Choledochal Cysts

Congenital cystic dilation of extrahepatic or intrahepatic bile duct.

Q44.4 Choledochal cyst

Congenital choledochal cysts are rare, and are seen in approximately 1 in 100,000-150,000 live births in western populations. The incidence is notably higher in patients of East Asian ancestry with a reported rate of 1 in 1,000. Approximately two thirds of the cases occur in Japan.^1,2 The female:male ratio is approximately 3:1 to 4:1.³

The etiology of choledochal cysts is still unknown, however there are several hypotheses that are postulated. The most popular theory suggests abnormal pancreatico-biliary duct junction. This theory postulates that the long common channel allows mixing of the pancreatic and biliary secretions leading to lysis and dilation of biliary duct via active enzymes.⁵ Due to increasing numbers of prenatally diagnosed choledochal cysts⁶, there is also a theory which suggests that embryologic overproliferation of epithelial cells results in dilation during the cannulation period of development. Obstruction and dilatation of the biliary duct causes inflammation and biliary tract epithelium damage. Chronic inflammation causes increased ductal pressure which results in ductal and liver damage. If untreated, this process can lead to cholestasis, biliary cirrhosis and liver failure. Congenital choledochal cysts are a precursor to cholangiocarcinoma with an overall risk of 10-15% as a result of chronic inflammation. The risk of cancer increases with age.⁴

Choledochal cysts are pathologically classified into five types. Type I is the most common type, accounting for 48-84% of cases. Type I is a dilation of the common bile duct alone without involvement of the intrahepatic ducts. Typically, the common hepatic duct proximal to the cyst remains normal.⁷ Type I can be further classified into three different subtypes. Type IA describes distinct cystic dilation of the entire extrahepatic duct. Type IB is a dilation of only a segment of the extra hepatic bile duct without pancreaticobiliary malunion.² Type IC consists of a smooth fusiform dilation of the entire extrahepatic bile duct with abnormal pancreaticobiliary duct junction. Type II includes a focal diverticulum of the CBD, whereas type III is a small diverticulum of the CBD involving only the intraduodenal portion of the duct. Type III is also referred to as a choledochocele.⁸ Type IV refers to multiple cysts, and can be further subdivided into IVA and IVB ⁸. Type IVA consists of multiple intrahepatic and extrahepatic cysts and IVB consists of multiple dilation of only extrahepatic ducts which is also described as a ‘string of beads.’² Finally, type V includes dilation of intrahepatic ducts with normal common bile duct.⁸. Type V is also termed Caroli disease and called Caroli syndrome if the intrahepatic cystic dilations are associated with congenital hepatic fibrosis.² These distinct entities are clinically relevant for repair, but difficult to evaluate prenatally.

A congenital choledochal cyst is most commonly an isolated single abnormality.⁹ However, they can be associated with many different developmental anomalies including:

• Colonic atresia
• Duodenal atresia
• Imperforate anus
• Pancreatic arteriovenous malformation
• Multiseptate gallbladder
• OMENS plus syndrome
• Ventricular septal defect
• Aortic hypoplasia
• Pancreatic divisum
• Pancreatic aplasia 
• Focal nodular hyperplasia
• cCongenital absence of portal vein
• Heterotopic pancreatic tissue
• Familial adenomatous polyposis

Congenital choledochal cysts are a rare pancreaticobiliary duct malformation with only postulated etiologies and thus are not known to have a definitive recurrence risk greater than the baseline risk. There have been several reports of familial cases of some subtypes, which has led to some speculation of X-linked dominant trait or autosomal dominant trait with relatively low penetrance.¹⁰ However because of the rarity of the disease this remains in question.

Prenatal ultrasonographic diagnosis of congenital choledochal cysts has been made as early as 15 weeks of gestational age, however the typical choledochal cyst is identified at an average of 26.9 weeks.^{11, 12} The most common ultrasonographic finding is an anechoic cyst in the right upper quadrant/upper abdomen, in close proximity to the gall bladder but separate from it, and is identified using colour Doppler to show the cyst’s relationship to the hepatic veins, umbilical vein and porta hepatis.¹³ Demonstrating short, tubular bile ducts entering the cystic mass is diagnostic.⁹ 

The differential diagnoses of choledochal cysts include:

• Duodenal duplication cyst
• Simple cyst of the liver 
• Omental or menseteric cyst
• Ovarian cyst
• Adrenal cyst 
• Renal cyst 
• Dilated intestinal loops 
• Gallbladder duplication 
• Hydronephrosis
• Congenital biliary atresia (absent gall bladder)⁹ 

Currently, there is no screening for congenital choledochal cysts. However, diagnosis can be made prenatally during routine obstetrical ultrasonography when a cystic mass is identified in the right upper quadrant of the fetal abdomen. Most importantly, a thorough evaluation for biliary atresia should be undertaken because this has a different prognosis. Existence of concurrent anomalies and biliary atresia is indicative of worse prognosis. Although MRI or three-dimensional ultrasound may be helpful in prenatal diagnosis, two-dimensional ultrasound is adequate in most cases. Prenatal diagnosis of choledochal cysts is essential to establishing prenatal surveillance as well as planning neonatal evaluation before birth and referral to tertiary centers for surgical treatment. Earlier diagnosis that leads to surgical repair at early stages results in fewer complications and better prognosis.

