Gastrointestinal Tract

The stool guaiac test finds hidden (occult) blood in the stool (bowel movement), even when you cannot see the blood yourself.

It is the most common form of fecal occult blood test (FOBT) in use today.

Guaiac smear test; Fecal occult blood test - guaiac smear; Stool occult blood test - guaiac smear

In the most common way of doing a stool guaiac test, a small sample of stool is placed on a paper card and a drop or two of testing solution is added. A color change is a sign of blood in the stool.

If the test is performed in an office or hospital, a doctor may collect a small amount of stool during a rectal examination.

If the test is performed at home:

• You will need to collect a stool sample from three bowel movements, one right after the other.
• You will then smear a small amount of stool on a card for each bowel movement, and mail it to a laboratory for testing.

There are many ways to collect the samples:

• You can catch the stool on plastic wrap that is loosely placed over the toilet bowl and held in place by the toilet seat. Then put the sample in a clean container.
• Some test kits supply a special toilet tissue that you use to collect the sample, then put the sample in a clean container.

Do not take stool samples from the toilet bowl water, because this can cause errors.

For infants and young children wearing diapers, you can line the diaper with plastic wrap. Place the plastic wrap so that it keeps the stool away from any urine. Mixing of urine and stool can spoil the sample.

To make sure the guaiac test is accurate, follow the manufacturer's instructions on how to collect the stool.

Do not eat red meat, cantaloupe, uncooked broccoli, turnip, radish, or horseradish for 3 days before the test. These foods can sometimes interfere with the test.

You may need to stop taking medicines that can interfere with the test. These include vitamin C, aspirin, and nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen.

Check with your health care provider about medication changes you may need to make. Never stop or decrease any medication without first talking to your health care provider.

There is no discomfort when the test is done at home, because this test only involves a normal bowel movement. If stool is collected during an exam, there may be some discomfort in the anal canal and rectum.

This test detects blood in the digestive tract for the following reasons:

• You are being screened or tested for colon cancer
• You have abdominal pain, changes in bowel movements, or weight loss
• You have anemia(low blood count)
• You report blood in the stool or black, tarry stools

A negative test result means that there is no blood in the stool.

Abnormal results may be caused by anything that causes bleeding in the stomach or intestinal tract, including:

• Colon cancer or other gastrointestinal (GI) tumors
• Colon polyps
• Esophageal varices and portal hypertensive gastropathy
• Esophagitis
• Gastritis
• GI infections
• Hemorrhoids
• Inflammatory bowel disease
• Peptic ulcer

Other causes of positive guaiac test may include:

• Nosebleed
• Coughing up blood

Abnormal tests require follow-up with your doctor. In many cases, however, no explanation for the abnormal result is found.

There can be false-positive and false-negative results. Using the right collection technique, avoiding certain drugs, and observing food restrictions can reduce errors.

Tack J. Dyspepsia. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 13.

Review Date: 01/14/2012

Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A digital rectal exam is an examination of the lower rectum. The doctor uses a gloved, lubricated finger to check for abnormalities.

DRE

The doctor will first examine the outside of the anus for hemorrhoids or fissures. Then the doctor will put on a latex glove and insert a lubricated finger into the rectum. In female patients, this exam may be done together with a pelvic exam.

The doctor will ask you to try to relax before the test and to take a deep breath during the actual insertion of the finger into the rectum.

You may feel mild discomfort during this test.

This test is performed for various reasons, but is most often done as part of a routine yearly physical examination in both men and women.

In men, the test is used to examine the prostate, looking for abnormal enlargement or other signs of prostate cancer.

In women, a digital rectal exam may be performed during a routine gynecologic examination.

A digital rectal exam is also done to collect stool for testing for fecal occult (hidden) blood as part of screening for colorectal cancer.

This procedure is also done before other tests, such as a colonoscopy, to make sure nothing is blocking the rectum before inserting an instrument.

The digital rectal exam is usually treated as an initial screening examination. It is usually done together with other tests to rule out abnormalities.

A "normal" finding is when the doctor does not feel any abnormalities -- but this test does NOT completely rule out potential problems.

Any bleeding in the gastrointestinal tract calls for emergency care. Patients should be evaluated in the emergency department for gastrointestinal bleeding (hemorrhage).

If tests reveal occult (hidden) blood, but there is no obvious hemorrhaging (bleeding), the patient will undergo blood tests for anemia, followed by colonoscopy.

A male patient with an enlarged or nodular prostate will undergo a blood test of prostate specific antigen (PSA test), and then possibly a prostate ultrasound and biopsy after referral to a urologist.

