What are the symptoms of pelvic phleboliths?

Pelvic Phleboliths Are Typically Asymptomatic

Pelvic phleboliths do not cause symptoms and are incidental findings on imaging studies. They are benign calcified thrombi within pelvic veins that have no clinical significance for the patient 1, 2.

What Are Pelvic Phleboliths?

• Pelvic phleboliths are calcified venous thrombi composed of laminated fibrous tissue with a surface layer continuous with vein endothelium 1.
• They are extremely common, occurring in 38.9%-48% of adults, with higher prevalence in individuals over age 40 1.
• Both genders are equally affected by phleboliths 1.
• They appear as rounded calcifications on imaging, often located near the ureters in the pelvis 1, 3.

Clinical Significance

• Phleboliths themselves produce no symptoms and are discovered incidentally during imaging performed for other reasons 4, 1.
• They may be associated with diverticulitis and vascular abnormalities, though this association does not imply causation of symptoms 1.
• The primary clinical importance of phleboliths is distinguishing them from ureteral stones in patients presenting with flank pain or suspected urolithiasis 1, 2, 3.

Distinguishing Phleboliths from Symptomatic Ureteral Stones

When a patient presents with acute flank pain and pelvic calcifications are identified on imaging, the following features help differentiate asymptomatic phleboliths from symptomatic ureteral stones:

Radiological Features Suggesting Phleboliths (Not Stones):

• Central lucency (8%-60% sensitivity, 100% specificity) visible on thin-slice CT 1, 3, 5.
• Rounded shape with 91% positive predictive value for phlebolith 1.
• "Comet tail sign" (21%-65% sensitivity, 100% specificity): an adjacent eccentric, tapering soft-tissue mass corresponding to the noncalcified portion of a pelvic vein 1, 3.
• Lower Hounsfield unit density (160-350 HU) compared to ureteral stones 1.
• Mean attenuation less than 278 HU on CT imaging 3.

Radiological Features Suggesting Ureteral Stones (Not Phleboliths):

• "Rim sign" (50%-77% sensitivity, 92%-100% specificity): circumferential soft tissue edema around the ureter 1, 2, 3.
• Geometric or irregular shape (100% positive predictive value for stone) 1, 3.
• Absence of central lucency on thin-slice CT 3, 5.
• Higher Hounsfield unit density compared to phleboliths 1.

Common Clinical Pitfall

• The major pitfall is misdiagnosing phleboliths as ureteral stones, leading to unnecessary interventions or anxiety 4, 2.
• In one case report, phleboliths were initially mistaken for an intraperitoneal intrauterine device, demonstrating how these calcifications can confound diagnosis across multiple clinical scenarios 4.
• When pelvic calcifications are ambiguous on standard imaging, thin-slice CT with 1-mm collimation can reveal central lucency in 60% of phleboliths, providing definitive differentiation 5.

Bottom Line for Clinical Practice

If a patient has pelvic calcifications identified on imaging but lacks symptoms of urolithiasis (acute flank pain, hematuria, nausea/vomiting) and imaging shows no signs of ureteral obstruction (hydronephrosis, perinephric stranding, rim sign), the calcifications are phleboliths and require no treatment or follow-up 1, 2, 3.