Diarrhea Tests  

The cause of diarrhea can be determined from diarrhea symptoms, or by below diarrhea tests:

• stool tests;
• blood tests;
• urine tests;
• neurological tests;
• food allergy and intolerance tests; 
• absorption tests;
• abdominal ultrasound, endoscopic ultrasound, CT, X-ray with barium, plain abdominal X-ray, abdominal arteriography, HIDA scan, ERCP and MRCP;
• colonoscopy, EGD, capsule endoscopy, double baloon enteroscopy;
• Octreoscan.

Stool Tests In Diarrhea

Stool tests are done in chronic or heavy acute diarrhea and may include:

• Stool culture can show bacteria, causing diarrhea. Clostridium difficile toxin test is recommended in antibiotic associated diarrhea. For diagnosis of some rare bacteria, like Vibrio cholerae, separate tests may be required. Ova and parasites (O&P) test is recommended when diarrhea lasts more than a week. Specific antigen tests for giardia, cryptosporidium, E. histolytica, Helycobacter pylori, or Rotavirus also exist. False positive results of stool culture are from contamination of stool sample with urine or blood, or due to more than an hour passed between sample taking and testing. False negative results may be from antibiotics, laxatives, antidiarrheal drugs, or recent barium or x-ray investigation.
• Fecal occult blood test (FOBT) should be done when intestinal bleeding is suspected (after hemorrhoids, anal fissure, menstruation, and urinary bleeding are excluded). Bloody diarrhea, or diarrhea with a hidden blood may appear in heavy bacterial or parasitic infection, inflammatory bowel disease, and in diverticulitis. Other causes of bloody diarrhea are rare. Stool guaiac test (e.g. Hemoccult) - may detect daily blood loss of about 10 ml (1). Positive test confirms presence of the blood in the stool, but not its origin. Negative result means, that no blood was in the stool during the testing period, so additional samples at different occasions may be required. Three days before the test, red meat, and food which contains blood have to be avoided to prevent false positive results, and radishes, horseradish, turnips, cauliflower, uncooked broccoli, figs, melon, citrus fruits, and vit C supplements have to be avoided to prevent false negative results. Test should not be done in bleeding hemorrhoids, urinary bleeding, or during the menstruation. Five samples from each of three consecutive stools have to be taken. Immunochemical test - iFOBT (e.g. HemSelect) uses antibodies which react with human hemoglobin. The test may detects smaller amount of blood (50 µg/g stool) than guaiac test, but only from lower GI tract, not from the stomach or above (32). No dietary or drug restrictions are needed before the test; one sample from one or two stools is required. Both guaiac and immunochemical test kits are available in pharmacies without prescription, but testing by a lab or doctor is more reliable.
• WBC stool test. White blood cells in the stool may be found in severe bacterial infection, Crohn’s disease or ulcerative colitis.
• Fecal proteins. Lactoferrin is released from leukocytes, and it can be detected in stool in 5 minutes. Increased lactoferrin is a sign of inflammation, so it is used in acute diarrhea to distuinguish between mild viral or parasitic infection (negative) and invasive bacteria (positive), and in chronic diarrhea to distinguish between IBS (negative) and IBD (positive). In later case lactoferrin test was found to be 86% sensitive and 100% specific (26,27). Calprotein is another leukocyte protein, excreted in stool, which correlates with activity of IBD (29). Fecal A1AT test detects serum protein alpha1-antitrypsin in the stool in the protein losing enteropathy (PLE). Radionuclide labeled proteins, injected into a vein, and then appearing in the stool, also speak for PLE. Tests for proteins, excreted in colorectal cancer, are still in the research phase. Protein CD23 was found in the stool of patients with a food allergy (31). 
• Fecal IgA antibodies may be found in certain food allergies (to milk, egg, soy). In one clinical trial, IgA antigliadin antibodies in the stool were found in only 30% of patients with celiac disease, so they were considered as useless for diagnosis (2).

