Phleboliths are small, calcified structures that can develop within veins in the body. These formations are a common occurrence and are generally considered harmless findings during medical examinations. While they can be present in various locations, they often go unnoticed as they typically do not cause symptoms.
What Phleboliths Are
A phlebolith, sometimes called a “vein stone,” is a calcified blood clot that forms inside a vein. These small masses are composed of calcium deposits that accumulate over time within a thrombus. Phleboliths typically appear as small, rounded, or oval structures, often measuring between 2 to 5 millimeters in diameter.
How Phleboliths Form and Where They Appear
Phleboliths develop when a blood clot within a vein undergoes calcification, as calcium gradually deposits onto the clot, causing it to harden. Factors contributing to their formation include slow blood flow, which can lead to blood pooling and clot formation. Conditions like chronic constipation, prolonged inactivity, or straining during bowel movements can increase vein pressure, potentially leading to clot formation and subsequent calcification.
Phleboliths are found in various parts of the body, most commonly in the pelvic region, particularly around the bladder and rectum. They are present in the pelvic region in approximately 44.2% of people and occur more frequently in females than males. Less commonly, phleboliths can also appear in the legs, head, or neck. Their presence can also be associated with venous malformations, which are abnormally developed veins with slow blood flow.
Identifying Phleboliths
Phleboliths are often discovered incidentally during medical imaging tests performed for other reasons. They might be seen on various imaging studies, including X-rays, CT scans, or ultrasounds. On X-ray images, phleboliths appear as small, dense, rounded or oval white spots.
Their appearance on imaging can sometimes include a radiolucent (transparent) center, which aids identification. While this central lucency is often visible on X-rays, it may not be apparent on CT scans, especially with thicker sections. Identifying these calcifications on imaging is important for distinguishing them from other conditions.
Managing Phleboliths
For most individuals, phleboliths are benign and do not require specific treatment. They are often considered a normal finding, especially as people age. However, it is important to differentiate phleboliths from other calcifications that may appear similar on imaging, such as kidney stones (ureteral calculi).
While both can appear as calcified structures, phleboliths originate in veins, whereas kidney stones form within the urinary tract. Specific imaging characteristics, such as the “comet tail sign” in phleboliths or a “soft tissue rim sign” in kidney stones, help distinguish them. If a person experiences unexplained pain or other symptoms, medical consultation is warranted to determine the underlying cause.