Ultrasound Management of biliary obstruction

Management of biliary obstruction obviously depends on the cause and the severity of the condition.  Removal of stones in the CBD may be performed by ERCP with sphincterotomy. Elective cholecystectomy may take place if gallstones are present in the gallbladder.
Laparoscopic ultrasound is a useful adjunct to surgical exploration of the biliary tree and its accuracy in experienced hands equals that of X-ray cholangiography. It is rapidly becoming the imaging modality of choice to examine the ducts during laparoscopic cholecystectomy.
Endoscopic ultrasound can also be used to examine the CBD, avoiding the need for laparoscopic exploration of the duct when performed in the immediate preoperative stage. The treatment of malignant obstruction is determined by the stage of the disease. Accurate staging is best performed using CT and/or MRI.
If surgical removal of the obstructing lesion is not a suitable option because of local or distant spread, palliative stenting may be performed endoscopically to relieve the obstruction and decompress the ducts (Fig. below). The patency of the stent may be monitored with ultrasound scanning by assessing the degree of dilatation of the ducts.
Clinical suspicion of early obstruction should be raised if the serum alkaline phosphatase is elevated, (often more sensitive in the early stages than a raised serum bilirubin). In the presence of ductal dilatation on ultrasound, further imaging, such as CT or MRCP, may then refine the diagnosis
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FIG. A,B & C
(A) This dilated CBD is obstructed by a mass (arrows) invading the lower end. (B) ERCP demonstrates a tight, malignant stricture, and can be used to position a palliative stent. (C) Stent in the CBD of a patient with a cholangiocarcinoma and malignant ascites. Decompression of the dilated biliary tree has been achieved, and ultrasound can be used to monitor the patency of the stent.
Choledochal cysts in adults are rare, and tend to be asymptomatic unless associated with stones or other biliary disease. They are sometimes associated with an anomalous insertion of the CBD into the pancreatic duct. The mechanism of the subsequent choledochal cyst formation is unclear, but it is thought that the common channel, which drains into the duodenum, is prone to reflux of pancreatic enzymes into the biliary duct. This can cause a biliary stricture, with subsequent proximal dilatation of the duct, forming a choledochal cyst [Fig. H]. Less commonly the dilatation is due to a nonobstructive cause in which the biliary ducts themselves become ectatic and can form diverticula. This may be due to a focal stricture of the duct which causes reflux and a localized enlargement of the duct proximal to the stricture.
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                            FIG.H
Complications of choledochal cysts include cholangitis, formation of stones and progression of the condition to secondary biliary cirrhosis, which may be associated with portal hypertension. It may be difficult to differentiate a choledochal cyst, particularly if solitary, from other causes of hepatic cysts. The connection between the choledochal cyst and the adjacent biliary duct may be demonstrated with careful scanning. 
ULTRASOUND IMAGES choledochal, ultrasound images of biliary cirrhosi, ultrasound images of choledochal cyst,
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