A CAT scan (computed axial tomography) or CT scan is a painless test that uses multiple x-ray images, taken from different angles, to create three-dimensional views of body structures. Increasingly, CAT scans use digital x-rays to produce their images on a computer screen.

CAT scans are among the leading imaging techniques used to diagnose a number of medical disorders, including gynecological conditions. Of all imaging tests that are currently available, the CAT scan is one of the best for producing images of bone, blood and soft tissues. For example, a CAT scan may be used to detect the spread of pelvic cancer into the fat behind the peritoneum, the membrane that lines the walls of the abdominal cavity. CAT scans can also detect collections of abdominal fluid or tumors.

However, because a CAT scan involves the use of radiation, pregnant women should not have an abdominal or chest CAT scan. This is a precaution to help protect a fetus from radiation exposure that could lead to developmental malformations or childhood cancer.

Images generated by CAT scans may be used to help a physician place a catheter or needle in the proper location for various procedures, such as a biopsy of breast tissue. Images from a CAT scan also can help a physician to guide a needle to an abscess for draining or to extract a collection of fluid.

A CAT scan of the pelvic region may be performed to identify any irregularities with the patient’s reproductive organs. It may also be used to detect the presence of masses. Other body regions that can be examined with a CAT scan include:

• The chest (thoracic) CAT scan, can produce very clear pictures of the heart and lungs. A cardiologist may order a chest CAT scan after an abnormality has been seen on a chest x-ray.
  
  
• The head, to determine the course of emergency treatment for a stroke. The head CAT scan allows the physician to determine whether a stroke is due to a cerebral hemorrhage (which will be seen immediately on the CAT scan) or cerebral swelling, which can take up to 48 hours to be seen on the CAT scan. It may also help the physician locate the exact position of the damage.
  
  
• The back, to assess for any bulging or herniated discs.
  
  
• The abdomen, to assess for any diseases of the liver, kidneys, pancreas or other internal organs.

An increasing number of people in the United States choose to have preventive CAT scans performed on an annual basis. These full-body CAT scans are designed to detect certain diseases in their very early stages, but their value is highly controversial among medical experts.

Critics point out that the body scans may detect ultimately benign conditions and, therefore, require a series of follow-up tests that only incur an increase in time and expense. In addition, though CAT scans can detect many diseases, patients often need an additional test to confirm a diagnosis. For example, a CAT scan can detect an abdominal mass, but a biopsy is necessary to confirm whether the mass is cancerous.

Another concern is that individuals may believe that a preventive CAT scan is a suitable alternative to regular physical examinations with their primary care physician.

It has been suggested that preventive CAT scans be reserved for higher risk individuals, as opposed to healthy, asymptomatic individuals younger than 40 years of age who do not have a family history of heart disease, cancer or other diseases.