Pediatric Choledochal Cyst Surgery 

Updated: Mar 22, 2018
Author: Gail E Besner, MD; Chief Editor: Harsh Grewal, MD, FACS, FAAP 

Overview

Background

Cystic dilatation of the common bile duct (CBD), also known as choledochal cyst, is a fairly uncommon anomaly of the biliary tract. Although it was first described by Vater and Ezler in 1723, Douglas published the first complete clinical description of the anomaly in a patient in 1853. He speculated about the congenital nature of this anomaly.

In 1959, Alonso-Lej et al published an extensive review of 94 cases in the literature and added two cases of their own.[1] They classified choledochal cysts into three types. In 1977, Todani et al further classified this anomaly into five types.[2] Subsequent subtypes based on cholangiographic findings have been described.

With the use of antenatal ultrasonography, an increasing number of choledochal cysts have been reported in the fetus.[3, 4, 5, 6, 7, 8, 9]  Incomplete gastric obstruction by a large cyst is one of the typical clinical manifestations in newborns and young infants.[10]  The earliest reported choledochal cyst was detected in a fetus at 15 weeks' gestation, which may correspond to the timing of the formation of pancreatic enzymes.

Antenatal demonstration of a cystic structure inferior to the liver strongly suggests the diagnosis. Fetal development should be carefully monitored with serial ultrasonography after such a discovery. Most centers prefer to excise the cyst shortly after birth. A waiting period of a few weeks is necessary to stabilize the baby and allow for proper preoperative evaluation.[11]  Surgical excision in the neonatal period has been shown to be technically feasible and well tolerated by the patient.

The management of choledochal cysts has evolved during the past several decades.[12] Complete excision of the cyst and biliary bypass have become the treatment of choice. Other procedures, such as cystoduodenostomy or cystojejunostomy, have been associated with high morbidity and the potential for malignant transformation in the residual cyst. Even after complete excision, sporadic cases of cancer in the remaining biliary tree have been reported.

Anatomy

Regarding the anatomic classification of choledochal cyst, in 1977, Todani et al modified the classic Alonso-Lej classification by adding two new types (types IV and V).[2] Others have subsequently added further subtypes (see the image below). The types are as follows:

  • Type I - Cystic or fusiform dilatation of the common bile duct (CBD); most frequent type (90-95% of the cases).
  • Type II - Diverticulum of the CBD, with normal size CBD
  • Type III - Choledochocele, a cystic dilatation of the distal intramural portion of the CBD, typically protruding into the second portion of the duodenum
  • Type IV - Cystic or fusiform dilatation of the CBD associated with cystic, fusiform, or saccular dilatation of intrahepatic bile ducts, also termed form fruste
  • Type V - Cystic, fusiform, or saccular dilatation of the intrahepatic bile ducts associated with a normal CBD; may be associated with hepatic fibrosis (referred to as Caroli disease)
Todani classification of the 5 types of choledocha Todani classification of the 5 types of choledochal cysts.

Pathophysiology

Pathogenesis

The exact cause of choledochal cyst remains obscure. Many authors believe that they are congenital because most of the cysts are diagnosed in infants and children. However, because approximately 20% are diagnosed in adults, including elderly patients, several theories have been postulated, as follows[5, 13] :

  • Weakness of the wall of the bile duct [14, 15, 16]
  • Obstruction of the distal choledochus [17]
  • Combination of obstruction and weakness [18]
  • Reflux of pancreatic enzymes into the CBD secondary to an anomaly of the pancreaticobiliary junction [14, 19, 20, 21, 22, 23]

In 1969, Babbitt et al carefully analyzed the cholangiograms of patients with choledochal cysts and found many with an anomaly of the pancreaticobiliary junction.[24] In these patients, a small distal CBD entered the pancreatic duct at 2-3.5 cm from the ampulla of Vater, whereas the normal common channel is 5 mm or less. This may represent failure of normal separation of these two ducts during embryologic development. This proximal junction precludes the proper functioning of the sphincter of Oddi. The pressure in the pancreatic duct (30-50 cm H2O) exceeds the pressure in the CBD (25-30 cm H2O) favoring reflux of pancreatic secretions into the CBD.

Babbitt et al also noted a high amylase content in the fluid from the cysts. The reflux of pancreatic juice could lead to weakness and dissolution of the wall of the CBD (see the image below).

Anomalous pancreaticobiliary ductal system theory Anomalous pancreaticobiliary ductal system theory of choledochal cyst etiology. From Babbitt DP. [Congenital choledochal cysts: new etiological concept based on anomalous relationships of the common bile duct and pancreatic bulb]. Ann Radiol (Paris). 1969;12(3):231-40.

