DefinitionAn 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
Alternative NamesComputed tomography scan - abdomen; CT scan - abdomen; CAT scan - abdomen
How the test is performedYou 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.Once you are inside the scanner, the machine's x-ray beam rotates around you. (Modern "spiral" scanners can perform the exam without stopping.)A computer creates separate images of the belly area, called slices. These images can be stored, viewed on a monitor, or printed on film. Three-dimensional models of the belly area can be created by stacking the slices together.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 scan should takes less then 30 minutes.
How to prepare for the testCertain exams require a special dye, called contrast, to be delivered into the body before the test starts. Contrast helps certain areas show up better on the x-rays.Contrast can be given through a vein (IV) in your hand or forearm. If contrast is used, you may also be asked not to eat or drink anything for 4-6 hours before the test.Let your doctor know if you have ever had a reaction to contrast. You may need to take medications before the test in order to safely receive this substance.Before receiving the contrast, tell your health care provider if you take the diabetes medication metformin (Glucophage) because you may need to take extra precautions.If you weigh more than 300 pounds, find out if the CT machine has a weight limit. Too much weight can cause damage to the scanner's working parts.You will be asked to remove jewelry and wear a hospital gown during the study.
How the test will feelSome people may have discomfort from lying on the hard table.Contrast given through a vein (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 performedAn abdominal CT rapidly creates detailed pictures of the structures inside the belly area (abdomen).This test may help detect or diagnose:The cause of abdominal pain or swellingHerniaThe cause of a feverMasses and tumors, including cancerInfections or injuryKidney stonesAppendicitis
What abnormal results meanThe abdominal CT scan may reveal certain cancers, including:Breast cancerCancer of the renal pelvis or ureterColon cancerHepatocellular carcinomaLymphomaMelanomaOvarian cancerPancreatic cancerPheochromocytomaRenal cell carcinoma (kidney cancer)Testicular cancerThe abdominal CT scan may show problems with the gallblader, liver, or pancreas, including:Acute cholecystitisAlcoholic liver diseaseCholelithiasisPancreatic abscessPancreatic pseudocystPancreatitisSclerosing cholangitisThe abdominal CT scan may reveal the following kidney problems:Acute bilateral obstructive uropathyAcute unilateral obstructive uropathyChronic bilateral obstructive uropathyChronic unilateral obstructive uropathyComplicated UTI (pyelonephritis)Kidney stonesKidney swelling (hydronephrosis)Kidney or ureter damagePolycystic kidney diseaseUteroceleAbnormal results may also be due to:Abdominal aortic aneurysmAbscessesAppendicitisBowel wall thickeningRetroperitoneal fibrosisRenal artery stenosisRenal vein thrombosis
What the risks areRisks of CT scans include:Being exposed to radiationAllergic reaction to contrast dyeCT scans do expose you to more radiation than regular x-rays. Having many x-rays or CT scans over time may increase your risk for cancer. However, the risk from any one scan is small. You and your doctor should weigh this risk against the benefits of getting a correct diagnosis for a medical problem. Some people have allergies to contrast dye. Let your doctor know if you have ever had an allergic reaction to injected contrast dye.The most common type of contrast given into a vein contains iodine. If a person with an iodine allergy is given this type of contrast, nausea or vomiting,sneezing, itching,or hives may occur.If you absolutely must be given such contrast, your doctor may give you antihistamines (such as Benadryl) or steroids before the test.The kidneys help remove iodine out of the body. Those with kidney disease or diabetes may need to receive extra fluids after the test to help flush the iodine out of the body.Rarely, the dye may cause a life-threatening allergic response called anaphylaxis. If you have any trouble breathing during the test, you should notify the scanner operator immediately. Scanners come with an intercom and speakers, so the operator can hear you at all times.
ReferencesShaw AS, Dixon AK. Multidetector computed tomography. In: Adam A, Dixon AK, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 4.