CDCs are a rare disease of bile duct dilation that was first proposed by Vater and Ezler in 1723 . Although cysts are benign lesions, they are closely related to many serious complications, such as malignant bile duct tumors, cholangitis, pancreatitis and intrahepatic bile duct stones [2, 11]. Therefore, surgery should be performed as soon as possible after the diagnosis is clear [12, 13]. Compared with traditional open surgery, laparoscopic CDC surgery has the following advantages [14, 15]: ① Laparoscopy can magnify the tissue 4–8 times, allowing precise separation of the cyst from the surrounding tissues, such as the hepatic artery, portal vein, pancreas and capillary network around the cyst, and thus avoiding side effects. ② Laparoscopy can penetrate into the hepatic hilum for a more accurate operation; meanwhile, bile duct abnormalities, such as labyrinthine bile duct and hepatic stenosis, can be visually detected. ③ Laparoscopic surgery causes less intestinal disturbance and allows faster postoperative intestinal peristalsis recovery. ④ The incision is small and aesthetic, and the pain is mild. The incidence of wound infection and incisional hernia is reduced after this operation. Total laparoscopic surgery, in addition to the above advantages, has the following additional advantages: ① There is almost no interference with the intestinal tract, and the intestinal tract does not need to be exposed outside the abdominal cavity; in theory, this method further reduces the chance of intestinal adhesions. ② The umbilical incision is smaller and more aesthetic, which is more satisfactory according to the needs of children and their families.
In the CLH group, the bowel was pulled out through umbilical incision to complete jejunal end-to-side anastomosis. Intestinal traction and exposure increase the risk of intestinal injury and adhesions in theory. We successfully performed total laparoscopic CDC excision and Roux-en-Y hepaticojejunostomy in 30 children. Compared with the CLH group, the postoperative fasting time and hospitalization duration were significantly shorter in the TLH group. These findings show that the total laparoscopic approach disturbs the bowel less and allows the faster recovery of gastrointestinal function. However, it is worth noting that the hospitalization cost in the TLH group was significantly higher than that in the CLH group, which may be due to the high cost of laparoscopic instruments. With the continuous development of surgical instruments, we believe that in the near future, the cost of laparoscopic instruments will gradually decrease.
The main difference between TLH and CLH is jejunum-to-jejunum anastomosis. We need to pay attention to the following points: ① When the jejunum is cut using an endoscopic stapler, the intestinal tube should be fully flattened to avoid overlap, which could result in insufficient cutting and intestinal fistula. ② A side-hole jejunotomy was created on the antimesenteric border just 0.5 cm from the end of the proximal jejunum, to minimize the occurrence of a "blind pouch". ③ When using an endoscopic cutter stapler for jejunal side-to-side anastomosis, the puncture hole in the intestinal wall need not be large. Its size should be suitable for placement at the end of the stapler to minimize the residual stoma and reduce the operative duration. Meanwhile, side-to-side anastomosis of the jejunum should be arranged in parallel with the mesentery to ensure full contact with the stapler. In the early stage of implementing total laparoscopic surgery, there was one case in which a child underwent jejunal side-to-side anastomosis with an uneven arrangement, resulting in excessive residual anastomosis, increased suture difficulties and a prolonged operation. In this study, the time for jejunal side-to-side anastomosis in the TLH group was longer than the time for jejunal end-to-side anastomosis in the CLH group, but there was no significant difference. We consider that this finding may be related to the learning curve for mastering total laparoscopic surgery.
The most serious complication of laparoscopic choledochal cystectomy is portal vein injury. To avoid portal vein injury, we first freed the distal end of the cyst from the stricture above the pancreas and cut it off; then, we lifted the cyst up and freed it close to the posterior wall of the cyst. This method can also avoid bile leakage in cysts and reduce the chance of abdominal contamination. Li et al  also believed that the cyst should be separated close to the wall of the cyst. Even if the wall of the cyst ruptured, it could be regarded as a "breakthrough point" to identify the cyst and its surrounding tissues and avoid side effects. We separated cysts according to this method without any instances of portal vein injury or blood transfusions required during the operation. There was no significant difference in intraoperative blood loss between the two groups.
Postoperative complications of laparoscopic CDC excision include pancreatitis , pancreatic fistula , cholangitis , biliary fistula and intestinal obstruction . In this study, one child in the TLH group required reoperation because the distal biliary jejunum herniated from the transverse mesocolic hiatus and compressed the proximal biliary loops, resulting in obstruction and necrosis. The transverse mesocolon and gastrocolonic ligament are often thicker in older children with CDCs complicated with repeated infection; thus, we suggest that after establishing a retrocolonic tunnel to cross the transverse mesocolon, the gastrocolonic ligament should be fully separated at the same time so that the intestinal tube can pass smoothly. Subsequently, the hepatic limb jejunal and transverse mesocolon should be sutured intermittently for 3 to 4 needles to avoid obstruction caused by intestinal hernia. In the TLH group, one child developed a postoperative pancreatic fistula and needed reoperation to retain the abdominal drainage tube. We considered the pancreatic fistula to have been caused by too deep of an operating position when the distal end of the cyst was separated, resulting in damage to the pancreatic duct. Li et al.  believed that in children with cystic dilatation, not ligating the distal stump is a feasible approach and may minimize pancreatic duct injury.
The limitations of this study are that the number of cases is small, and follow-up period is short. The long-term effect in the two groups needs further study.