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Abdominal CT Scan

Definition

An abdominal CT scan is an imaging method that uses x-rays to create cross-sectional pictures of the belly area. CT stands for computed tomography.

See also: CT scan

How the test is performed

You will be asked to lie on a narrow table that slides into the center of the CT scanner. Usually, you will lie on your back with your arms raised above the head.

The health care provider may inject a dye into one of your veins. This helps certain diseases and organs show up better on the images.

Once inside the scanner, the machine's x-ray beam rotates around you. Small detectors inside the scanner measure the amount of x-rays that make it through the abdomen. A computer takes this information and creates several individual images, called slices.

You must be still during the exam, because movement causes blurred images. You may be told to hold your breath for short periods of time.

The actual scan time only takes a few minutes, although the entire procedure usually takes much longer.

How to prepare for the test

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

If contrast or sedation is used, you may also be asked not to eat or drink anything for 4-6 hours before the test.

Since x-rays have difficulty passing through metal, you will be asked to remove jewelry and wear a hospital gown during the study.

How the test will feel

The x-rays are painless. Some people may have discomfort from lying on the hard table.

Contrast give through an IV may cause a slight burning sensation, a metallic taste in the mouth, and a warm flushing of the body. These sensations are normal and usually go away within a few seconds.

Why the test is performed

An abdominal CT rapidly creates detailed pictures of the belly area. The test may be used to:

• Study blood vessels
• Identify masses and tumors, including cancer
• Look for infections, kidney stones, or appendicitis

What abnormal results mean

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
• 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 syndrome
• Cushing 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

An abdominal CT scan is usually not recommended for pregnant women, because it may harm the unborn child. Women who are or may be pregnant should speak with their health care provider to determine if ultrasound can be used instead.

CT scans and other x-rays are strictly monitored and controlled to make sure they use the least amount of radiation. CT scans do create low levels of ionizing radiation, which has the potential to cause cancer and other defects. However, the risk associated with any individual scan is small. The risk increases as numerous additional studies are performed.

In some cases, a CT scan may still be done if the benefits greatly out weigh the risks. For example, it can be more risky not to have the exam, especially if your health care provider thinks you might have cancer.

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

Special considerations

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

Review Date: 1/24/2007

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