Online Medical Reference

Ovarian Cysts

Elisa Ross, MD

Chelsea Fortin, MD

Published: August 2016


Ovarian cysts, also known as ovarian masses or adnexal masses, are frequently found incidentally in asymptomatic women. Ovarian cysts can be physiologic (having to do with ovulation) or neoplastic and can be benign, borderline (low malignant potential), or malignant. Ovarian cysts are sometimes found in the course of evaluating women for pelvic pain though the cysts may or may not be the cause of the pain.

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Estimates of the prevalence of ovarian cysts vary widely, with most authors reporting between 8% and 18% of both premenopausal and postmenopausal women having ovarian cysts. Most post-menopausal cysts persist for years.1

In the United States, approximately 5% to 10% of women undergo surgical exploration for ovarian cysts in their lifetime though only 13% to 21% of these cysts are malignant.2 Presurgical evaluation of ovarian cysts is critical to prevent unnecessary surgical intervention while still detecting potential malignancy.

For the vast majority of women, ovarian cysts are not precancerous lesions and do not increase the risk of developing ovarian cancer later in life. Removal of benign cysts does not decrease future mortality from ovarian cancer.1,3-5

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Provided below is a brief description of the pathophysiology of various types of physiologic and neoplastic ovarian cysts and the potential complications that may arise.

Physiologic/Functional Cysts

During normal ovulation, a follicle matures and then ruptures, releasing an oocyte. After ovulation, the corpus luteum forms and subsequently involutes. When the follicle fails to rupture and continues to grow, a follicular cyst occurs. When the corpus luteum fails to involute and continues to grow, a corpus luteum cyst occurs. Both types of cysts are considered physiologic or functional and neither have any malignant potential. Either type of cyst can become a hemorrhagic cyst (see below).

Hemorrhagic Cysts

The granulosa layer of the ovary remains avascular until the time of ovulation. After ovulation occurs, the granulosa layer quickly becomes vascularized by thin-walled vessels, which rupture easily, giving rise to a hemorrhagic cyst.6

Dermoids (Mature Cystic Teratomas)

Dermoid cysts contain mature tissue of ectodermal (eg, skin, hair), mesodermal (eg, muscle, urinary), and endodermal (eg, gastrointestinal, lung) origin.7 Dermoid cysts are almost always benign but have the potential to rupture, spilling sebum, or torse.


Endometrioma is a type of cyst that is filled with menstrual blood and endometrial tissue. Endometrioma cysts arise either via retrograde menstruation from the uterus or bleeding from an endometriotic implant itself.

Ovarian Malignancy

Studies suggest that some seemingly ovarian serous carcinomas actually originate in the fallopian tubes and then spread to the ovary. These tubal lesions have also been found to spread to the peritoneum, leading to an apparent peritoneal carcinoma. Germ cell and stromal tumors do arise from the ovary itself.


  • Ovarian torsion: all ovarian cysts have the potential to twist on their axes or "torse," occluding vascular supply. Larger cysts (over 6 cm) are more likely to torse. Ovarian torsion is a surgical emergency as the ovary must be promptly untwisted to restore perfusion and preserve ovarian tissue. Ultrasound with Doppler can identify lack of blood flow to the ovary.
  • Cyst rupture: all cyst types can potentially rupture, spilling fluid into the pelvis, which is often painful. If the contents are from a dermoid or abscess, surgical lavage may be indicated.
  • Hemorrhage: In the case of hemorrhagic cysts, the management of hemorrhage depends on the hemodynamic stability of the patient, but is most often expectantly managed.

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Signs and Symptoms

Most women with benign or malignant ovarian cysts are asymptomatic and the cysts are found incidentally. Among women with symptoms, pelvic or lower-abdominal pressure or pain are the most common symptoms. Acute pain related to ovarian cysts can occur with ovarian torsion, hemorrhage into the cyst, cyst rupture with or without intra-abdominal hemorrhage, ectopic pregnancy, and pelvic inflammatory disease with tubo-ovarian abscess.8 Vague symptoms such as urinary urgency or frequency, abdominal distention or bloating, and difficulty eating or early satiety have also been reported.9 The positive predictive value of this symptom constellation is only about 1%; however, the usefulness increases if symptoms arose recently (within the past year) and occur more than 12 days a month.10

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The differential diagnosis of benign ovarian cysts includes:

  • Simple cysts
  • Hemorrhagic corpus luteum cysts
  • Dermoids (mature cystic teratomas)
  • Endometriomas
  • Pedunculated Fibroids
  • Hydrosalpinges
  • Paratubal and paraovarian cysts
  • Peritoneal inclusion cysts (also known as pseudocysts)
  • Pelvic kidneys
  • Appendiceal or diverticular abscess
  • Ectopic pregnancy

The diagnosis of an ovarian cyst is most often made based on imaging rather than by physical examination, laboratory testing, or diagnostic procedures.


