Diagnosis of Choledochal Cyst:
The diagnosis generally made using a combination of the following:
A physical exam of the child
Tests including blood tests and an ultrasound scan
A choledochal cyst most often suspected if an abdominal ultrasound scan shows a dilated bile duct in a baby or child with jaundice or if the child abdominal pain. Once suspected some other tests required to get more information.
For example, there any blockage in the duct by a stone or there an abnormal junction of the bile duct with pancreatic duct (a long common channel)? These extra tests carried out to get more information about the type of choledochal cyst present which helps the surgeon to get a ‘road map’ to plan the operation. These tests may include:
A detailed ultrasound scan to look not only at the bile ducts but also to look at the blood vessels going to the liver which run alongside the bile ducts.
MRCP (Magnetic Resonance Cholangio-Pancreatography)
This type of detailed scan is carried out in a large machine. It not require X-rays but the patient does need to lie flat and still and so babies and small children often require a general anaesthetic. The bile ducts and the pancreatic duct, shown better on an MRI scan.
ERCP (Endoscopic Retrograde Cholangio-Pancreatography)
This a specialised procedure which is not often needed. It done under a general anaesthetic. In this procedure, a flexible tube with a small camera on the end (an endoscope) passed through the mouth down into the intestine. A tiny plastic tube then passed through this endoscope into the opening of the bile duct and dye is injected to outline the choledochal cyst and the pancreatic duct.
This helps to give information about the junction of bile duct with pancreatic duct (long common channel) and if there any blockage in the bile duct due to stones etc. This investigation can sometimes stir up inflammation in the pancreas (pancreatitis) causing temporary abdominal pain and vomiting afterwards. It rarely done as it an invasive investigation.
Rarely a HIDA (liver scan)
becomes necessary, if they’re only a single cyst in the liver and the MRCP cannot confirm it to a choledochal cyst/anomaly. § The exact nature of the choledochal cyst sometimes only becomes clear at the time of surgery when the dye injected into the bile duct system (an operative cholangiogram).