Outline
Normal and Inconsequential Findings, 920
Ovarian Cysts With Typical Benign Features, 920
Ovarian Cysts With Typical Malignant Features, 924
Ovarian Cysts With Indeterminate Features, 925
Solid Ovarian Masses, 926
Pitfalls in Evaluating the Ovary, 928
Ovarian Masses in Pregnancy, 929
Syndromes and Diseases Associated With Ovarian Neoplasms, 929
Summary, 930
Summary of Key Points
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A simple cyst less than 3 cm in the ovary of a premenopausal patient is best termed a follicle and is a normal finding.
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A simple cyst less than 1 cm in the ovary of a postmenopausal patient is considered inconsequential.
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Most ovarian masses are benign and have a typical sonographic appearance that allows accurate diagnosis.
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Many simple and hemorrhagic cysts do not need sonographic follow-up in asymptomatic patients.
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Before diagnosing a simple ovarian cyst, it is important to search carefully for small nodules along the wall.
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A solid area with flow on Doppler imaging is the most important morphologic characteristic of an ovarian mass that raises concern for malignancy.
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The occasional indeterminate appearing ovarian mass can be managed variably by repeat sonography, magnetic resonance imaging (MRI), or surgical evaluation.
Pelvic sonography, including transvaginal scanning, is the preferred initial imaging modality for evaluation of a suspected ovarian or other adnexal mass. Its high sensitivity and specificity for ovarian malignancy, lack of ionizing radiation, relatively low cost, and wide availability make it an ideal method for evaluation of the ovary. In most patients, sonography is adequate to evaluate an ovarian mass. Scoring systems have been used to characterize ovarian and other adnexal masses sonographically, and they perform reasonably well. However, subjective assessment has been shown to perform as well or better than mathematical scoring systems. Although accurate and timely identification of ovarian malignancy is extremely important, most adnexal masses are benign and most have a typical sonographic appearance. Thus, it is essential to recognize these common benign ovarian masses as frequently as possible and not mistake them for ovarian malignancy. Appropriate sonographic characterization of adnexal masses may help prevent unnecessary follow-up imaging along with its attendant patient anxiety and unnecessary surgery as well as its attendant risks. Detailed sonographic evaluation can prompt referral to gynecologic oncologists for management of adnexal masses that are likely to be malignant. When an adnexal mass has one of the classic benign appearances (to be discussed in this chapter), characterization is complete, although some may warrant sonographic follow-up. If a mass has characteristic malignant findings, imaging for characterization or diagnosis is also typically complete, though further evaluation for staging may be needed. For masses with indeterminate sonographic findings, management will vary depending upon the clinical circumstances, but options would typically include follow-up sonography, MRI, or surgical evaluation. Standardized terminology and reporting have been suggested for ovarian masses; neither has been widely adopted at this time, but both may be further developed in the future.
In a small minority of patients, additional pelvic imaging with MRI may be helpful when ultrasound fails to clarify the origin of an adnexal mass, when the sonographic features are indeterminate, or when an adnexal mass is inadequately imaged with ultrasound (such as in an obese patient or in one who cannot undergo or declines transvaginal scanning). Although computed tomography (CT) is helpful in staging of patients with known or suspected ovarian malignancy, it does not usually have a significant role in the characterization of adnexal masses. CT may occasionally be helpful if a gastrointestinal origin of an adnexal mass is suspected or to search for a primary neoplasm when ovarian metastases are suspected. Positron emission tomography/CT has little, if any, role at this time in the primary evaluation of ovarian masses, although it too may be helpful to search for a primary neoplasm if ovarian metastases are suspected.
In this chapter, we will review a few normal findings specific to the ovary, discuss sonographic features of benign and malignant ovarian masses, present an approach to assessing indeterminate ovarian masses, and review pitfalls in evaluation of the ovary. When appropriate, the findings and recommendations of the Society of Radiologists in Ultrasound consensus conference on ovarian and other adnexal cysts have been included in this chapter. Some aspects of ovarian disease will not be discussed or will be mentioned only briefly, as they are covered elsewhere in this text. Ovarian torsion is discussed in Chapter 29 , nonovarian adnexal masses including tubo-ovarian abscess in Chapter 31 , and polycystic ovary syndrome and ovarian hyperstimulation syndrome in Chapter 32 .
Summary of Key Points
- •
A simple cyst less than 3 cm in the ovary of a premenopausal patient is best termed a follicle and is a normal finding.
