CHOLEDOCHOLITHIASIS GALLSTONES

Choledocholithiasis : Stones may pass from the gallbladder into the common duct, or may develop de novo within the common duct. Stones in the CBD may obstruct the drainage of bile from the liver, causing obstructive jaundice. Due to shadowing from the duodenum, ductal stones are often not demonstrated with ultrasound without considerable effort. Usually they are accompanied by stones in the gallbladder and a degree of dilatation of the CBD. In these cases the operator can usually persevere and demonstrate the stone at the lower end of the duct. However, the duct may be dilated but empty, the stone having recently passed. Stones may be seen to move up and down a dilated duct. This can create a ball-valve effect so that obstruction may be intermittent. It is not unusual to demonstrate a stone in the CBD without stones in the gallbladder, a phenomenon which is also well-documented following cholecystectomy. This may be due to a single calculus in the gallbladder having moved into the duct, or stone formation within the duct. It is a  so important to remember that stones in the CBD may be present without duct dilatation and attempts to image the entire common duct with ultrasound should always be made, even if it is of normal calibre at the porta. In rare cases, stones may perforate the inflamed gallbladder wall to form a fistula into the small intestine or colon. A large stone passing into the small intestine may impact in the ileum, causing intestinal obstruction.

Biliary reflux and gallstone pancreatitis
A stone may become lodged in the distal common bile duct near the ampulla. If the main pancreatic duct joins the CBD proximal to this, bile and pancreatic fluid may reflux up the pancreatic duct, causing inflammation and severe pain. Reflux up the common bile duct may also result in ascending cholangitis, particularly if the obstruction is prolonged or repetitive. Cholangitis may result in dilated bile ducts with mural irregularity on ultrasound, but endoscopic retrograde cholangiopancreatography (ERCP) is usually superior in demonstrating intrahepatic ductal changes of this nature. Bile reflux is also associated with anomalous cystic duct insertion, which is more readily recognized on ERCP than ultrasound.

Further management of gallstones
ERCP demonstrates stones in the duct with greater accuracy than ultrasound, particularly at the lower end of the CBD, which may be obscured by duodenal gas and also allows for sphincterotomy and stone removal. Laparoscopic cholecystectomy is the preferred method of treatment for symptomatic gallbladder disease in an elective setting and has well-recognized benefits over open surgery in experienced hands. Acute cholecystitis is also increasingly managed by early laparoscopic surgery, with a slightly higher rate of conversion to open surgery than elective cases. Laparoscopic ultrasound may be used as a suitable alternative to operative cholangiography to examine the common duct for residual stones during surgery. Both ultrasound and cholescintigraphy are used in monitoring postoperative biliary leaks or haematoma. Other, less common options include dissolution therapy and extracorporeal shock wave lithotripsy (ESWL). However, these treatments are often only partially successful, require careful patient selection and also run a significant risk of stone recurrence.