eMedicine Specialties > Emergency Medicine > Obstetrics & Gynecology

Ovarian Cysts: Differential Diagnoses & Workup

Author: Walter W Valesky Jr, MD, Clinical Assistant Instructor, Department of Emergency Medicine, State University of New York Downstate, Brooklyn
Coauthor(s): Mark A Silverberg, MD, FACEP, MMB, Assistant Professor, Assistant Residency Director, Department of Emergency Medicine, State University of New York Downstate College of Medicine; Consulting Staff, Department of Emergency Medicine, Staten Island University Hospital, Kings County Hospital, University Hospital, State University of New York Downstate at Brooklyn; Andrew A Aronson, MD, Assistant Professor of Emergency Medicine, Drexel University School of Medicine; Consulting Staff, Department of Emergency Medicine, Allegheny General Hospital
Contributor Information and Disclosures

Updated: Aug 11, 2009

Differential Diagnoses

Other Problems to Be Considered

During the ED workup, it is imperative that life-threatening or causes of abdominal and/or pelvic pain associated with high morbidity be excluded before ovarian cyst is diagnosed. This includes ruling out emergent female gynecological and urological symptoms such as ectopic pregnancy, ovarian torsion, or even tubo-ovarian abscess and abdominal causes of lower abdominal pain such as appendicitis.

After etiologies of acute abdominal pain are ruled out, the physician's primary concern is to assess whether the pain or pelvic mass reflects a possible neoplastic etiology, which must be assessed further by a gynecologist in the ED or in an outpatient setting in an appropriate time frame.

Workup

Laboratory Studies

• A urinary pregnancy test should always be performed in all women of childbearing age with abdominal pain or similar complaints.
• A complete blood cell (CBC) count should be obtained, focusing on the hematocrit and hemoglobin levels to evaluate for anemia caused by acute bleeding. The white blood cell (WBC) count may be elevated, not only in complications of ovarian cyst, especially torsion, but also in infectious abdominal pathologic conditions such as appendicitis.
• Urinalysis should be obtained to rule out other possible causes of abdominal or pelvic pain, such as urinary tract infections or kidney stone.
• If pelvic inflammatory disease is among the differential diagnoses, endocervical swabs should be obtained to assess for chlamydia and gonorrhea.
• A type and screen with Rh status should be obtained in all pregnant patients with vaginal bleeding in the ED to screen for potential isoimmunization. Patients who are Rh-negative should be given anti-RhD immunoglobulin G (IgG) within 72 hours to prevent Rh disease in subsequent pregnancies.³
• CA-125 should not be drawn in pregnant patients with ovarian cysts or in the acute setting with ovarian cyst accidents, as this marker is raised in peritonitis, hemorrhage, cyst rupture, and infection, as well as in menstruation, fibroids, and endometriosis. It is prudent to draw this marker in the postmenopausal patient for workup of an ovarian cyst and for distinction from an ovarian neoplasm, along with ultrasonography.^3,15

Imaging Studies

• Ultrasonography
  • Ultrasonography is the most favored imaging modality to assess ovarian cysts. Transabdominal ultrasonography allows for a better overall view of the abdomen and pelvis in visualizing large ovarian masses and their subsequent complications, such as hydronephrosis or free fluid. It is best performed with a full bladder to use as an acoustic window in order to better visualize structures. Transvaginal ultrasonography with a higher-frequency probe allows better resolution of the ovary than a transabdominal lower-frequency probe.
  • A normal ovary is 2.5-5 cm long, 1.5-3 cm wide, and 0.6-1.5 cm thick. In the follicular phase, several follicles are usually visible within the ovarian tissue.
  • On a sonogram, ovarian cysts have a thin rounded wall and a unilocular appearance that is either hypoechoic or anechoic. They usually measure 2.5-15 cm in diameter, and posterior acoustic enhancement (a hyperechoic area) may be visible deep to the fluid-filled cyst.⁷
  • The corpus luteum (especially in pregnancy) tends to be larger and more symptomatic than the follicular cyst and is prone to hemorrhage and rupture. On a sonogram, it has a varied appearance ranging from a simple cyst to a complex cystic lesion with internal debris and thick walls.⁶
  • A corpus luteal cyst is typically surrounded by a circumferential rim of color on Doppler flow referred to as "the ring of fire." Compared with a follicular cyst, a corpus luteal cyst has thicker, more echogenic, and more vascular walls. A hemorrhagic corpus luteal cyst has a variable echogenic pattern on ultrasonography, depending on clot formation and lysis in the cyst.² Fresh blood appears acutely anechoic. There is mixed echogenicity subacutely; chronically, the blood appears anechoic again, which is consistent with clot formation, retraction, and lysis.⁷
  • Hemorrhage into the cyst appears diffuse with a reticular pattern described as a "fishnet pattern" or "spider web" appearance. Color Doppler shows no vascularity within the clot, whereas a solid nodule may show vascularity.
  • The ultrasonographic appearance of ovarian torsion varies, but, most commonly, the ovary is enlarged. Massive ovarian edema may be seen with torsion, as the twisting of the pedicle impedes lymphatic drainage and venous outflow, leading to ovarian enlargement. Torsion may be intermittent and recurrent with spontaneous detorsion, allowing both arterial and venous flow to the ovary to be observed on ultrasonography. Occasionally, a twisted vascular pedicle (referred to as the "whirlpool sign") may be visible during active torsion. However this is not a sensitive finding.⁶
  • If the ultrasonographic features are not typical of an ovarian cyst, follow-up ultrasonography can be performed to exclude ovarian neoplasm. Follow-up ultrasonography can show resolution of cyst.¹⁶
• CT scanning
  • CT scanning is more sensitive but less specific than ultrasonography in detecting ovarian cysts. The addition of CT scanning in the workup of ovarian cysts offers very little additional information and usually does not alter treatment plans.¹⁵
  • CT scanning is best in imaging hemorrhagic ovarian cysts or hemoperitoneum due to cyst rupture. It can also be used to distinguish other intra-abdominal causes of acute hemorrhage from cyst rupture.¹⁶ However, CT scanning should be avoided in pregnancy, if possible, to prevent radiation exposure to the fetus. MRI is a better option in these patients when ultrasonography cannot clearly elucidate the adnexal mass.
• MRI
  • MRI in conjunction with ultrasonography may provide marginal improvements in specificity, but, in most cases, the additional cost in not justified.¹⁵
  • MRI is reserved for cases in which ultrasonography and CT scanning findings are indeterminate in identifying the mass as an ovarian cyst safely in a pregnant patient.
  • Simple ovarian cysts show a low signal intensity with T1-weighted images and a high signal intensity with T2-weighted images owing to the intracystic fluid.
  • Hemorrhagic cysts result in a high signal on T1-weighted images and intermediate to high signal on T2-weighted images. Hemoperitoneum after cyst rupture appears bright on T2-weighted images and slightly hyperintense on T1-weighted images.¹⁶

Procedures

• Culdocentesis, a procedure largely of historical interest because of its associated complications (bowel perforation, abscess rupture, trauma to a pelvic kidney), is used to look for intraperitoneal fluid. Its use has largely been replaced by ultrasonography.
• Laparoscopy offers the advantage of decreased morbidity, improved postoperative recovery, and decreased cost compared with laparotomy.
• Bilateral oophorectomy and, often, hysterectomy are performed in many postmenopausal women with ovarian cysts because of the increased incidence of neoplasms in this population.

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