Peroral Cannulation of the Ampulla of Vater for Direct Cholangiography and Pancreatography

Abstract

Existing radiologic methods may fail to demonstrate the biliary ducts in some jaundiced patients and do not at all opacify the pancreatic ducts. As a new approach, it was decided to test the feasibility of cannulating the ampulla of Vater by intubation through the mouth, using television fluoroscopic monitoring. A prototype instrument has been designed and constructed for this purpose. The factors which required consideration were biological and technical. Biological Factors a. While there is considerable variation in the anatomic arrangement of the biliary and pancreatic ducts in relation to the duodenum, these ducts usually open into the second or third part of the duodenum, generally joining together at Vater's ampulla. b. For visualization of the ampulla of Vater, the instrument was constructed to poise a cannula over the usual anatomic site of the papilla, bearing in mind that the ampulla is ordinarily not identified fluoroscopically even with barium in the duodenum. It was hoped that with the instrument thus in the vicinity of the ampulla, manipulation of the cannula into the duct orifice might be possible. Such proved to be the case in 2 out of 3 autopsy block specimens of duodenum, pancreas, and bile ducts examined under fluoroscopic control. c. In respect to resistance of the sphincter of Oddi, entrance with modest pressure has been found possible in fresh pathologic material and in anesthetized patients. Drugs such as the nitrites are available to relax smooth muscle if the resistance proves an obstacle. d. Injection of contrast material into the pancreas has been shown to be safe under proper conditions (2). Technical Factors a. For intubation of the duodenum, the instrument requires flexibility to insure safety and adaptability to the variations in anatomy between patients, yet enough rigidity and shape to provide for direct manipulation of the instrument into the duodenum without depending on peristalsis. b. With respect to cannulation, the duct orifice of the ampulla is commonly elevated on a papilla above the level of the duodenal wall. It is, then, necessary to raise the probing cannula from the mucosal surface correspondingly. Since the ampulla is not visible fluoroscopically, the instrument must automatically align it with the cannula. The duct orifice usually opens in a distal direction so that the cannula must approach it from distal to proximal. The instrument must be stiff enough to effect cannulation but flexible enough to safeguard the mucosa and to change shape for passage and withdrawal. The Instrument The instrument employed at present has two parts (Fig. 1). a. The outer tube consists of a flexible coil spring 130 ern long, covered with vinyl tubing similar to materials used in a smallbowel biopsy instrument (1). At the “duodenal” end is a short slotted nylon tube. Upon this is mounted a pair of runners joined by a cross strut and counteracted by a single back strut, all made of nylon-covered wire.