COMMONLY DONE TESTS IN GALL STONE DISEASE PATIENTS

These are the investigations available for gall stone disease. The requirement of investigations are decided by the consulting doctor depends on the clinical presentation of the patient. The commonly done investigations are:

1. Blood investigations;
2. i) Blood total white blood cell (WBC) count will give an idea about the presence of infection and it will be increased in the presence of infection. It does not have any diagnostic value in the diagnosis of gall stones. But it will tell whether the patient has associated infection or not.
3. ii)Liver function test (LFT)

Various blood tests are included in the liver function test. The commonly done LFTs are serum bilirubin, SGOT, SGPT, GGTP, SAP, Serum proteins including albumin and globulin, prothrombin time with INR (International Normalized Ratio) and serum ammonia level. In patients with simple gall stone disease, the LFT will be normal. There will be alterations of liver function test in case of associated hepatitis or stones in the bile duct. Also, serum bilirubin alone will be increased in case of haemolytic jaundice and in case of gangrenous cholecystitis.

1. Serum bilirubin: Increased in hepatitis, bile duct stones, hemolytic jaundice and gangrenous cholecystitis.

Sometime it is very difficult to differentiate the actual reason for jaundice but it needs attention to make a diagnosis of actual reason for the jaundice. Analysis of associated liver enzyme elevation may help to differentiate the actual cause of raise in serum bilirubin. Also sometime needs hemolytic work up to rule out the possibility hemolytic jaundice

b). SGOT (Serum Glutamic Oxaloacetic Transaminase). This is a liver enzyme usually raised in any liver cell injury. The common pathology is hepatitis due to any type of virus or alcohol or any drugs or toxins.

c). SGPT (Serum Glutamic Pyruvate Transaminase). Again, a liver enzyme elevated in any type of liver cell injuries.

d). GGT (Gamma Glutamyl Transpeptidase). This is a very important enzyme elevated in biliary obstruction, liver cell injury due to drugs and also liver injury due to alcohol.

Raise in GGT may be the first indicator of bile duct obstruction and also alcoholic liver cell injury. Also, in case of recovery phase of Viral hepatitis there will be increase in the GGTP level known as cholestatic phase of viral hepatitis. So, patients with gall stone and increased GGT, always suspect possibility of biliary obstruction due to bile duct stones. Also, alcoholism and recovering hepatitis has to be considered.

1. SAP (Serum Alkaline Phosphatase). This enzyme is similar to GGTP and will be raised in case of biliary obstruction and sometimes will be raised in problems related to bone. So, increase in SAP is an indicator of possible biliary obstruction.
2. Serum proteins. The common proteins checked are serum albumin and globulin. The important point to be noted is that albumin is purely synthesized in liver only. So, any decrease in albumin is an indicator of long-standing liver injury either due to hepatitis or long-time alcohol intake.

Globulin is synthesized in liver and other parts of the body including bone marrow. So, globulin may not be grossly decreased in liver cell injury because of the synthesis happens from other sites also. So, reversal of albumin globulin ratio is noticed in long standing liver cell disease.

1. Serum ammonia.

This is one of the main indicators of liver function and will be altered in chronic liver disease. This serum ammonia estimation is not done routinely, but done in cases of suspected chronic liver disease patient and in jaundiced patients. Increased serum ammonia is an indicator of poor liver function. Increased serum ammonia carries high risk for any surgery.

I) Serum Amylase and Lipase

These enzymes are indicators of pancreatitis. Patients with pancreatitis with gall stones in the absence of alcohol intake, the possibility of biliary pancreatitis must be considered. So, to confirm pancreatitis, serum amylase and serum lipase levels must be checked.

These enzymes will be increased with liver enzymes together or alone in case of pancreatitis. In case of pancreatitis with gall stones, liver function test should be checked and if there is any abnormality, further evaluation is required to rule out bile duct stones.

II) Plain X-ray of abdomen.