How to prepare? 1-2 weeks before the test, antacids, anti-diarrheal and anti-parasite medications, antibiotics, enemas, and laxatives should be avoided (after discussion with the doctor). Urinating before defecating is recommended, so urine doesn’t contaminate the stool. Stool collection kit with instructions may be obtained from a doctor. Stool for the test should be collected in a plastic bag, put over the toilet, or from a diaper, then stored in a clean sealable container and taken to the laboratory within 1 hour, or according to doctor/lab instructions. In the lab, only stool tests, specifically ordered by the doctor, and not all possible tests, will be done. The stool will be checked for color, consistency, weight (volume), shape, odor, and the presence of mucus.

Blood Tests

Blood tests are recommended in suspicious inflammation, infection, allergies or poisoning:

• Chem-20 (Metabolic panel 20): total proteins  are lowered in protein loosing enteropathy, marasmus and kwashiorkor, glucose is elevated in diabetes, sodium and potassium are usually lowered in dehydration, bilirubin and liver enzymes are elevated in liver or biliary tract disease (3);
• CBC: red cells (and ferritin, folate or vitamin B12) may be lowered in parasites, celiac, and Crohn’s disease; white cells are elevated in infection or inflammation; eosinophils are elevated in food allergies and parasites;
• ESR (Erythrocyte Sedimentation Rate) is raised in ulcerative colitis and Crohn’s disease, and reflects the activity of inflammation in the colon, but not in the small intestine; the test is used to evaluate a response to therapy (29). ESR may be also elevated in advanced colorectal cancer and carcinoid. 
• CRP (C-Reactive Protein) is elevated in acute phases of Crohn’s disease or ulcerative colitis (29);
• The combination of serum antibodies pANCA and ASCA is used to distinguish between ulcerative colitis (UC) and Crohn’s disease (CD). Combination pANCA+/ASCA- was found 94-97% specific for UC, and combination ASCA+/pANCA-, 81-98% specific for CD (28).
• IgE antibodies are elevated in food allergies and parasites; specific IgA and IgG antibodies may be elevated in celiac disease, Crohn’s disease, hepatitis, autoimmune diseases (SLE, systemic sclerosis, autoimmune thyroiditis), AIDS, Herpes simplex virus, cytomegalovirus or tuberculosis;
• hormones: thyroxine is elevated in thyroid nodules or Graves disease, TSH (thyroid stimulating hormone) is elevated in adenoma of pituitary gland, serotonin in elevated in carcinoid syndrome, insulin is lowered in diabetes, cortisol and aldosterone are lowered in Addison’s disease and congenital adrenal hyperplasia;
• heavy metals or drugs (lead, mercury, lithium, arsen) concentrations may be elevated in intoxication.

How to prepare? Don’t eat overnight before the test.

Urine Tests

The following tests may be done:

• Urine specific gravity is increased in dehydration;
• Urine 24h volume is decreased (< 500 ml) in dehydration, increased (> 2.5 l) in diabetes or renal disease;
• Bilirubin is increased in liver, gallbladder or biliary tract disease;
• Urine culture is positive in urinary infection.

How to prepare? Don’t eat overnight before the test.

Neurological Tests

Autonomic neuropathy may be diagnosed: 

• by neurologist: bedside clinical tests, EMG, EKG, skin conduction tests (4);
• by gastroenterologist: gastric emptying test etc.  

Food Allergy and Intolerance Tests

How to prepare? Antihistaminic and antidepressant drugs should be stopped 3-5 days before tests for allergy, but only with doctor approval.

Skin Prick Test

A skin prick test is done to confirm allergies to certain foods. A drop of a solution with the suspected food is placed on the forearm and pricked with a needle, what allows a small amount of food to enter beneath the skin; a red bump, appearing in 10-15 minutes (in delayed reaction in several hours), speaks for allergy (5). False positive results are common, but false negative results are rare. The size of the skin reaction does not reflects the severity of allergy. A rare, but life threatening anaphylactic reaction may occur during the test.

