Pelvic vein stones seen by chance on an X-ray or CT

What the report words mean

Phlebolith. A small calcium spot in the wall of a small vein. It forms when a tiny clot stuck to the vein wall hardens in layers. (Jendeberg 2021)(Yu 2022) Reviews describe phleboliths as benign (harmless). (Carius 2022)
Pelvic calcification. Any bright, dense spot in the pelvis on an X-ray or CT. A phlebolith is one kind; a stone in the ureter (the tube from the kidney to the bladder) is another. On CT both show as small dense dots. (Yu 2022)
Central lucency. A lighter centre inside the spot. On a plain X-ray many phleboliths have one, which points away from a stone. (Traubici 1999)
Comet sign or tail sign. A thin tapering soft tail next to the spot on CT, which is the rest of the small vein. It points to a phlebolith. (Bell 1998)(Boridy 1999)
Rim sign. A ring of swollen ureter wall around the spot on CT. It points to a stone, not a phlebolith. (Bell 1998)(Carius 2022)
Other calcium spots. Calcium in large arteries and in the prostate have their own pages: aortic calcification and prostate calcium spots.

How common they are by age

A study of pelvic X-rays in 1000 adults aged 16 to 79 found phleboliths in 44.2%. Women aged 35 to 54 had them more often than men of the same age, older people had more of them, and they were more common on the left side. (Mattsson 1980)

How often pelvic phleboliths are seen, by group
Group	Share with phleboliths	Source
Children aged 9 to 17	About 1 in 800 pelvic X-rays	(Marquis 1977)
Adults aged 16 to 79, all	44.2%	(Mattsson 1980)
Adult men	37.3%	(Mattsson 1980)
Adult women	50.1%	(Mattsson 1980)
Adults, range across studies	38.9% to 48%	(Luk 2017)

A review notes they are more common in adults over 40. (Luk 2017) On CT they are seen as often as, or more often than, ureter stones. (Carius 2022) Phleboliths higher up, beside the lower spine, are uncommon: about 2% in one X-ray study. (Curry 1983)

How reports tell them apart from other calcified spots

A phlebolith can sit close to the ureter, so the main question is whether a spot is a phlebolith or a small ureter stone. (Jendeberg 2021)

Shape. In one study, 97% of phleboliths were round on thin-slice CT. A spot with straight edges or corners points to a stone. (Arac 2005)(Bell 1998)
Lighter centre. Seen in about two thirds of phleboliths on a plain X-ray, but almost never on routine CT (1 of 120 in one study). Thin-slice CT showed it in 60%. (Traubici 1999)(Arac 2005)
Tail sign. Seen next to 65% of phleboliths and next to none of 82 ureter stones in one CT study. When there is no tail, the spot stays uncertain. (Boridy 1999)
Rim sign and a blocked kidney. A rim was seen around 76% of stones and 2% of phleboliths. Signs of a blocked or swollen kidney on the same side point to a stone. (Bell 1998)(Guest 2001) See swollen kidney (hydronephrosis).
Readers do not always agree. Radiologists often disagreed about whether a rim or tail was there. (Guest 2001) Seven radiologists judging only a small area around each spot were right 86% of the time on average; the authors say the whole scan and the person's symptoms are needed. (Jendeberg 2021)

When a repeat or different scan is suggested

Found by chance, no symptoms. The sources here describe phleboliths as harmless and do not describe a routine follow-up scan for them. (Carius 2022)(Luk 2017)
Pain or signs of a stone. When a spot near the ureter is hard to place, a CT urogram (a CT with dye that outlines the ureters) is one way to tell a stone from a phlebolith. (Jendeberg 2021) Reviews say symptoms, examination and other signs on the scan matter more than any one sign. (Carius 2022)
Otherwise. Whether you need another scan depends on your symptoms and the rest of the report. Your doctor decides.
Worry is real. See after an abnormal screening result.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 (or your local urgent care elsewhere) if you think you have kidney stones and you are in severe pain, or you have a high temperature or feel hot, cold or shivery. It describes kidney stone pain as usually starting in the side of the tummy or lower back and possibly spreading to the groin. (NHS)

Other things a belly or pelvic scan may show

The same scan may mention other findings, each with its own page: calcium in the aorta, prostate calcium spots, bladder wall thickening and fibroids.

Who it applies to

Adults told that an X-ray or CT done for something else shows phleboliths or small calcified spots in the pelvis. Children, people with a known vein malformation and people being checked for a kidney or ureter stone right now are outside this page.

Routine age-based screening

A phlebolith on a scan does not replace the routine screenings for your age. See screenings by age and gender.

Where they differ:

Women and men. One X-ray study of 1000 adults found phleboliths more often in women (50.1% against 37.3%). (Mattsson 1980) A later review says they appear to affect both sexes equally. (Luk 2017)
The lighter centre on CT. Two routine CT studies found it rarely, in 1 of 120 and in 9% of phleboliths. (Traubici 1999)(Bell 1998) A thin-slice CT study found it in 60%. (Arac 2005)
Density and size cut-offs. One study proposed density and volume cut-offs to tell a stone from a phlebolith. (Tanidir 2017) A later study could not confirm them. (Jendeberg 2021)

Your doctor decides what your result means for you.

Questions people ask

What is a phlebolith?

A phlebolith is a small calcium spot in the wall of a small vein, most often in the pelvis. It forms from a tiny old clot that has hardened. It is a different thing from a stone made in the urine. (Jendeberg 2021) (Yu 2022) (Carius 2022)

How common are phleboliths?

Very common. Studies put them at about 40% of adults, and in one study of 1000 adults they were seen in 44.2%. They are more common with age and rare in children. (Jendeberg 2021) (Mattsson 1980) (Luk 2017) (Marquis 1977)

Are phleboliths harmful?

Reviews describe them as benign, meaning harmless. Their main importance is that on a scan they can look like a small stone in the tube from the kidney to the bladder (the ureter). (Carius 2022) (Luk 2017)

How does a radiologist tell a phlebolith from a ureter stone?

They look at the shape, the centre, the tissue around it and the rest of the scan. A round spot with a lighter centre on an X-ray, or a small soft "tail" on CT, points to a phlebolith. Swelling around the spot and signs of a blocked kidney point to a stone. No single sign is perfect. (Luk 2017) (Boridy 1999) (Bell 1998) (Carius 2022)

Will I need another scan?

Not usually for the phlebolith itself. When pain or other signs suggest a ureter stone and the spot is hard to place, a CT with dye that shows the ureters is one way to tell. Your doctor decides what your result means for you. (Jendeberg 2021) (Carius 2022)

Pelvic vein stones (phleboliths) seen by chance on an X-ray or CT