In the evaluation of gynecological causes of pain, TVS can not only help to identify the likely etiology, but also separate surgical conditions from medical ones. For example, functional ovarian cyst or pelvic inflammatory disease is more compatible with medical management, whereas ovarian torsion is a surgical emergency. The initial role of sonography in the evaluation of patients at risk for ovarian torsion is to help exclude other causes of acute abdominal pain such as appendicitis, pelvic inflammatory disease, ruptured ovarian cyst, and ectopic pregnancy.5,6 Characteristic findings may be routinely seen by transvaginal and transabdominal sonography, although appearances may be nonspecific. For example, the most common sonographic gray-scale finding of ovarian torsion is an enlarged ovary or ovarian mass complex (Figure 36-1A). The presence of an adnexal mass or enlarged ovary has been documented in all subjects in several studies. Ovarian volumes within these studies have ranged from 26 to 4308 cm3.7,8,9, and 10 However, if the twisted ovary is located in the right lower quadrant of the abdomen, it may be mistaken for an appendiceal abscess.7
An ovarian cyst is acting as a fulcrum to potentiate torsion in a 19-year-old female with severe right lower quadrant pain. A: A sagittal image of the right ovary demonstrates an enlarged edematous ovary containing a hemorrhagic functional cyst. B: Color Doppler evaluation of the right ovary fails to demonstrate flow within the ovary. Note that color Doppler signal is seen in the adjacent iliac vessels.
Several distinguishing gray-scale appearances of ovarian torsion have been described using transabdominal sonography in children and adolescents. A large cystic mass with internal debris has been shown to be fairly specific for torsion in neonates.11,12,13, and 14 In older children and adolescents, a unilaterally enlarged ovary containing peripheral follicular cysts has been described as characteristic of torsion in as many as 74% of cases (Figure 36-2).7,10,15 Weed and Collins,16 in an experimental study using an animal model, produced passive congestion and cystic dilatation of follicles by ligating the ovarian vessels. Follicular enlargement was ascribed at least partially to transudation of fluid into the follicles due to vascular impairment. Reports of cases of massive ovarian edema, a condition attributed to partial torsion of the ovary, describe similar follicular structures in the cortex of an enlarged ovary.17 It is possible to conclude that this combination of findings in the prepubertal age group in which follicular enlargement is not expected may be specific for ovarian torsion.
Enlarged ovary containing peripheral follicular cysts in a prepubertal patient. Nine-year-old female presenting with right lower quadrant pain. Transabdominal sonography demonstrates sagittal (A) and transverse (B) images of an edematous ovary with peripheral follicular cysts, which is a characteristic appearance of torsion in the prepubertal age group.
In the postmenarchal population, ovarian appearances are more difficult to interpret. An irregular internal texture of the ovary seems to correlate with intraovarian hemorrhage (Figure 36-3). Peripherally placed follicles and homogeneous echoes seen centrally consistent with areas of edema within enlarged ovaries have also been reported,10,15 although these descriptors are nonspecific. Entities such as endometriomas, hemorrhagic cysts, tubo-ovarian complexes, and hyperstimulated ovaries undergoing ovulation induction are often similarly described. Free fluid within the cul-de-sac is another nonspecific finding frequently described associated with cases of ovarian torsion.15 The fluid may be a transudate from the ovarian capsule secondary to obstruction of veins and lymphatic vessels.18 On the other hand, a small amount of fluid is often physiologic in females of reproductive age.
Intraovarian hemorrhage manifested by an irregular internal texture of the ovary. Twenty-two-year-old female with recurring right lower quadrant pain. A hemorrhagic, edematous ovary with an associated hemorrhagic cyst, the presumed fulcrum for torsion, was seen laparoscopically. Detorsion was performed by cyst drainage. Transvaginal sonography in sagittal (A) and transverse (B) planes demonstrates an irregular, heterogeneous consistency peripherally due to parenchymal hemorrhage and edema (long arrows) as well as a more circumscribed echogenic area centrally, which corresponds to hemorrhage within a cyst (short arrows).