Experimental support for this concept was reported in 1974 by Kato et al, who anastomosed the main pancreatic duct to the gallbladder in dogs.[18] Within 9 days after the anastomosis, all the tested animals had varying degrees of dilatation of the CBD, with edematous changes of the CBD wall. They concluded that proteolytic enzymes were responsible for the damage.

In 1977, Spitz supported the concept of distal CBD obstruction as a cause of choledochal cyst when he demonstrated bile duct dilatation in lambs by means of ligation of the duct near the duodenum.[17] However, the same experiment failed to reproduce dilatation of the bile duct in mature sheep.

Miyano et al (1981) established an experimental model of an anomalous choledochopancreatic ductal junction by creating a choledochopancreatic end-to-side ductal anastomosis in puppies.[25] They successfully reproduced the dilatation of the CBD in all experimental animals without exception.

In 1984, Todani et al conducted an analysis of endoscopic retrograde cholangiopancreatograms and other cholangiograms and confirmed this long common-channel anomaly.[26] The anomaly was found in most patients. Other authors have reported the same findings in their series.[27, 19, 20, 21, 28] Reflux of pancreatic enzymes into the CBD can happen early in life, even in fetal life, resulting in damage to the ductal wall. The distal portion of the CBD is most at risk, and with repeated irritation, it can become stenotic.

All of these theories are applicable to choledochal cyst type I, III, and IV anomalies, but they cannot be used to explain type II and V choledochal cysts in which the CBD is normal. Perhaps genetic factors play a role.[16, 29, 30] Despite this, the two most accepted theories are still reflux of pancreatic enzymes into the CBD secondary to an anomalous pancreaticobiliary junction and obstruction of the distal CBD.

Pathologic features

Grossly, the size of a type I choledochal cyst widely varies.[16, 27, 31, 32, 5, 33, 34, 35] The cysts contain a few hundred milliliters of bilious fluid that is rich in pancreatic enzymes. The cyst wall thickness also varies, ranging from very thin to a few millimeters in thickness.

In type IV and V anomalies, intrahepatic cysts can be fusiform or saccular and are in continuity with the CBD. Dilatation of the proximal common duct is frequent, particularly just proximal to the long common channel. Sludge and stones are sometimes present within the cyst.[16, 29] The bile duct distal to the cyst is usually stenotic. The liver may have variable degrees of fibrosis or established cirrhosis with portal hypertension. Histologic studies of the wall of choledochal cysts show dense fibrous connective tissue with inflammation and ulceration of the mucosa and submucosal layers (see the image below).

Photomicrograph shows the cyst wall, with inflamma Photomicrograph shows the cyst wall, with inflammation and ulceration of the mucosa and submucosa.

The inflammation is significantly less in younger patients than in older children in whom chronic inflammatory changes abound.[29, 28, 36, 37, 35] With severe inflammation, only a relatively thin and fragmented lining, rather than the typical biliary mucosa, is observed lining the cyst. Intramucosal glandular structures are frequently observed; this suggests epithelial metaplasia secondary to repeated destruction and regrowth of the lining of the cyst. Inflammation has been noted to be more severe in intrahepatic cysts than in extrahepatic cysts.

Carcinoma arising in a choledochal cyst wall or remaining biliary tree after complete cyst excision is well recognized.[38] Malignancy is believed to be the result of chronic inflammation and metaplasia (see the image below). The typical malignancy is adenosquamous carcinoma or occasional cases of small cell carcinoma.

Media file shows the wall of the cyst, with inflam Media file shows the wall of the cyst, with inflammation and metaplasia.

Epidemiology

Population prevalence estimates of choledochal cysts range from approximately 1 case in 13,000 people to 1 case in 2 million people. Cystic diseases of the bile duct are more common in Japan and Asia.[16] In an extensive review published in 1980, Yamaguchi et al reviewed 1433 cases from the literature; of these, 1204 (more than two thirds) were from Japan.[39]

In all reported series, the most frequent type of choledochal cyst is type I (see the image below and Anatomy). In types I and IV choledochal cysts (fusiform dilation of the CBD without or with dilated intrahepatic ducts, respectively), the female-to-male ratio is roughly 4:1. However, in types II (diverticulum of the CBD), III (choledochocele), and V (dilation of intrahepatic ducts only), the cysts occur with equal frequency in both sexes.

Todani classification of the 5 types of choledocha Todani classification of the 5 types of choledochal cysts.

