Abdominal CT scan

• Illustrations
• Definition
• How the test is performed
• How to prepare for the test
• How the test will feel

• Why the test is performed
• What abnormal results mean
• What the risks are
• Special considerations

Definition    Return to top

An abdominal CT scan involves X-ray images of the abdomen from many angles. The X-ray beams are detected by the scanner and analyzed by a computer. The computer reconstructs the data into a picture of the body area being scanned. These images can be viewed on a monitor or reproduced as photographs.

How the test is performed    Return to top

The CT scanner is a free-standing machine with a large hole in the center. The patient lies on a narrow table that slides into the hole. In most cases the patient will be on his or her back with arms raised above his head. Patients who have difficulty with enclosed spaces such as those found with some MRI scanners do not usually have a problem with this type of test.

A dye may be injected into a peripheral vein to better evaluate certain diseases and organs. The radiologist will decide if this is necessary. Tell the technician or radiologist if you have any allergies or have had difficulty with prior CT scans.

It is very important that the patient remains still throughout the exam and holds his or her breath when asked. This will allow for better images.

The actual scan time is usually about two minutes, although the entire procedure usually takes much longer.

How to prepare for the test    Return to top

Tell the health care provider if you have any allergies or have had difficulty with prior CT scans.

You may be advised to fast for 4 to 6 hours if contrast dye or sedation is to be used.

You will be given a hospital gown to wear during the procedure. You may be asked to sign a consent form.

For infants and children:

The preparation you can provide for this test depends on your child's age and experience. For specific information regarding how you can prepare your child, see the following:

• Infant test or procedure preparation (birth to 1 year)
• Toddler test or procedure preparation (1 to 3 years)
• Preschooler test or procedure preparation (3 to 6 years)
• Schoolage test or procedure preparation (6 to 12 years)
• Adolescent test or procedure preparation (12 to 18 years)

How the test will feel    Return to top

The X-rays are painless. The primary discomfort may be from the need to lie still on the table.

If a dye is needed to increase the contrast between different tissues or organs, it is administered by injection into a vein. The injection may sting and the site may be tender to the touch for several minutes. Dye injections may cause a warm sensation, a metallic taste and, in a few cases, hives. Very rarely more severe contrast reactions can occur.

Why the test is performed    Return to top

An abdominal CT is a noninvasive way for a health care provider to evaluate a patient's internal organs and tissues. There are many reasons for this test to be ordered. Some common uses are for the evaluation of tumors, infections, kidney stones, or appendicitis.

What abnormal results mean    Return to top

The CT scan may show the following:

• Abdominal aortic aneurysm
• Abscesses
• Acute bilateral obstructive uropathy
• Acute cholecystitis
• Acute unilateral obstructive uropathy
• Addison's disease
• Amebic liver abscess
• Appendicitis
• Bilateral hydronephrosis
• Bowel wall thickening
• Carcinoma of the renal pelvis or ureter
• Cholangiocarcinoma
• Choledocholithiasis
• Cholelithiasis
• Chronic bilateral obstructive uropathy
• Chronic cholecystitis
• Chronic pancreatitis
• Chronic unilateral obstructive uropathy
• Complicated UTI (pyelonephritis)
• Cystinuria
• Cysts
• Echinococcus
• Enlarged lymph nodes
• Enlarged organs
• Gastrointestinal or bowel obstruction
• Glucagonoma
• Hairy cell leukemia
• Hepatocellular carcinoma
• Histoplasmosis; disseminated
• Hodgkin's lymphoma
• Islet of Langerhans' tumor
• Multiple endocrine neoplasia (MEN) II
• Nephrocalcinosis
• Nephrolithiasis
• Non-Hodgkin's lymphoma
• Ovarian cancer
• Pancreatic abscess
• Pancreatic carcinoma
• Pancreatic pseudocyst
• Pancreatitis
• Pheochromocytoma
• Primary hyperaldosteronism
• Pyelonephritis; acute
• Pyogenic liver abscess
• Renal cell carcinoma
• Retroperitoneal fibrosis
• Sclerosing cholangitis
• Spontaneous retroperitoneal hemorrhage
• Stones (bladder, kidney, liver, gall bladder)
• Testicular cancer
• Tumors
• Unilateral hydronephrosis
• Ureterocele
• Wilms' tumor
• Wilson's disease
• Zollinger-Ellison syndrome

• Acute renal failure
• Alcoholic liver disease (hepatitis/cirrhosis)
• Atheroembolic renal disease
• Chronic glomerulonephritis
• Chronic renal failure
• Cushing's syndrome
• Cushing's syndrome caused by adrenal tumor
• Injury of the kidney and ureter
• Medullary cystic disease
• Multiple endocrine neoplasia (MEN) I
• Polycystic kidney disease
• Reflux nephropathy
• Renal artery stenosis
• Renal vein thrombosis
• Skin lesion of histoplasmosis

What the risks are    Return to top

CT scans and other X-rays are monitored and regulated to provide the minimum amount of radiation exposure needed to produce the image. CT scans provide low levels of radiation. During pregnancy, an abdominal CT scan is usually not recommended, because there is some evidence of risk to the fetus.

The most common dye used is iodine based. A person who is allergic to iodine may experience nausea, sneezing, vomiting, itching, or hives. Rarely, the dye may cause anaphylaxis (a life-threatening allergic response).

Special considerations    Return to top

A CT scan provides a better picture of internal organs than conventional X-rays. The benefits of an abdominal CT scan usually far outweigh the risks of radiation exposure.