With the advent of color and spectral Doppler analysis of ovarian arterial and venous waveforms, it was assumed that this would prove to be an accurate tool for the evaluation of ovarian torsion. In actuality, studies of Doppler flow patterns in torsion are variable with the Doppler findings varying depending on degree of torsion and its chronicity. In some cases of torsion, there can be focal areas of blood flow, whereas in those cases that are more complete, no intraovarian venous or arterial flow is present (see Figure 36-1B). Lack of arterial and venous Doppler flow should enable confident diagnosis, although false-positive diagnoses may be obtained as a result of the depth of penetration being greater than the capabilities of the ultrasound beam, improper Doppler or gray-scale priority settings, and too high filter pulse repetition frequency (PRF) settings.19,20, and 21 Conversely, ovarian color Doppler signal has been frequently reported in cases of surgically proven torsion.7,8
Multiple studies have supported the use of Doppler interrogation of the ovary in the evaluation of torsion. Ben-Ami et al19 reported a positive predictive value for torsion in the absence of venous flow of 94%, and that torsion is highly unlikely if Doppler interrogation reveals venous flow. Fleischer et al20 and Lee et al21 assert that the presence of arterial and venous flow within adnexa that were found to be torsed upon subsequent surgical exploration was predictive of the ultimate viability of the organs. The study by Lee et al found that gray-scale and color Doppler sonography preoperatively identified twisting of the vascular pedicle in 28 of 32 patients with surgically confirmed torsion (Figure 36-4). The same study described 57% of cases as having both arterial and venous flow within the vascular pedicle, but later concluded, using pathologic findings or clinical follow-up after a procedure to uncoil the twisted vascular pedicle, that 15 of these 16 ovaries with Doppler flow were viable organs. Investigations by Fleischer et al showed no venous Doppler flow centrally within all 10 cases of surgically proven nonviable ovaries. In addition, venous Doppler signal was seen centrally within all 3 surgically proven viable ovaries. However, these findings were not confirmed in another series by Tepper et al.22
Imaging of Imaging of the twisted ovarian pedicle. A: Artist's rendering of a twisted ovarian pedicle containing broad ligament and fallopian tube with associated engorgement of the ovary. B: Sagittal view of the right adnexa demonstrating a twisted pedicle adjacent to the ovary by gray-scale sonography (arrow). A diagnosis of ovarian torsion was confirmed intraoperatively. C: Contrast-enhanced CT image of the pelvis in the same patient also demonstrating twisting of the ovarian pedicle (arrow).
Other investigators have found Doppler findings to be less reliable. Several case reports and retrospective studies of adnexal torsion diagnosed at the time of surgical intervention have described an abnormal appearance of the ovary with normal arterial and venous Doppler signal (Figure 36-5).7,8,23,24 In a retrospective series, Albayram and Hamper8 evaluated 15 pathologically proven torsed ovaries, of which 53% demonstrated some degree of arterial signal and 27% showed evidence of venous signal within the ovary. Interestingly, in 14 out of the 15 cases, abnormal Doppler flow was described when compared to Doppler flow within the normal contralateral ovary. Similar results have also been found in a retrospective series of 39 patients with pathologically proven ovarian torsion performed at Vanderbilt University Medical Center.25 Twenty-one (54%) patients had documented arterial Doppler signal within the torsed ovary and 13 (33%) had documented venous flow.
Intraovarian arterial and venous Doppler signal seen in a pathology-proven infarcted, hemorrhagic ovary. Thirty-one-year-old postpartum female with worsening abdominal pain. A: Transvaginal sonogram of the right ovary in the sagittal plane demonstrates enlargement with a heterogeneous, hypoechoic parenchyma centrally. A focus of calcification is seen peripherally, although there was no evidence of tumor in the pathology specimen. B: Power Doppler evaluation demonstrates an abundance of Doppler signal within the ovary. Duplex Doppler evaluation showing arterial (C) and venous (D) signal.
