The liver is the most commonly evaluated organ in abdominal ultrasound. Whether you're performing a right upper quadrant study, a full abdominal scan, or a specific hepatic evaluation, knowing what's normal and what's not — and how to describe it — is fundamental.

Normal Liver Assessment

Size: Measured in the midclavicular line (MCL) in sagittal as the craniocaudal span.

Normal: ≤ 15 cm (some references use ≤ 16 cm MCL)
15–17 cm depending on body habitus: hepatomegaly

Normal echogenicity: Isoechoic or slightly hyperechoic compared to the right renal cortex. Slightly hyperechoic compared to the spleen is normal.

Texture: Homogeneous, smooth.

Margins: Smooth, sharp capsule. The hepatic dome should show a smooth superior surface.

Vasculature: Hepatic veins and portal veins visible. Portal veins have echogenic walls (visible as bright lines surrounding the anechoic lumen). Hepatic veins have thin walls and converge toward the IVC at the hepatic confluence.

Fatty Liver (Hepatic Steatosis)

The most common diffuse liver disease in ultrasound practice. Prevalence is increasing with obesity and metabolic syndrome.

Grading by echogenicity:

Grade	Appearance	Vascular Visibility
Mild	Slightly hyperechoic vs kidney	Portal vein walls still visible
Moderate	Moderately hyperechoic, similar to spleen	Portal vein walls barely visible
Severe	Markedly hyperechoic, brighter than spleen	Portal vein walls not visible; poor posterior penetration

Practical grading:

Compare liver to the right kidney: liver should be equal to or slightly brighter than the kidney cortex
In fatty liver, the liver becomes increasingly bright relative to the kidney
Severe steatosis: markedly echogenic liver, poor penetration to the posterior liver, diaphragm may be difficult to see

What to document: "Diffuse increased liver echogenicity consistent with hepatic steatosis, mild/moderate/severe grade. Decreased visualization of portal vein walls and posterior hepatic parenchyma."

Focal fat sparing: Areas that appear hypoechoic against the background of a fatty liver. Classic locations: adjacent to the gallbladder fossa, periportal. They are geographic, non-mass-forming — no mass effect, no distortion of vessels.

Focal fat deposition: The opposite — echogenic foci in a normal liver. No mass effect, no vascular distortion.

Cirrhosis

End-stage chronic liver disease characterized by fibrosis and nodular regeneration.

Sonographic findings:

Coarse, heterogeneous echogenicity (fibrosis disrupts the normal texture)
Nodular liver surface (the "lumpy" contour of regenerative nodules)
Increased echogenicity overall
Atrophy of the right lobe and hypertrophy of the caudate lobe (Couinaud segment I) — caudate-to-right lobe ratio > 0.65 is suggestive
Small liver (late stage) — shrunken, heterogeneous

Portal hypertension signs:

Enlarged portal vein (> 13 mm in the porta hepatis)
Reversed portal venous flow (hepatofugal) — a critical finding indicating severe portal hypertension
Splenomegaly (> 12 cm in the long axis)
Ascites (free fluid in the peritoneal cavity)
Collateral vessels: umbilical vein recanalization (a worm-like vascular structure in the hepatoduodenal ligament, patent flow on Doppler), gastric varices, caput medusae

Ascites: Free anechoic fluid surrounding the liver, in the hepatorenal space (Morison's pouch), and in the pelvis. Complex ascites (internal echoes, septations) may indicate infection (SBP) or hemorrhage.

Focal Liver Lesions

Focal lesions are common incidental findings. Your role: describe the lesion, not diagnose it.

Simple Liver Cyst

Anechoic, thin walls, posterior acoustic enhancement, round
No internal echoes, no vascularity on Doppler
Benign, no follow-up needed
Polycystic liver disease: Multiple cysts replacing liver parenchyma, often with associated polycystic kidneys

Hemangioma

Most common benign liver tumor
Classic appearance: well-defined, hyperechoic (brighter than surrounding liver), homogeneous
"Flame sign" on power Doppler sometimes seen peripherally
Posterior acoustic enhancement behind larger hemangiomas
In fatty liver, hemangiomas may appear isoechoic or relatively hypoechoic (contrast reversal)

Hepatocellular Carcinoma (HCC)

In a cirrhotic liver, any new focal lesion requires evaluation for HCC
Appearance varies: hypoechoic, isoechoic, hyperechoic (smaller tumors), or heterogeneous (larger)
"Mosaic" pattern: heterogeneous appearance with internal septa
Halo sign: thin hypoechoic rim around the lesion
Vascular invasion: tumor thrombus in portal vein branches is characteristic
AFP elevation + imaging = high suspicion

Metastases

Most common malignant focal liver lesion (liver is a common metastatic site)
Variable appearance: "target" lesion (hypoechoic center, hyperechoic rim), bull's-eye, echogenic, cystic, or calcified
Multiple lesions throughout the parenchyma
Common primaries: colon, breast, lung, pancreas, neuroendocrine

Abscess

Bacterial: heterogeneous, complex, often contains echogenic debris or gas
Amoebic: typically anechoic or mildly complex, smooth borders
Clinical context (fever, pain, recent travel) is important

Hepatic Vasculature

Portal vein Doppler:

Normal: hepatopetal (toward the liver), phasic (respiratory variation)
Enlarged: > 13 mm = portal hypertension concern
Hepatofugal (away from liver): severe portal hypertension — critical finding
Thrombosis: echogenic material in the lumen, absent or markedly reduced flow

Hepatic veins Doppler:

Normal: triphasic pulsatile waveform (reflects right atrial pressure)
Damped (monophasic): hepatic venous outflow obstruction, right heart failure, hepatic congestion
Budd-Chiari syndrome: hepatic vein occlusion — absent hepatic venous flow + caudate lobe hypertrophy

Hepatic artery:

Normal RI: 0.55–0.75
Low RI or absent diastolic flow in transplant: hepatic artery thrombosis (emergency in post-transplant)

Liver Transplant Evaluation

Standard protocol: Hepatic artery PSV, RI (< 0.50 is abnormal in early post-transplant), portal vein flow direction and velocity, hepatic vein waveforms, IVC, hepatic parenchymal echogenicity, bile ducts (biloma?), perihepatic collections.

Critical findings post-transplant:

Hepatic artery thrombosis (absent Doppler signal in hepatic artery) — surgical emergency
Portal vein thrombosis — urgent
Biliary complications (biloma, stricture): dilated ducts, perihepatic fluid

Documentation Tips

For diffuse disease: describe echogenicity relative to the right kidney, note texture, vascular visibility, surface, and size.

For focal lesions: location (by Couinaud segment if possible), size (three dimensions), echogenicity, margins, internal characteristics (cystic, solid, heterogeneous), posterior features, Doppler vascularity, and relationship to adjacent vessels.

Segment reference (simplified):

Right lobe: segments V, VI, VII, VIII
Left lobe: segments II, III, IV
Caudate: segment I

SonoBuddy's Measurements section includes liver size reference values and hepatic Doppler normal values — use them for quick bedside reference.

Liver Pathology by Ultrasound: Fatty Liver, Cirrhosis, Masses, and More