Insulinoma: the value of intraoperative ultrasonography.

Ideally, surgical exploration for insulinomas would be met with uniform success in both finding and removing the tumor, incurring no postoperative mortality or morbidity. In reality, however, insulinomas remain undetected by even experienced surgeons in 10 to 20% of patients, including present-day series. Additionally, postoperative complications may occur in 10 to 25% of patients, principally related to the pancreatic dissection. Although dispensing with any attempt to preoperatively localize the tumor has been advocated, most authors agree that localization efforts are necessary and helpful. To review the results and surgical implications of current localization techniques, 41 adult patients who were surgically treated for insulinomas at the Mayo Clinic from 1980 through June 1987, were reviewed. Tumor size ranged from 5 mm to 4 cm, and the sensitivity of tumor localization using arteriography, computed tomography, preoperative and intraoperative ultrasonography were 55%, 27%, 59%, and 90%, respectively. Since the introduction of intraoperative ultrasonography into our clinical practice in 1982, all 29 of our adult patients' insulinomas have been identified with a combination of this technique and palpation by an experienced surgeon. There were no false positive interpretations with intraoperative ultrasonography, and tumors were imaged in four patients that were not palpable. In 18 of these 29 (62%) patients, the information gleaned from the images appeared to influence the surgical management. While there is no substitute for exploration by an experienced surgeon, his ability is enhanced by the addition of both preoperative and intraoperative ultrasonography.