Sometimes it is impossible to dislodge a calculus from the region of Vater's papilla by careful and repeated manipulation, and a more radical procedure is followed. Under such circumstances the duodenum is mobilized by the Kocher maneuver, and the common duct is exposed throughout its course down to the duodenal wall. An incision is made in the lateral part of the peritoneal attachment of the duodenum, making it possible to mobilize the second portion of the duodenum (Figure 12). After the peritoneal attachment has been incised with long, curved scissors, blunt gauze dissection is used to sweep the duodenum medially. Occasionally, this will expose the retroduodenal portion of the common duct and will allow more direct palpation (Figure 13). A blunt metal probe is introduced downward to the point of the obstruction, and the location of the stone is more accurately determined by palpation. A scoop is passed down to the region of the ampulla of the common bile duct, and its course is directed carefully with the index finger and thumb of the surgeon's left hand (Figure 14). With the tissues being held firmly by the thumb and index finger, it is usually possible to break up the impacted calculus with the scoop. Should this prove unsuccessful, it is necessary to open the anterior duodenal wall and to expose Vater's papilla (Figure 15).