[Pancreatic insulinoma. Peroperative topographical diagnosis].

Difficult problems may arise and place the surgeon in an uncomfortable position in cases where neither pre-operative investigations nor palpation of the pancreas have enabled pancreatic insulinomas to be localized. However, 3 examinations performed during the operation should help solve these problems, as shown by the case presented here. These examinations are insulin assays in the peripancreatic venous blood, blood glucose measurements under constant rate glucose infusion, and intra-operative ultrasonography. Pre-operative radioimmunological assays of insulin have been used for about 10 years, but owing to technical advances and shortening of the incubation time these assays can now be performed during surgery and, above all, with immediate results. Blood glucose measurements are good pointers, and this method has long been used in this type of surgery. Intra-operative ultrasonography has recently been introduced; it is very effective in diagnosing endocrine tumours of the pancreas, since the images it provides are quite characteristic. These 3 examinations combined should be used to localize pancreatic insulinomas; they may replace most of the pre-operative examinations that are still carried out.