is to reposition the patient. Asking the patient to “turn from side to side” (Option D) can help in assessing whether the fluid shifts position — a hallmark feature of free intraperitoneal fluid. This positional change is highly useful in confirming the diagnosis and distinguishing ascites from other potential mimics (e.g., cystic masses, lymphoceles, or bowel wall thickening).

In contrast:

Drinking water (A) is often used in imaging the urinary bladder or gastrointestinal tract but not for fluid characterization.

Standing upright (B) may shift fluid but is less practical during real-time ultrasound.

Breathing quietly (C) doesn’t significantly aid in visualizing peritoneal fluid mobility.