Pass AB-Abdomen Exam Guide

The normal hepatic vein Doppler waveform is triphasic, reflecting cardiac cycle variations in central venous pressure transmitted from the right atrium through the IVC. Loss of triphasicity may suggest elevated right atrial pressures or hepatic venous obstruction.

According to Rumack’s Diagnostic Ultrasound:

“The normal hepatic vein waveform is triphasic due to transmitted right atrial pressure variations.”

The technique shown in the video is compression. In ultrasound imaging—especially of soft tissue masses, the bowel, or venous structures—compression is used to evaluate the compressibility of structures. The image demonstrates a classic grayscale ultrasound view of a lesion or structure being compressed with the probe.

Compression sonography is particularly important in:

Evaluating venous patency (e.g., for deep vein thrombosis)

Differentiating cystic from solid structures

Evaluating bowel wall abnormalities or intussusception

Assessing lymph nodes and soft tissue masses (as shown here)

When a structure compresses easily under probe pressure, it suggests that the lesion is fluid-filled or soft. In contrast, incompressibility may indicate a solid mass or thrombus.

Differentiation from other options:

B. Valsalva: Involves forced expiration against a closed airway, used primarily to assess venous reflux or inguinal hernias—not what is demonstrated here.

C. Exhalation: A respiratory maneuver that passively alters thoracoabdominal pressure, not actively performed by the operator or causing focal structural change.

D. Deep inspiration: Used to improve visualization of the liver, diaphragm, or gallbladder—not to evaluate the compressibility of soft tissue.

Addison disease (primary adrenal insufficiency) results in insufficient production of cortisol and aldosterone. The hallmark laboratory findings include:

Hyponatremia (low sodium)

Hyperkalemia (high potassium)

Elevated liver enzymes (due to nonspecific hepatic involvement)

Fatigue, weight loss, and hypotension are common clinical features.

Conn syndrome (B) causes hyperaldosteronism, leading to hypokalemia (not hyperkalemia).

Acute pancreatitis (C) would typically show elevated amylase/lipase.

Hepatocellular carcinoma (D) may present with elevated liver enzymes but not the electrolyte pattern described.

Reference Extracts:

Nieman LK. "Diagnosis and Treatment of Primary Adrenal Insufficiency." J Clin Endocrinol Metab. 2011;96(7):1957-1966.

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

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Salivary glands are superficial structures, and high-frequency transducers (10–15 MHz) are optimal to obtain high spatial resolution. Lower frequencies are inappropriate as they lack sufficient resolution for superficial structures. A 12 MHz transducer provides excellent detail necessary for detecting small lesions, duct abnormalities, and vascular structures.

According to Rumack et al., Diagnostic Ultrasound:

"High-frequency linear transducers (10–15 MHz) are recommended for evaluating superficial structures such as salivary glands." (Rumack CM et al., Diagnostic Ultrasound, 5th ed.).