Ultrasonography is considered the gold standard for the assessment of ovarian cysts. Transvaginal sonography is preferred, as the probe proximity to the ovary can result in superior images. If transvaginal sonography is not available or not tolerated by the patient, transabdominal sonography through a full bladder or transperineal sonography in virginal or atrophic women can still provide helpful, albeit limited, information. In some cases, ultrasound can specifically diagnose the type of ovarian cyst, especially if certain characteristic findings are present (Box 1). Figures 1– 5 illustrate and describe characteristic findings seen with simple cysts, hemorrhagic corpus luteum cysts, dermoid cysts, endometriomas, and malignant cysts.8

Box 1: Characteristics of Simple and Malignant Cysts
Simple cyst Malignant cyst
Round or oval
No solid component
Smooth, thin walls
No internal flow
No septation
Posterior acoustic enhancement
Non-hyperechoic solid areas (especially if blood flow)
Thick septations ( >2 - 3 mm wide, especially if blood)
Excrescences on inner/outer aspect of cystic area
Other pelvic/omental masses

Identifying certain cyst characteristics is especially important in differentiating benign from malignant processes. The ten "Simple Rules" are five ultrasound features indicative of benign cysts (B-features) and five ultrasound features indicative of a malignant cysts (M-features) based on the presence of tumor morphology, degree of vascularity, and ascites (Table 1).11

Table 1: "Simple Rules" Differentiating Benign and Malignant Cysts
Benign (B) features Malignant (M) features
B1 unilocular cysta
B2 solid components present, but <7 mm
B3 acoustic shadowsb
B4 smooth multilocular tumor, largest diameter <100 mm
B5 no blood flow; color score 1
M1 irregular solid tumor
M2 ascitesa
M3 at least 4 papillary structures
M4 irregular multilocular-solid tumor, largest diameter ≥100 mmb
M5 very strong flow; color score 4
If only B features are present → benign tumor
If only M features are present → malignant tumor
If both B and M features or neither B nor M features present → inconclusive

a Most predictive feature.

b Least predictive feature.

Data from Timmerman D, Van Calster B, Testa A, et al. Predicting the risk of malignancy in adnexal masses based on the Simple Rules from the International Ovarian Tumor Analysis group. Am J Obstet Gynecol 2016; 214:424–437.

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is a valuable tool when ultrasound is inconclusive or limited. The advantages of MRI are that it is very accurate and it provides additional information on the composition of soft-tissue tumors.8 On the other hand, MRI is more expensive, is usually less available, and is more inconvenient for the patient than ultrasound. MRI for the evaluation of ovarian cysts is usually ordered with contrast, unless contraindicated.8 In one study of MRI as second-line imaging for indeterminate cysts, contrast-enhanced MRI contributed to a greater change in the probability of ovarian cancer compared with computed tomography (CT), Doppler ultrasound, or MRI without contrast.12 This may result in a reduction in unnecessary surgeries and in an increase in proper referrals in cases of suspected malignancy.

Computed Tomography

Computed tomography (CT) is usually not used in the evaluation of ovarian cysts. CT offers poor discrimination of soft tissue and exposes the patient to more radiation than does ultrasound or MRI. The utility of CT is primarily in the preoperative staging of a suspected ovarian cancer.13 Cysts discovered via CT scan should be further evaluated using ultrasonography.

Diagnostic Procedures

It is almost never appropriate to aspirate an ovarian cyst for diagnostic purposes. False negative results are common and leakage of cyst contents into the peritoneal cavity potentially increases the stage of any cancer found, decreasing patient survival.

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Appropriate management of patients with an ovarian cyst depends on the presence of symptoms, likelihood of torsion or rupture, and level of concern for malignancy.

Symptomatic Cysts

The differential diagnosis for pain in women with ovarian cysts include tubo-ovarian abscess, ruptured ectopic, ruptured hemorrhagic cyst, and ovarian torsion.8

If the patient with pain is at low risk of a surgical emergency, pain medication and outpatient management is appropriate. If pain persists, refer the patient to a gynecologist. For a patient who appears toxic or is in shock, an immediate surgical consultation with a gynecologist is warranted.

For patients with symptomatic cysts that are concerning for cancer, consult a gynecologic oncologists directly.

Simple Cysts

Management of patients with simple cysts should follow the algorithm shown in Figure 6.