Patch Skin Test

Patch skin test is used when delayed allergic reaction is expected. A series of a patches with different allergens is placed on the back for 48-72 hours and then skin reaction is observed (6).

RAST

RAST, a Radio-Allergo-Sorbent Test, measures the amount of IgE antibodies in the serum. RAST is used in small children with undeveloped immune system, in pregnancy, in expected strong allergic reaction, or when antihistamine drugs cannot be safely stopped. In a laboratory, suspected radio-labeled allergen is added into a blood sample, and if specific IgE antibodies are present, antibody-allergen complexes are formed, and can be measured by the radio-detector. RAST is less accurate than skin prick test. Cross reactivity with some respiratory allergens is possible, and IgE from outgrown allergies may still be present. In some allergies, IgE are not raised enough to be detected. Amount of specific IgE antibodies does not necessary correlates with severity of symptoms. It may take few days to get results.

Elimination Diet and Food Challenge Test

Elimination diet test may be tried in the hospital, when allergy tests are negative, but food intolerance is still suspected. Many or even all regular foods may be eliminated at once and generally well tolerated elemental diet given for 1-4 weeks until diarrhea improves. Certain food samples, or placebo, are then added one by one by a 3rd party dietitian, without patient or his/her doctor knowing what the sample contains (double blind placebo controlled food challenge). Irritant food often causes diarrhea within minutes or few hours after the testing meal. If there is no diarrhea, the next day a challenge with a new food sample is performed. The test bases on the  increased irritant effect of previously eliminated food (7). It may take a month or more to find a food which causes diarrhea. If food allergy is suspected despite negative skin prick and blood tests, an oral challenge test may be done. A sample of suspected food is placed over the lower lip, and, if no reaction, into a mouth, and then symptoms of allergy are monitored in the next 20 minutes. In a drug challenge test, diluted solution of a suspected drug is injected into a vein in subsequent increasing concentrations, and then symptoms are observed (8). Some simple elimination diet tests may be done “at home”:

• Lactose-free diet should stop diarrhea in 1-2 days in a person with lactose intolerance.
• Gluten-free diet should lessen diarrhea in some days in celiac disease; full recovery may last for several months to two years though.
• Low-fructose diet for 4 days leads to dramatical improvement of symptoms in dietary fructose intolerance (DFI) or hereditary fructose intolerance (HFI).
• Low-sugar diet, with limiting glucose (sweets, sodas), fructose (fruits), lactose (milk), and maltose (beer) can help in small intestinal bacterial overgrowth (SIBO) , diverticulitis or other causes of diarrhea with bloating in lower abdomen.
• Low-fat diet should help in diarrhea from fat malabsorption in 1-2 days.
• Low-carb diet (candida diet), should lessen diarrhea from intestinal candida overgrowth in some weeks (after possible initial worsening due to candida die-off).
• Low-fiber diet, with limiting raw vegetables, fruits, and cereals may help in IBS, hyperthyroidism, and in other cases of mild diarrhea.

Hydrogen Breath Tests for Lactose Intolerance

How to prepare? Don’t eat for 12 hours (overnight), don’t take aspirin and don’t smoke few days before the test. The test is not appropriate for persons on antibiotic treatment, and for small children. Procedure. A fluid with radio-labeled lactose is drunk. In lactase deficiency, lactose won’t be digested in the small intestine, but will reach the colon, where bacteria will break it down and produce hydrogen. This hydrogen is radio-labeled and can be detected when patients exhalls into a testing machine. The test takes about two hours.

Lactose Intolerance Test

In lactose intolerance test, after lactose meal, lactose in a healthy person is broken down by lactase into glucose and galactose, and glucose raise in the blood can be be detected. Serum glucose level is checked every 30 minutes for two hours. In lactose intolerance (lactase deficiency), there is no or smaller glucose raise in the blood, since lactose can’t be digested and absorbed. Test is not done in diabetics and in small children. 

Stool Acidity Test

Stool acidity test is used to confirm lactose intolerance in small children. A small amount of lactose is given to a child. Unabsorbed lactose will reach the colon, where bacteria will break it down into lactic acid, which lowers pH of the stool.

