Ultrasound is a non invasive test. It is performed by placing a probe onto the abdominal wall. Sound waves generated by the probe are reflected by structures in the abdomen and picked up again by the probe which can then generate a picture. This is the same principle as sonar in a submarine. Gallstones cause most of the waves to reflect and are easily identified on an ultrasound. We can also look at the gallbladder wall to see if it has been inflammed - it appears thickened. Ultrasound can also assess the bile duct. We can measure the diameter of the duct (it may be dilated if a bile duct stone is present) and can identify duct stones themselves.
Dynamic HIDA scan
This is a scan that is helpful if we suspect that the gallbladder is not contracting properly (biliary dyskinesia) and is causing pain. It requires an injection of a non harmful radio-isotope that is taken up by the liver and gallbladder. A drug is given to make the gallbladder contract and the amount of isotope that is ejected from the gallbladder can be measured. The diagnosis of dyskinesia is made if only a small proportion of the radio-isotope (<30%) is secreted from the gallbladder.
Endoscopic Retrograde Choledocho Pancreatogram ERCP
ERCP is an endoscopic procedure that is rarely used these days to make a diagnosis, but more frequently as a therapeutic tool to deal with gallstones that are stuck in the common bile duct.
The procedure is performed under sedation, rarely under a general anaesthetic. An endoscope (a thin flexible camera) is passed via the mouth, through the stomach and into the duodenum (first part of the bowel) where the exit of the common bile duct is located. X-Rays (cholangiogram) of the duct can be performed and gallstones can be removed. If this is not possible on the first occasion then a stent (a fine plastic tube akin to a straw) can be placed to relieve the jaundice. A further procedure can then be performed at a later date to remove the stent and residual stones.
The vast majority of ERCPs can be performed without complication. Occasionally an ERCP can cause bleeding, pancreatitis or rarely bowel perforation.
Liver Function Tests
Liver function tests (LFTs) are a blood test commonly performed when gallstones are suspected. A rise in the LFTs may suggest that a stone has passed into the bile duct or that the pain may be due to other causes apart from gallstones.
Magnetic Resonance Choledocho Pancreatogram (MRCP)
MRCP is a form of Magnetic resonance imaging - again it is non invasive and does not use radiation. It is a very good technique to identify whether there are stones within the bile duct.
Sphincter of Oddi Manometry
The Sphincter of Oddi is a muscle valve which allows bile to pass from the bile duct to the duodenum. If Sphincter of Oddi dysfunction is suspected then the diagnosis can be confirmed by manometry. This is an endoscopic procedure where a catheter is placed into the sphincter via an endoscope. The pressure within the muscle is then recorded. An elevated pressure within the muscle can confirm the diagnosis. The procedure carries a small risk of causing an acute pancreatitis.