Gallbladder Tests: Ultrasound, CT, HIDA Scan, ERCP

Blood Tests in Gallbladder Disease

When upper right abdominal pain suggests gallbladder disease or obstruction of the common bile duct, the following blood tests may be performed:

• Bilirubin and liver enzyme alkaline phosphatase (AP) are often elevated in cases of gallstones in the gallbladder and common bile duct (1)
• Aspartate aminotransferase (AST) and alanin aminotransferase (ALT) are often elevated in cases of gallstones in the common bile duct (1)
• White blood cells are usually elevated in the inflamed gallbladder or common bile duct (mostly due to gallstones) (1)
• Tumor marker CA 19-9 may be significantly elevated in gallbladder or common bile duct cancer, which are rare before 60 years of age (2)

NOTE. Gallstones in a non-inflamed gallbladder and early carcinoma of the gallbladder or bile duct may be present without any detectable changes in the blood.

Gallbladder Ultrasound

Ultrasonography is usually the first imaging investigation undertaken in suspected gallbladder disorder. Liver and pancreas are also usually investigated at the same time. Ultrasound can detect (1):

• Gallstones in the gallbladder (but not reliably in bile ducts) as small as 2 mm
• Thickened gallbladder wall in a gallbladder inflammation with gallstones (not reliable if no stones)
• Cancer mass in the gallbladder can be detected in 50-75% of cases (3)

Combination of a normal ultrasound result and normal bilirubin and liver enzymes in the blood quite reliably excludes the possibility of stones in the common bile duct (1).

Ultrasound of the gallbladder can be safely done in pregnancy but can not be done in severe cases of skin disease or in non-cooperative patient. In obese patients, obtained images may not be sufficiently clear to confirm a diagnosis.  Ultrasound can not detect functional gallbladder or bile duct disorders, such as sphincter of Oddi dysfunction.

Negative result of gallbladder ultrasound (no abnormalities detected) does not 100% exclude any gallbladder disorder.

Preparation and Procedure

You will need to fast (not eat or drink anything) 6 hours before the procedure. You will lie flat on your back on the examination table and the doctor (gastroenterologist) will apply gel onto your upper abdomen. This allows for lubrication and prevents distortion of ultrasound waves when they penetrate the abdominal wall. The doctor will guide the probe over your belly skin and observe the image of the gallbladder, liver and pancreas on the monitor. The procedure usually lasts about 15 minutes, is usually not painful and sedation or anesthesia is not necessary. You will be able to discuss the results immediately after the procedure and you will get a written report within a few days.

Complications

There is no known harmful effect of ultrasound waves. Transmission of infection from patient to patient through the use of a common ultrasound probe is rare.

HIDA Scan (Cholescintigraphy)

HIDA scan of the gallbladder may be donewhen a gallbladder disorder is suspected but no gallstones are found by an ultrasonography.

Preparation and Procedure

You should have no barium tests two days prior to investigation and four hours of fasting is required before the procedure. You will lie on the table and a non-harmful radioactive dye HydroxyIminoDiaetic Acid (HIDA) will be injected into a vein in your arm. HIDA is excreted by liver into the bile and distribution of the bile among gallbladder, cystic and common bile duct can be traced and recorded by radio-detective camera. Then a hormone cholecystokinin (CCK), which causes gallbladder contraction, will be injected into your vein and another set of images will be made (this part of investigation is not always done). Percent of HIDA that is ejected out from the gallbladder is called ejection fraction (EF). EF above 50% is considered as normal, EF between 30-50% as boundary, and EF below 30% as abnormal (4). The test takes 1-2 hours.

HIDA scan may reveal:

• Stones in the gallbladder (gallbladder is not completely filled with the dye)
• Obstruction in the cystic duct (dye does not enter the gallbladder at all)
• Obstruction of the common bile duct (dye is not excreted into the duodenum)
• Bile leakage, if there is a perforation in the gallbladder or bile ducts (dye outside of biliary system)
• Biliary dyskinesia (improper painful contraction of the gallbladder containing no gallstones) may be detected by CCK-HIDA scan (5)

False positive results (gallbladder or bile ducts do not fill with contrast, even if there is no gallstones or obstruction) may occur in liver disease (alcoholic cirrhosis) or in those fasting or receiving all nutrients through an intravenous infusion (1).

Normal HIDA scan does not exclude disorders of bile duct function (biliary dyskinesia, sphincter of Oddi dysfunction).

The whole procedure takes about two hours. HIDA scan should not be done in pregnancy and in a known iodine allergy. Breast milk should be discarded for 48 hours after the test.

Complications

Side effects of HIDA scan are rare and include allergy to HIDA, pain during CCK injection, chills, nausea and rash.

ERCP

ERCP (Endoscopic Retrograde Cholangio-Pancreatography) is a combination of endoscopic and X-ray investigation of the biliary tract; it can be performed when obstruction of cystic, common bile or pancreatic duct is suspected.

Preparation and Procedure

Preparation is like in gastroscopy (upper endoscopy). You should not eat or drink anything 6 hours prior the investigation. You’ll get sedative medication as an injection into the vein.

Procedure. Gastroscope – a flexible viewing tube – is administered through the mouth and proceeded toward the duodenum. A contrast substance is injected into biliary tract through its opening (papilla Vateri). An X-ray image is done to check eventual blockage of contrast distribution (due to gallstones, scars, inflammation, or cancer in biliary tree). Small stones can be removed or a stent (tube) inserted to keep affected duct open. A sample of the bile duct tissue can be cut (biopsy) for further investigation when cancer is suspected. The procedure lasts from 30 minutes to 2 hours. When gallstone is removed, patient stays in the hospital overnight.

Complications

Possible complications of ERCP include pancreatitis (quite often but usually mild), perforation of the esophagus, stomach, duodenum or bile duct, bleeding, infection and side effects of sedation (6). Some complications may be life threatening, so detailed discussion about the benefits and risks with your doctor is recommended.

Picture 1. ERCP: gallstones within the common bile duct

MRCP

MRCP (Magnetic Resonance Cholangio-Pancreatography) is an investigation of the cystic, common hepatic and pancreatic duct using MRI (magnetic resonance imaging). It is done for the same purposes like ERCP (see above) and can provide results of the same accuracy (7). The downside of MRCP is that unlike in ERCP, no treatment can be performed during the procedure.

Picture 2. MRCP image showing two gallstones in the common bile duct
(source: Wikipedia)

Computer Tomography (CT)

CT of gallbladder is made to find:

• Biliary sludge (condensed bile) or gallstones in the cystic or common bile duct
• Cancer in the gallbladder or bile ducts, or to evaluate its spread
• Complications, like rupture of the gallbladder or bile duct, or porcelain gallbladder
• Air in the gallbladder (in gallbladder infection)

X-Ray of Abdomen

X-ray of the abdomen, usually done for other purposes, can show big calcified gallstones in the gallbladder. In gallbladder infection, the air in the gallbladder can be sometimes seen.

References:

1. Gallbladder cancer  (emedicine.medscape.com)
2. Ultrasound and gallbladder cancer  (emedicine.medscape.com)
3. HIDA scan  (mypacs.net)
4. CCK-HIDA scan for diagnosis of biliary dyskinesia  (cheboygansurgical.com)
5. ERCP  (digestive.niddk.nih.gov)
6. MRCP vs ERCP  (louisville.edu)