Key points for the Chen's transpancreatic continuous U-suture technique for pancreaticojejunostomy

1. Introduction Pancreaticoduodenectomy is an essential surgical procedure for the treatment of malignant tumors in the pancreatic head, distal common bile duct, and duodenal papilla, and is widely used in clinical practice. One of the primary determinants of surgical success is the durability of the pancreaticojejunal anastomosis. According to previous reports,[1–5] the incidence of postoperative pancreatic fistula following pancreaticoduodenectomy remains high, with clinically relevant pancreatic fistula (grade B or grade C) occurring in 9.7%–23.9% of cases. Once clinically relevant pancreatic fistula develops, hospital stays are significantly prolonged and medical costs substantially increase. Particularly, for patients who develop grade C pancreatic fistula, the mortality rate may exceed 10%. To address this ongoing challenge, we developed the transpancreatic transverse U-suture technique for pancreaticojejunal anastomosis in 1995 (Figure 1).[6,7] Compared with techniques reported at that time, this method not only reduced the incidence of postoperative pancreatic fistula but also simplified the surgical procedure and shortened operative time, ultimately yielding excellent patient outcomes. In 2009, Kleespies et al.[8] incorporated the transpancreatic U-suture technique into their modification of the Blumgart pancreaticojejunal anastomosis.Figure 1: Schematic diagram of transpancreatic transverse U-suture technique (this method was created in 1995). (a) Pancreatic stump surface. (b) Intestinal wall. (c) Stent in the pancreatic duct.However, clinical experience has revealed certain drawbacks of the transpancreatic transverse U-suture technique for pancreaticojejunal anastomosis. Specifically, the tension applied during knot tying is challenging to control; excessive tension may cause ischemic necrosis of the pancreatic stump, which can lead to massive hemorrhage or life-threatening pancreatic fistula due to anastomotic dehiscence. To address this limitation, we modified the suturing direction to run parallel to the pancreatic stump, resulting in the transpancreatic longitudinal U-suture technique, which effectively prevents ischemic necrosis at the pancreatic stump (Figure 2).[9] This technique was initially applied using interrupted sutures and is particularly suitable for laparoscopic pancreaticojejunostomy.[10] In 2015, we began employing a continuous U-suture approach with 3–0 or 4–0 atraumatic Prolene sutures for pancreaticojejunal anastomosis.[11] Our team has demonstrated this technique in nearly 200 hospitals across 32 provincial-level administrative regions in China, including major cities such as Beijing, Shanghai, Tianjin, Chongqing, Guangzhou, Hangzhou, and Shenzhen. To date, the technique has been applied in more than 3000 cases. Among these, 193 patients were classified as high risk for pancreatic fistula—defined by a soft pancreas and a main pancreatic duct (MPD) diameter ≤3 mm. Thirty-six patients in the high-risk group did not undergo pancreatic duct stenting as the ducts were too narrow. Among the patients without stent placement, seven (19.4%) developed grade A pancreatic fistula, and no grade B or grade C pancreatic fistula was observed.Figure 2: Schematic diagram of the transpancreatic longitudinal U-suture technique. (a) The needle first enters from the ventral side of the pancreas, passes through the pancreas, and exits from its dorsal side. (b) The needle passes through the seromuscular layer of the jejunal loop and sutures the posterior wall of the jejunal loop. (c) The needle returns, enters from the dorsal side of the pancreas, passes through the pancreas, and exits from its ventral side. (d) The needle passes through the seromuscular layer of the jejunal loop and sutures the anterior wall of the jejunal loop.2. Methods 2.1. Pancreatic transection The pancreatic transection line is created at least 10 mm from the tumor margin. The pancreatic parenchyma is resected using electrocautery or an ultrasonic scalpel, with meticulous attention to hemostasis. A 3- to 5-mm length of the pancreatic stump is mobilized from the surrounding tissue. A plastic tube with a diameter of 2–3 mm is inserted into the main pancreatic duct as a stent and secured with absorbable sutures. When the pancreatic duct is extremely small or cannot be identified, pancreatic duct stenting may not be necessary. The pancreatic stump is sutured using three to five nonabsorbable sutures, either with the mattress technique or with interrupted sutures (Figure 3), to prevent postoperative bleeding from the stump.Figure 3: Management of the pancreatic stump. (a) A plastic tube as the stent is inserted into the pancreatic duct and secured by suturing. (b) Stitches (3–5) are placed at the pancreatic stump using the mattress or interrupted suturing technique.2.2. Preparation of the jejunal loop After pancreaticoduodenectomy, the proximal end of the jejunum is closed. Approximately 40 mm distal to the closed end, an incision is made in the intestinal wall on the antimesenteric side. The incision at the jejunal loop is typically approximately 5 mm in length. 