X-ray evaluation of abdomen has limited role in the diagnosis of gall stones. Less than 10% of patients will have radio opaque gall stones. X-ray examination of abdomen is done in patients with acute abdominal pain. X-ray examination of abdomen and chest will be useful in gall stone disease patients to rule out other possible diseases like duodenal ulcer with perforation which shows free air in the abdominal cavity, multiple air fluid levels in case of intestinal obstruction and right lower lobe pneumonia of lung will have similar right sided upper abdominal pain.

III) Ultrasonography of the abdomen:

Trans abdominal ultrasonography of the abdomen is a very important and most sensitive test for the diagnosis of gall stones. It is sensitive, inexpensive, reliable and reproducible test to evaluate gall bladder and biliary tree. Gall bladder is better visualized with trans abdominal ultrasonography because of its superficial position of the gall bladder and no gas containing organ lies over this area. Better result will be obtained if the test is done at empty stomach.

Presence of movable shadows within the gall bladder is suggestive of gall stone and the presence of after shadows usually confirms the gall stones. Along with gall stones, presence of gall bladder wall thickening and fluid collection around the gall bladder (pericholecystic fluid collection) is a suggestive of acute cholecystitis. Porcelain gall bladder is an entity in which calcified gall bladder wall, will appear as a curvilinear echogenic focus along the entire gall bladder wall, with posterior shadowing.

The common problem which looks like gall stone is gall bladder polyps. Common differentiating point between gall bladder polyps and gall stones are that gall stones move while changing the position of the patient. But polyps will not move while changing the position of the patient. Another important point is that there will be a shadow behind the Gallstones known as After shadows. This After shadows will not be there in gall bladder polyps.

The nature of bile ducts whether dilated or not is also very important and that can be assessed by ultrasonography examinations. Bile duct within the liver or outside the liver may be dilated. Dilatation of biliary radicals within the liver (IHBR DILATATION-INTRAHEPATIC BILIARY RADICALS DILATATION) are assessed easily than dilatation of bile duct out outside the liver. Intrahepatic biliary radicals will be dilated in case of bile duct obstruction at the lower part of bile duct. So dilated intrahepatic biliary radicals are suggestive of the possibility of common bile duct obstruction either due to stones or due to any other obstruction at any part of bile duct. Bile duct will be dilated proximal to the site of obstruction. Other causes of bile duct obstruction are due to stricture by benign or malignant disease of bile duct.

IV) Computerised Tomography of Abdomen (CT Abdomen)

This test is very useful to assess the severity of cholecystitis. This investigation usually confirms the presence of gall stones and also confirms the presence of inflammation. The cholecystitis is assessed by the thickness of the gall bladder. Limitation of this investigation is that most gall stones are radiographically isodose to bile and many will be indistinguishable from bile. So, CT examination of may miss the gall stone disease. But, the additional information by the CT abdomen is identification of gall bladder perforation, pus around the gall bladder and liver abscesses. Important information obtained from CT is that it will talk about the nature of intrahepatic biliary radicals. Dilated intrahepatic biliary radicals are highly suggestive of associated bile duct obstruction. 

CT scan also gives an idea about the presence of stones within the bile duct. Also, some individuals develop gall bladder infection without gall stones. This entity is particularly confirmed by CT scan with intravenous contrast study. Presence of gall stone induced pancreatitis is confirmed by computerized tomography of the abdomen with intravenous contrast.

When performed for the evaluation of hepatic or pancreatic or possible neoplastic process, CT is invaluable in the pre operative planning, and the use of arterial phase, portal venous phase and delayed phase imaging, known as triple phase CT, has essentially diagnostic angiography of liver. 

V) Magnetic Resonance Cholangio Pancreatography (MRCP).

This test is very important to assess the biliary system. This test uses the water in bile to delineate the biliary tree and thus provides superior anatomic definition of the intrahepatic and extrahepatic biliary tree and pancreas. This will confirm the gall stones and also gives information about the common bile duct. The presence of filling defects within the bile duct is suggestive of bile duct stones. Common bile duct stones are usually associated with jaundice with or without pancreatitis. MRCP will give an idea about common bile duct obstruction including cause of obstruction, site of obstruction and size of the bile duct. In case of common bile duct stones, MRCP usually give an idea about the site, size and number of stones which will be very useful to decide about the further line of treatment.

