Sonography of the ovary: Review of current practice

Sonographic evaluation of the ovaries is performed as part of a complete pelvic sonogram by using transabdominal or endovaginal techniques or both. The ovaries are typically located anteromedial to the iliac artery in Waldeyer's fossa. They are visualized as ovoid or round structures. Ovarian size varies with menstrual status, and the ovaries can be difficult to identify in postmenopausal women. In menstruating women, the ovaries contain small follicles, which facilitates their identification; the corpus luteum develops from rupture of the dominant follicle. Generalized ovarian abnormalities can result in ovarian enlargement and multiple cysts. Abnormalities that can affect the appearance of the ovary include polycystic ovary syndrome, ovarian hyperstimulation, oophoritis, and ovarian torsion. Because the range of normal ovarian size is wide, the diagnosis of a generalized ovarian abnormality resulting in ovarian enlargement is strongly dependent on clinical or endocrine findings or both. Thus one cannot conclusively identify ovarian abnormality on the basis of ovarian enlargement alone unless there is marked asymmetry in size, the ovaries are massively enlarged, or there are interval changes in size recognized with serial measurements. Furthermore, for the diverse group of functional abnormalities that lead to persistent anovulation, the absence of sonographic abnormalities cannot be used to exclude polycystic ovarian syndrome. On the other hand, because ovarian torsion leads to enlargement of the affected ovary, an ovary that appears normal sonographically and is symmetric in size to the contralateral ovary is very unlikely to be torsed. Ovarian masses are seen as adnexal abnormalities discovered on physical examination or incidentally noted on pelvic sonography. The sonographic analysis of an adnexal mass should follow a reasoned approach that recognizes that the vast majority of adnexal masses are nonneoplastic ovarian cysts. The first step in this analysis is to determine whether the mass in question is a unilocular cyst, as unilocularity is a feature not associated with malignancies. Further analysis of a unilocular cyst is directed at assessing the probability that the cyst is self-limiting from demonstrated stability, location, size, and patient hormonal status. Hemorrhage within a unilocular cyst does not alter the likelihood that the cyst is benign but can result in features that appear ominous. Thus the second step in the analysis of an adnexal mass not characterized as a unilocular cyst is to determine whether the questioned findings could be accounted for by hemorrhage. Short-interval sonographic follow-up is a reasonable strategy to pursue when a mass has features consistent with a hemorrhagic cyst. For those masses with features inconsistent with a hemorrhagic cyst, the third step in the analysis is to determine whether there are features that are reasonably characteristic of a specific diagnosis or limited diagnostic set. Paraovarian entities that can have a suggestive sonographic appearance include an exophytic leiomyoma, hydrosalpinx, or paraovarian cyst; likewise, ovarian entities such as an endometrioma, dermoid, or other ovarian neoplasm can be confidently suggested from on the sonographic appearance. Once an adnexal mass passes through the preceding three layers of analysis without conclusion as to its probable origin and appropriate treatment, one is left,vith either surgical evaluation or alternative imaging methods. Although some investigators advocate that Doppler waveform analysis has utility in the evaluation of an adnexal mass, there is considerable disagreement in the literature, and we believe that its role is extremely limited.