With the index finger of the left hand above and the thumb below compressing the specimen to be excised, the surgeon applies right-angle clamps in pairs to the strand of tissue that extends from the portal vein into the pancreas (Figure 24). Within this strand of tissue, there are a number of small veins that must be ligated very carefully lest troublesome bleeding occur. All areas should be ligated to keep the specimen as free of clamps as possible while the third portion of the duodenum is freed from the region of the ligament of Treitz and the superior mesenteric vein and artery (Figure 25). This can be one of the most difficult steps in the procedure. An incision into the peritoneum about the third portion of the duodenum produces an opening directly into the general peritoneal cavity, through which the upper jejunum eventually will be pulled for the anastomosis (Figure 25). The blood supply in the mesentery to the third part of the duodenum and adjacent jejunum is very short, and it is often difficult to mobilize the area about the ligament of Treitz with a minimal loss of blood. Small bits of the mesentery near the duodenal wall are incorporated between pairs of small curved clamps, and the contents are ligated as this area of the duodenum is further freed (Figure 26). The attachment of the duodenum that tends to fix the duodenum beneath the inferior mesenteric vein may be identified more easily and clamped if a portion of the upper jejunum is pulled through the opening made in the transverse mesocolon in the region of the ligament of Treitz (Figure 27). The remaining short mesenteric attachments, including arterial branches going into the inferior mesenteric artery, can then be clamped carefully with curved clamps if a portion of the upper jejunum is pulled through the opening made in the mesocolon (Figure 28). Alternatively, the surgeon may choose to dissect the ligament of Treitz and proximal jejunum from the left side of the mesentery. This approach is preferred in obese patients in whom exposure in this area is difficult.