Diagnosis of Cholecystitis

Diagnosis of acute cholecystitis can be quite difficult since there are a number of other conditions which can cause acute pain in the same region, and even if the ultrasound is used to detect gallstones, there is no guarantee that the pain was caused by the gallstones (oftentimes the presence of gallstones is asymptomatic). In order to diagnose acute cholecystitis it should be differentiated from other disorders which include:

• Irritable Bowel Syndrome (IBS). The symptoms of IBS are quite similar to those of acute cholecystitis, which includes nausea and difficulty digesting fatty food; however, the pain caused by IBS is usually located in the lower abdomen rather than being in the right hypochondium.
• Pancreatitis. It can often be quite challenging to differentiate between acute cholecystitis and pancreatitis, but it is crucial, since the treatment will be very different. Pancreatitis is usually diagnosed if high levels of lipase and amylase are detected within the blood. Imaging techniques including ultrasound and computed tomography can also help differentiate between the two and evaluate the severity of the patient’s condition.
• Pancreatic Cancer. All the symptoms of pancreatic cancer can be identical to those of the acute cholecystitis. One thing the doctor should look for is suspicious results on CT scans of the pancreas and sudden weight loss.
• Other conditions which may mimic acute cholecystitis include acute appendicitis, ulcerative colitis, Crohn’s disease, stomach ulcers, pneumonia, hiatal hernia, gastroesophageal reflux, urinary tract infections, kidney stones, viral hepatitis, diverticulitis or diverticulosis, pregnancy complications, and even myocardial infarction.
  
  

Laboratory tests

Patients with acute cholecystitis that was caused by stones in the common bile duct may show a number of symptoms that include pancreatitis, jaundice, and dark urine. In such a case the doctor will decide to perform a number of blood tests including:

• Test for alkaline phosphatase. The levels of alkaline phosphatase rise when there is some damage to the liver cells. When there is some form of obstruction in the bile ducts, it causes a buildup of bile within the ducts and consequently damages the liver cells. It is usually one of the first signs of stones in the common bile ducts.
• Test for bilirubin. There are two types of bilirubin a blood test can detect: direct (conjugated) and indirect (unconjugated). When the bile ducts become obstructed the levels direct bilirubin rise, which is a sign that there is an increased pressure within the ducts and the liver cells are dying.
• Test for liver enzymes: alanine aminotransferase and aspartate aminotransferase. These enzymes also spike when the liver cells are damaged.

Imaging techniques

In order to verify the diagnosis a number of imaging techniques can be used, including:

• Ultrasound – is a simple, noninvasive and quick imaging technique. It can easily detect gallstones and is the first method to be used when diagnosing acute cholecystitis. The patient is asked not to eat for at least 6 hours before the procedure, which takes about 15 minutes to complete. During the procedure, the doctor can scan the biliary and pancreatic ducts, liver, pancreas, and the gallbladder to see if its walls have thickened (which is characteristic for cholecystitis). This method can detect stones that are at least 2 mm long with 90-95% accuracy. If the ultrasound didn’t detect any gallstones, but there is still a strong suspicion that they are present, the test should be repeated.
  
  
• Endoscopic retrograde cholangiopancreatography (ERCP) - this method involves using an endoscope to see into the duodenum and inject a contrast medium into the pancreatic or biliary ducts. This can easily show if there any foreign object or obstructions in the ductal systems. However, this method can introduce infection into the pancreas and gallbladder; therefore it should be used with caution.

• X-rays. Regular x-rays of the abdominal region can detect gallstones and gas. X-rays can be taken using two methods:
  1. Cholangiography. During this method the contrast medium is injected directly into the duct system.
  2. Oral cholecystography. For this method the patient has to take a pill that contains a special dye about 8-12 hours before the test. This dye is released with bile and fills the gallbladder. After this the X-ray images can be taken.

• Computed Tomography (CT). This method can be used if the doctor suspects possible complications including perforation, stones in the common duct, or cancer. CT allows viewing the exact location of the problem and determining the possible tactic for treatment.

• Magnetic Resonance Imaging (MRI). It can be either used alone or in combination with cholangiography (Magnetic resonance cholangiography), which makes this procedure especially accurate. MRC is very good at detecting cancer in the biliary tract; however, the only drawback of this procedure is its price.