January 24, 2011

Bladder Stones

Transverse ultrasound image of the urinary bladder shows a 5-cm mobile hyperechoic lesion (between arrows) with posterior acoustic shadowing within the bladder lumen.

  • Risk factors: urinary stasis (voiding dysfunction i.e., urethral stricture, benign prostatic hyperplasia, bladder neck contracture, neurogenic bladder), infection, bladder diverticula, foreign body (Foley catheter balloon, suture material, etc)
  • Common compositions: uric acid, ammonium urate, calcium oxalate
  • Uric acid stones predominate in a setting of bladder outlet obstruction
  • Magnesium ammonium phosphate and apatite stones predominate in a setting of urinary tract infection (UTI)
  • Patient presentation: hematuria, suprapubic pain, interruption of urine stream
  • If sufficiently calcified, bladder stones may be visible on radiography
  • Tends to locate in the midline when the patient is supine
  • If calcification is located laterally, think of a stone in the diverticulum or ureterocele
  • Key to confirm that the abnormality is a stone = mobility (either on radiography or ultrasound)
1. Zagoria RJ. Genitourinary Radiology: the Requisites, 2004.
2. Tanagho EA, McAninch JW. Smith's General Urology, 2004.

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