Cysts with a High Likelihood of Malignancy

Women with ovarian cysts with a high likelihood of malignancy should be referred directly to a gynecologic oncologist. High likelihood of malignancy exists if malignant features are found on ultrasound, in women with a personal history or a first-degree relative with history of ovarian or breast cancer, or if cancer antigen 125 (CA 125) is >35 (postmenopausal women) or CA 125 >200 (premenopausal women) (Figure 7). Direct referral to and treatment by gynecologic oncologists has been shown to improve survival rates in women with ovarian cancer.14-16

Cysts with an Indeterminate Likelihood of Malignancy

For women with cysts with an intermediate likelihood of malignancy, further workup is warranted. The most cost-effective test is a second ultrasound and a second opinion at a tertiary center. Obtaining the CA 125 level can be helpful in this instance (Figure 7).

Cysts with an Unclear Likelihood of Malignancy but Likely Benign

For women with cysts with an unclear likelihood of malignancy but most likely benign, repeat ultrasound in 6 to 12 weeks is warranted.8 There are no official guidelines as to when to stop serial imaging, but one or two ultrasounds to confirm size and morphologic stability has been suggested.17 Of course, once a lesion has resolved, there is no need for further imaging.

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Prevention and Screening


Oral contraceptives may prevent new functional cysts from forming.18-19 Oral contraceptives do not, however, hasten the resolution of preexisting cysts. Some practitioners will, nevertheless, prescribe oral contraceptives in an attempt to prevent new cysts from confusing the picture. Oral contraceptives are also protective against ovarian cancer.20

Bilateral oophorectomy protects against ovarian and breast cancer but is associated with an increase in the all-cause mortality rate.21 Current research suggests that removal of the fallopian tubes is protective against ovarian cancer.22


Screening women with an average risk for ovarian cancer is not recommended.3,23 The incidence of ovarian cancer is too low, ultrasonography and CA 125 testing are too nonspecific, and the biology of ovarian cancer does not lend itself to screening. In one recent large study (N = 78,216), yearly screening with CA 125 and ultrasound did not decrease the mortality rate from ovarian cancer, and the surgical evaluation of false-positive screens was associated with complications.5

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Special Populations


Ovarian cysts in pregnancy are usually benign. Benign cystic teratomas (also called dermoid cysts) are the most common ovarian tumor during pregnancy, accounting for one-third of all benign ovarian tumors in pregnancy. The second most common benign ovarian cyst is a cystadenoma. In caring for pregnant women with ovarian cysts, a multidisciplinary approach and referral to a perinatologist and gynecologic oncologist is advised.

Neonates and Prepubertal Children

Ovarian cysts in the neonate are exceedingly rare. It is estimated that 5% of all abdominal masses in the first month of life are ovarian cysts. While there are no precise guidelines for the monitoring and management of neonatal ovarian cysts, it is generally agreed that cysts >2 cm are considered pathologic. The majority of neonatal ovarian cysts are benign and self-limiting. Ovarian malignancy becomes more common in the second decade of life than in the neonatal period. In one small study, approximately 33% of adnexal masses were malignant in children >8 years whereas 2.9% of adnexal masses were malignant in children <8 years.24

Women with a History of Breast Cancer

Women diagnosed with ovarian cysts with a personal or family history of breast or ovarian cancer in a first degree relative should be referred directly to a gynecologic oncologist.

Polycystic Ovarian Syndrome

The finding of multiple small ( <1 cm) cysts in both ovaries ("string of pearls" appearance) on ultrasonography is indicative of polycystic ovarian syndrome, a condition unrelated to other ovarian cyst conditions. The "string of pearls" appearing cysts are a component of a multi-system syndrome, which usually also includes irregular ovulation and aspects of metabolic syndrome.

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  • Ovarian cysts are common. Most are variations of normal ovulatory function. Regardless of age, the likelihood of malignancy is significantly less than the likelihood of a benign lesion.
  • Patients with ovarian cysts with benign characteristics (round or oval, anechoic, smooth, thin walls, no solid component, no internal flow, no or single thin septation, posterior acoustic enhancement) may be followed by the primary care provider according to the algorithm in Figure 6, until resolution or stability of the cyst has been ascertained.
  • Women with symptomatic ovarian cysts, those with cysts over 6 cm in diameter, or those with an uncertain, but likely benign diagnosis, can be managed by a general gynecologist.
  • Patients with cysts with frankly malignant characteristics (complex structure with thick >3mm septations, nodules or excrescences, especially if multiple or with internal blood flow, solid areas, or ascites) should be referred directly to a gynecologic oncologist. Referral should also be made to gynecologic oncology if the patient has an elevated CA 125 value, a personal or family history of breast or ovarian cancer in a first degree relative, or evidence of metastases.


Thank you very much to Mina Tirabassi, RDMS, for the ultrasound images.


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Elisa Ross, MD; nothing to disclose. Chelsea Fortin, MD; nothing to disclose.