The variety and discrepancy of Doppler findings in the literature associated with ovarian torsion may be linked to the completeness of obstruction of the vascular supply.26 Venous thrombosis may cause symptoms prior to the development of arterial occlusion, explaining the more frequently demonstrated absence of venous Doppler signal. Persistent Doppler arterial and/or venous flow may also be related to the dual blood supply to the ovary. To date, there appear to be no large-scale studies in the English literature evaluating the predictive value of Doppler flow in cases of ovarian torsion.
Although characteristic sonographic findings of torsion have been reported in the prepubertal age group, there is much less specificity of sonographic findings in the postmenarchal age group. The enlarged, abnormal-appearing ovary does appear to be a common denominator in most, if not all, cases of ovarian torsion. Evidence strongly points to the diagnosis in the presence of an enlarged ovary with absence of associated arterial and venous Doppler signal.19,20, and 21 However, multiple case reports and series in the literature suggest the presence of both arterial and venous Doppler signal within the ovary or associated vascular pedicle in cases of ovarian torsion. Furthermore, these cases in which vascularity is still present may be the very patients who would benefit from conservative surgery. Surgical exploration then should not be delayed when clinical suspicion remains high in the setting of an enlarged ovary with Doppler flow. Perhaps investigators should now turn their attention to research that would develop methods to determine the viability of the ovary. The demonstration of the twisted ovarian pedicle may be a promising avenue to explore since its appearance has been shown to be characteristic of ovarian torsion in both the sonographic and CT literature (see Figure 36-4), and the presence or absence of vascular flow within the pedicle may correlate with ovarian viability. Comparing the vascularity of the abnormal-appearing ovary with that of the normal contralateral side may prove helpful. Additionally, further investigation of the use of contrast-enhanced sonography may provide more accurate assessment of ovarian vascular flow and viability.
Functional ovarian cysts are physiologic and not neoplastic lesions of the ovary, whose appearance and disappearance is hormone driven. These cysts may be simple or hemorrhagic and are commonly divided into 3 categories dependent upon the clinical scenario, the follicular cyst, the corpus luteum cyst, and the theca lutein cyst. Acute abdominal pain is most often caused by internal hemorrhage, rupture, or leakage, but may be simply a result of its large size, which is greater than 2.5 to 3.0 cm. The most common form is the follicular cyst, which is the result of abnormal follicular enlargement due to anovulation. It is often associated with hemorrhage and rapid resorption, with most resolving within 2 months. However, it should be emphasized that resolution may be delayed if the patient continues to be anovulatory, without a normal menstrual cycle, unless cyst rupture occurs. The corpus luteum cyst is a result of enlargement of the corpus luteum of pregnancy with resolution usually by 14 weeks' gestational age. Theca lutein cysts are associated with very high levels of b-hCG often seen with trophoblastic disease and multiple gestations. They are usually very large and numerous, and may persist for weeks after the withdrawal of the stimulus.
The sonographic appearance of the functional cyst without hemorrhage is that of a thin-walled simple cyst, although with hemorrhage appearances vary with chronicity. Acute hemorrhage is hyperechoic and may be suggestive of a solid mass. A diffuse pattern of low-level echoes may be seen, although this pattern is more commonly associated with an endometrioma (Figure 36-6A). With hemolysis and retraction of clot, a reticular network of stranding, septations, or fluid–fluid levels between fluid components and congealed red blood cells is demonstrated (Figure 36-7). Internal echoes with septations are often seen. Leakage of hemorrhagic fluid with associated peritoneal irritation is common.
Hemorrhagic cyst (A) demonstrating a hyperechoic parenchymal pattern suggestive of a solid mass. Doppler evaluation (B) demonstrates only peripheral Doppler signal consistent with internal hemorrhage.
Variable appearances of hemorrhagic cysts demonstrate a reticular pattern (A) with hemolysis and retraction of clot and a fluid–fluid level (B) between fluid components and congealed red blood cells.
Color and spectral Doppler evaluation is characteristic with typical findings of peripheral color Doppler signal with arterial low-impedance flow (see Figures 36-6B and 36-8.).27 Since solid components are not present, there is no central vascularity. This is extremely helpful in the differentiation of an echogenic hemorrhagic cyst from a solid mass.