VI) Percutaneous Transhepatic Cholangiography (PTC)

This is an invasive procedure to evaluate biliary tree less frequently used now a days. A needle is passed directly into the liver to access one of the biliary radicals, and the tract is used for the insertion of transhepatic catheters. Through this catheter, contrast will be injected and biliary radicals can be studied. With the advent of MRCP, usage of this procedure for diagnostic purpose is not much. Instead MRCP gives all the information. Similarly, some interventions can be done through this technique. But ERCP has replaced this procedure for therapeutic purpose. PTC is used in case where ERCP is technically not possible or poor general condition of the patient where the patient will not withstand the ERCP procedure. PTC can be utilized in selected group of patients to drain the infected biliary system.

VII) Endoscopic Ultrasound (ENDOULTRASOUND)

Endoscopic ultrasound means usage of ultrasound with upper gastrointestinal endoscopy. This has limited role in the evaluation of gall bladder pathology but has more role in the assessment of distal bile duct and ampulla. This assesses the common bile duct stones details and also to assess the local invasive nature of ampullary tumours like periampullary carcinoma. This endo-ultrasound is very useful to take biopsy from suspected lower bile duct tumours or pancreatic cancer. Endo-ultrasound is very useful in assessing the pancreatic cystic lesion and assessing the pancreatic necrosis in cases of acute pancreatitis. Pancreatic ductal dilatation can also be assessed with endo-ultrasound. Pseudocyst of pancreas can be drained with the help of endo-ultrasound.

VIII) Intra Operative Cholangigraphy (IOC)

This is a imaging tool for the diagnosis of biliary tree abnormalities during surgery. An injection catheter is introduced into the cystic duct while doing cholecystectomy and radio-opaque dye is injected into the biliary system which delineates anomalous biliary anatomy and identify bile duct stones (Choledocholithiasis). This will give a better idea about the biliary anatomy which will be useful if biliary reconstruction if required. Now with the availability of diagnostic MRCP and therapeutic ERCP has reduced the of usage of this intraoperative cholangiography technique.

IX) Hepatobiliary Imino Diacetic Acid (HIDA) Scan.

Also known as biliary scintigraphy is used to evaluate physiologic secretion of bile. This is a radio-isotope study of Biliary system. The injection of iminodiacetic acid, which is processed via the liver and secreted with bile, allows identification of bile flow. Therefore, failure to fill the gall bladder 2 hours after injection demonstrates the obstruction of cystic duct, as seen in acute cholecystitis. In addition, this scan identifies biliary leaks which happen after surgery. But now this information is given by MRCP. This investigation may be useful in patients with biliary tract pain without stones to assess the condition known as biliary dyskinesia. Some patients have pain abdomen after taking food from impaired emptying of gall bladder known as biliary dyskinesia with little clinical significance.

X) Fluro Deoxy Glucose Positron EmissionTomography (FDG-PET)

FDG-PET exploits the metabolic difference between highly metabolically active tissue, such as neoplasm, and normal tissue. This is an important investigation but not commonly done to make a diagnosis of gall stone and related problems. This is the investigation done in case of suspected gall bladder carcinoma associated with gall stone disease. In suspected gall stone disease with gall bladder carcinoma, this PET scan is very useful to confirm or rule out the possibility of gall bladder cancer so that the treatment plan can be decided accordingly. The limitations of this test are that it is an expensive test and also not available freely in all the places.

XI) Upper Gastro Intestinal Endoscopy (UGIE)

This is the endoscopic examination of oesophagus, stomach and duodenum. The common presentation of gall stone disease is recurrent abdominal pain with or without vomiting. The duodenal ulcer or gastric ulcer patient also present with recurrent abdominal pain with varying intensity. So, in patient with gall stone disease, upper gastro intestinal endoscopy is done to rule out the possibility of co-existing gastric or duodenal ulcer disease.