Abdominal CT scan
An abdominal CT scan is an imaging method. This test uses x-rays to create cross-sectional pictures of the belly area. CT stands for computed tomography.
How the Test is Performed
You will lie on a narrow table that slides into the center of the CT scanner. Most often, you will lie on your back with your arms raised above your 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.
x-ray
X-rays are a type of electromagnetic radiation, just like visible light. An x-ray machine sends individual x-ray waves through the body. The images...
Read Article Now Book Mark ArticleA computer creates separate images of the belly area. These are called slices. These images can be stored, viewed on a monitor, printed on film or saved to a disk. Three-dimensional models of the belly area can be made 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.
In many cases, an abdominal CT is done with a pelvis CT.
Pelvis CT
A computed tomography (CT) scan of the pelvis is an imaging method that uses x-rays to create cross-sectional pictures of the area between the hip bo...
Read Article Now Book Mark ArticleThe scan should take less than 30 minutes.
How to Prepare for the Test
You need to have a special dye, called contrast, put into your body before some exams. Contrast helps certain areas show up better on the scans. Contrast can be administered in various ways. Such as:
- 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 to 6 hours before the test.
- You may have to drink the contrast before the exam. When you drink it will depend on the type of exam being done. Contrast has a chalky taste, although some are flavored so they taste a little better. The contrast you drink will pass out of your body through your stools and is harmless.
Let your health care provider know if you have ever had a reaction to contrast. You may need to take medicines before the test to safely receive this substance.
Before receiving the contrast, tell your provider if you take the diabetes medicine metformin (Glucophage). People taking this medicine may have to stop taking it for a while before the test.
Let your provider know if you have any kidney problems. The IV contrast can worsen kidney function.
Too much weight can damage the scanner. Find out if the CT machine has a weight limit if you weigh more than 300 pounds (135 kg).
You will need to take off your jewelry and wear a hospital gown during the study.
How the Test will Feel
Lying on the hard table may be a bit uncomfortable.
If you have contrast through a vein (IV), you may have:
- Slight burning sensation
- Metallic taste in the mouth
- Warm flushing of the body
These feelings are normal and go away within a few seconds.
Why the Test is Performed
An abdominal CT scan makes detailed pictures of the structures inside your belly very quickly.
This test may be used to look for:
- Cause of blood in the urine
- Cause of abdominal pain or swelling
- Cause of abnormal blood test results such as liver or kidney problems
- Hernia
- Cause of a fever
- Masses and tumors, including cancer
- Infections or injury
- Kidney stones
Kidney stones
A kidney stone is a solid mass made up of tiny crystals. One or more stones can be in the kidney or ureter at the same time.
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Appendicitis
Appendicitis is a condition in which your appendix gets inflamed. The appendix is a small pouch attached to the end of the large intestine.
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What Abnormal Results Mean
The abdominal CT scan may show some cancers, including:
- Cancer of the renal pelvis or ureter
Cancer of the renal pelvis or ureter
Cancer of the renal pelvis or ureter is cancer that forms in the renal pelvis (center of the kidney) or ureter (tube that carries urine from the kidn...
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- Hepatocellular carcinoma
Hepatocellular carcinoma
Hepatocellular carcinoma is cancer that starts in the liver.
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- Melanoma
- Ovarian cancer
- Pancreatic cancer
Pancreatic cancer
Pancreatic cancer is cancer that starts in the pancreas.
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Pheochromocytoma
Pheochromocytoma is a rare tumor of adrenal gland tissue. It results in the release of too much epinephrine and norepinephrine, hormones that contro...
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Renal cell carcinoma
Renal cell carcinoma is a type of kidney cancer that starts in the lining of very small tubes (tubules) in the kidney.
Read Article Now Book Mark Article - Spread of cancers that began outside the belly
The abdominal CT scan may show problems with the gallbladder, liver, or pancreas, including:
- Acute cholecystitis
Acute cholecystitis
Acute cholecystitis is sudden swelling and irritation of the gallbladder. It causes severe belly pain.