Hydrogen Breath Tests with Fructose

Breath test with fructose uses the same principle as hydrogen test with lactose (see above), and it can reveal fructose malabsorption.

Intestinal Absorption Tests

Fecal Fat Test

Finding more than 6 grams of fat in the stool in a day reveals fat malabsorption, which mostly results from small intestinal or pancreatic disease. Procedure. During three days of diet containing about 100 g of fat daily, all the stool is collected and amount of fat measured (9). Causes of pale, fatty or oily stool.

D-Xylose Test

D-xylose test is made to distinguish between pancreatic and intestinal cause of fat malabsorption. D-xylose is a carbohydrate, which is absorbed in the small intestine without the help of any enzyme. If few hours after D-xylose ingestion, its concentration in the blood and urine raises, it means that the small intestinal absorption is normal, so the cause of fat malabsorption is probably a pancreatic disorder. Absent or sub-normal raise of blood D-xylose speaks for intestinal disease.

Pancreatic Function Tests

Pancreatic function tests measure the activity of pancreatic enzymes and thus show extent of pancreatic damage.

• fecal elastase is lowered in pancreatic insufficiency (10) ;
• serum lipase is raised in acute pancreatitis, and normal in chronic pancreatitis or cancer;
• secretin/CCK stimulation test: hormones secretin and cholecystokinin (CKK), which stimulate pancreatic bicarbonate and enzyme secretion, are administered via naso-duodenal tube, then pancreatic juice is sucked, and concentrations of secreted pancreatic enzymes and bicarbonate is measured;
• in the bentiromide test, bentiromide is ingested, and after being broken down by pancreatic enzymes, its breakdown products are measured in the urine.

Fecal Reducing Substances

Concentration of reducing substances (lactose, fructose, glucose, galactose) in the stool is increased in lactose, fructose or glucose/galactose intolerance, in short bowel syndrome, toddler’s diarrhea etc. When these substances exceed 2 g/dl of the stool, they reduce the reagent copper sulphate into copper oxide and thus change its color. The test may distinguish between infectious diarrhea and diarrhea due to sugar malabsorption, and between genetic and acquired sugar malabsorption. NOTE: only liquid stool is appropriate for the test.

Breath Test for Bacterial Overgrowth and Rapid Intestinal Transit

An emulsion with unabsorbable and radio-labeled lactulose is drunk. In small intestinal bacterial overgrowth (SIBO), bacteria will break down some lactulose and produce hydrogen, detectable in expired air. When the remaining lactulose will reach the colon, it will be broken down again by colonic bacteria, and hydrogen will be detected again. If only the later hydrogen raise is detected, it means there is no small intestinal bacterial overgrowth. In rapid transit through the small intestine, the 2nd hydrogen raise will occur sooner as in a healthy person (11). The test is completed in few hours.

Indirect Calorimetry

With indirect calorimetry the extent of absorption in the intestine can be determined. Principle: for 1 calory of energy produced by body, 208 milliliters of oxygen are required. So, from reduced amount of oxygen in the expired air, calories of produced energy may be calculated, and in this way the rate of absorption in the intestine can be estimated. The test is usually used to determine the required amount of nutrients, especially in short bowel syndrome (21).

Ultrasound of Abdomen

Ultrasound may reveal liver cyst, hepatitis, cirrhosis, cancer, or metastases, pancreatic cysts, pancreatitis, or cancer, gallstones in the gallbldder or biliary duct, but it often misses small gallstones, biliary sludge, or infection in the biliary tract. Liver and spleen enlargement may be evaluated, and free abdominal fluid (ascites) detected. How to prepare? Fat free meal in the evening, and fasting 8-12 hours before the test is usually recommended before the ultrasound of the gallbladder. Procedure. Investigation takes 30-60 minutes, and it should be not uncomfortable; patient lies on the back and doctor moves the ultrasound probe over abdominal skin. Contraindications are severe abdominal skin infection or burns. There are no known risks from ultrasound waves, complications like infection transmission from patient to patient are rare.

