Abdominal Ultrasound in the Clinic: A Systematic Survey

Abdominal scanning is often the first application a GP clinic adds after early pregnancy. The probe and preset, how to prepare the patient, a survey that covers every organ in the same order each time, the findings clinics see most, and when to refer.

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Also called Abdominal ultrasound, Abdomen scan, Ultrasound abdomen

Published: 17 October 2026

Last updated: 16 October 2026

Probe and settings

Convex probe

The standard abdominal probe: curved, low frequency for depth, with a wide field of view that still fits under the ribs.

Probe types and frequencies

Abdomen preset

Loads depth, gain, harmonics and the abdominal measurement package. Set the depth so you can see just behind the organ you are studying.

Phased-array probe

Its small face fits between the ribs for the liver and spleen when the window under the ribs is poor.

Linear probe

For the abdominal wall, hernias and lumps, and for bowel and the appendix in children and thin adults.

Colour Doppler

Shows flow in the liver vessels, kidneys and aorta, and tells a dilated bile duct (no flow) from the vessel beside it.

Colour Doppler explained

Preparing the patient

Fasting for 6–8 hours before an upper abdominal scan, so the gallbladder is full and there is less bowel gas. Sips of water are usually allowed.
A morning appointment makes fasting easier. Patients with diabetes need advice on fasting and the timing of their medicines.
Most medicines are taken as usual with a little water — follow the referring doctor’s instructions.
Chewing gum and smoking before the scan add swallowed air, so ask patients to avoid them.
For the bladder and pelvis, a comfortably full bladder, usually by drinking water beforehand and not passing urine.
In an emergency, scan without preparation and note in the report that the patient had not fasted.

A systematic survey

Scan in the same order every time, so nothing is skipped when one finding catches your eye.

Liver: size, outline and texture in longitudinal and transverse, the hepatic and portal veins, and the liver’s brightness compared with the right kidney.
Gallbladder: in two planes, then with the patient turned onto the left side to see whether stones move; wall thickness and tenderness under the probe.
Bile ducts: the common bile duct where it crosses the portal vein, using colour Doppler to tell duct from vessel.
Pancreas: in transverse, with the splenic vein as a landmark. Bowel gas often hides part of it; scanning upright or after a drink of water can help.
Spleen: its length from the left side, with the patient breathing in or turned onto the right side.
Kidneys: length, cortex and the collecting system, looking for hydronephrosis, stones and cysts.
Aorta: from the diaphragm to where it divides, measured outer wall to outer wall in transverse.
Bladder: wall and contents and, if needed, the volume before and after the patient passes urine.
Finish with a look for free fluid around the liver, in the flanks and in the pelvis.

Findings clinics see most

Finding	What it looks like	Usual next step
Gallstones	Bright foci in the gallbladder with a clean shadow behind, moving when the patient turns	Surgical referral if symptomatic; urgent if there is fever, tenderness under the probe or a thick wall
Fatty liver	Liver brighter than the right kidney’s cortex, with the deeper liver harder to see	Assess metabolic risk and liver tests; elastography or referral to assess scarring
Simple kidney cyst	Round, black and thin-walled, with enhancement behind it	Usually no follow-up if truly simple; refer if it has thick walls, septa or solid parts
Hydronephrosis	A dilated, fluid-filled collecting system in the kidney	Look for the cause — stone, bladder outlet, pregnancy; urgent if infected or on both sides
Kidney stones	Bright foci with a shadow, often with colour twinkling	Manage by size and symptoms; refer if there is obstruction or infection
Enlarged aorta	Diameter of 3 cm or more: an abdominal aortic aneurysm	Refer to vascular surgery — urgently if large, tender or the patient is unwell
Free fluid	Black fluid around the liver, in the flanks or in the pelvis	Find the cause — liver disease, dengue plasma leakage, gynaecological causes, trauma

When to refer

Refer for formal imaging or specialist review when there is:

A solid or complex lesion in the liver, kidney, pancreas or spleen — anything that is not a simple cyst.
Dilated bile ducts or jaundice. A common bile duct of about 6 mm is often taken as the adult upper limit, with larger ducts accepted with age and after gallbladder removal — use your own reference range.
A thick-walled, tender gallbladder with fever, or a stone stuck in the gallbladder neck.
An aorta of 3 cm or more, or an aorta you could not see fully in a patient at risk.
Hydronephrosis with fever, in a single kidney, or on both sides.
A scan you could not complete. Write down what limited it — gas, body build, pain — so the next scan is planned differently.

What to look for in a machine

A convex probe that still sees clearly in larger patients — test it on your heaviest patients, not a slim volunteer.
Harmonics and compounding you can switch quickly, so the shadow behind a small stone is not smoothed away.
Colour Doppler sensitive enough for kidney and liver vessels.
An abdominal measurement package and report template: organ lengths, aorta diameter, bladder volume.
Elastography if you plan a fatty-liver service, and a linear probe for the abdominal wall and children.
Clip storage and DICOM export, so images travel with the referral.

Ultrasound Machine supply near you

Written quotes for clinics across Malaysia, handled from Batu Caves, Kota Kinabalu and Kuching.

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Frequently asked questions

Do I need to fast before an abdominal ultrasound?

For an upper abdominal scan, usually for 6–8 hours, so the gallbladder is full and there is less bowel gas. Sips of water are usually allowed. Follow the instructions given when the scan is booked.

Which probe is used for abdominal ultrasound?

A curved (convex) low-frequency probe. A phased-array probe helps between the ribs, and a linear probe for the abdominal wall, hernias, children and thin adults.

Can abdominal ultrasound see the pancreas?

Often only partly, because bowel gas lies in front of it. A fasted patient, an upright position or a drink of water can help; CT or MRI is used when the whole pancreas must be seen.

What size of aorta is an aneurysm on ultrasound?

An abdominal aortic diameter of 3 cm or more, measured outer wall to outer wall, is the usual definition of an abdominal aortic aneurysm.

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