Mrs. C, 29, tells her NP that she has had intermittent left lower abdominal pain, particularly midway through her menstrual cycle, for the last 3 months. She also describes pain with intercourse over the last 3 months. Mrs. C feels generally well and has no other complaints. However, she is concerned because the pain seems to be getting worse every month.

During her history, Mrs. C states that the pain is not interfering with her work or home life. She has taken ibuprofen with relief. Her last menstrual period was 2 weeks earlier, and she describes her periods as regular, lasting approximately 4 days each month. Mrs. C's last Pap test was 6 months ago, and the results were normal. She is happily married and has two young children. Mrs. C denies sexual partners other than her husband of 10 years and does not believe he has had other partners since their marriage.

Upon exam, Mrs. C is a well-groomed and pleasant historian. Her abdominal exam is normal; her genitalia exam revealed pink vaginal walls with rugae. A small amount of thin, white vaginal discharge was noted on exam. The bimanual exam revealed pain with deep palpation of the left adnexal area. After completing Mrs. C's history and physical exam, the NP told Mrs. C that she was going to order a test to assist in the differential diagnosis. A transvaginal ultrasound (TVU) was ordered to check for uterine or ovarian abnormalities.

Chronic pelvic pain

Because there are a multitude of causes of chronic pelvic pain, the diagnostic process can frustrate the NP and confound the patient. Factors such as underreporting, reluctance to undergo an exam, and the potential need for numerous diagnostic tests may further complicate the achievement of an accurate diagnosis.1 The nonspecific nature of pelvic pain can emerge from numerous sources, such as gynecologic, urologic, gastrointestinal, musculoskeletal, and psychoneurologic conditions.1

The variety of conditions that present with pelvic pain include, but are not limited to, endometriosis, adenomyosis, lichen sclerosus, ovarian cysts, ovarian cancer, interstitial cystitis, pudendal neuralgia, dyspareunia, and pelvic inflammatory disease (PID).1 Diagnostic tests for these conditions may include TVU, Pap test, laparoscopy, abdominal computed tomography (CT), and urinalysis.2 The numerous differentials, extensive testing, and varied patient factors can lead to a lengthy diagnostic process.

Ultrasound

A commonly used imaging tool in obstetrics and gynecology since 1958, ultrasound was developed to monitor pregnancies and identify gynecologic tumors.3 Historically, the images were crude and visualized on a cathode ray tube by rocking a transducer over the abdomen.3 Compared with X-ray, ultrasound has no ionizing radiation exposure.4

Current technology allows for real-time images and sound to be displayed on both monochrome and color displays.3 Ultrasound is a necessary tool of obstetrics and gynecologic practice. It can be used to determine gestational age and fetal development, assess heart sounds, and determine gender. Outside of obstetrics and gynecology, ultrasound can be used to visualize abdominal tissue and organs, and provide biopsy guidance.4

TVU is a variation of abdominal ultrasound and is an essential tool for visualization of the pelvic cavity because it allows for imaging that is unattainable through traditional abdominal ultrasound techniques. While more specialized testing may require the use of an imaging center with a trained sonographer, TVU can usually be performed in the clinical setting by a specially trained NP or physician.

TVU is used as an aid for diagnosing ectopic pregnancy, endometrial thickening, uterine fibroids, uterine cancer, ovarian cysts, ovarian cancer, PID, and the assessment of new-onset postmenopausal bleeding.2 Compared with external anterior abdominal pelvic ultrasound, TVU may offer increased diagnostic accuracy.2 The minimally invasive and relatively inexpensive nature of TVU allows for quick assessment and works in conjunction with serologic, urologic, and histologic testing along with a thorough history and physical exam to explore the differentials.