Endoscopic Ultrasound 

Endoscopic ultrasound is investigation with the ultrasound probe on the tip of the endoscope (23). It may provide more accurate images of liver, gallbladder, pancreas and the bowel wall. Fasting from the evening prior to investigation is required. Investigation is done under slight sedation, and lasts 30-60 minutes. Patient is not allowed to drive after the procedure. Contraindications for the procedure are the same as in upper endoscopy (see below). Possible complications are: pancreatitis, bowel inflammation, bleeding, injury or perforation of esophagus, stomach or intestine.   Endoscopic ultrasound can detect:

• small gallstones in the main biliary tract (procedure is safer than ERCP);
• pancreatitis, pancreatic cysts or cancer; 
• masses within the bowel wall, like neuro-endocrine tumors;
• anal causes of  incontinence, and anal fistula.

Aspiration of pancreatic cyst, lymph nodes around esophagus, and abdominal tumors is possible during the procedure. 

CT of Abdomen

CT may reveal liver enlargement, cyst or mass, stones in gallbladder or biliary tract, pancreatitis, pancreatic cyst or cancer, thickened intestinal wall in lymphoma or inflammation, diverticulitis, abscesses, inflammed, enlarged lymph nodes and other abdominal masses. CT can miss lesions in bowel mucosa, small gallstones or biliary sludge.

Image 1. CT of abdomen: thickened small intestine (in the midle upper part of the image), probably due to intestinal lymphoma

How to prepare? No barium investigations should be done within 4 days before CT, and no solid foods should be eaten from the preceding evening. Procedure. Patient lies on the table which is moved toward the CT machine, which looks like a ring or short tunnel. Rotating scanner scans abdomen as slices, as thin as 1mm, using X-rays, and produces multiple horizontal cross-section images (image 1). Intravenously administered iodine, or barium enema, may be used to get more clear images. Investigation is comfortable, non-painful, and lasts only few minutes. Anxious patients may receive a sedative. Complications and contraindications. The received dose of radiation is about 10 mSv, what is 500 times more than in chest X-ray, or in 3 years of exposure to natural radiation (30). Repeated CT scans slightly raise the risk for developing a cancer later in life. CT should not be done in pregnancy. Rarely, allergic reaction to iodine occurs. If iodine was used, breast milk should be thrown away for the 48 hours after investigation.

Plain X-ray of Abdomen

Plain abdominal X-ray may reveal kidney stones, gallstones, pancreatic calcifications (in the cyst or chronic pancreatitis), air trapped in the intestine (in intestinal obstruction), or under diaphragm (in intestinal perforation), colonic distension, or swallowed objects.

Abdominal Arteriogram

Abdominal arteriogram is an X-ray image of intestinal arteries (24). A long catheter is inserted into a femoral artery and proceeded toward aorta. From there a contrast substance is injected into mesenteric artery and its distribution within arterial branches in observed with fluorography. This investigation may show obstruction of intestinal arteries due to arteriosclerosis (often in diabetes) or embolus, what causes ischemic colitis, mostly in patients after age of 60. The site of intestinal bleeding may also be determined from eventual leakage of contrast substance into intestinal hollow.

X-ray with Barium (”Lower and Upper GI”)

Contrast x-ray investigation of the colon with barium enema (”lower GI”) may show colitis, polyps, or diverticula. Contrast investigation of stomach and small intestine with barium swallow (”upper GI”) may show changes the small intestine in Crohn’s disease or lymphoma. 

