CHAPTER 24 Choledochal Cysts
Step 1: Surgical Anatomy
♦ The anatomic configurations of a CdC were first classified by Alonso-Lej and colleagues and subsequently modified by Todani and colleagues into five subtypes (Fig. 24-1).
Types II, III, and V choledochal cysts are rare variants.
Types II, III, and V choledochal cysts are rare variants.
• A type II CdC is a diverticulum arising from the wall of the bile duct. This abnormality is thought to occur because of a localized weakness in a segment of the common bile duct.
Step 2: Preoperative Considerations
Presentation
♦ Classically a patient presents with abdominal pain, jaundice, and a right upper quadrant mass; however, rarely are all three present at diagnosis.
♦ Some patients are diagnosed with cholangitis when they present with Charcot triad: jaundice, fever, and right upper quadrant pain.
♦ Others have recurrent episodes of pancreatitis as a result of sludge within a CdC, which causes intermittent obstruction of the pancreatic duct.
♦ A giant CdC can spontaneously perforate. Because bile causes chemical peritonitis, these patients require urgent care.
Diagnosis
♦ Laboratory studies performed in patients with a CdC are often normal. Serum conjugated and unconjugated bilirubin and hepatocellular transaminase levels are within normal limits unless the patient has cholangitis or has developed cirrhosis. In patients who present with pancreatitis, serum amylase levels may be elevated.
♦ Cross-sectional imaging of the abdomen is necessary to define the anatomic configuration of a choledochal cyst. Computerized tomography or magnetic resonance imaging should be used to define the anatomic extent of disease. Hepatobiliary scintigraphy (HIDA) scan is helpful to determine patency of the biliary tract. On occasion, endoscopic retrograde cholangiopancreatography (ERCP) or, more recently, magnetic resonance cholangiopancreatography may be helpful to define anatomy more clearly, especially in cases in which the cyst size is small.
Treatment Strategy
♦ Treatment of a CdC is essential because it will cause recurrent episodes of cholangitis and may cause the development of biliary cirrhosis or evolve into a cholangiocarcinoma. All of these patients will require surgical intervention, but the type of procedure performed varies according to the subtype of CdC diagnosed. For a patient who presents with cholangitis or acute pancreatitis, surgical intervention is delayed until the inflammatory process has resolved.
Step 3: Operative Steps
Types I and IV Choledochal Cyst
♦ A right subcostal incision is used to enter the peritoneal cavity. If necessary, the incision is extended across the midline.
♦ An intraoperative cholangiogram performed through the gallbladder is helpful to determine where the proper hepatic duct appears normal and where the pancreatic duct joins the biliary tract (Fig. 24-2).
♦ If possible, the common duct is circumferentially mobilized, which allows the application of traction to the CdC, during which identification of the hepatic artery and portal vein can be performed.
♦ In cases in which the size of the CdC distorts the hilar anatomy, decompression of the cyst will facilitate safer dissection (Fig. 24-3).
♦ Dissection should proceed distally until the duct narrows to normal caliber where the cyst can be divided. The CdC will often extend into the head of the pancreas. Although it is rare for it to extend to the junction of the pancreatic duct, care must be taken to avoid injury to the pancreatic duct (see Fig. 24-2).
♦ Superiorly applied traction to the cyst and close adherence to the wall of the CdC allow for safe dissection. Complete resection of the cyst is important because its division at the superior edge of the duodenum may leave residual cyst wall in the head of the pancreas, which could lead to a recurrence or a future malignancy. Once the neck of the cyst is defined, ligation at its base using a nonabsorbable suture is performed.
♦ The proximal dissection in a type I cyst carries up the common hepatic duct to where its caliber appears normal and it is divided (Fig. 24-4). For a type IV cyst, we have found that the intrahepatic duct dilatation has resolved after the abnormal common bile duct has been removed. Because of this, we divide a type IV cyst just distal to the confluence of the right and left proper hepatic ducts. If the mucosa appears abnormal, we perform a frozen-section biopsy at the line of division to ensure that the biliary epithelium is intact. If the mucosa appears histologically normal, a hepaticojejunostomy is performed at this level. If the mucosa is abnormal, more proximal dissection must be undertaken.
