A pelvic ultrasound (gynecologic) study examines the area from the umbilicus to the pubic bone in women. It may be used in the evaluation of pelvic masses, to determine the position of an IUD, to evaluate postmenopausal bleeding, or to aid in the diagnosis of cysts, tumors, abscess, fibroids, cancer, or thickened endometrium. Information can be provided on the size, location, and structure of masses. Spectral or color Doppler can be applied to pelvic vessels, demonstrating normal flow changes associated with the menstrual cycle, and can evaluate abnormal flow patterns to masses/tumors. The examination cannot provide a definitive diagnosis of pathology but can be used as an adjunct procedure when the diagnosis is not readily apparent. It is also used in treatment planning and follow-up radiation therapy for gynecologic cancer. Additionally, follicle development after infertility treatment can be monitored.

A pelvic ultrasound may be performed using a transvaginal approach whereby a slim, covered, lubricated transducer is gently introduced into the vagina. A full bladder is not required. Because the sound waves do not need to transverse abdominal tissue, exquisite image detail is produced. This approach is most advantageous for examining the patient who is obese, the patient with a retroverted uterus, or the patient who has difficulty maintaining bladder distention. The transvaginal method is the approach of choice in monitoring follicular size during fertility workups and during aspiration of follicles for in vitro fertilization.

For a pelvic ultrasound using a transabdominal approach, a full bladder is necessary. The distended bladder serves three purposes: it acts as a “window” for transmission of the ultrasound beam; it pushes the uterus away from the pubic symphysis, thereby providing a less obstructed view; and it may be used as a reference for comparison in evaluating the internal characteristics of a mass under study.

Transvaginal (Endovaginal) Method

1. Have the patient lie on an examining table with hips slightly elevated in a modified lithotomy position. Drape the patient.

2. Lubricate and introduce a slim vaginal transducer, protected by a condom or sterile sheath, into the vagina. The patient may be given the option to insert the transducer herself.

3. Perform scans by using a slight rotation or movement of the handle and by varying the degree of transducer insertion. Typically, the transducer is inserted only a few inches into the vaginal vault.

4. Tell the patient that the examination time is about 15–30 minutes.

5. See Chapter 1 guidelines for intratest care.

1. Uterine abnormalities such as fibroids, intrauterine fluid collections, and variations in structure such as bicornuate uterus can be detected. Uterine and cervical carcinomas may be visualized, although definitive diagnosis of cancer cannot be made by ultrasound alone.

2. Endometrial abnormalities such as polyps can be visualized by ultrasound. This procedure involves distention of the endometrial canal with saline and subsequent ultrasound scanning. Very small adnexal masses may not be demonstrated by ultrasound studies. Masses identified on ultrasound may be evaluated in terms of size and consistency.

3. Cysts:

   1. Ovarian cysts (the most common ovarian mass detected by ultrasound) appear as smoothly outlined, well-defined masses. Cysts cannot be confirmed as either malignant or benign, but ultrasound studies can increase the suspicion that a particular mass is malignant.

   2. A corpus luteum cyst is a single, simple cyst commonly visualized in early pregnancy.

   3. Theca-lutein cysts are associated with hydatidiform mole, choriocarcinoma, or multiple pregnancy.

   4. Because normal ovaries often have numerous visible small cysts, the diagnosis of polycystic ovaries is difficult to make on the basis of ultrasound alone.

   5. Dermoid cysts or benign ovarian teratomas may be found in young adult women and have an extremely variable appearance. Because of their echogenicity, they are often missed on ultrasound. The only initial clue may be an indentation of the urinary bladder. When a dermoid cyst is suspected on ultrasound, a pelvic x-ray should be obtained.

4. Solid ovarian tumors such as fibromas, fibrosarcomas, Brenner tumors, dysgerminomas, and malignant teratomas are not differentiated by diagnostic ultrasound. Ultrasound documents the presence of a solid lesion but can go no further in narrowing the diagnosis.

5. Metastatic tumors of the ovary may be solid or cystic in ultrasonic appearance. They are variable in size and are usually bilateral. Because ascites is often present, the pelvis and remainder of the abdomen should be scanned for fluid.

6. Ultrasound differentiation between pelvic inflammatory disease and endometriosis is difficult. Evaluation of laboratory results and the clinical history leads to correct diagnosis. Other entities that may have similar ultrasonic presentation include appendicitis with rupture into the pelvis, chronic ectopic pregnancy, posttraumatic hemorrhage into the pelvis, and pelvic abscesses from various causes (e.g., Crohn disease, diverticulitis).

7. Any distortion of the bladder raises the possibility of an adjacent mass. Tumor, infection, and hemorrhage are the major causes of increased thickness of the urinary bladder wall. Masses such as calculi and catheters may be seen within the bladder lumen. Urinary bladder calculi are highly echogenic. A urinary bladder diverticulum appears as a cystic mass adjacent to the urinary bladder. It may be mistaken for a cystic mass arising from some other pelvic structure, so attempts are made to demonstrate its communication to the bladder.

8. Ultrasound studies can help to determine whether a pelvic mass is mobile.

9. Solid pelvic masses such as fibroids and malignant tumors may be differentiated from cystic masses, which show sound patterns similar to those of the bladder.

10. Lesions may be shown to have metastasized.

11. Studies may aid in the planning of tumor radiation therapy.

12. The position of an IUD may be determined.

Pretest Patient Care

1. Explain the purpose, benefits, and procedure of the test. Tell the patient that fasting is not required.

2. Have the patient drink four glasses of water or other liquid 1 hour before transabdominal scans and that she should not void until the test is over.

3. If a transvaginal (endovaginal) approach is to be used, tell the patient that no preparation is required.

4. Explain that a liberal coating of coupling agent must be applied to the skin so that there is no air between the skin and the transducer and to allow for easy movement of the transducer over the skin. A sensation of warmth or wetness may be felt. The couplant (ultrasound gel) does not stain or discolor clothing, but the patient may prefer to don a gown.

5. Determine whether the patient has a latex sensitivity and communicate such sensitivities to the sonographer, if a transvaginal (endovaginal) approach is to be used. See latex precautions in Chapter 1.

6. Reassure the patient that the procedure is not painful.

7. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

1. Severe obesity, intestinal gas, or barium in the intestine from recent procedures.

2. The success of a transabdominal scan depends on full bladder distention.

Normal

• Normal pattern image of bladder, uterus, fallopian tubes, vagina, and surrounding structures

• Normal Doppler flow patterns of major pelvic blood vessels