2.3. The transpancreatic continuous U-suture technique for pancreaticojejunal anastomosis The specific steps are as follows (Figure 4). The 3–0 or 4–0 atraumatic vascular Prolene suture is used.Figure 4: Suturing steps. (A) Approximately 10 mm from the pancreatic stump, the needle is inserted from the ventral side toward the dorsal side. (B) The needle then passes through the seromuscular layer of the jejunal loop, suturing the posterior wall from the point proximal to the mesentery to the point distal to the mesentery. (C) At approximately 3–5 mm from the pancreatic stump, the needle is inserted from the dorsal side toward the ventral side. (D) The needle passes through the seromuscular layer of the jejunal loop, suturing the anterior wall from the point distal to the mesentery to the point proximal to the mesentery, thus completing the first U-suture. (E) Continuous suturing of the pancreas and jejunal loop is then performed using the same method (a. entry point on the posterior wall of the jejunal loop; b. exit point on the anterior wall of the jejunal loop). (F) After completion of continuous pancreaticojejunal suturing, the suture is tightened, resulting in invagination of the pancreatic stump into the jejunal loop. (1) Starting at either the inferior or superior margin of the pancreas, the needle is inserted at approximately 10 mm from the pancreatic stump, penetrating the pancreas from the anterior (ventral) side to the posterior (dorsal) side. (2) After the needle exits, the posterior wall of the jejunal loop at the upper end of the jejunal opening is sutured. The needle is inserted at approximately 5–10 mm proximal to the mesentery and exits distal to the mesentery, passing approximately 5–10 mm within the seromuscular layer of the intestinal wall. (3) The needle is then redirected to the pancreas, entering from the posterior (dorsal) side approximately 3–5 mm from the pancreatic stump and exiting from the anterior (ventral) side. The entry points used in steps 1 and 3 lie parallel to each other along the longitudinal axis of the pancreas, spaced approximately 5–10 mm apart. (4) After exiting from the anterior (ventral) side of the pancreas, the needle is used to suture the anterior wall of the jejunum at points mirroring those on the posterior wall. It enters distal to the mesentery and exits proximal to the mesentery, again running approximately 5–10 mm within the seromuscular layer of the intestinal wall. This completes the first U-suture. Following these four steps, continuous transpancreatic running U-sutures are applied to approximate the pancreas to both the anterior and posterior walls of the jejunal loop, progressing toward the inferior or superior margin of the pancreas. The suture is then tied. Notably, during suturing of the superior and inferior pancreatic margins, the surrounding connective and adipose tissues should be incorporated into the suture to prevent tearing of the pancreatic parenchyma during knot tying and to enhance the tensile strength of the anastomosis. Each stitch may be tightened immediately. As the suturing progresses, the pancreatic stump is gradually invaginated into the intestinal lumen. Upon completion of the final stitch, the jejunal wall inverts around the pancreatic stump, fully invaginating it into the small-bowel lumen and achieving an effect equivalent to a two-layer pancreaticojejunal anastomosis (Figure 5).Figure 5: After the suture is tied, the pancreatic stump is invaginated into the intestinal lumen by the inverted cut edges of the jejunal loop. (a) Needle entry points in the pancreas are covered by the intestinal wall. (b) Second layer of the inverted intestinal wall. (c) First layer of the inverted intestinal wall.3. Key points 3.1. Hemostatic suturing of the pancreatic stump This step is critical for preventing delayed bleeding from the pancreatic stump or secondary hemorrhage caused by pancreatic stump necrosis and sloughing. Interrupted sutures are typically used, although mattress sutures may also be employed. When the continuous U-suture technique is used with a small incision in the jejunal loop, the pancreatic stump may not require separate hemostatic suturing (as demonstrated in the video). 3.2. Size of the jejunal loop incision Because intestinal tissue is highly elastic, the incision in the jejunal loop is typically approximately 5 mm. It should not exceed 10 mm to prevent overstretching and creating an excessively large opening. 3.3. Whether complete invagination of the pancreatic stump into the jejunal lumen is necessary Either complete invagination of the pancreatic stump or intussusception of the pancreatic duct and the surrounding stump tissue may be performed. Anatomical variations of the pancreatic duct are common; some patients have an accessory pancreatic duct, in addition to the main duct (Figure 6A). Furthermore, the pancreatic duct branches in a tree-like pattern, with numerous small duct openings at the cut surface of the stump, many of which are extremely fine and difficult to visualize (Figure 6B). If the pancreatic stump—or at least the portion surrounding the main pancreatic duct—is not adequately invaginated into the jejunal lumen, postoperative pancreatic fistula is likely to occur.Figure 6: (A) Intraoperative view of the pancreatic stump (a, main pancreatic duct; b, accessory pancreatic duct). (B) Cast specimen of the pancreatic duct (a, main pancreatic duct at the stump; b, small pancreatic branch ductules at the stump).3.4. Pancreatic parenchymal atrophy or severe fibrosis with dilated main pancreatic duct (>3 mm) In cases where the pancreatic parenchyma is atrophic or severely fibrotic and the main pancreatic duct is relatively large (>3 mm), intussusception of only the main pancreatic duct into the jejunal lumen is sufficient (Figure 7). A jejunal incision of approximately 5 mm is adequate. A pancreatic duct catheter is inserted as a stent and positioned into the jejunal lumen. Pancreatic juice from the small residual surface of the pancreatic stump can be drained into the intestinal lumen through the opening in the jejunal wall. The anastomosis is then completed using the method described above. After tightening the suture, the jejunal wall covers and envelops the pancreatic stump at the intestinal opening, which not only prevents pancreatic fistula but also mitigates the risk of pancreatic stump bleeding.