- •
A simple cyst less than 1 cm in the ovary of a postmenopausal patient is considered inconsequential.
- •
Most ovarian masses are benign and have a typical sonographic appearance that allows accurate diagnosis.
- •
Many simple and hemorrhagic cysts do not need sonographic follow-up in asymptomatic patients.
- •
Before diagnosing a simple ovarian cyst, it is important to search carefully for small nodules along the wall.
- •
A solid area with flow on Doppler imaging is the most important morphologic characteristic of an ovarian mass that raises concern for malignancy.
- •
The occasional indeterminate appearing ovarian mass can be managed variably by repeat sonography, magnetic resonance imaging (MRI), or surgical evaluation.
Pelvic sonography, including transvaginal scanning, is the preferred initial imaging modality for evaluation of a suspected ovarian or other adnexal mass. Its high sensitivity and specificity for ovarian malignancy, lack of ionizing radiation, relatively low cost, and wide availability make it an ideal method for evaluation of the ovary. In most patients, sonography is adequate to evaluate an ovarian mass. Scoring systems have been used to characterize ovarian and other adnexal masses sonographically, and they perform reasonably well. However, subjective assessment has been shown to perform as well or better than mathematical scoring systems. Although accurate and timely identification of ovarian malignancy is extremely important, most adnexal masses are benign and most have a typical sonographic appearance. Thus, it is essential to recognize these common benign ovarian masses as frequently as possible and not mistake them for ovarian malignancy. Appropriate sonographic characterization of adnexal masses may help prevent unnecessary follow-up imaging along with its attendant patient anxiety and unnecessary surgery as well as its attendant risks. Detailed sonographic evaluation can prompt referral to gynecologic oncologists for management of adnexal masses that are likely to be malignant. When an adnexal mass has one of the classic benign appearances (to be discussed in this chapter), characterization is complete, although some may warrant sonographic follow-up. If a mass has characteristic malignant findings, imaging for characterization or diagnosis is also typically complete, though further evaluation for staging may be needed. For masses with indeterminate sonographic findings, management will vary depending upon the clinical circumstances, but options would typically include follow-up sonography, MRI, or surgical evaluation. Standardized terminology and reporting have been suggested for ovarian masses; neither has been widely adopted at this time, but both may be further developed in the future.
In a small minority of patients, additional pelvic imaging with MRI may be helpful when ultrasound fails to clarify the origin of an adnexal mass, when the sonographic features are indeterminate, or when an adnexal mass is inadequately imaged with ultrasound (such as in an obese patient or in one who cannot undergo or declines transvaginal scanning). Although computed tomography (CT) is helpful in staging of patients with known or suspected ovarian malignancy, it does not usually have a significant role in the characterization of adnexal masses. CT may occasionally be helpful if a gastrointestinal origin of an adnexal mass is suspected or to search for a primary neoplasm when ovarian metastases are suspected. Positron emission tomography/CT has little, if any, role at this time in the primary evaluation of ovarian masses, although it too may be helpful to search for a primary neoplasm if ovarian metastases are suspected.
In this chapter, we will review a few normal findings specific to the ovary, discuss sonographic features of benign and malignant ovarian masses, present an approach to assessing indeterminate ovarian masses, and review pitfalls in evaluation of the ovary. When appropriate, the findings and recommendations of the Society of Radiologists in Ultrasound consensus conference on ovarian and other adnexal cysts have been included in this chapter. Some aspects of ovarian disease will not be discussed or will be mentioned only briefly, as they are covered elsewhere in this text. Ovarian torsion is discussed in Chapter 29 , nonovarian adnexal masses including tubo-ovarian abscess in Chapter 31 , and polycystic ovary syndrome and ovarian hyperstimulation syndrome in Chapter 32 .
