Localisation of insulinomas.

Small insulinomas may be undetectable by arteriography or palpation of the pancreas. They can be identified, however, by the point at which high insulin levels are detected in the venous effluent sampled at several sites by catheterisation of the splenic and portal veins at laparotomy or via the percutaneous transhepatic route. Diagnosis by catheterisation techniques made it possible to resect only that part of the pancreas containing the tumour (in one patient the head and in another the body of the pancreas). Improved localisation is essential in planning an operation, and often removes the need for lengthy trials of medical therapy before laparotomy.