Causes of chronic pelvic pain

Uterine problems such as endometriosis and endometrial thickening are primarily visualized with TVU.2 An evaluation for the presence of adhesions, fibroids, scar tissue, or uterine septum should also be done. Each of these can be visualized, and while not all are responsible for pelvic pain, they can be incidental findings. Endometrial thickening can be suggestive of endometrial carcinoma or endometrial polyps. Normal endometrial stripe in premenopausal women is menstrual cycle-dependent.5

During menstruation, the thickness of the endometrium should be 2 mm to 4 mm, early proliferative 5 mm to 7 mm, late proliferative-pre ovulatory phase up to 11 mm, and secretory phase 7 mm to 16 mm.5 If outside of this range, biopsy is indicated to discern the nature of the thickening. Although endometriosis may be identified with TVU, the diagnosis must be confirmed by laparoscopic visualization.6 Less invasive and more cost effective than magnetic resonance imaging or CT scan, TVU is a good option for visualizing deeply infiltrating endometriosis.6 An experienced sonographer is able to visualize and access larger lesions in the bladder as well as deep nodules and endometriomas.5

For evaluation of the uterus, TVU can be used to measure the thickness, evaluate the nature of polyps, and identify those that need to be biopsied. The sensitivity and specificity of TVU when detecting risk for endometrial cancer in postmenopausal women are 80.5% and 86.2%, respectively.7 The definitive diagnostic for endometrial cancer is a biopsy, but this must be obtained and is indicated for postmenopausal women who have bleeding and a 5 mm or greater endometrial stripe.8 Guidelines indicate that premenopausal women are at increased suspicion for uterine cancer with abnormal uterine bleeding and endometrial thickening at 5 mm.9

As an initial screening or secondary to an elevated cancer antigen 125 (CA-125), TVU can detect changes in the morphology of the ovaries.10 With TVU, ovarian changes can be noted as papillary protrusions, volume expansion, and solid areas on the ovaries that require further investigation. Incidentally, TVU has found ovarian cancer in individuals without symptoms as frequently as 30.4%.11 Due to its low predictive value, TVU must be used in conjunction with serologic testing, such as CA-125.10

When used in conjunction with a serum tumor marker such as CA-125, TVU offers a diagnostic value with a sensitivity of 90.63%, specificity of 97.14%, positive predictive value of 93.94%, and negative prediction of 98.55% for ovarian cancer.12

PID resulting from undiagnosed and untreated sexually transmitted infections may cause chronic pelvic pain. PID can result in life-threatening disease and/or the loss of fertility if not diagnosed early in the disease process. TVU can identify the results of PID, such as blockage to the fallopian tubes, damage to the ovaries, and pelvic adhesions. TVU may be uncomfortable for the patient if the PID is in an acute phase.13

Ovarian cysts are a common cause of chronic pelvic pain in women of childbearing age and can be identified and clearly illustrated by TVU. If the cyst shows density, is larger than 5 cm, or does not resolve in 1 to 2 months after identification, further testing is indicated because it may indicate ovarian cancer.14 Ovarian cysts identified with TVU should be monitored over time for resolution.

Performing TVU

When performing TVU, the urinary bladder must be empty, and the vaginal canal should be free of tampons.15 When describing the procedure to the patient, inform her that she will be supine on the exam table with knees bent, possibly in stirrups, and that the transducer probe will be inserted into the vagina during the exam. If possible, the patient should be allowed to insert the vaginal probe. If the patient has not been sexually active and the hymen is intact, this test may be contraindicated, in which case a CT scan would be obtained.

The invasive nature of this procedure also suggests that a chaperone should be present. Education for the patient includes allergy assessment because the probe is covered in a latex condom lubricated with gel.2 The test can last approximately 30 minutes.16 NPs should clarify that while it may be uncomfortable, TVU is a painless procedure, and the probe may be repositioned to assist with visualization of the abdominal cavity.15

Case study revisited

The results of Mrs. C's TVU revealed a 5 cm anechoic cystic lesion in the left adnexal area attached to the left ovary. Mrs. C has read about treatment for ovarian cysts and asked the NP about oral contraceptives to shrink the cyst. The NP explained that research did not support the use of oral contraceptives for this purpose.17 She further explained that most ovarian cysts resolved on their own in 6 to 8 weeks. Mrs. C was given a prescription for a nonsteroidal anti-inflammatory drug for her pelvic pain. A follow-up visit was scheduled for Mrs. C to repeat her physical exam and TVU if necessary. Mrs. C was advised of the signs and symptoms of enlarging or rupturing ovarian cysts and instructed to get emergency care if these occurred.

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