Parasites and Biliary stones

Endoscopic retrograde cholangiopancreatography ١١٤
to 30% (half-strength) concentration is recommended for
cholangiography. Biliary stricture detail is better defined with full-
strength contrast, however. Non-ionic and lower osmolality contrast
media, which are more expensive, offer no safety advantage. Contrast
media injection is done with continuous fluoroscopic monitoring. The
extent of ductal filling should be correlated with the clinical need to know
the ductal anatomy (Whithouse et al., 1996).
Complete pancreatography involves filling of the main duct and side
branches to the tail. High-resolution fluoroscopy is required to see such
detail. In settings where there is excess overlying gas or obesity, under
filling of the pancreatic duct is recommended to avoid acinarization
(instillation of contrast media into the pancreatic parenchyma). For a very
dilated duct, initial aspiration of fluid will allow better contrast
visualization without over distention of the duct (Sherman and Lehman,
1999).
Contrast media mixes slowly with gallbladder bile and final films
are best taken in the supine position after endoscope withdrawal (and
additional time for mixing with gallbladder contents). Occasionally,
delayed gallbladder films taken 4 to 12 hours after completion of the
procedure allows for passage of intralumenal gas, giving better diagnostic
film quality (Hawes and Sherman, 1995).
In setting of tight biliary strictures, limited contrast filling upstream
should be done until catheter access above the stricture is achieved.
Similarly, limited pseudocyst filling should be done unless immediate
drainage is certain. Several views of each ductal position are
recommended both in the limited filling and more completely filled state
(Varghese, 2000).