Normal and Inconsequential Findings
Although normal ovarian findings and ultrasound technique is more thoroughly discussed in Chapter 26 , a few observations unique to the ovary bear additional mention here ( Fig. 30-1 ). Ovarian follicles typically achieve a size of 2 to 3 cm before ovulation. Hence, simple (unilocular, thin-walled, anechoic) ovarian cysts less than 3 cm in greatest diameter in premenopausal women should generally be considered normal findings. In order to prevent confusion with pathologic findings, it is best not to use the term “cyst” for normal ovarian structures and better to describe them as follicles or to simply report the ovary as normal. Simple ovarian cysts less than 1 cm in greatest diameter may be present in postmenopausal women and have been reported in approximately 20% of women 5 or more years following menopause. Hence, simple ovarian cysts less than 1 cm in maximal diameter in a postmenopausal woman generally require no follow-up and are considered inconsequential. The corpus luteum, which typically appears as a thick-walled cystic lesion less than 3 cm in diameter with internal echoes and crenulated wall, should also be recognized as a normal finding in premenopausal women. The wall of the corpus luteum may be quite vascular on Doppler interrogation.
Echogenic foci are a normal finding in many ovaries ( Fig. 30-2 ). Tiny echogenic foci, measuring 1 to 3 mm in width, have no posterior shadowing (although comet-tail artifact may be seen) and may be due to psammomatous calcifications associated with epithelial inclusion cysts, hemosiderin deposition, or bright specular reflections off the back walls of tiny follicles. These ovarian echogenic foci are found both in premenopausal and postmenopausal women. They are generally of no significance and may occasionally be helpful in identifying an ovary. Larger echogenic foci in the ovary, usually from isolated calcifications, are also typically benign findings ( Fig. 30-3 ). Echogenic foci 5 mm and larger, some of which may demonstrate posterior acoustic shadowing, seen in otherwise normal ovaries have been attributed to corpus albicans. Some association between these foci and adenofibromas has been reported. The pattern of calcifications within the ovary should be examined, as a more extensive peripheral rind of calcifications has been reported in a patient with endosalpingiosis and serous borderline ovarian neoplasms. Larger coarse ovarian calcifications, in the absence of a mass, are generally benign and can be followed sonographically. Anecdotal evidence suggests that patients with larger or more extensive calcifications in an otherwise normal-appearing ovary should receive additional evaluation or closer follow-up.
Ovarian Cysts with Typical Benign Features
Ovarian lesions with classic features of simple cysts, hemorrhagic cysts, endometriomas, or dermoids are highly likely to be benign. It is important to recognize the characteristic sonographic features that, when seen, are highly predictive of these benign entities. Reliable characterization of ovarian masses using these sonographic features requires that the mass be fully and adequately visualized by ultrasound. Occasionally, in a patient with a suboptimal ultrasound examination, the interpreting physician will need to decide how to proceed based on available imaging findings and degree of clinical concern. When reporting on adnexal masses seen on pelvic sonograms, it is important to describe specific sonographic features (detailed later) that allow one to determine the likely diagnosis. Use of the word “complex” as a descriptor, with no additional explanation, is problematic as the “catch-all” term is often used for any cystic mass that is not a simple cyst. There are many features that may result in a “complex” sonographic appearance, including a typical reticular pattern suggesting benign hemorrhagic cyst and typical solid nodule worrisome for malignant ovarian carcinoma. Thus, if an ovarian cyst is reported as “complex,” further descriptors detailing those features making it complex should also be provided.
Simple Cysts
As with cysts elsewhere in the body, ovarian cysts with thin walls, anechoic internal contents, posterior acoustic enhancement, and no septations or solid components meet sonographic criteria for simple cysts ( Fig. 30-4 ). Follicular or corpus luteal cysts and serous cystadenomas may appear as simple cysts by sonographic criteria. Simple ovarian cysts occur in 4% to 17% of postmenopausal women and the majority resolve or remain stable on follow-up ultrasound evaluation. However, annual follow-up sonography for simple ovarian cysts larger than 1 cm (though some practices may choose to raise this threshold to 3 cm) is recommended in postmenopausal women. In premenopausal women, it is recommended that cysts between 5 and 7 cm in largest diameter be followed yearly by ultrasound examination. The vast majority of simple ovarian cysts are benign. With increasing cyst size, however, there is a risk of inadequate assessment of the cyst wall for detection of small solid nodules or papillary formations, which, if present, increase the likelihood of malignancy. The rare occurrence of malignancy in an apparent simple ovarian cyst is more likely in larger cysts, in which small mural nodules may be overlooked. Hence, when evaluating what appears to be a simple cyst, it is important to confirm that the cyst is adequately imaged in its entirety and to carefully assess for small nodules before concluding that it is indeed a simple cyst. Simple cysts measuring larger than 7 cm are still likely benign, though one should consider further imaging evaluation with MRI to confirm that there is no solid component overlooked by sonography.
