The Role of Imaging Techniques in Gynecology

Saturday, August 16, 2008

Case Report
C.O. is a 29-year-old white female, Justify Fullwho presented with a history of infertility for several years, followed by a history of recurrent pregnancy losses.
Her past medical and surgical histories were negative. Gynecologically, she was remarkable in that she reported severe dysmenorrhea for the previous several years relieved by NSAIDs (nonsteroidal anti-inflammatory drugs). Her gynecologist found a low luteal phase progesterone and treated her with 50 mg of clomiphene citrate (CC) days 5–9 of the cycle.
She responded very well to the medication with a conception. The pregnancy resulted in a spontaneous abortion 5 weeks later. No D&C was required and she recovered well. She was still unable to conceive on her own and was again placed on CC. Again, she conceived and again had a spontaneous abortion—this time at 7 weeks' gestation. No D&C was performed.
The patient was then evaluated for recurrent pregnancy losses. Karyotype was normal for both partners. Hormonal evaluation was normal with the exception of a low mid-luteal phase progesterone. Immunologic and infectious screening also failed to reveal a cause for the recurrent losses. The hysterosalpingogram (HSG) demonstrated a midline filling defect similar to the one seen in Figure 3–1.

Figure 3–1. Müllerian anomaly as demonstrated by hysterosalpingogram. (Reproduced, with permission, from Doyle MB: Magnetic resonance imaging in müllerian fusion defects. J Reprod Med 1992;37:33.)


The patient was informed of the results and the potential for future miscarriages. The need for further evaluation and possible repair hysteroscopically or abdominally was carefully explained to the patient together with its risks and benefits. She elected to try CC one more time and hoped to avoid surgery.
At 8 weeks' gestation, vaginal ultrasonography revealed positive fetal cardiac activity in a CC-induced ovulation. While still on micronized progesterone, 100 mg 3 times daily, she was referred to her gynecologist for routine obstetric care.
At 12 weeks' gestation, the patient had an incomplete abortion that required a D&C. She recovered uneventfully and later returned to the office for further evaluation and treatment.
Several months were allowed to lapse before a hysteroscopy/laparoscopy revealed a broad-based intrauterine septum and stage I endometriosis. To evaluate the depth and width of the septum, a LaparoScan (EndoMedix, Irvine, CA) laparoscopic 7.5-Hz probe was used during the procedure. The septum was removed with a hysteroscopic resectoscope loop on a 40-watt setting. After the resection had been carried out, the ultrasonic probe was again used to measure the thickness of the myometrium and to verify the resection of the septum. A 30-mL 18F Foley catheter with the distal tip resected was placed in the fundus and inflated. The patient was discharged and placed on a broad-spectrum antibiotic and conjugated estrogen, 2.5 mg daily.

Discussion
As we entered the new millennium, a proliferation of imaging techniques used in medical practice occurred. Research into the development, refinement, and application of imaging in gynecology is very apparent in the literature.
The HSG has been considered the gold standard in the imaging of the uterine corpus for benign disorders (submucous myomas, submucous polyps, localization of tubal occlusion, and evaluation of müllerian fusion defects) and malignant disease (endometrial carcinoma).
In the case reported, the standard scout film was obtained and the cervix was prepared after the following were assured: the position of the uterus, absence of pelvic tenderness, and a negative pregnancy test. The water-soluble contrast medium was injected into the uterine cavity and oblique and anteroposterior films were obtained. These showed a midline uterine filling defect of the type usually seen with septate or bicornuate uteri.
Ultrasonography (US) performed on this patient during her pregnancies failed to show the filling defect. If suspected, the septum might have been encountered by more careful scanning. The scans of the last pregnancy revealed only an eccentrically placed pregnancy that might have been seen ultrasonographically even in normally structured uteri. Although not helpful at this point, ultrasonographic examination of the uterus between conceptions might have been helpful if used with a distending medium. This is especially useful in patients allergic to iodine contrast medium (Table 3–1). This technique of ultrasonic HSG is performed by occluding the cervix with a uterine injector and distending the uterus. This method can demonstrate the separate cavities as well as the possible difference between the septate and the bicornuate uterus while demonstrating tubal patency. The technique was adopted for this patient during her uterine septum resection to add ultrasonic contrast between the endometrial cavity and septum and the myometrium. Readers are referred to the many fine texts on diagnostic pelvic ultrasound for instruction and further discussion of these techniques. The development of “sonicated” contrast solutions may add greatly to the usefulness of US

Using 2 video cameras (one for the resectoscope and the other for the laparoscope and the LaparoScan laparoscopic ultrasound probe), all aspects of the surgery were evaluated. This setup allowed the operating surgeon adequate visualization of the uterine cavity during the resection and enabled other personnel in the operating room to follow the progress of the surgery. The laparoscopic video allowed the careful monitoring of the uterine surface and assured the surgeon that there would be less likelihood of a uterine perforation. This complication could have resulted in possible bowel injury.
The usefulness of the laparoscopic ultrasound probe with a picture within a picture was that it allowed the visualization of the 2 separate cavities and measurement of the length and width of the septum. It also enabled the operator to demonstrate the complete removal of the septum (Fig 3–2).





