RDMS Abdomen key terms

The liver is divided into eight functional segments, each with its own portal venous, hepatic arterial, and biliary branches. These segments guide surgical planning and help localize focal liver lesions.

The portal vein, proper hepatic artery, and common bile duct travel together in the hepatoduodenal ligament. This bundle supplies and drains the liver and is a key landmark in abdominal ultrasound.

The hepatorenal recess, a potential space between the liver and right kidney. It is the most dependent part of the peritoneal cavity when a patient is supine, so free fluid often collects there.

The omental bursa, a peritoneal space behind the stomach and anterior to the pancreas. It communicates with the greater sac through the epiploic foramen and can collect fluid in pancreatitis.

The main duct of Wirsung drains pancreatic secretions from tail to head and joins the common bile duct at the ampulla of Vater. It is visualized within the pancreatic parenchyma.

The space behind the peritoneal cavity containing the kidneys, pancreas, aorta, inferior vena cava, and parts of the bowel. Organs there are less mobile and often show different artifact patterns.

A Doppler measure calculated as peak systolic velocity minus end-diastolic velocity, divided by peak systolic velocity. It reflects downstream resistance; normal renal values are roughly 0.6 to 0.7.

A Doppler index calculated as peak systolic velocity minus end-diastolic velocity divided by mean velocity. It describes waveform pulsatility and is used to assess organ perfusion and vascular resistance.

A dampened arterial waveform with a slow systolic upstroke and low-peak velocity. It occurs downstream of a severe stenosis and is often seen in the renal artery beyond a narrow segment.

A display of blood flow velocities over time as a waveform. It allows measurement of peak systolic and end-diastolic velocities and calculation of resistive and pulsatility indices.

A Doppler mode that displays the amplitude of moving blood rather than velocity and direction. It is more sensitive to slow flow but does not show flow direction or aliasing.

Dilatation of the renal collecting system caused by obstructed urine flow or reflux. Ultrasound shows fluid-filled branching structures within the kidney; severity ranges from mild pelvic fullness to marked cortical thinning.

The presence of gallstones in the gallbladder. Stones appear as echogenic foci with posterior acoustic shadowing and may move with patient repositioning.

Inflammation of the gallbladder, usually from cystic duct obstruction by a stone. Signs include wall thickening, pericholecystic fluid, and a sonographic Murphy sign.

Excess fat accumulation in liver cells, producing a diffusely echogenic liver that can obscure deep structures. It may be reversible and is often linked to obesity or metabolic disease.

Chronic liver injury with fibrosis and regenerative nodules that distort architecture. Ultrasound may show a nodular surface, coarse echotexture, enlarged caudate lobe, and signs of portal hypertension.

Increased pressure in the portal venous system, often from cirrhosis. Ultrasound signs include splenomegaly, ascites, a dilated portal vein, and portosystemic collaterals such as varices.

A focal enlargement of the abdominal aorta, commonly defined as diameter of 3 cm or more. Ultrasound measures the outer-to-outer wall diameter and monitors growth to guide repair decisions.

A tear in the aortic intima allows blood to enter the media, creating a true and false lumen. Ultrasound may show an intimal flap; CT angiography is often used for full evaluation.

Narrowing of one or both renal arteries, usually from atherosclerosis or fibromuscular dysplasia. Doppler findings include elevated peak systolic velocity at the stenosis and tardus-parvus flow downstream.

A blood clot within the portal vein that can obstruct liver blood flow. Ultrasound shows echogenic material in the vein and absent or reduced flow; chronic thrombosis may cause cavernous transformation.

Obstruction of hepatic venous outflow, often by thrombosis of the hepatic veins or inferior vena cava. It leads to liver congestion, ascites, and portal hypertension.

A contained rupture of an artery in which blood leaks into surrounding tissue and forms a sac lined by fibrous tissue. Doppler shows a yin-yang sign and a neck with to-and-fro flow.

Focused Assessment with Sonography for Trauma, a rapid bedside scan of the pericardium and dependent abdominal spaces for free fluid after injury. It guides urgent triage but does not identify specific organ injury.

Blood collected between an organ's capsule and its parenchyma, often after blunt trauma. On ultrasound it appears as a crescent-shaped fluid collection compressing the organ surface.

Ongoing bleeding seen as a jet or pooling of blood on contrast-enhanced imaging. On ultrasound, color Doppler may show flow outside a vessel lumen at an injury site.

A tear in the spleen from trauma that can cause subcapsular or perisplenic blood. Ultrasound may show heterogeneous parenchyma and free fluid, but CT is more sensitive.

A kidney surgically placed in the iliac fossa, usually with anastomoses to iliac vessels and a ureter connected to the bladder. Ultrasound monitors graft size, vascularity, and collections.

A fluid collection containing lymph that can form after surgery or transplant, often near iliac vessels. It appears as an anechoic, thin-walled collection and may compress nearby structures.

A collection of urine outside the urinary tract caused by a leak, often after trauma or transplant surgery. Ultrasound shows an anechoic fluid collection that may require drainage or stent placement.

A catheter placed through the skin into the kidney to drain urine, usually to relieve obstruction. Ultrasound guides placement and checks tube position and residual hydronephrosis.

The resistance of a medium to sound transmission, determined by tissue density and stiffness. Differences in impedance at tissue boundaries create the echoes that form ultrasound images.

Increased brightness behind a fluid-filled structure because sound is attenuated less there than in surrounding tissue. It is a common artifact behind cysts and the gallbladder.

Reduced echo brightness behind a structure that strongly reflects or absorbs sound, such as bone or a gallstone. Clean shadowing is typical of stones; dirty shadowing occurs behind gas.

Multiple equally spaced echoes caused by sound bouncing between two strong reflectors. It appears as parallel lines and can mimic pathology near the abdominal wall or within fluid.

Wrapping of the Doppler waveform when blood velocity exceeds the Nyquist limit, showing flow on the opposite side of the baseline. Adjusting scale, baseline, or angle can correct it.

As Low As Reasonably Achievable, the principle of minimizing ultrasound exposure while obtaining diagnostic information. It guides adjustment of power, dwell time, and output, especially in sensitive populations.

The process of explaining an ultrasound exam's purpose, risks, benefits, and alternatives so the patient can voluntarily agree. It respects autonomy and is documented before invasive or contrast procedures.

A brief pause before a procedure to confirm patient identity, correct site, procedure plan, and team roles. It is a safety practice that reduces wrong-site errors and improves communication.

The prompt, documented notification of a referring clinician when an ultrasound reveals a potentially life-threatening finding. It ensures timely care and is part of professional and legal responsibility.