Color Doppler evaluation of a hemorrhagic cyst (A) demonstrating peripheral color Doppler flow with no internal vascularity. Spectral Doppler (B) demonstrates low impedance arterial flow.
Pelvic Inflammatory Disease
Pelvic inflammatory disease (PID) consists of inflammation of the endometrium, fallopian tubes, pelvic peritoneum, and adjacent structures. The infection is usually ascending and caused by multiple organisms including Neisseria gonorrhoeae, Chlamydia, anaerobic bacteria, and superinfecting organisms from the vagina. Typically, the primary infection is a sexually transmitted disease in the normal pelvis, although with previous disruption of endometrial and tubal tissue due to prior infection or postsurgical or postpartum changes, the patient can be infected by her own vaginal flora. The disease is manifested by tubo-ovarian complexes, peritonitis, and abscess formation. It is usually bilateral but may be unilateral in patients with intrauterine devices.
The clinical diagnosis of pelvic inflammatory disease has been difficult. No simple diagnostic test exists. The accuracy with which signs and symptoms predict the presence of this disease has been evaluated using a laparoscopic "gold standard."28 The data set included women who had an initial diagnosis based on clinical presentation and subsequent laparoscopic evaluation. A total of 623 patients were included in the analysis; 494 patients were laparoscopically confirmed as having PID and 129 were not, giving a false-positive rate of 26%. The 3 variables which significantly influenced the prediction were elevated erythrocyte sedimentation rate (ESR), fever, and adnexal tenderness. However, together they correctly classified only 65% of women with laparoscopically diagnosed pelvic inflammatory disease.
The advent of imaging with transvaginal sonography with color or power Doppler has significantly improved our ability to detect abnormalities, but its sensitivity and specificity in the imaging literature has been highly user and equipment dependent and is determined by the findings which have been used to make the diagnosis. TVS can usually only detect complications of the disease since early changes are often subtle. Increased echogenicity of peritoneal fat and indistinctness of the uterus may be seen early in the disease process but are very difficult to appreciate. Sonographic findings of the fallopian tubes are the most specific and conspicuous indicators of PID. The tubal wall is usually not visualized without intraluminal or peritoneal fluid unless a truly targeted study is performed. With inflammation, the tube swells, endosalpingeal folds thicken, and with progressive inflammation and distal occlusion of the lumen, the tube fills with purulent echogenic material becoming a pyosalpinx (Figure 36-9). In the presence of a fluid-distended fallopian tube, common findings include wall thickness greater than 5 mm, incomplete septa seen as the tube folds back upon itself, and thickening of endosalpingeal folds (cogwheel sign), which is best seen when the tube is viewed in cross section (Figure 36-10).29 Color or power Doppler may also be a sensitive method of detecting hyperemia in the walls and incomplete septi associated with fallopian tube inflammation.30 Nonspecific findings of PID include fluid in the endometrial cavity and/or cul-de-sac, and ovarian enlargement often with numerous small cysts ("polycystic ovary" appearance"; Figure 36-11).31,32
Images of a pyosalpinx by transvaginal sonography show a tubular structure distended with echogenic, purulent fluid (A) as well as color Doppler signal within its wall, suggesting inflammation (B).
Examples of common sonographic findings in a tubo-ovarian complex or abscess are shown, which include thickening of endosalpingeal folds (A), the cogwheel sign, and incomplete septa (B) in the presence of a fluid-distended fallopian tube.
The "polycystic ovary" appearance, a nonspecific sign of pelvic inflammatory disease, is illustrated in this image of the right ovary in a patient with known disease.
With progression of disease, there is exudation of pus from the distal fallopian tube and the ovary can become involved. An inflammatory mass including the tube and adjacent ovary is formed. If a separate ovary is still visualized, this indicates a tubo-ovarian complex. A tubo-ovarian abscess results in complete breakdown of tubal and ovarian architecture so that separate structures are no longer identified and there is obscuration of the posterior and lateral margins of the uterus.33