Choledochal cysts can occur in persons of any age. Two thirds of the cysts are diagnosed before the patient is aged 10 years.[31, 32, 13] Approximately 20% of cysts are diagnosed in much older patients.[5, 21, 34] In rare cases, choledochal cysts have been detected at prenatal ultrasonography as early as 15 weeks' gestation.

 

Presentation

History and Physical Examination

Two distinct clinical groups of patients are recognized with regard to age at presentation.[32, 13, 5, 35, 36, 37]  The first group is the infantile group consisting of babies younger than 1 year, with or without obvious hepatomegaly, with obstructive jaundice and acholic stools. This clinical picture is indistinguishable from that of biliary atresia in the absence of a palpable mass in the right side of the abdomen. However, the cystic mass can usually be detected either at clinical examination or on ultrasonography; this finding suggests a diagnosis of choledochal cyst.

In 1995, Todani et al found that 26 of 28 infants younger than 1 year had a mass, whereas only three of eight infants aged 13-24 months had a mass.[35] Other symptoms, such as vomiting, fever, and abdominal pain with hyperamylasemia are extremely infrequent.[34] In infants with a prenatal diagnosis of choledochal cyst, jaundice often does not manifest until 1-3 weeks after birth.[40, 41]

In contrast, infants older than 1 year, with the so-called adult form of choledochal cyst, generally have one or more components of the classic triad: pain, jaundice, and a palpable mass. The entire triad is present in fewer than 30% of patients.[13] Jaundice is intermittent and often associated with vague abdominal pain. The pain has been described as being similar to that of cholangitis or recurrent mild pancreatitis. Undiagnosed choledochal cysts can lead to choledocholithiasis, cirrhosis with portal hypertension, cyst rupture, or biliary carcinomas.

 

Workup

Laboratory Studies

Laboratory studies that may be useful for the diagnosis and preoperative evaluation of a patient with a choledochal cyst include direct bilirubin, alkaline phosphatase, serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), and coagulation profiles. A complete blood count (CBC) should also be obtained to exclude any associated or underlying anemia prior to surgery.

Imaging Studies

Imaging studies are the cornerstone of diagnosis of choledochal cysts. They serve not only to confirm the diagnosis but also to outline the anatomy of the anomaly in preparation for surgical intervention.

Ultrasonography

Ultrasonography is the best initial study.[39] In neonates, it may be the only test needed. Ultrasonography can demonstrate changes in the bile ducts as well as in the liver (see the image below).

Ultrasonogram shows a large unilocular cyst under Ultrasonogram shows a large unilocular cyst under the liver.

Endoscopic retrograde cholangiopancreatography

Endoscopic retrograde cholangiopancreatography (ERCP) remains the criterion standard diagnostic study. In expert hands, ERCP can be performed with a high rate of success, even in small infants. When successful, ERCP clearly shows the anatomy of the pancreaticobiliary junction.[31, 27, 2, 22] With forceful injection of contrast even small choledochoceles can be imaged, presumably by distension of the cyst wall.

Magnetic resonance cholangiopancreatography

Magnetic resonance cholangiopancreatography (MRCP) has largely supplanted ERCP as the diagnostic test of choice for choledochal cysts because it offers high resolution detailed images of relevant anatomy, is noninvasive, and does not suffer from complications such as postprocedure pancreatitis (see the image below).[42] MRCP detects most choledochal cysts with sensitivities from 90-100% and specificities from 73-100%, with the exception of small choledochoceles and minor ductal anomalies.[43, 44] MRCP has been shown to be effective in neonates,[45] children,[46] adults,[47] and fetuses.[48]

Magnetic resonance cholangiopancreatography shows Magnetic resonance cholangiopancreatography shows dilated hepatic ducts and common bile duct (CBD) of a type IV cyst.

Computed tomography

Computed tomography (CT) may also be useful to delineate the cyst and its relationship to surrounding structures. In older patients, especially adults, CT combined with cholangiography may be useful (see the image below).[49]

CT scan shows a large cyst with wall thickening. CT scan shows a large cyst with wall thickening.

Other studies

Upper gastrointestinal imaging and cholangiography with oral or intravenous contrast enhancement are of limited value in the setting of hyperbilirubinemia and are generally outdated.

Scintigraphy with technetium-99m diisopropyl iminodiacetic acid (DISIDA) may show complete obstruction of the distal bile duct without any drainage to the intestine.[5, 13]

 

Treatment

Approach Considerations

Total excision of the cyst with adequate bile drainage is the standard treatment for choledochal cyst.[50] However, in the setting of extensive inflammation, a cyst mucosectomy and cystoenterostomy can be performed.