Untreated congenital choledochal cysts have potential risks of ascending cholangitis, cyst rupture, feeding difficulty, vomiting or obstruction of gastrointestinal tract.¹⁴ Delayed surgical interventions can cause obstructive jaundice, liver damage, fibrosis and cirrhosis. Early neonatal surgical treatment of choledochal cysts diagnosed prenatally is safe and effective with good outcomes post-operatively.¹⁴

Reevaluation of the size of the cyst is recommended with ultrasound in the third trimester. Antepartum testing can be considered beginning at 36 weeks of gestation. Antenatal consultation with a maternal fetal medicine specialist and a pediatric surgeon is helpful to plan the management and postnatal follow-up.⁹ Surgical treatment with Roux-en-Y hepaticojeunostomy is done after birth. Timing of the surgery is at the discretion of the pediatric surgeons, and depends on the clinical status of the neonate. Typically, surgery is performed before 6 months of age.¹⁵

1. O'Neill JA, Jr. Choledochal cyst. Current problems in surgery. 1992;29(6):361-410.

2. Singham J, Yoshida EM, Scudamore CH. Choledochal cysts: part 1 of 3: classification and pathogenesis. Can J Surg. 2009;52(5):434-40.

3. González Ruiz Y, Bragagnini Rodriguez P, Fernández Atuán RL, Álvarez García N, Siles Hinojosa A, González Martínez-Pardo N, et al. Prenatal diagnosis of a giant choledochal cyst. Journal of Pediatric Surgery Case Reports. 2016;4:1-3.

4. Shimotakahara A, Yamataka A, Yanai T, Kobayashi H, Okazaki T, Lane GJ, et al. Roux-en-Y hepaticojejunostomy or hepaticoduodenostomy for biliary reconstruction during the surgical treatment of choledochal cyst: which is better? Pediatric surgery international. 2005;21(1):5-7.

5. Babbitt DP, Starshak RJ, Clemett AR. Choledochal cyst: a concept of etiology. The American journal of roentgenology, radium therapy, and nuclear medicine. 1973;119(1):57-62.

6. Schroeder D, Smith L, Prain HC. Antenatal diagnosis of choledochal cyst at 15 weeks' gestation: etiologic implications and management. Journal of pediatric surgery. 1989;24(9):936-8.

7. Todani T, Watanabe Y, Toki A, Morotomi Y. Classification of congenital biliary cystic disease: special reference to type Ic and IVA cysts with primary ductal stricture. J Hepatobiliary Pancreat Surg. 2003;10(5):340-4.

8. Todani T, Watanabe Y, Narusue M, Tabuchi K, Okajima K. Congenital bile duct cysts: Classification, operative procedures, and review of thirty-seven cases including cancer arising from choledochal cyst. Am J Surg. 1977;134(2):263-9.

9. Weng R, Hu W, Cai S, Guo X, Luo Q. Prenatal diagnosis and prognosis assessment of congenital choledochal cyst in 21 cases. Journal of obstetrics and gynaecology : the journal of the Institute of Obstetrics and Gynaecology. 2016;36(3):324-7.

10. Iwasaki J, Ogura Y, Nakagawa S, Kato K, Kondo A, Shiraki K. Familial occurrence of congenital bile duct dilatation. World J Gastroenterol. 2008;14(6):941-3.

11. Benhidjeb T, Chaoui R, Kalache K, Mau H, Muller JM. Prenatal diagnosis of a choledochal cyst: a case report and review of the literature. American journal of perinatology. 1996;13(4):207-10.

12. Lugo-Vicente HL. Prenatally diagnosed choledochal cysts: observation or early surgery? Journal of pediatric surgery. 1995;30(9):1288-90.

13. Howell CG, Templeton JM, Weiner S, Glassman M, Betts JM, Witzleben CL. Antenatal diagnosis and early surgery for choledochal cyst. Journal of pediatric surgery. 1983;18(4):387-93.

14. Diao M, Li L, Cheng W. Timing of surgery for prenatally diagnosed asymptomatic choledochal cysts: a prospective randomized study. Journal of pediatric surgery. 2012;47(3):506-12.

15. Lee IH, Kim GJ. Fetal choledochal cyst diagnosed at 22 weeks of gestation by three-dimensional ultrasonography: a case report. Journal of Korean medical science. 2008;23(5):909-11.

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