Investigation of the biliary tract

Plain radiograph

The skilfully taken plain X-ray of the gall bladder will show radio-opaque gallstones in 10 per cent of patients (Fig. 54.3). It will also show the rare cases of calcification of the gall bladder, a so-called ‘porcelain’ gall bladder (Fig. 54.4). The importance of this appearance is that it is premalignant and an indication for cholecystectomy. Limey bile is a curiosity and is frequently related to multiple small stones (Fig. 54.5). This lesion is not a premalignant lesion.

Oral cholecystography (Graham—Cole test) (Figs 54.6 and 54.7)

Iopanoic acid BP is taken as tablets on the night before the examination. A control radiograph is taken before the tablets are given and a series of X-rays is taken on the following day, with further films after a fatty meal. The fatty meal stimulates gall-bladder contraction and reveals the adequacy of gall­bladder function.

This investigation has been discarded by most hospitals because of its inaccuracy except to show diverticulae and polyps, and to assess function; adequate films depend on the patient taking the tablets, and the tablets being absorbed, secreted by the liver and concentrated in the gall bladder after passing into the gall bladder through an unobstructed cystic duct. Thus, a cholecystogram which shows no concentration of contrast can result from many causes and it not diagnostic of gallstone disease.

Intravenous cholangiography

Intravenous cholangiography (biligram—meglumine ioglycamate) permits radiological visualisation of the bile ducts. The drug is given intravenously and is rapidly secreted by the liver into the biliary tree. Careful radiography with or without tomography can clearly define the ducts and the gall bladder delineating the presence of stone disease. The contrast agent can cause allergic reactions such that this test has been discarded in most units.

Ultrasonography

Ultrasonography (Figs 54.8 ,54.9,54.10,54.11,54.12 and54.13) is noninvasive and is now the standard initial imaging technique for the investigation of the patient suspected of having a gallstone, and is also the prime investigation for the patient presenting with jaundice. It will demonstrate biliary calculi, the size of the gall bladder, the thickness of the gall-bladder wall, the presence of inflammation around the gall bladder, the size of the common bile duct and, occasionally, the presence of stones within the biliary tree. It may even show a carcinoma of the pancreas occluding the common bile duct.

Radioisotope scanning

Technetium-99m (99mTc)~labelled derivatives of imino­diacetic 

 acid (HIDA, PIPIDA) are excreted in the bile and ate used to visualise the biliary tree. In acute cholecystitis the gall bladder is not seen. The technique is used when biliary enteric anastomoses are functioning inadequately as it will show the extent of obstruction at the anastomosis and indicate the delay in 

excretion.

 

Computerised tomography (CT)

 

CT is not a useful technique in investigating the biliary tree. Its only value is in the investigation of patients who may have a cancer of the gall bladder or bile ducts, and in these patients will 

define its extent, the presence of lymphadenopathy and the presence of metastases.

 

Magnetic resonance cholangiopancreatography

(MRCP)

 

MRCP is now becoming the standard technique for investigation of the biliary tree. Contrast is not necessary and, with appropriate computing, a clear outline of the biliary tree can be 

achieved with a sensitive and specific diagnosis of bile-duct stones. This technique will replace alternative diagnostic aids as the appropriate magnets with the specific software become more widely available (Fig. 54.14).

 

Endoscopic retrograde

 

cholangiopancreatography (ERCP)

 

The ampulla of Vater can be cannulated with the aid of a fibre-optic duodenoscope. The bile ducts are visualised after injecting water-soluble contrast. Bile can be sent for cytological 

and microbiological examination, and brushings can be taken from strictures for cytological studies. Acute cholangitis may follow ERCP when contrast fills a dilated and obstructed duct; antibiotics are given as prophylaxis, and if obstruction is encountered relief of that obstruction by the placement of a stent 

must be undertaken. If drainage cannot be achieved then percutaneous transhepatic drainage should be performed. 

Diagnostic ERCP is now less commonly performed, but its value is its ability to remove stones and stent strictures, thus becoming a therapeutic rather than a diagnostic technique (Figs 54.15,54.16,54.17,54.18,54.19 and 54.20).

This investigation is only undertaken once a bleeding tendency has been excluded and the patient’s prothrombin time is normal. Antibiotics should be given prior to the procedure. Under fluoroscopic control, a needle (the Chiba or Okuda needle) 15 cm long and 0.7 mm in diameter is advanced into the liver through the eighth intercostal space in the mid­axillary line to a point about 2 cm short of the right margin of the vertebral column. The stilette is then removed and while injecting contrast (e.g. meglumine iothalamate 60 per cent, w/v) the needle is slowly withdrawn until contrast is seen entering a bile radical. Addition to this technique enables placement of a catheter into the bile ducts to provide external biliary drainage or the insertion of indwelling stents. The scope of this procedure can be further extended by leaving the drainage catheter in situ for a number of days and then dilating the track sufficiently for a fine flexible choledochoscope to be passed into the intrahepatic biliary tree in order to diagnose strictures, take biopsies and remove stones.

 

Peroperative cholangiography

During cholecystectomy a catheter can be placed in the cystic duct and contrast injected into the biliary tree. The technique defines the anatomy and excludes the presence of stones. With improved preoperative imaging and a more careful operative approach the value of this technique is debatable. The limitation of the technique using single plates can be overcome by an X-ray image intensifier with a television monitor which enables a much more accurate diagnosis of biliary pathology (Figs 54.23, 54.24, 54.25).

 

Operative biliary endoscopy (choledochoscopy)

At operation a flexible fibre-optic endoscope can be passed down the cystic duct into the common bile duct enabling stone identification and removal under direct vision. The technique can be combined with an X-ray image intensifier to ensure complete clearance of the biliary tree. After exploration of the bile duct, a tube can be left in the cystic duct remnant or in the common bile duct (a T-tube) and drainage of the biliary tree established. After 7—10 days, a track will be established. This track can be used for the passage of a choledochoscope to remove residual stones in the awake patient in an endoscopy suite. This technique is invaluable in the management of difficult stone disease and prevents the excessive prolongation of an operative exploration of the common bile duct.