High incidence of arteriovenous fistula after biopsy of kidney allografts.

Arteriovenous fistula (AVF) is a well known but rarely diagnosed complication of percutaneous biopsy of kidney allografts. In the past diagnosis was usually made when clinical signs of an AVF occurred but Doppler ultrasonography has now enabled non-invasive diagnosis. Doppler examination of kidney allografts was performed after 100 biopsies. A total of ten AVFs were diagnosed within 2 weeks of biopsy. On repeated examination 2 months later, no additional fistula was detected. All fistulas were detected by abnormal colour shading of the artery and vein of the fistula caused by high blood velocity. Quantification in the artery supplying the fistula showed a higher systolic velocity compared with that in a normal artery of comparable size and location in the graft (mean (range) 64 (25-150) versus 36 (20-65) cm/s, P < 0.05). Diastolic velocity was also higher in the artery supplying the fistula than in a normal artery (mean (range) 34 (9-72) versus 7 (0-13) cm/s, P < 0.05). In the group with an AVF the proportion with a prolonged bleeding time (> 3 min) was higher (80 versus 47 per cent, P < 0.05), as was the prevalence of a platelet count < 200 x 10(9)/l (60 versus 22 per cent, P < 0.05). After detection of the fistula, four of the grafts were lost because of rejection and two patients died from sepsis during antirejection treatment. During follow-up of the remaining four AVFs, three disappeared spontaneously and one persisted. None of the fistulas has had an impact on renal function requiring intervention. In conclusion, AVF is a complication observed frequently after kidney allograft biopsy that can be detected and monitored by Doppler ultrasonography.