Alternative names: CAT scan – pelvis; Computed axial tomography scan – pelvis; Computed tomography scan – pelvis; CT scan – pelvis
Definition: 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 bones. This part of the body is called the pelvic area.
Structures inside and near the pelvis include the bladder, prostate and other male reproductive organs, female reproductive organs, lymph nodes and pelvic bones.
Single CT images are called slices. The images are stored on a computer, viewed on a monitor, or printed on film. Three-dimensional models of the body area can be created by stacking the slices together.
How the Test is Performed
You are asked to lie on a narrow table that slides into the center of the CT scanner.
Once you are inside the scanner, the machine’s x-ray beam rotates around you. You will not see the rotating x-ray beams.
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 take less than 30 minutes.
How to Prepare for the Test
Certain exams require a special dye. It is called contrast media. It has to be delivered into the body before the test starts. The contrast helps certain areas show up better on the x-rays.
- Contrast can be given through a vein (IV) in your hand or forearm. Or you may be asked to drink a liquid form of contrast. If contrast is used, you may also be asked not to eat or drink anything for 4 to 6 hours before the test.
- Let your health care provider know if you have ever had a reaction to contrast. You may need to take medicines before the test in order to safely receive this substance.
- Before receiving the contrast, tell your provider if you take the diabetes medicine metformin (Glucophage) because you may need to take extra precautions.
Before receiving the contrast, tell your provider if you have kidney problems. You may not be able to get IV contrast if this is the case.
If you weigh more than 300 pounds (136 kilograms), find out if the CT machine has a weight limit. Too much weight can damage the scanner’s working parts.
You will be asked to remove jewelry and wear a hospital gown during the study.
You may be asked to drink an oral contrast solution.
How the Test will Feel
Some people may have discomfort from lying on the hard table.
Contrast given through an IV may cause:
- Slight burning sensation
- Metallic taste in the mouth
- Warm flushing of the body
These sensations are normal and most often go away within a few seconds.
Why the Test is Performed
CT rapidly creates detailed pictures of the body, including the pelvis and areas near the pelvis. The test may be used to diagnose or detect:
- Masses or tumours, including cancer
- The cause of pelvic pain
- Injury to the pelvis
This test may also help:
- Guide a surgeon to the right area during a biopsy or other procedures
- Your provider plan for surgery
- Plan radiation treatment for cancer
Results are considered normal if the organs of the pelvis that are being examined are normal in appearance.
What Abnormal Results Mean
Abnormal results may be due to:
Risks of CT scans include:
- Being exposed to radiation
- Allergic reaction to contrast dye
CT scans do expose you to more radiation than regular x-rays. Having many x-rays or CT scans over time may increase your risk of cancer. But the risk from any one scan is small. You and your provider 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 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 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, you may be given 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.
In rare cases, the dye causes a life-threatening allergic response called anaphylaxis. If you have any trouble breathing during the test, you should tell the scanner operator right away. Scanners come with an intercom and speakers, so the operator can hear you at all times.
Bishoff JT, Rastinehad AR. Urinary tract imaging: basic principles of computed tomography, magnetic resonance imaging, and plain film. In: Wein AJ, Kavoussi LR, Partin AW, Peters CA, eds. Campbell-Walsh Urology. 11th ed. Philadelphia, PA: Elsevier; 2016:chap 2.
Chernecky CC, Berger BJ. Computed tomography of the body (spiral [helical], electron beam [EBCT, ultrafast], high resolution [HRCT], 64-slice multidetector [MDCT]). In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. Philadelphia, PA: Elsevier Saunders; 2013:375-376.
Herring W. Recognizing the normal abdomen and pelvis on computed tomography. In: Herring W, ed. Learning Radiology. 3rd ed. Philadelphia, PA: Elsevier; 2016:chap 15.
Nicholas JR, Puskarich MA. Abdominal trauma. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier; 2018:chap 39.