The treatment of choledochal cyst is typically complete surgical excision at the time of presentation, with the exception of type V (multiple intrahepatic cysts) which may benefit from conservative therapy including percutaneous drainage and medical management.

Surgical Therapy

Treatment of choledochal cysts is surgical, except for type V multiple intrahepatic cysts, which can benefit from medical management for variable periods of time.

In the past, operative aspiration and external drainage were used extensively because most patients were quite sick, and a simple quick procedure was convenient. These external drainage procedures of the biliary tree were unsuccessful because of numerous complications, including repeated cholangitis and biliary fistulae. Mortality was high.[16, 51, 52, 31, 5, 13] Today, in the setting of acute severe disease, percutaneous cholecystostomy drainage can be performed before the definitive procedure. This is safe and generally well tolerated; however, it is not necessary in most patients.

Internal drainage, either with cystoduodenostomy or cystojejunostomy with Roux-en-Y biliary reconstruction, was used in the past. These procedures left the cyst behind, and the free reflux of pancreatic enzymes into the cyst via the anomalous pancreaticobiliary junction resulted in a high incidence of calculi, recurrent cholangitis, anastomotic strictures, and carcinoma arising from the cyst.[12] Of patients treated with either cystoduodenostomy or cystojejunostomy, 65% remained symptomatic, and 40% required repeat surgery at a later date.[53, 54] Recurrent cholangitis and chronic inflammation in the remaining cyst eventually produces metaplasia that leads to malignant transformation.

Total excision of the cyst in types I, II, and IV followed by reconstruction of the biliary tree with hepaticojejunostomy in a Roux-en-Y fashion has been widely accepted as the procedure of choice in treating choledochal cysts and has been found to be superior to hepaticoduodenostomy.[55] This procedure implies excision of the distal common bile duct (CBD). Consequently, it blocks the reflux of pancreatic enzymes into the biliary tract, thereby decreasing the incidence of carcinoma of the bile duct.

Total excision of the cyst is possible in virtually all infants and young children. In older patients with repeated cholangitis and marked pericystic inflammation, this disease may be best managed with resection of the anterolateral part of the cyst followed by an endocystic resection of the lining, leaving the back wall adjacent to the portal vein in place, as reported by Lilly in 1977.[56] This technique also appears to be most useful in patients who have previously undergone cystoenterostomy and who require repeat surgery because of recurrent cholangitis. This technique makes the dissection less hazardous.

Several groups have successfully performed laparoscopic-assisted and laparoscopic total cyst excision with Roux-en-Y hepatoenterostomy with complication rates comparable to those of the open procedure.[57] Li et al performed laparoscopic cyst excision with laparoscopic-assisted Roux-en-Y hepatoenterostomy in 35 children (33 cyst type, two fusiform) without conversion to the open procedure and with postoperative stays of 3-5 days.[58, 59, 60] The procedure is described in detail for both choledochal cyst and biliary atresia surgery by Martinez-Ferro et al (2005).[61] Liuming et al[62] and Liem et al[63] also concluded that laparoscopic excision was as safe as open excision.

Intraoperative cholangiography obtained via puncture of the cyst or via the gallbladder is always obtained. It outlines the exact anatomy of the choledochal cyst and its relationship with the pancreas. Cholecystectomy is routinely performed at the same time.

Biliary reconstruction can be performed with a Roux-en-Y hepaticojejunostomy as high as possible, near the hilum of the liver.[64, 52, 31, 29] Some authors, including Raffensperger and Shamberger, have interposed a reversed segment of jejunum to prevent reflux.[65, 66, 8] This idea has not been universally accepted. No stents are routinely necessary.

With regard to type II choledochal cysts, a simple excision of the diverticulum with ductoplasty for reconstruction of the CBD is all that is required. Laparoscopic excision has been successfully performed in this rather rare disease.[67, 68]

With type III choledochal cysts, the general approach is one of lateral duodenotomy with unroofing of the choledochocele to drain the bile duct and pancreatic duct directly into the duodenum. The two ductal openings should be carefully examined to determine whether ductoplasty is required.[52, 27, 69]

In patients with type IV choledochal cysts with intrahepatic cysts, each case is individually evaluated, and the principle of adequate bile drainage is taken into account. Excision of the dilated extrahepatic bile ducts as far as the porta hepatis, with hepaticojejunostomy at the level of the hilum, may provide good biliary drainage and effective decompression of the intrahepatic cysts. If the intrahepatic cysts are localized in a small portion of the liver, partial hepatectomy may be required.[70, 71, 21]

With regard to type V choledochal cysts, patients with localized disease may benefit from a hepatic lobectomy. If the disease is diffuse, involving both lobes of the liver, treatment is palliative and liver transplantation may be required.[52, 13, 72, 26]

Complications

Complications after surgery have been mainly observed with types I, IV, and V choledochal cysts. They are much less common in excisional procedures. The overall morbidity is less than 10%. Mortality and repeat surgery rates are low after excision, compared with the ratesassociated with internal drainage operations.

