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,
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.