Abdominal calcification and stones on X-ray

Written by the X-Ray Atlas editorial team from the sources listed below · Medical review pending · Updated 24 October 2026 · Level: Intermediate

Calcium is dense and shows up white on a plain film, so the abdominal X-ray (AXR) is full of small calcifications. Most are harmless, such as phleboliths, costal cartilage and calcified lymph nodes. Some matter: renal and ureteric stones, a calcified abdominal aortic aneurysm, chronic pancreatitis, a gallstone causing gallstone ileus, or an appendicolith. The skill is to localise each calcification to an organ, recognise its pattern, and know the limits of the film: most gallstones and some kidney stones are invisible on it, and the correct test is usually ultrasound or CT. This page works through the abdomen organ by organ.

1. How to look

After the systematic abdominal review of gas, bowel and bones, do a deliberate sweep for calcification. For each one, describe:

• Location: which organ does it project over? Remember the film is two-dimensional: something projecting over the kidney may be in front of or behind it.
• Shape and pattern: round, laminated, branching, curvilinear (in a wall), stippled, or popcorn-like.
• Size in millimetres.
• Associated findings: obstruction, pneumobilia, a soft-tissue mass.

Compare with previous films: a calcification that has moved along the line of the ureter is likely to be a stone.

2. Renal and ureteric stones

• Staghorn calculus: a large branching stone filling the renal pelvis and calyces, often struvite, associated with infection.
• Nephrocalcinosis: calcification within the kidney tissue itself, either medullary (clustered in the pyramids, for example in medullary sponge kidney, renal tubular acidosis or hyperparathyroidism) or cortical (much rarer, for example after cortical necrosis).

Non-contrast CT (CT KUB) is the reference test for suspected renal colic in adults, and NICE NG118 recommends it within 24 hours of presentation (with ultrasound preferred in pregnancy and in children and young people). A plain KUB film is still used to follow up known radiopaque stones and to plan treatment.

3. Following the ureter, and phleboliths

To decide whether a calcification could be a ureteric stone, trace the expected course of the ureter on each side:

1. from the renal pelvis, down along the tips of the lumbar transverse processes;
2. across the sacroiliac joint;
3. down towards the ischial spine;
4. then medially into the bladder.

Stones tend to lodge at three natural narrowings: the pelviureteric junction, where the ureter crosses the iliac vessels near the pelvic brim, and the vesicoureteric junction.

4. Gallstones and the gallbladder

• Only about 10–15% of gallstones are radiopaque enough to be seen on a plain film (some sources quote up to 20%). [VARIES] When seen, they are often laminated or faceted and clustered in the right upper quadrant.
• Ultrasound is the test for suspected gallstones and cholecystitis. A normal AXR does not exclude gallstones.
• Porcelain gallbladder: curvilinear calcification of the gallbladder wall, associated with chronic cholecystitis and a (debated) increased risk of gallbladder cancer.
• Emphysematous cholecystitis: gas rather than calcium in the gallbladder wall or lumen, typically in older or diabetic patients. A surgical emergency.
• Gallstone ileus: a calcified stone in the right iliac fossa, with small bowel obstruction and gas in the biliary tree (Rigler's triad). See small bowel obstruction.

5. Pancreatic calcification

Speckled or clustered calcification across the upper abdomen, typically around the level of L1–L2 and crossing the midline in the line of the pancreas, suggests chronic pancreatitis, most often related to alcohol. It may be confined to the head (right of the spine) or extend along the body and tail towards the spleen. CT is used to assess the pancreas further.

6. Vascular calcification

• Aortic calcification is very common in older people. It shows as curvilinear lines in the wall of the aorta, just to the left of the lumbar spine.
• Abdominal aortic aneurysm (AAA): if the calcified walls are seen and the aortic diameter is more than 3 cm, an aneurysm is likely. The plain film cannot exclude an aneurysm (many are not calcified) and cannot measure it reliably. Ultrasound is the screening and surveillance test; CT angiography is used when rupture is suspected or for planning repair.
• Splenic artery calcification: a tortuous, "ring-like" or serpiginous calcification in the left upper quadrant, common in older people. A rounded ring may indicate a splenic artery aneurysm.
• Calcified iliac and femoral arteries, and calcified mesenteric vessels.

7. Other calcifications

Calcification	Appearance and meaning
Appendicolith	A small round or laminated calcification in the right iliac fossa. In a patient with right iliac fossa pain it supports appendicitis, but the AXR is not a test for appendicitis.
Calcified mesenteric lymph nodes	Irregular, mottled calcifications that may move between films, often from old infection (including TB). Usually harmless.
Costal cartilage calcification	Calcification at the ends of the lower ribs, overlying the upper abdomen. Normal with age.
Adrenal calcification	Above the kidneys; after haemorrhage (including in childhood) or TB.
Calcified uterine fibroids	Coarse "popcorn" calcification in the pelvis of an older woman.
Dermoid cyst (ovarian teratoma)	May contain a tooth or bone, with a lucent area of fat.
Bladder stone	A large, often laminated stone in the midline of the pelvis.
Prostatic calcification	Small calcifications just above or behind the symphysis pubis in men.
Injection granulomas	Small calcifications in the buttock soft tissues from previous injections.

Distinguish calcification from swallowed tablets and other ingested material, and from external objects. See foreign bodies and artefacts and mimics.

Red flags: act now

What to focus on, by role

Role	Priorities
Medical student	Which stones are radiopaque, the course of the ureter, phleboliths, and why ultrasound is the test for gallstones.
Nurse	Recognise the renal colic patient with fever, and the older patient with abdominal or back pain and collapse.
Junior doctor	Request CT KUB rather than a plain film for suspected renal colic, and escalate an infected obstructed kidney or suspected AAA immediately.
Radiographer	Full coverage from the upper poles of the kidneys to the bladder base for a KUB film.
Advanced / FRCR	Nephrocalcinosis patterns, phlebolith versus stone, and the full differential of abdominal calcification.

Practise on abdominal X-rays →

References

1. NICE. Renal and ureteric stones: assessment and management (NG118). nice.org.uk
2. Royal College of Radiologists. iRefer: making the best use of clinical radiology. irefer.org.uk
3. Radiology Masterclass. Abdominal X-ray tutorials. radiologymasterclass.co.uk
4. NICE. Abdominal aortic aneurysm: diagnosis and management (NG156). nice.org.uk

For education only. Not a substitute for a formal report, senior review or your local policy. Never use this page to make decisions about a real patient.