General Health · Gallbladder

Gallstones on Ultrasound — Appearance, Symptoms and When to Scan

Ultrasound is the method of choice for finding gallstones. Here is what they actually look like on screen, what your report’s terms mean, whether stones can be missed — and the symptoms that should prompt a scan.

Gallstones are hardened deposits of digestive fluid that form in the gallbladder — the small, pear-shaped organ under the liver that stores bile and squeezes it out to digest fat. Many cause no symptoms at all; others announce themselves with the unmistakable pain of biliary colic after a fatty meal. Either way, when gallstones are the question, abdominal ultrasound is the answer’s first test: no radiation, around 30 minutes, and the standard diagnostic used across the NHS and private care alike — the examination itself is our abdominal ultrasound scan.

On The Screen

What do gallstones look like on ultrasound?

Gallstones on ultrasound (cholelithiasis): bright echogenic stones in the gallbladder casting dark posterior acoustic shadows

On screen, gallstones are distinctive: bright (echogenic) curved structures inside the gallbladder that cast a dark “acoustic shadow” behind them — the stone reflects almost all the sound, so nothing returns from beyond it. Stones typically move when you change position on the couch, which is one of the checks your sonographer performs. The radiological term for gallstones is cholelithiasis, and that is the word you will usually see in a report.

Ultrasound sees more than the stones themselves. Biliary sludge appears as low-level echoes layering in the gallbladder without a shadow — thickened bile that can cause identical symptoms and precede stones. An inflamed gallbladder (cholecystitis) shows a thickened wall, sometimes fluid around it, and focal tenderness exactly where the probe presses — the sonographic Murphy’s sign. And the scan measures the bile ducts: a dilated duct raises the question of a stone that has escaped the gallbladder and is blocking the drainage system.

Your Report

Reading a gallbladder ultrasound report

The phrases that appear most often, translated: “cholelithiasis” — gallstones are present (the report will usually note the largest stone’s size and whether there are single or multiple stones). “Biliary sludge” — thickened bile, managed on symptoms. “Gallbladder wall thickening” — possible inflammation, read together with your symptoms and the Murphy’s sign. “CBD not dilated” — the common bile duct measures normal, reassuring against an escaped stone. “Gallbladder contracted” — often simply means you weren’t fasted, which is why preparation matters.

Our reports translate these findings in plain English at the scan itself, and the wider vocabulary is covered in our guide to understanding your abdominal ultrasound report.

Honest Limits

Can gallstones be missed on ultrasound?

Occasionally, yes — and an honest page says so. Ultrasound is highly accurate for stones inside the gallbladder, but very small stones and sludge can sometimes escape notice, and stones that have moved into the bile ducts are genuinely harder to see because overlying bowel gas obscures the lower duct. A gallbladder that is contracted (not fasted) also hides its contents — one more reason the four-hour fast matters.

If your scan is normal but typical biliary pain continues, that result is still useful evidence — and the next step belongs with your GP: a repeat fasted scan, blood tests, or specialised imaging of the ducts (MRCP or endoscopic ultrasound, arranged through a specialist) all build on the report you already hold.

Symptoms

Gallstone symptoms — when a scan is worth booking

The hallmark is biliary colic: a steady, intense pain in the upper right abdomen or centre-top of the tummy, classically an hour or so after a fatty meal, often radiating to the back or right shoulder blade, lasting from thirty minutes to several hours, sometimes with nausea. Between attacks you may feel completely well. Less specific patterns — recurring indigestion, bloating after eating, intolerance of fatty food — overlap with other causes, which is exactly what the scan untangles; our guide to stomach pain after eating maps the possibilities.

Symptoms that need urgent care, not a scan booking

Pain with fever or chills, yellowing of the skin or eyes (jaundice), dark urine with pale stools, persistent vomiting, or severe pain that will not settle can signal an inflamed gallbladder, a blocked duct or pancreatitis — go to A&E or call 999. A booked scan is never a reason to delay emergency care.

From Our Practice

The pattern we see most

Months of post-meal discomfort, managed as indigestion with antacids — and a ten-minute look at the gallbladder finds the sludge or small stones that explain the whole story. The finding changes the conversation from managing symptoms to addressing a cause, with a report the GP or surgeon can act on, usually within two hours.

The reverse matters too: plenty of scans confirm a healthy, stone-free gallbladder — and that documented exclusion redirects attention to the real culprit rather than leaving “probably gallstones” hanging unproven. These are generalised patterns from our imaging casebook, not individual cases; your own findings are always discussed with you at your scan.

FAQs

Gallstones and ultrasound — your questions answered

Do gallstones show up on ultrasound?
Yes — ultrasound is the method of choice. Stones appear as bright structures with a dark acoustic shadow behind them, and the scan also assesses the gallbladder wall, sludge and the bile ducts in the same examination.
How should I prepare for a gallbladder ultrasound?
Fast for four hours beforehand — fasting keeps the gallbladder distended with bile so stones stand out and the wall can be measured properly. Water is fine. Our preparation guide has the full detail, including diabetic guidance.
Does the size of a gallstone matter?
Size is documented in every report and feeds the management conversation, but symptoms matter more than millimetres: a small stone that blocks the duct outlet can cause more trouble than a large one sitting quietly. What to do about a measured stone is a GP or surgical decision made on your symptoms and the whole picture.
Can gallstones be missed on an ultrasound?
Occasionally — very small stones, sludge, an unfasted (contracted) gallbladder, and stones already in the bile ducts are the classic reasons. If typical symptoms persist after a normal scan, tell your GP: a repeat fasted scan or duct-specific imaging (MRCP) is the usual next step.
Do gallstones always need surgery?
No. Gallstones found incidentally and causing no symptoms are very often simply left alone. Recurrent biliary colic or complications shift the conversation towards gallbladder removal — a decision for you and a surgeon, made far easier by a clear ultrasound report documenting what is there.
How is this diagnosed on the NHS, and why scan privately?
The NHS pathway is the same test: GP assessment, then an abdominal ultrasound. Going privately changes the timeline, not the science — a self-referred scan with a written report, usually within two hours of your appointment, that your GP or an NHS surgical team can act on directly.
Related

Where to go from here

£159Abdominal Ultrasound Scan

The gallstone examination — liver, gallbladder, pancreas, spleen, kidneys and aorta in one visit.

About the scan →SymptomStomach Pain After Eating

Gallbladder, stomach or something else — the post-meal pain map.

Read the guide →Your ReportAbdominal Report, Explained

The full vocabulary of an abdominal ultrasound report, translated.

Read the guide →

Is it your gallbladder? Find out this week.

A 30-minute fasted abdominal ultrasound, findings shown to you on screen, and a written report — usually within two hours — that your GP or surgeon can act on.

£159
General abdominal scan

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Kensington, London W8 4ED
3 mins from Notting Hill Gate

Clinical context on gallstones reflects NHS guidance on gallstones. This article is general information, not individual medical advice — management decisions belong with your GP or surgeon, and our reports are written to support exactly those decisions.

Written and clinically reviewed by the HCPC-registered sonographers who perform this scan at IUS London — a CQC-registered diagnostic ultrasound clinic (Provider ID 1-2775844974). Your own findings are explained to you at the scan and set out in your report.

Author: Yianni Kiromitis, Senior Sonographer, HCPC RA38415
Medically reviewed: 31 July 2026