Figure 3–2. Uterine septum. A: Laparoscopic view shows a broad uterine fundus. B: Laparoscopic probe on the fundus of the uterus demonstrates the depth and width of the septum. C: Hysteroscopic view showing the resection of the uterine septum. D: Laparoscopic probe on the fundus of the uterus demonstrates the resected septum. (Note the echogenicity of the debris in the fundus.)


Imaging of the Uterus
Pelvic ultrasonography plays a significant role in the diagnosis of uterine leiomyomas (submucous, intramural, and subserosal) and polyps. The laparoscopic probe may be very useful in evaluating myomas during surgery for more accurate assessment of location and vascularity. The feasibility of continuing the procedure may also be assessed by this method intraoperatively.
Occasionally, the detection and localization of myomas, assessment of size, and their differential diagnosis are difficult. In these circumstances it is sometimes useful to perform magnetic resonance imaging (MRI) of the pelvis. MRI can accurately measure the volume of the myoma. This is an aid in determining whether medical management of myomas has resulted in shrinkage or if conservatively treated myomas are growing. Malignant degeneration of myomas visualized by MRI as described by some authors allows for early and appropriate intervention.
MRI also may be useful in the differential diagnosis of myomas and adenomyosis, benign and malignant ovarian pathology, pelvic kidney, and pelvic abscess.
One team of researchers described MRI of müllerian defects as an effective method of discerning between the septate and the bicornuate uterus, thus avoiding the more costly laparoscopy. In patients with very complicated müllerian fusion defects (didelphys with transverse vaginal septum or noncommunicating uterine segment), MRI may give a clear anatomic picture of the condition and allow for a properly planned surgical repair. If pelvic MRI had been performed on the patient in the case report that opens this chapter, it would probably have had the same appearance as the MRI in Figure 3–3. (Readers are referred to the review of MRI in müllerian fusion defects in Table 3–2.)


Imaging of the Endometrium
To obtain interobserver consistency in the evaluation of the endometrium, the following guidelines should be adhered to. Measurements are made in the midfundal region on the sagittal plane. Obtain the maximal double-thickness dimension, remembering to exclude the hypoechoic area between the myometrium and the endometrium and any fluid found between the anterior and posterior walls should be subtracted from the total measurement. The endometrium measures from 4–8 mm in thickness during the follicular phase. The uterine lining ranges from 7–14 mm during the luteal phase and has a uniform echogenic appearance.
Premenopausal women should be evaluated during the early follicular phase, immediately following the menses when the endometrium has a uniform linear appearance.
Menopausal women usually have an endometrial stripe of less than 4 mm. Menopausal women on hormone replacement therapy (HRT) may have endometrial thickness that exceeds 8 mm and a small amount of fluid (<> 4 mm.
In the future, three-dimensional ultrasound may be able to improve the diagnosis and staging of endometrial cancer.

Imaging of the Ovaries
About 12,000 women in the United States die annually as a result of ovarian cancer. Unfortunately, the ability of the pelvic examination to detect early ovarian malignancy is low. The same can be said of Ca-125 monoclonal marker for ovarian cancer, which has been found to be a poor predictor of early cases.
The flat plate of the abdomen may still be useful in the diagnosis of dermoid cysts of the ovary. However, cystic and solid structures of the ovary are now better evaluated by transabdominal ultrasonography (TAUS), transvaginal ultrasonography (TVUS), computed tomography (CT), and MRI.
Morphologic criteria have been assigned to increase suspicion concerning ultrasound findings when ovarian cancer is suspected. Cysts > 4 cm, solid and cystic components, septa, and papillary nodules have all been described.
TVUS combined with color flow and Doppler waveform was shown by Kurjak and colleagues to be sensitive and specific enough for application in an ovarian cancer screening program. Color flow allows the identification of vessels not previously identifiable with gray scale. With the use of the Doppler waveform, high- and low-resistance vessels in the ovaries can be distinguished. The resistance index (RI) is the systolic flow velocity peak minus the diastolic trough divided by the systolic peak. Using these techniques in 1000 women, these researchers were able to identify 83 women with the ultrasonographic signs or symptoms that led to surgery (Fig 3–4). Twenty-nine tumors were malignant, 4 from the asymptomatic group (Table 3–3). Color flow was not seen in only 2 of the malignant tumors. This demonstrates a sensitivity of 93% (Table 3–4). With a specificity of 65% for color flow alone, Doppler measurements are needed (Table 3–5). On the basis of distribution of RI values in benign and malignant tumors, a statistical cutoff value for the RI is 0.41 (Fig 3–5). The ability to identify malignant ovarian tumors with a combination of the above-mentioned techniques rather than the simpler laparoscopic approaches to benign adnexal disease may allow for more timely referral to gynecologic oncologists.

