Page 377 - Libro 2

23 — Evaluation of Kidney and Liver Transplants
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Figure 23-13 A urinoma. Grayscale images demonstrating an anechoic large fluid collection (U) at the lower pole of the kidney between the transplanted kidney and the bladder (not visualized on this image).
VASCULAR COMPLICATIONS
Vascular complications may occur immediately postoperatively or may have a delayed presenta- tion. In the immediate postoperative period, venous or arterial thrombosis is suspected when there is
Figure 23-14 A lymphocele. A grayscale longitudinal image demonstrating an anechoic fluid collection (L) with several fine septations anterior to the kidney. Despite the large size of this collection, there is no mass effect on the kidney.
sudden anuria or acute inset of pain in the region of the transplant. This is an emergent situation and the diagnosis must be made quickly to allow for the appropriate percutaneous or surgical intervention to salvage the kidney.
Arterial Thrombosis
Predisposing risk factors for renal artery thrombosis (RAT) include hypercoagulable states, hypotension, intraoperative trauma, mismatch of vessel size, and vascular kinking. Severe acute rejection and, rarely, emboli may result in occlusion or thrombosis of the intraparenchymal renal arteries. An intrarenal arterial thrombus may propagate to involve the main renal artery. RAT is estimated to occur in less than 1% of patients. Sonographic findings of RAT include intraluminal echoes and an absence of ar- terial and venous flow on color, power, or spectral Doppler interrogation of the intrarenal or main re- nal arteries and veins (Figs. 23-15 and 23-16). The sonographer should ensure that all color Doppler controls, such as color velocity scale, color gain, color wall filter, and output power, are optimized for the detection of slow flow before making the diagnosis of RAT.
Figure 23-15 A renal artery thrombosis. A color Doppler im- age of a newly transplanted kidney demonstrating a complete absence of both venous and arterial flow in the kidney.