Are coagulation studies necessary before percutaneous nephrostomy?

Performance of coagulation studies for patients undergoing percutaneous nephrostomy (PCN) has been advocated by some investigators. We performed a retrospective study to assess this practice.

The medical records of 180 patients subjected to PCN for various reasons between October 1991 and July 1998 were reviewed. This represents a subset of patients in whom PCN was performed by an experienced interventional radiologist at our institution. Patients were excluded if they had a history of active liver disease, hematologic or bleeding disorder, current use of heparin or warfarin, or platelet count <100,000. The remaining 160 patients were separated into two groups. Group 1 consisted of 153 patients with a normal prothrombin time (PT) and partial thromboplastin time (PTT). Group 2 comprised 7 patients with an abnormal PT or PTT. Demographic and laboratory data including PT, PTT, complete blood, and platelet counts were analyzed to determine if a hemorrhagic complication could be predicted by an abnormal PT or PTT.

In group 1 the mean PT was 12.2 seconds and the mean PTT was 25.0 seconds; in group 2 the mean PT was 13.9 seconds and the mean PTT was 30.3 seconds. The hemorrhagic complication rates were not statistically different between the two patient cohorts (p = .203). Demographic and standard laboratory data were not predictive of abnormal coagulation parameters.

Screening coagulation studies are unnecessary in the standard patient subjected to PCN.