Not all studies are in agreement. A more recent evaluation of 47 patients with histologically proven ovarian cancer found that transvaginal color Doppler analysis of intratumoral blood flow didn't provide additional information concerning discriminatory characteristics when scanning individual tumors.
In an attempt to discriminate between malignant and benign adnexal masses in patients having color Doppler and serum Ca-125, one team of researchers developed a complementary multivariate logistic regression analysis. It was determined that the most useful variables among the 31 studied were the menopausal status, the serum Ca-125 level, the presence of one or more papillary growth (> 3 mm in length), and a color score indicative of tumor vascularity and blood flow. The model resulted in a sensitivity of 95.9% and a specificity of 87.1%. This team concluded that the use of a combination of diagnostic criteria and clinical information is more accurate than reliance solely on a single type of data.
CT may be useful for staging ovarian cancer preoperatively or for planning second-look procedures. In patients with benign-appearing adnexal masses (ovarian cysts or tubo-ovarian abscesses), CT may be very useful for biopsy and drainage. The contraindications to needle biopsy and drainage include lack of a safe unobstructed path for the needle, bleeding disorders, and lack of a motivated patient.

Imaging of the Fallopian Tubes
The best direct evaluation of the patency and architecture of the fallopian tubes is by means of endoscopic techniques. The best evaluation of tubal function indirectly is with HSG. This method allows demonstration of tubal patency and visualization of tubal rugations while avoiding the more costly laparoscopic surgery. Some disadvantages of HSG are pelvic infection, dye allergies, failure to detect adnexal adhesions, and false-positives for tubal occlusion. Hysterosalpingo-contrast sonography and MRI are also alternatives to laparoscopy, since women with normal findings probably have a normal pelvis.
The reader is referred to the sections on pelvic inflammatory disease and tubo-ovarian abscess elsewhere in this text for more on the radiographic diagnosis and management of these conditions.

Imaging in Ectopic Pregnancy
One team found that when human chorionic gonadotropin (hCG) levels reach 6500 mIU/mL, most normal intrauterine pregnancies can be detected as a gestational sac by TAUS. The value of adnexal sonography in the management of ectopic pregnancies was demonstrated by another set of researchers. They showed that if no gestational sac was seen on TAUS by 28 days and the hCG level was greater then 7500 mIU/mL, an ectopic gestation should be suspected. In a second related report, another team stated that the presence of fluid in the cul-de-sac and a noncystic adnexal mass had a predictive value of 94% in the diagnosis of ectopic pregnancy. However, the sonographic appearance of a pseudogestational sac should not be confused with the gestational sac. In the latter, a double-ring sign caused by the decidua parietalis is seen abutting the decidua capsularis.
TVUS, on the other hand, has the advantage of earlier and improved localization of the pregnancy with less pelvic discomfort since the bladder is not painfully distended. An hCG level of 1000 to 1500 mIU/mL (based on the International Reference Preparation) is the discriminatory zone in which an intrauterine pregnancy can be detected by TVUS. One must identify the double-ring sign of the intrauterine pregnancy and/or the yolk sac to ensure that the pregnancy is intrauterine. When an intrauterine pregnancy is not visualized on TVUS and the hCG level exceeds 1000–2000 mIU/mL, then suspicion for an ectopic pregnancy should be high. Also, multiple gestations may take several more days to be identified, and heterotopic pregnancies will be encountered more frequently in the patients using assisted reproductive techniques. The reader is referred to the section on ectopic pregnancy for a more complete discussion of this topic.
In a study of 71 patients with suspected ectopic pregnancies, one team failed to find an improvement in the diagnostic results when color Doppler imaging was used versus TVUS.
In the past decade, three-dimensional ultrasound has shown great promise in both obstetrics and gynecology. The technology is based on computer-generated three-dimensional images from a series of two-dimensional slices through the arc of tissue under the transducer. The resulting display shows longitudinal, transverse, and horizontal planes from which the 3-D image is calculated. This ever-improving technology is beginning to produce excellent imaging to detect uterine structural abnormalities. The precise size and location of polyps and myomas, as well as complete delineation of müllerian fusion defects have been reported. The 3-D measurements of ovarian pathology (with or without color Doppler) offers improved detection of early ovarian cancers with a greater degree of accuracy than the imaging techniques discussed here. Unfortunately, these techniques require a great deal of time and skill to produce these images, and they will require more refinement before they replace the widely used 2-D images.

Conclusion
The imaging techniques prevalent today have proven to be valuable tools in the diagnosis and early treatment of benign and malignant gynecologic disorders. To provide the patient with the highest level of medical care, the contemporary practicing gynecologist must constantly keep abreast of the new developments and applications of diagnostic imaging.
No matter what technology is used today and in the future, the goal will always be the same: to provide quick, low-risk, accurate diagnosis of gynecologic conditions, while keeping in mind the cost-effectiveness of the care delivered.

1 comments:

micky mayor said...

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