♦ Biliary drainage is achieved by an end-to-side hepaticojejunostomy into a 40- to 45-cm limb of a Roux-en-Y brought to the hilum in a retrocolic position (Fig. 24-5). A mucosa-to-mucosa anastomosis is important because it limits the likelihood of a stricture in the postoperative period. We perform a single-layer interrupted anastomosis using absorbable suture to complete the hepaticojejunostomy. Sutures are placed such that all the knots lie in an extraluminal position, thereby reducing the likelihood of choledocholithiasis. Anchoring sutures from the Roux to tissue around the bile duct are placed to decrease tension on the anastomosis. In cases where the cyst extends up to the confluence of the right and left hepatic duct, we spatulate the lateral wall of both ducts, creating a larger-diameter opening that allows for a wide anastomosis.
Type II Choledochal Cyst
Type III Choledochal Cyst
♦ For patients with a type III choledochal cyst, the recommendations for treatment vary according to the type of epithelium found within the CdC. An ERCP should be performed before surgical intervention. At the time of ERCP, biopsy of the mucosa lining the cyst should be performed. If the biopsy reveals mucosa of duodenal origin, the lesion can be treated by a sphincterotomy or meatotomy to enlarge the opening and to relieve the obstruction. This can be done endoscopically or with open surgery.
♦ In cases where the epithelium lining the lesion appears to be of biliary tract origin, excision of the cyst with reimplantation of both the bile duct and the pancreatic duct has been recommended. Here again, it is essential to excise all of the biliary epithelium so as to minimize the likelihood of the development of a cholangiocarcinoma.
Step 4: Postoperative Care
♦ Suppressive antibiotics are started and maintained for at least 6 months. If no episodes of cholangitis occur during the 6-month period, antibiotics are discontinued.
♦ The use of ursodeoxycholic acid (Actigall) may be beneficial in the perioperative period, but if no complications arise, it can be discontinued.
Step 5: Pearls and Pitfalls
♦ In infants with a prenatal diagnosis of a cystic anomaly in the hilum of the liver, patency of the extrahepatic biliary tree needs to be determined in the first weeks of life. If the child passes pigmented stool, no further study is necessary. If it is unclear, an HIDA scan is obtained in the first few weeks of life.
♦ If the scan reveals uptake into the liver but no excretion into the gastrointestinal tract, surgical intervention is performed in the first few weeks of life. This is to avoid a delay if the child has biliary atresia. If the HIDA scan reveals flow into the gastrointestinal tract, operative intervention is performed when the child is between 3 and 4 months of age, which allows the infant time to grow but minimizes the likelihood of an episode of cholangitis. Intervention before the onset of cholangitis reduces the amount of inflammation found within the hilum, which makes the technical aspects of dissection less difficult.
♦ In patients who have a longstanding CdC, recurrent bouts of cholangitis may cause significant inflammation throughout the hilum. The biliary epithelium within a cyst may be significantly damaged, resulting in marked metaplasia or may have progressed to a cholangiocarcinoma. In some cases the epithelium is replaced by granulation tissue and fibrosis. Dissection around the choledochal cyst may be difficult, creating the potential for injury to the hepatic artery or the portal vein. In this circumstance, the CdC may be opened longitudinally and the mucosa of the cyst excised from within (Fig. 24-6). The posterior remnant of the cyst wall is left in place, minimizing the likelihood of injury to hilar structures. Here again, it is important to excise all of the cyst mucosa because of the risk of the development of a cholangiocarcinoma in the abnormal biliary epithelium left behind. Dissection is carried distally until the cyst narrows to normal caliber, where it is sewn over.
♦ In patients who have a perforated CdC, the first step is to control the biliary ascites. Suitable drainage can be achieved through operative placement or by interventional radiographic techniques. Percutaneous transhepatic biliary drainage assists in controlling the leak and defines the cyst anatomy. Only after suitable control of the biliary leak and the treatment of accompanying sepsis have been achieved should operative resection and reconstruction be undertaken.
♦ Some surgeons have recommended the placement of an “anti-reflux” valve in the Roux to reduce the incidence of postoperative cholangitis. The key to avoiding cholangitis is good biliary drainage. The placement of these “anti-reflux” valves may actually slow biliary drainage; therefore we have not performed these anti-reflux measures and have found that the incidence of cholangitis is rare.
♦ Recently minimally invasive surgical techniques have been applied to the treatment of choledochal cysts. If a laparoscopic approach is used, complete cyst excision should still be performed. We dissect the cyst into the head of the pancreas, where it tapers to a normal caliber and only then divide the cyst. If a choledochal cyst is divided at the superior edge of the duodenum, residual cyst epithelium left within the head of the pancreas could lead to cyst recurrence or, because of its malignant potential, a cholangiocarcinoma.
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