There are three methods of performing pelvic ultrasound: abdominal (transabdominal), vaginal (transvaginal, endovaginal) in women, and rectal (transrectal) in men. The same principles of high-frequency sound apply in each technique.
For the transabdominal approach, the patient has a full urinary bladder and is positioned on an examination table. A clear gel is applied to the lower abdomen to help the transducer make secure contact with the skin. The sound waves produced by the transducer cannot penetrate air, so the gel helps to eliminate air pockets between the transducer and the skin. The sonographer then presses the transducer firmly against the skin and sweeps it back and forth to image the pelvic organs. Doppler sonography can be performed through the same transducer.
Transvaginal ultrasound involves the insertion of the transducer into the vagina after the patient empties her bladder and is performed very much like a gynecologic exam. The tip of the transducer is smaller than the standard speculum used when performing a Pap test. A protective cover is placed over the transducer, lubricated with a small amount of gel, and then inserted into the vagina. Only two to three inches of the transducer end are inserted into the vagina. The images are obtained from different orientations to get the best views of the uterus and ovaries. Doppler sonography can be performed through the transvaginal transducer, which is the same transducer used during sonohysterography. Below is an example of a transvaginal transducer (probe). Transvaginal ultrasound is usually performed with the patient lying on her back and with her feet in stirrups as during a gynecologic exam.
The prostate gland is located directly in front of the rectum, so the ultrasound exam is performed transrectally. A protective cover is placed over the transducer, lubricated, and then placed into the rectum so the sound need only travel a short distance. The images are obtained from different orientations to get the best view of the prostate gland. Ultrasound of the prostate is most often performed with the patient lying with his left side down on the table and with his knees bent up slightly toward the chest.
If a suspicious lesion is identified within the prostate gland, by ultrasound or with a rectal examination, an ultrasound-guided biopsy can be performed. This procedure involves advancing a needle into the prostate gland while the radiologist watches the needle placement with ultrasound. A small amount of tissue is taken for microscopic examination. Below is an example of a transrectal transducer (probe).
Each method has its advantages. The transabdominal approach offers an expanded view of the entire pelvis, showing where one internal structure is in relation to another. Since the transducer is brought closer to the area being examined in the transvaginal and transrectal approaches, improved visualization may be achieved. Thus, it can be helpful in locating the embryonic heartbeat in an early pregnancy, evaluating the uterine texture, or measuring a cyst in an ovary. Your physician or radiologist will decide whether one or a combination of approaches is best for your particular case.
When the examination is complete, the patient may be asked to dress and wait while the ultrasound images are reviewed, either on film or on a monitor. Often, though, the sonographer or radiologist is able to review the ultrasound images in real time as they are acquired, and the patient can be released immediately..