[6,12] In recent years, we have routinely performed pancreaticojejunal anastomosis using this technique in a cumulative total of 2650 cases, achieving excellent outcomes: 97 cases (3.7%) of grade A pancreatic fistula, 22 cases (0.8%) of grade B pancreatic fistula, and no cases of grade C pancreatic fistula or postoperative massive hemorrhage. Using 3–0 or 4–0 atraumatic vascular Prolene sutures can reduce leakage of pancreatic juice through needle holes. In addition, the distance between the needle entry point on the posterior wall of the jejunal loop and the exit point on the anterior wall should correspond to the thickness of the pancreatic stump, typically 20–30 mm (Figure 4E). This spacing ensures that, after suturing and tying, the jejunal wall adequately covers and envelops around the pancreatic stump, sealing the needle holes and preventing leakage of pancreatic juice.Figure 7: Intraoperative views of pancreaticojejunostomy. (A) As indicated by the arrow, the incision on the intestinal wall measures approximately 5 mm. (B) The pancreatic duct stent is inserted into the intestinal lumen, as shown by the arrow. (C) Continuous suturing of the pancreaticojejunal anastomosis. The arrow indicates the pancreatic stump. The needle is entering the seromuscular layer of the intestinal wall. (D) As the suture progresses, the pancreatic stump is gradually invaginated into the intestinal wall. (E) After completion of the continuous U-suture and tying of the suture, the surface of the pancreatic stump surrounding the pancreatic duct, as well as the superior and inferior borders of the stump, are completely covered and enveloped by the intestinal wall, with no visible sutures or needle holes on the pancreas.4. Discussion Pancreatic fistula remains a major challenge in pancreaticoduodenectomy because of its association with substantial morbidity and mortality. The Chen's transpancreatic continuous U-suture technique has been developed and refined over several decades. Its low incidence of postoperative pancreatic fistula may be attributed to several key mechanisms. First, this technique addresses pancreatic leakage originating from accessory pancreatic ducts and the side branches of the pancreatic ductal system. Notably, up to 25% of individuals have an accessory pancreatic duct,[13] and considerable anatomic variation exists in the branching pattern of the pancreatic ducts. By completely invaginating the pancreatic stump into the jejunal lumen, pancreatic secretions from MPD, accessory ducts, and side branches are drained into the intestinal lumen, thereby preventing leakage into the abdominal cavity. Second, the technique employs transpancreatic penetrating sutures, a concept widely accepted in approaches such as the Blumgart method. This feature may reduce the risk of pancreatic fistula because the pancreatic parenchyma is firmly bundled by each suture, decreasing the likelihood of laceration—particularly in patients with a soft, friable gland that is prone to tearing.[14,15] Advocates of transpancreatic suturing note that it minimizes radial stress on the anastomosis and can be performed quickly, both of which contribute to reduced fistula rates.[16] Compared with the Blumgart method—which emphasizes placing sutures widely within the jejunal seromuscular layer away from the pancreas—the Chen technique places broad seromuscular bites on the jejunum to achieve secure imbrication of the pancreatic stump. This approach creates two points of contact between the pancreatic stump and the bowel wall, mitigating excessive suture tension that could otherwise lead to ischemic necrosis of the pancreatic parenchyma (Figures 2 and 5). In addition, the extent of pancreatic remnant mobilization differs: the Blumgart technique typically mobilizes approximately 2 cm of the pancreas, whereas the modified Chen U-suture technique requires only minimal dissection—approximately 3–5 mm superiorly and inferiorly and only 2–3 mm posteriorly. The rationale for this limited dissection is to preserve the pancreatic capsule, which provides structural support and protection to the pancreas. Furthermore, after the needle exits the posterior wall of the pancreas, the bite includes the fibrous tissue between the pancreas and the superior mesenteric vein, along with the jejunal seromuscular layer, effectively eliminating the posterior dead space in the Chen technique. The fibrous tissue at the superior and inferior margins of the pancreas is also incorporated to reinforce tissue strength and reduce the risk of tearing during anastomotic tension. Incorporation of these fibrous tissues additionally helps seal needle tracks in the pancreas and may offer further protection against leakage (Figure 7E). Lastly, the modified Chen U-suture technique requires only a few stitches using a single suture, and no duct-to-mucosa anastomosis is necessary. This principle significantly simplifies the surgical procedure, shortens operative time, reduces the number of needle punctures, and minimizes pancreatic trauma—ultimately contributing to a lower rate of pancreatic fistula. In conclusion, we have detailed the technical aspects and underlying mechanisms of the Chen transpancreatic continuous U-suture technique. We aim to provide surgeons with an additional, effective tool in addressing pancreatic fistula and reducing postoperative complications.