Measurement of peritoneal fluid urea nitrogen and creatinine levels is useful to detect iatrogenic urinary tract leakage in colorectal surgery.

BACKGROUND Increased peritoneal drainage after colorectal surgery is a common problem. Measurement of peritoneal fluid urea nitrogen (UN) and creatinine (Cr) is a diagnostic tool to detect the urinary tract leakage (UTL). We evaluated its application in colorectal surgery. METHODS We conducted a retrospective chart review study. We enrolled patients with iatrogenic UTL, and measured their UN and Cr levels in peritoneal fluid and compared them with those in blood and urine. Meanwhile, we assigned patients without UTL to a control group and compared clinical parameters of both groups. RESULTS Twenty-three patients with iatrogenic UTL were recruited. The overall incidence was 0.5%. UN level in peritoneal fluid (322 ± 56 mg/dL) was significantly higher than that in blood (18.7 ± 4.0 mg/dL, p < 0.001); Cr level in peritoneal fluid (69.7 ± 14.3 mg/dL) was also significantly higher than that in blood (1.5 ± 0.5 mg/dL, p < 0.001). UN level in peritoneal fluid was significantly higher in the iatrogenic UTL group than in the control group (322 mL/dL vs. 9.3 mL/dL, p < 0.001); Cr level in peritoneal fluid was also significantly higher (69.7 mg/dL vs. 0.98 mg/dL, p < 0.001). CONCLUSION When increased peritoneal drainage is found postoperatively in colorectal surgery, measurement of UN and Cr levels in peritoneal fluid can be a useful diagnostic tool to determine intraperitoneal iatrogenic UTL.