Image 2. Lower GI - barium enema

Colonoscopy

Causes of diarrhea, which may be found by colonoscopy: infection, Crohn’s disease, ulcerative colitis, ischemic colitis, collagenous/microscopic colitis, diverticula, intestinal worms, systemic sclerosis, Whipple’s disease, amyloidosis, polyps, cancer, or candidiasis. Colonoscopy is an investigation of rectum and colon (and few centimeters of the small intestine - terminal ileum) by a finger-thick flexible instrument (colonoscope) with the light and camera attached on the end (12). Additional channels allow inflation of air, administration of drugs, taking samples of tissue (biopsy), removing abnormal tissue (polyps, cancer) and suction of secretions. Lower GI is usually performed some days before the procedure to exclude gross colonic changes, which would represent a risk for colonoscopy

Image 3. Colonoscopy

Colonoscopy preparation. Intestinal symptoms, other diseases, current medications, and eventual allergies are discussed with the gastroenterologist. Aspirin, anti-rheumatic drugs, iron pills and barium investigations are not allowed in a week before the procedure. Only clear liquids may be ingested for 2-3 days, and a laxative given a day before the colonoscopy (bowel cleanse). No solid foods should be eaten after laxative, and complete fasting is needed for 6-8 hours before the procedure. Written instructions about colonoscopy prep may be obtained from gastroenterologist. Procedure. In a hospital or outpatient office, patient will usually get a mild intravenous sedative, which will make him/her drowsy. Patient will be aware of the procedure, but often won’t be capable to communicate with the doctor. No sedation, or complete anesthesia are also possible. Patient lies on the examining table on his/her left side, and after manual rectal examination, the colonoscope is administered and gently advanced toward the end of the colon. Then the colonoscope is slowly pulling out, the colon wall is observed, and eventual biopsies or other procedures are performed. Investigation lasts about 30 minutes, it is usually painless, but some cramping may appear. When extensive inflammation, or biliary tract disorders are expected, larger dose of sedatives may be given to prevent pain. After the investigation, patient rests for about an hour to completely wake up. Most patients don’t remember anything about the procedure. After discussion with the doctor, patient may go home, but is not allowed to drive. Bloating, due to inflated air may be experienced for the next day or two. Results. Biopsy samples will be sent to pathology lab, and doctor will be able to inform patient about diagnosis in a week or so. Complications of colonoscopy are rare: bleeding (can be stopped during the procedure), arrhythmia, small bowel obstruction, diverticulitis, or colon perforation (13). Possibility of transmission of a disease from one patient to another is practically excluded. Sedatives may cause anxiety, nausea, allergy or respiratory depression. Bleeding may appear as late as a week later, and usually stops spontaneously, but sometimes another colonoscopy is needed.

Relative Contraindications for Colonoscopy

Unless important reason exists, colonoscopy shouldn’t be done in (14):

• Pregnancy;
• Acute cardiac disease;
• Bowel perforation or complete obstruction;
• Acute diverticulitis;
• Fulminant colitis, toxic megacolon, colonic necrosis;
• Acute peritonitis;
• Symptomatic abdominal aortic aneurysm larger than 5-6 cm;
• Prominent neutropenia, thrombocytopenia or coagulopathy;
• Bochdalek hernia;
• Non-cooperative and non-treatable patient.

Flexible Sigmoidoscopy

In flexible sigmoidoscopy only the last 60 cm of the colon (rectum, sigmoid and descending colon) is investigated. Procedure is used in pregnancy instead of colonoscopy, whenever only changes in distal colon are expected, and as screening for early signs of colorectal cancer. Preparation is with clear liquids a day before, and cleansing enema right before the procedure, which lasts 10-20 minutes. Complications are rare. 

Virtual Colonoscopy (CT Colography)

Virtual colonoscopy (VC) is performed on a computer from CT images of the colon (15). The same colon prep is needed as in conventional colonoscopy, and the air has to be inflated into a colon before CT images are taken; the procedure takes about 10 minutes. No sedation is needed, and colonoscope is not used. VC may be used as a screening for colorectal cancer, since it can provide clear images of small changes throughout entire colon. The procedure is expensive, not regularly available, there’s no less discomfort as during conventional colonoscopy, no therapeutic intervention is possible, and there is considerable exposure to radiation.

Esophago-Gastro-Duodenoscopy - EGD (Upper Endoscopy)

In chronic diarrhea, upper endoscopy is usually done, when celiac disease or Crohn’s disease are suspected. Intestinal parasites, and rarely Whipple disease, systemic sclerosis, and amyloidosis are other small intestinal causes of diarrhea, which may be found by EGD.

