Internal Medicine

0521779407-21 CUNY1086/Karliner 0 521 77940 7 June 7, 2007 18:59

Upper Urinary Tract Obstruction 1485

Specific Diagnostic Tests

■Erythrocyte sedimentation rate (ESR): retroperitoneal fibrosis

■Prostate Specific Antigen (PSA): locally advanced prostate cancer

■Carcinoembryonic antigen (CEA): colon cancer

■Urine cytology (voided or wash): transitional cell carcinoma

Imaging

■Non-enhanced, thin-cut CT of kidneys and ureters

➣Study of choice for acute flank pain

➣Highly sensitive for ureteral stones

■Intravenous urogram (IVU)

➣Identifies presence and site of obstruction

■Renal sonogram

➣Rapid means of detecting hydronephrosis but nonspecific for

site of obstruction

■Retrograde pyelogram

➣Identifies distal extent of obstruction

➣May differentiate intrinsic from extrinsic obstruction

■Diuretic renogram

➣Differential renal function

➣Quantifies degree of obstruction

■Whitaker test

➣Pressure-flow test of kidney

➣When renal scan equivocal

differential diagnosis

Intrinsic Obstruction

■Renal/ureteral calculi: non-enhanced helical CT highly sensitive

■Renal/ureteral tumor (most commonly transitional cell carcinoma):

non-radiopaque filling defect on IVU, CT or retrograde pyelogram

■Sloughed papilla from papillary necrosis

➣Associated with urinary tract infection

➣Usually in diabetics

➣Associated with interstitial nephritis from analgesic abuse

➣IVU and history highly suggestive

■Fungus ball:

➣Commonly seen in immunocompromised patients

➣History and positive urine fungal culture suggestive

➣Filling defect on IVU, CT

■Ureteral stricture: IVU and retrograde pyelogram suggest intrinsic

obstruction