Cholangitis

In 1996, Miyano et al reported a 2.3% incidence of cholangitis after cyst excision.[29]  In 1995, Todani et al found cholangitis in 10 patients in their 25-year review of 97 patients who underwent cyst excision.[35] In contrast, Chijiiwa et al (in 1993 and 1994) found that 88% of patients who previously underwent cystoenterostomy had cholangitis.[53, 54]

Biliary stone formation

In 1993 and 1994, Chijiiwa et al reported a 25% rate of choledocholithiasis and a 33% rate of hepatolithiasis after cystoenterostomy.[53, 54] In 1997, Yamataka et al reported stone formation in three of 18 patients who underwent previous cyst excision.[73] Two patients had stones at the porta hepatis, and one patient had stones at both the porta hepatis and within the left hemiliver.

Stones can be observed in the intrapancreatic bile duct. Usually, cholangitis and stone formation are observed in the same patient. These complications are thought to result from many factors, including the following:

  • Stricture of the anastomosis
  • Residual debris in the intrahepatic bile duct
  • Dilated intrahepatic ducts, especially in type IV and type V choledochal cysts

Anastomotic stricture

Apart from technical errors, anastomotic strictures may be a progressive phenomenon after surgery. In a 1993 report, Hata et al found a 4.1% rate of anastomotic strictures.[64]

The diameter of an adequate anastomosis is usually reduced by 20-30% after a few weeks. Such a reduction in the anastomotic diameter may result from excessive devascularization of the duct during dissection. A wide anastomosis as far as the hepatic hilum may prevent anastomotic stricture.

Residual debris in intrahepatic bile ducts

Residual debris is commonly observed in older patients. Debris left within the intrahepatic duct or pancreatic duct during cyst excision may be responsible for postexcisional stone formation and pancreatitis.[54, 52, 70, 37, 74]

Intrahepatic bile duct dilatation

Dilatation usually regresses after cyst excision and hepaticojejunostomy in young patients. In older patients and adults, this dilatation tends to persist. Dilatation and residual debris may cause cholangitis and stone formation.[70, 71] Some authors recommend endoscopic examination of the duct during surgery to clean out all the debris.[75, 76]

Malignancy

Malignancies in choledochal cyst can arise from the distal CBD, the wall of the cyst (even after successful drainage at cystoenterostomy), or the intrahepatic bile ducts. Any type of cyst is susceptible to malignancy, but the greatest prevalence is observed with types I, IV, and V. Factors thought to contribute to the development of malignancy include prolonged bile stasis and chronic inflammation of the cyst wall.

The risk of cancer appears to be related to the age of the patient.[15, 77, 78, 13, 2, 79, 80, 81] Inflammatory and metaplastic changes increase with patient age, and they are frequently observed in association with carcinoma of the bile duct. The increased risk of biliary tract malignancy, even after surgery, warrants close surveillance in any case of choledochal cyst.

More than half of the cancers arise from the cyst wall, even after successful internal drainage. The risk of carcinoma in the retained cyst approaches 50% in patients treated with cystoenterostomy and is approximately 20 times greater than in the general population.[15, 54, 52, 80] With regard to intrahepatic ducts, adequate bile drainage may prevent malignant transformation.

Total cyst excision had been promising in eliminating the risk of cancer development. However, sporadic cases of carcinoma in the intrahepatic ducts and distal common duct after complete cyst excision have been reported.[70, 82] Malignancy can develop many years after excision of the cyst and can develop in areas of the biliary tree remote from the cyst, such as the gallbladder and terminal common duct, which is left behind after excisional surgery.

The risk of detecting a biliary tree malignancy in a resected cyst is 0.7% in patients who undergo surgery before age 10 years, 6.8% in patients who undergo surgery at age 11-20 years, and 14.3% in patients who undergo surgery after age 20 years.

In a 1997 report, Yamataka et al recommended excision of the intrapancreatic terminal choledochus.[73]

Long-Term Monitoring

Long-term follow-up is necessary to detect any late complications, especially the development of malignancy.