Structural Liver Disease
Choledochal malformations (CM, previously also called ‘choledochal cysts’ or ‘bile duct cysts’), are congenital malformations of the biliary tract. Bile is secreted by the liver into small ducts that join to form the common bile duct. Between meals, secreted bile is stored in the gall bladder. During a meal, the bile is secreted into the duodenum to aid in the absorption of dietary fats and oils. In case of a CM, all parts of the bile ducts may be dilated. These dilatations might therefore occur both in the bile ducts in the liver as well in the bile ducts outside of the liver. Choledochal malformations are classified according to the Todani classification. This classification distinguishes choledochal malformations in five subtypes based on the location of the cyst or dilatation. As of yet, the etiology of CM is unknown.
CM is an extremely rare disorder, with an incidence of 1 in 45.000 to 1 in 100.000 live births in Europe. CM occurs much more frequently in females. In Asian countries the incidence is much higher, up to 1 in 13.000 live births.
Eight out of ten of children with CM develop abdominal complaints before the age of ten. Symptoms in childhood are relatively age-specific. Newborns and young children might present with jaundice and pale stools, necessitating a rapid workup to rule out ‘biliary atresia’. Older children complain of right upper quadrant abdominal pain, but can also present with fever, nausea, vomiting and jaundice. These symptoms are sometimes enhanced by infection of the bile ducts and/or the pancreas. In neonates and infants, CM may also present with rupture of the malformations leading to bile leakage into in the abdomen. Asymptomatic presentation is rare in childhood but is seen in nearly one-third of adult patients with CM.
If left untreated, bile duct cancer might develop in the CM at a relatively young age. This can be considered the most important complication. Before the age of 18 years, malignancy is rare (0- 0.4% of cases) while in adults with CM malignant change is observed in 11% of patients. The mechanism of this malignant change remains unclear. However, the combination of prolonged reflux of pancreatic juice and stasis of bile may play an important role.
The majority of choledochal malformations are diagnosed in childhood. In the current time of improved quality of antenatal ultrasounds, some 25% is detected even before birth. All bile duct cysts detected before birth should be seen in a dedicated paediatric center shortly after birth. Your doctor can establish the diagnosis by using blood tests and imaging techniques such as ultrasound, MRI or CT scan.
The main goal in the treatment of choledochal malformations is – besides providing symptomatic relief – preventing malignant change. Therefore, complete removal of the malformation is mandatory. During this operation, the CM and gallbladder will be removed. Bile flow from the liver to the intestine will be restored by connecting an intestinal loop between the liver and the intestinal tract. This operation could be performed by laparotomy or via key-hole surgery. Nowadays robot-assisted procedures have also been developed. So far, no treatment modality is superior to another and is determined by the surgeon’s preference and experience. When symptomatic, treatment should be performed relatively early. When asymptomatic, treatment can be safely delayed until the child has grown slightly bigger to make the operation safer and easier to perform, especially in the case of a keyhole (robot-assisted) procedure.
Overall, surgery for choledochal malformations is well tolerated. Early complications of surgery for choledochal malformations can include leakage of bile or bowel content into the abdominal cavity due to inadequate healing of the connections at the liver and intestinal side. Furthermore, bleeding, wound infection and injury of pancreas, liver and intestinal tract may occur. The most common long term complication is narrowing of the connection between liver and intestine, mostly caused by infections of the biliary tract (cholangitis). It is estimated that one out of five operated patients experience this during their lifetime. This stenosis of the outflow of the bile may cause pale stools, jaundice, pruritus and if left untreated, irreversible liver damage. Several treatment options exist to solve this problem. Although the risk of malignant degeneration (less than 0.3% for adults) is very low after resection of a CM, long-term follow up is strongly recommended.