PANCREAS TRANSPLANTATION ULTRASOUND

PANCREATIC TRANSPLANT
In patients with insulin-dependent diabetes mellitus with end-stage renal disease, simultaneous pancreatic and kidney transplant is a successful treatment which improves the quality of life and the survival of the patients. Typically such patients also have severe complications, such as retinopathy and vascular disease, which may be stabilized, or even reversed, by transplantation.

Simultaneous pancreas and kidney transplantation now has a 1-year graft survival of almost 90% due to improved organ preservation techniques, surgical techniques and immunosuppression. The transplanted kidney is placed in the iliac fossa with the pancreas on the contralateral side. The donor kidney is transplanted in as usual, with anastomoses to the recipient iliac artery and vein. The pancreatic vessels are anastamosed to the contralateral iliac vessels.

The pancreatic secretions are primarily by enteric drainage, as the previous method of bladder drainage was associated with an increased incidence of urologic complications such as urinary tract infection, haematuria or reflux pancreatitis.

Postoperative monitoring of the pancreatic transplant is difficult, on both clinical and imaging grounds. No one imaging modality has proved without limitations and a combination of ultrasound, CT, MRI, angiography and nuclear medicine may be required. Postoperative complications include thrombosis, infection, inflammation, anastomotic leaks and rejection. Localized postoperative bleeding usually resolves spontaneously.

Ultrasound appearances
The donor pancreas is usually situated in the iliac fossa but can be placed more centrally, particularly if a renal transplant has also been performed. Ultrasound is limited in its ability to assess the transplanted pancreas, even if it can be located amongst the bowel loops. The lack of an adjacent reference organ, such as the liver, makes assessment of its echogenicity subjective, and therefore subtle degrees of inflammation are difficult to detect. Fluid collections are frequently concealed beneath bowel and, when identified, their appearance is non-specific. Contrast CT is more successful in detecting anastomotic leaks and collections, and is usually used for guided aspiration.

Colour Doppler should display perfusion throughout the pancreas and the main vessels may be traced to their anastomoses, depending on overlying bowel. Neither CT nor ultrasound is particularly helpful in evaluating rejection, and it is difficult to differentiate transplant pancreatitis from true rejection. The Doppler resistance index does not correlate with a rejection process and has not been found useful. MRI has been found to display more positive findings in pancreatic rejection than other imaging modalities.