HIDA Scan

HIDA scan is an investigation of a gallbladder, which is done when gallbladder disorder is suspected, but no gallstones are found by ultrasound. The test may reveal stones in the gallbladder, or obstruction in the biliary tract. How to prepare? No barium tests should be done two days prior to investigation, and four hours of fasting is required before the procedure. Procedure. Patient lies on the table, and radio-labeled HydroxyIminoDiaeticAcid (HIDA) is injected intravenously. HIDA is uptaken by the liver and excreted into a biliary system. After a while, the table with a patient is moved toward the radionuclide scanner, by which liver, gallbladder, biliary tree and duodenum may be seen within 30 minutes. A serial of images is made. A hormone cholecystokinin (CCK), which causes gallbladder contraction may be injected into a vein and gallbladder ejection fraction (EF) is calculated. EF above 50% is consdidered as normal, EF between 30-50% as boundary, and EF below 30% as abnormal (22). The whole procedure takes about two hours. HIDA scan should not be done in pregnancy and in known iodine allergy. Breast milk should be discarded for 48 hours after the test. Side effects are rare and include: allergy to the HIDA, pain during CCK injection, chills, nausea and rash. Normal HIDA scan doesn’t exclude motility disorders, so MRCP, ERCP or manometry of sphincter of Oddi may be tried, if gallbladder-like symptoms persist.

ERCP

ERCP (Endoscopic Retrograde Cholangio-Pancreatography) is endoscopic/X-ray contrast investigation of biliary tract (cystic, common hepatobiliary and pancreatic duct) in diarrhea due to malabsorption. Using a gastroscope, contrast substance is injected into biliary tract which is then checked by x-ray for gallstones, scars, inflammation, or cancer, which may all block the ducts. Small stones can be removed, or a stent inserted during the procedure, which lasts from 30 minutes to 2 hours. Preparation and precautions are like in upper endoscopy. If gallstone are removed, patient will stay in the hospital overnight. Possible complications of ERCP: pancreatitis (quite often but usually mild), esophageal, gastric, duodenal, or bile duct perforation, bleeding, and side effects of sedation (17). Alternative investigation - MRCP (Magnetic Resonance Cholangio-Pancreatography) has comparable diagnostic value, there’s no need for injection of contrast substance, there are no known side effects, but also no curative possibility (18). 

Image 4. ERCP: gallstones within the hepatobiliary duct

Capsule Endoscopy

Capsule endoscopy is an investigation of the small intestinal mucosa, using a 26 x 11 mm sized capsule with a video camera (PillCam), which patient ingests. Main indications are anemia in suspected gastrointestinal bleeding, diagnosis of early changes in Crohn’s disease, refractory celiac disease, benign and malign tumors, and NSAIDs related intestinal injury (19). Preparation with 10 hours fasting is needed. No sedation is needed and patient may freely walk around during the investigation. Pill camera can make up to 50,000 photos, which are recorded for 8 hours on a recorder, worn on a belt around the patient’s waist. The capsule with the camera is excreted naturally within 8-72 hours and it doesn’t need to be returned. From obtained images, a video is made on a computer and studied by a doctor. Complications are rare, the main one is intestinal obstruction. PillCam doesn’t trigger abdominal cramping. Capsule endoscopy should not be used in known intestinal obstruction. 

Image 5. PillCam for Capsule Endoscopy

Double Baloon Enteroscopy

Double baloon enteroscopy is endoscopic investigation of entire small intestine, using a gastroscope or colonoscope and a tube with two baloons, which help to drag the intestine over the endoscope (20). Investigation is done to make biopsies of suspicious mucosal lesions found by capsule endoscopy, mainly for for diagnosis of celiac disease and Crohn’s disease and for dilatation of strictures, removing of foreign objects, stopping of bleeding etc. Procedure takes from 45 minutes to 2 hours under sedation or short term anesthesia. Preparation is the same as for colonoscopy. 

