In the Whitaker test for upper urinary tract obstruction, which perfusion pressure above baseline is considered diagnostic of obstruction?

• A >10 cmH₂O
• B >22 cmH₂O ✓
• C >15 cmH₂O
• D >30 cmH₂O

Explanation

The Whitaker test involves antegrade perfusion of the renal pelvis at 10 mL/min while measuring pelvic pressure; a differential pressure >22 cmH₂O above bladder pressure is diagnostic of obstruction, 10–22 is equivocal, and <10 is unobstructed. It is invasive and largely replaced by diuresis renography (MAG3 scan) but remains the gold standard for equivocal cases. The perfusion must mimic high urine flow to unmask obstruction.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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