Intraoperative peritoneal washing cytology with the rapid immunoperoxidase method using microwave irradiation.

The rapid immunocytochemical staining of gastrointestinal cancer-associated antigens, carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9), for intraoperative peritoneal washing cytology of pancreatic or biliary carcinoma can be completed in only 25 minutes by using microwave irradiation to accelerate incubation of the primary antibody. Only 3-second irradiation at 500 W for fresh smears produced specific antigen staining of malignant cells similar to that obtained with longer incubation, and the sensitivity of intraoperative cytology was greater than by the conventional staining method. The rapid immunocytochemical staining method of peritoneal washings at laparotomy can provide sensitive information for determining more aggressive therapy for intraperitoneal spread of malignant cells before closing the abdominal wall.