OctreoScan  

OctreoScan is an radionuclide imaging test for neuroendocrine tumors like carcinoid, insulinoma, gastrinoma, or VIPoma (25). Radio-labeled octreoide or pentetreotide is injected into a vein, and its distribution in the body is scanned after 24 and 48 hours; octreoide tends to accumulate into neuroendocrine tumors. Test should not be done in pregnancy. 

1. http://www.wdxcyber.com/ncanc10.htm FOBT
2. http://www.bmj.com/cgi/content/full/332/7535/213 ANTI-GLIADIN IgA IN THE STOOL EVALUATION
3. http://health.nytimes.com/health/guides/test/chem-20/overview.html CHEM-20
4. http://www.emedicine.com/neuro/TOPIC720.HTM AUTONOMIC NEUROPATHY
5. http://www.allergyuk.org/allergy_skintest.aspx SKIN PRICK TEST
6. http://www.allergyuk.org/allergy_patchtest.aspx PATCH TEST
7. http://www.allergyclinic.co.uk/tests_challenge.htm ELIMINATION DIET
8. http://www.health.qld.gov.au/informedconsent/ConsentForms/shared/shared_file_14.pdf DRUG CHALLENGE TEST
9. http://www.gicare.com/pated/edtgs16.htm FECAL FAT TEST
10. http://www.genovadx.com/products/PE1ProductOverview81103.pdf PANCREATIC ELASTASE
11. http://www.childrenshospital.org/az/Site1581/mainpageS1581P0.html BREATH TEST FOR SHORT BOWEL SYNDROME
12. http://www.cigna.com/healthinfo/hw209694.html COLONOSCOPY
13. http://www.emedicine.com/med/topic2966.htm#section~Complications COLONOSCOPY COMPLICATIONS
14. COLONOSCOPY CONTRAINDICATIONS
15. http://www.emedicine.com/med/topic2966.htm#section~VirtualColonoscopy VIRTUAL COLONOSCOPY
16. http://www.emedicine.com/med/topic2965.htm  UPPER ENDOSCOPY COMPLICATIONS AND CONTRAINDICATIONS
17. http://digestive.niddk.nih.gov/ddiseases/pubs/ercp/index.htm ERCP
18. https://www.fhshealth.org/DI_proced/MRCP.html MRCP
19. http://www.fda.gov/fdac/features/2005/205_pillcam.html CAPSULE ENDOSCOPY
20. http://www.doubleballoonenteroscopy.com/ DOUBLE BALOON ENTEROSCOPY
21. http://www.korr.com/applications/indirect.htm INDIRECT CALORIMETRY
22. http://www.mypacs.net/cases/NORMAL-HIDA-SCAN-818324.html  HIDA SCAN
23. http://www.mayoclinic.org/endoscopic-ultrasound/  ENDOSCOPIC ULTRASOUND
24. http://www.baylorhealth.com/healthinformation/1/003819.htm  ABDOMINAL ARTERIOGRAM
25. http://imaging.mallinckrodt.com/_Attachments/PackageInserts/Octreoscan%20PI.pdf OCTREOSCAN
26. http://www.techlab.com/product_details/docs/t5002nccls.doc  LEUKO-TEST®
27. http://www.sonoraquest.com/documents/lactoferrin.pdfSTOOL LACTOFERRIN
28. http://www.questdiagnostics.com/hcp/intguide/jsp/showintguidepage.jsp?fn=TH_IBD_DifPnl.htm ASCA and pANCA
29. http://www.medscape.com/viewarticle/552624_2  ESR in IBD
30. http://www.fda.gov/cdrh/ct/risks.html  RECEIVED IRRADIATION DOZE IN CT
31. http://www.rxpgnews.com/research/immunology/article_4720.shtml  STOOL PROTEIN CD23 in FOOD ALLERGY
32. http://www.labcorp.com/datasets/labcorp/html/chapter/mono/nt000400.htm  iFOBT