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- Cholelithiasis
Cholelithiasis
Gallstones are hard deposits that form inside the gallbladder. These may be as small as a grain of sand or as large as a golf ball.
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Pancreatic abscess
A pancreatic abscess is an area filled with pus within the pancreas.
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Pancreatic pseudocyst
A pancreatic pseudocyst is a fluid-filled sac in the abdomen that arises from the pancreas. It may also contain tissue from the pancreas, enzymes, a...
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- Blockage of bile ducts
The abdominal CT scan may reveal the following kidney problems:
- Blockage of the kidneys
- Hydronephrosis (kidney swelling from the backflow of urine)
Hydronephrosis
Hydronephrosis is swelling of one kidney due to a backup of urine. This problem may occur in one kidney.
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- Kidney stones
- Kidney or ureter damage
- Polycystic kidney disease
Polycystic kidney disease
Polycystic kidney disease (PKD) is a kidney disorder passed down through families. In this disease, many cysts form in the kidneys, causing them to ...
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Abnormal results may also be due to:
- Abdominal aortic aneurysm
Abdominal aortic aneurysm
The aorta is the main blood vessel that supplies blood to the abdomen, pelvis, and legs. An abdominal aortic aneurysm (AAA) occurs when an area of t...
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Abscesses
An abscess is a collection of pus in any part of the body. In most cases, the area around an abscess is swollen and inflamed.
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Appendicitis
Appendicitis is a condition in which your appendix gets inflamed. The appendix is a small pouch attached to the end of the large intestine.
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Bowel wall thickening
Irritable bowel syndrome (IBS) is a disorder that leads to pain in abdomen and changes in bowel movements. IBS is not the same as inflammatory bowel...
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- Renal artery stenosis
- Renal vein thrombosis
Renal vein thrombosis
Renal vein thrombosis is a blood clot that develops in the vein that drains blood from the kidney.
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Risks
Risks of CT scans include:
- Allergy to contrast dye
- Exposure to radiation
- Damage to kidney function from contrast dye
CT scans expose you to more radiation than regular x-rays. Many x-rays or CT scans over time may increase your risk for cancer. However, the risk from any one scan is small. Most modern scanners are able to reduce the radiation exposure. Talk to your provider about this risk and the benefit of the test for getting a correct diagnosis of your medical problem.
Some people have allergies to contrast dye. Let your provider 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 you have an iodine allergy, you may have nausea or vomiting, sneezing, itching, or hives if you get this type of contrast. If you must be given such contrast, your provider may give you antihistamines (such as Benadryl) or steroids before the test.
Nausea or vomiting
Nausea is feeling an urge to vomit. It is often called "being sick to your stomach. "Vomiting or throwing-up forces the contents of the stomach up t...
Read Article Now Book Mark ArticleSneezing
A sneeze is a sudden, forceful, uncontrolled burst of air through the nose and mouth.
Read Article Now Book Mark ArticleItching
Itching is a tingling or irritation of the skin that makes you want to scratch the area. Itching may occur all over the body or only in one location...
Read Article Now Book Mark ArticleHives
Hives are raised, often itchy, red bumps (welts) on the surface of the skin. They can be an allergic reaction to food or medicine. They can also ap...
Read Article Now Book Mark ArticleAntihistamines
An allergy is an immune response, or reaction, to substances (allergens) that are usually not harmful. In someone with allergies, the immune respons...
Read Article Now Book Mark ArticleYour kidneys help remove IV dye from the body. You may need extra fluids after the test to help flush the iodine out of your body if you have kidney disease or diabetes.
Rarely, the dye may cause a life-threatening allergic response. Tell the scanner operator right away if you have any trouble breathing during the test. Scanners come with an intercom and speakers, so the operator can hear you at all times.
Reviewed By
Jason Levy, MD, FSIR, Northside Radiology Associates, Atlanta, GA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
Al Sarraf AA, McLaughlin PD, Maher MM. Current status of imaging of the gastrointestinal tract. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 18.
Levin MS, Gore RM. Diagnostic imaging procedures in gastroenterology. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 124.
Martinez JP. Abdominal pain. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 23.