One week after receiving a cadaver renal allograft, the recipient remains oliguric and dialysis dependent. Ultrasonography reveals a larger perigraft fluid collection. Your next step in management includes:

D. Aspiration of the perigraft fluid collection for chemical analysis.

DISCUSSION: Urine leaks usually occur early after transplantation, and the most frequent site of leakage is from the ureteroneocystostomy or ischemic ureter. The clinical signs are pain, swelling, and deterioration of renal function before leakage from the wound is observed. Aspiration of the perigraft fluid collection for chemical analysis of blood urea nitrogen (BUN) and creatinine would aid the differentiating urinoma from lymphocele. The composition of urinoma reveals BUN and creatinine concentrations several orders of magnitude higher than those of a lymphocele, which are comparable to the values in blood.