Pelvic CT scan

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, small intestine, colon, 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.

Alternative Names

CAT scan - pelvis; Computed axial tomography scan - pelvis; Computed tomography scan - pelvis; CT scan - pelvis

How the Test is Performed

You will be 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 10 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.

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:

• Infection in the pelvis
• Masses or tumors, 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

Normal Results

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:

• Abscess (collection of pus)
• Bladder stones
• Broken bone
• Cancer
• Diverticulitis

Risks

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.

References

Bishoff JT, Rastinehad AR. Urinary tract imaging: basic principles of CT, MRI, and plain film imaging. In: Partin AW, Dmochowski RR, Kavoussi LR, Peters CA, eds. Campbell-Walsh-Wein Urology. 12th ed. Philadelphia, PA: Elsevier; 2021:chap 3.

Herring W. Recognizing the normal abdomen and pelvis: computed tomography. In: Herring W, ed. Learning Radiology: Recognizing the Basics. 5th ed. Philadelphia, PA: Elsevier; 2024:chap 13.

Rischall ML, Puskarich MA. Abdominal trauma. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 38.