A transvaginal ultrasound, also called transvaginal sonogram (TVS), is an ultrasound that uses an internal probe, or transducer, that enters the vaginal cavity. Either a radiology technician or physician performs the test, and a radiologist interprets the results.
An internal probe allows for closer access to the structures that need evaluation. With closer access, higher frequency sound waves can be used, which provides a clearer image due to better resolution. It is often used to evaluate suspected cancer or abnormal growths in the female reproductive system.
While the transvaginal ultrasound produces a clearer image, it may also create false positive results. This can lead to unnecessary testing to further evaluate the condition, with its accompanying physical and emotional impact.
The transvaginal ultrasound uses a small, wand-like transducer, or probe, which is inserted into the vagina. The probe emits high-frequency sound waves, which are not audible by humans. These sound waves painlessly bounce off the structures in its path. The returning echo wave is picked up by the probe. This information is fed into an attached computer that then creates an image, or sonogram, on a screen. It can differentiate between structures that are solid, such as a tumor, or filled with fluid, such as a cyst. It can be used to measure the thickness of the lining of the uterus, as well as of other organs.
A technique called color flow Doppler imaging may be used to evaluate the blood flow to certain structures. This can be helpful in establishing whether blood flow has been obstructed or enhanced to an organ. It cannot tell if a solid mass is malignant or benign. Other tests, such as a biopsy, would be needed to gather that information. It is done on an outpatient basis, is less expensive than imaging tests such as magnetic resonance imaging (MRI), and is considered safe, using sound waves rather than radiation to generate an image.
Little preparation is needed for the transvaginal ultrasound. A woman will need to undress from the waist down, and lie face-up on the examination surface. Legs may be put in stirrups, or a bolster may be placed under the hips to tilt the pelvic area upwards to facilitate use of the probe, both for insertion as well as for the ultrasound process itself. The test is done with an empty bladder, which is more comfortable than the full bladder required for the abdominal ultrasound. This method may be a preferred choice for women who have difficulty with bladder
Because of the small amount of gel used on the probe for easier insertion, a woman may wish to use a sanitary pad to protect her underpants from any minor leakage after she stands up. After the test a woman will be able to resume her regular scheduled activities.
The risk involved in using the transvaginal ultrasound is that of obtaining a false positive result, any resulting tests that would be ordered unnecessarily, and their accompanying emotional burden.
The normal results of a transvaginal ultrasound are the finding of the normal shape and size of any structure evaluated, with no abnormal thickness, masses or growths of any kind found.
Abnormal results include the finding of growths, such as masses or cysts, and any unexpected thickness of the structures evaluated. Because of the risk of false positive results, any abnormal findings should be further evaluated and confirmed before undergoing surgery or treatment for the suspected condition. Magnetic resonance imaging (MRI) is often ordered to further evaluate masses. An endometrial biopsy is performed to further evaluate a thickened uterine lining.
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—A false positive is a positive finding of a test when, in fact, the true result was negative. This would mean that the test results indicate that a patient had a particular condition or disease when they do not.
QUESTIONS TO ASK THE DOCTOR
- What are you looking for with this test?
- Who will perform the test? Is that person board-certified?
- Who will read the results? Is that person board-certified?
- Does the facility utilize color flow Doppler imaging?
- When, how and from whom will I receive the results?
- If the result is positive, how will you evaluate if it was a false positive?
- Will my insurance cover the cost of this test?