How to Perform a Complete Abdominal Ultrasound: Protocol and Image Checklist
A step-by-step complete abdominal ultrasound protocol for sonographers — organ-by-organ scanning technique, key images for PACS, and a full report checklist to ensure you never miss a finding.
A complete abdominal ultrasound is the bread-and-butter exam of general sonography — and the one where a systematic approach pays off most. Done right, it's efficient and comprehensive. Done without a protocol, you'll find yourself scrambling to re-image organs you forgot to document.
This guide gives you a complete abdominal ultrasound protocol — organ by organ, image by image, with practical technique tips for the tricky parts.
Before You Start
Patient Preparation
- Fasting: Ideally 4–6 hours for gallbladder visualization. For urgent cases, scan what you can.
- Position: Start supine. You'll use left lateral decubitus (LLD) for gallbladder and right lateral decubitus (RLD) for spleen and left kidney.
- Probe: Curved array (2–5 MHz) for most adult patients. Higher frequency for thin patients or pediatrics.
Quick History Check
Before scanning, confirm:
- Indication (RUQ pain, elevated LFTs, jaundice, etc.)
- History of prior surgeries (cholecystectomy, splenectomy, transplant)
- Current medications that affect the gallbladder (TPN, opioids)
- Relevant lab values (bilirubin, creatinine, LFTs)
Scanning Protocol: Organ by Organ
1. Liver
Position: Supine, subcostal and intercostal approach
Key images:
- Right lobe — longitudinal (with hepatic veins, IVC)
- Right lobe — transverse (at portal vein bifurcation)
- Left lobe — transverse and longitudinal
- Caudate lobe — if abnormality suspected
- Hepatic veins — all three (RHV, MHV, LHV) converging at IVC
- Portal vein — longitudinal, with diameter measurement (normal ≤ 13 mm)
- Hepatic artery — pulsatile flow at porta hepatis
What to assess:
- Echogenicity (compare to right kidney cortex)
- Homogeneity of parenchyma
- Surface contour (smooth vs. nodular — cirrhosis)
- Focal lesions (cysts, masses, hemangiomas)
- Vascular patency (portal vein, hepatic veins)
- Biliary dilation (intrahepatic ducts > 3 mm = abnormal)
Normal liver:
- Mildly hyperechoic to right kidney cortex
- Homogeneous texture
- Smooth surface
- Span (midclavicular line): ≤ 15 cm
2. Gallbladder
Position: Supine → LLD to demonstrate mobility of stones
Key images:
- Longitudinal with length measurement
- Transverse with width (AP) measurement
- Wall thickness at the anterior wall (normal ≤ 3 mm fasting)
- CBD at the hepatic hilum with diameter measurement
- Any stones or sludge — document shadow and mobility
- Color Doppler (for cholecystitis workup)
Sonographic Murphy's sign: Apply probe pressure directly over the GB — document positive, negative, or equivocal.
Normal GB:
- Anechoic lumen
- Thin wall (≤ 3 mm)
- No intraluminal stones or sludge
- No pericholecystic fluid
3. Common Bile Duct (CBD)
Position: Supine or slight LLD
- Measure AP diameter at hepatic hilum or just below — avoid including the hepatic artery
- Normal: ≤ 6 mm (< 60 years), ≤ 8 mm (≥ 60 years), ≤ 10 mm (post-cholecystectomy)
- Trace distally toward the pancreatic head if dilated
- Color Doppler to differentiate CBD from adjacent portal vein
4. Pancreas
Position: Supine; have patient drink water to create acoustic window if needed
Key images:
- Head (near C-loop of duodenum)
- Body (anterior to SMV and SMA)
- Tail (toward splenic hilum — often most difficult to see)
- Pancreatic duct measurement if dilated (normal: ≤ 3 mm)
What to assess:
- Echogenicity (isoechoic to liver normally; increases with age/fat deposition)
- Ductal dilation (> 3 mm = dilated; > 5 mm = significantly abnormal)
- Focal masses or calcifications
Technique tips:
- The SMA is your landmark — the pancreatic body sits directly anterior to it
- Water in the stomach improves visualization of the body and tail
- Respiratory maneuvers (deep breath holds) push the pancreas into view
5. Spleen
Position: Right lateral decubitus (RLD) or right posterior oblique
Key images:
- Longitudinal with length measurement
- Transverse with width/depth measurements
- Splenic hilum — vessels and echogenicity
- Color Doppler at hilum (optional unless pathology suspected)
Normal spleen:
- Length ≤ 12 cm (adult; some use 13 cm for men)
- Homogeneous, isoechoic to slightly hyperechoic to liver
- Smooth capsule
Splenomegaly thresholds:
| Degree | Length |
|---|---|
| Mild | 12 – 15 cm |
| Moderate | 15 – 20 cm |
| Severe | > 20 cm |
6. Right Kidney
Position: LLD or supine with right flank approach
Key images:
- Longitudinal with length measurement
- Transverse with AP and width measurements
- Cortical echogenicity compared to liver
- Any hydronephrosis, stones, or masses
- Doppler RI (interlobar or arcuate arteries)
Normal kidney:
- Length 9–12 cm
- Cortex ≥ 10 mm, hypoechoic to liver
- No hydronephrosis
- RI 0.58–0.70
7. Left Kidney
Position: RLD or right posterior oblique; coronal approach through the flank
Key images: Same as right kidney
- Compare cortical echogenicity to spleen (not liver)
- Left kidney often slightly longer than right
8. Aorta and IVC
Position: Supine, midline
Key images:
- Aorta — longitudinal (proximal, mid, distal)
- Aorta — transverse with AP diameter measurement at widest point (outer-to-outer)
- IVC — longitudinal showing collapsibility with respiration
- Color Doppler aorta
Normal aorta: ≤ 3.0 cm (AP diameter) Normal IVC: Collapses with sniff/inspiration (indicates normal RA pressure)
Report Checklist
When writing your worksheet, ensure you document:
- Liver size and echogenicity
- Focal liver lesions (describe or "none identified")
- Portal vein diameter and flow direction (hepatopetal = normal)
- Biliary system — CBD diameter, intrahepatic ducts
- Gallbladder — wall thickness, contents, Murphy's sign
- Pancreas — head/body/tail visualization, echogenicity, ductal size
- Spleen — length, echogenicity
- Right kidney — length, echogenicity, hydronephrosis
- Left kidney — length, echogenicity, hydronephrosis
- Aorta — diameter at widest point
- Free fluid (ascites) — present or absent
- Any incidental findings requiring follow-up
Common Pitfalls to Avoid
| Pitfall | Solution |
|---|---|
| GB wall artificially thick | Confirm fasting status; rescan in LLD |
| Pancreatic tail not visualized | Note limitations; try water technique |
| Left kidney obscured by bowel | Prone or posterior approach |
| Aorta shadowed by bowel gas | Graded compression, lateral decubitus |
| IVC vs. aorta confusion | IVC is right-sided, lacks pulsation, collapses with sniff |
Access the Full Protocol in SonoBuddy
SonoBuddy's Complete Abdominal Protocol includes step-by-step technique, probe selection, key images list, and a full report checklist — organized exactly the way you'd scan.
Open SonoBuddy → Protocols → Complete Abdominal.
References: AIUM Practice Parameters for Abdominal Ultrasound. ACR–AIUM–SPR Practice Parameter for performance of abdominal ultrasound. SonoBuddy protocol team review.
SonoBuddy is a reference tool, not a diagnostic authority. Clinical decisions must involve the ordering provider and interpreting physician.
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