The exam itself generally carries no risk, but it is possible to have a normal exam and still have an occult (unidentified/hidden) source of bleeding.

Pellagra is not a vitamin, it's a disease.

It can be classed as either primary or secondary pellagra. Primary pellagra is typically caused by insufficient levels of dietary niacin, also known as vitamin B3 (exogenous production) or of the amino acid tryptophan, from which the body synthesizes niacin (endogenous production). It may result from decreased dietary intake, decreased nutrient absorption or increased nutritional requirements, or a combination of these factors. It may occur secondary to alcoholism, chronic gastrointestinal disease, carcinoid syndrome, or Hartnup disease, amongst a range of other conditions. Secondary pellagra is due to impaired amino acid conversion.

Pellagra is also frequently seen amongst populations that consume large quantities of corn and minimal animal protein, as corn is low in both niacin and biologically available tryptophan.

Catherine Convery Walsh

Registered Dietitian

MSc Human Nutrition and Metabolism, University of Aberdeen Medical School

Barium enema is a special x-ray of the large intestine, which includes the colon and rectum.

Lower gastrointestinal series; Lower GI series

This test may be done in a doctor's office or hospital radiology department. It is done after the colon is completely empty. Your doctor will give you instructions on how to empty the colon.

You will lie flat on your back on the x-ray table and an x-ray will be taken.

• You will then be told to lie on your side. The health care provider will gently insert a well-lubricated tube (enema tube) into your rectum. The tube is connected to a bag that holds a liquid containing barium sulfate. It is placed in the rectum.
• The liquid is a type of contrast material that highlights specific areas in the body, creating a clearer image. The barium flows into your colon, and eventually passes out of your body with your stools.

A small balloon at the tip of the enema tube may be inflated to help keep the barium inside your colon. The health care provider will monitor the flow of the barium on an x-ray fluoroscope screen, which is like a TV monitor.

There are two types of barium enemas:

• Single contrast barium enema uses barium to highlight your large intestine.
• Double contrast barium enema uses barium, but also delivers air into the colon to expand it. This allows for even better images.

You will be asked to move into different positions and the table will be slightly tipped to get different views. At certain times when the x-ray pictures are taken, you will hold your breath and be still for a few seconds so the images won't be blurry.

The enema tube will be removed after the pictures are taken. You will be given a bedpan or helped to the toilet, so you can empty your bowels and remove as much of the barium as possible. One or two x-rays may be taken after you use the bathroom.

You must completely empty your bowels before the exam. This may be done using an enema or laxatives combined with a clear liquid diet. Your health care provider will give you specific instructions. Thorough cleaning of the large intestine is necessary for accurate pictures.

When barium enters your colon, you may feel like you need to have a bowel movement. You may also have a feeling of fullness, moderate to severe cramping, and general discomfort. Try to take long, deep breaths during the procedure. This may help you relax.

The barium enema is used to detect colon cancer, although it is used much less often than in the past.

It may also be used to diagnose and evaluate the extent of inflammatory bowel disease (IBD) or other bowel disease.

Barium should fill the colon evenly, showing normal bowel shape and position and no blockages.

Abnormal test results may be a sign of:

• Acute appendicitis
• Colitis due to Crohn's disease
• Colorectal cancer
• Colorectal polyps
• Diverticulitis
• Twisted loop of the bowel (volvulus)
• Ulcerative colitis

Other conditions under which the test may be performed:

• Hirschsprung's disease
• Intestinal obstruction
• Intussusception

There is low radiation exposure. X-rays are monitored and regulated to provide the smallest amount of radiation exposure needed to produce the image. Most experts feel that the risk is low compared with the benefits. Pregnant women and children are more sensitive to x-ray risks.

A more serious risk is a perforated colon, which is very rare.

Colonoscopy is another way to diagnose and monitor diseases in the colon.

Bresalier RS. Colorectal cancer. In: Fedlman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier;2010:chap 123.

Pickhardt PJ. Diagnostic imaging procedures in gastroenterology. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, PA: Saunders Elsevier; 2007:chap 135.

Review Date: 12/14/2010

David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

The anus itself would not swell. The fat tissue and area surrounding the anus could feel swollen. The main symptom would be feeling a fullness between your buttocks. However, this would be extremely uncommon as a medical complaint, unless you had surgery there.

One particular reason you could feel fullness in the buttocks lower is if nerves or blood vessels are compromised, such as from a spinal injury or post-DVT in large veins.