Sonographic evaluation of clinically significant perigraft hematomas in kidney transplant recipients

OBJECTIVE. The purpose of this study was to assess the sensitivity of ultrasound in evaluating peritransplant hematomas that require surgical evacuation in recipients of kidney transplants. MATERIALS AND METHODS. Thirty-four patients who underwent 37 hematoma evacuations underwent ultrasound examinations in the 24 hours before surgical evacuation. The operative reports were evaluated for presence and size of collection, presence of active bleeding at operation, and composition of the hematoma. The clinical findings leading to the ultrasound examination were recorded. Ultrasound examinations were evaluated in consensus by two board-certified and fellowship-trained abdominal radiologists for the presence, size, and echogenicity of the collection; subjective perfusion visualized with color and power Doppler ultrasound; velocities of the renal arteries; and arcuate artery resistive indexes. RESULTS. Ten of the 37 imaged hematomas (27%) had either no or small (<50 mL) fluid collections on ultrasound examination. With sonographic volumetry, the reported intraoperative volumes were underestimated by 46%. The mean arcuate artery resistive index was 0.82 in the superior pole, 0.81 in the mid pole, and 0.78 in the inferior pole of the kidney. A decrease in hemoglobin level was the most sensitive clinical finding for determining the presence of perigraft hematomas. CONCLUSION. Our results suggest that gray-scale sonography alone appears to have limited sensitivity in detecting clinically significant peritransplant hematomas and that its use may result in overall underestimates of hematomas.