Case of the Month December 2014, page 5

Answer

B

A young woman on fertility management presenting with hypotension, nausea, abdominal pain, and bloating is concerning for ovarian hyperstimulation syndrome. Imaging confirmed the diagnosis with massive symmetric enlargement of both ovaries with multiple cysts, ascites, and pleural effusions. Ovarian torsion is usually unilateral. Meigs syndrome, ovarian neoplasm, and pseudomyxoma peritonei are unlikely given lack of ovarian mass or peritoneal implants on recent MRI.

Ovarian Hyperstimulation Syndrome

Ovarian hyperstimulation syndrome (OHSS) is a rare complication of ovarian induction. OHSS may rage from mild to severe. Mild OHSS affects 65% of women undergoing ovarian induction and features nausea, diarrhea, abdominal pain, and enlarge ovaries. Moderate OHSS affects 3-6% of cases, featuring ultrasonographic evidence of ascites and hemoconcentration (elevated hematocrit and WBC). Severe OHSS affects 0.1-3% of cases and features increased ascites, pleural effusions, dyspnea, hypotension, severe abdominal pain, renal failure, and electrolyte derangements.

The pathophysiology of OHSS is though to be due to shift of protein rich intravascular fluid to the third space (mainly the abdominal cavity) due to increased vascular permeability in response to human chorionc gonadotropin (hCG). The degree of third spacing of intravascular fluid determines the severity of manifestations.

Risk factors for OHSS include polycystic ovarian syndrome (which this patient had), young age (<33 years), previous OHSS, and lean body habitus.

Imaging findings of OHSS are classified by the Golan scheme. Mild OHSS has ovaries of <6cm. Moderate OHSS ovaries rage from 6-12 cm with ultrasound evidence of ascites. Severe OHSS has ovaries >12 cm with ascites and pleural effusions. The ovaries are usually symmetrically enlarged with the parenchyma largely replaced by multiple follicular and corpus luteum cysts. and demonstrate a “wheel spoke” appearance with enhancing central ovarian tissue and follicular walls between the fluid filled follicular cysts. There should be no thickened irregular septations or enhancing mural masses. Follicular cysts are usually simple, but can be hemorrhagic.

Enlargement of the ovaries puts patients at risk for ovarian torsion, which occurs in up to 7.5% of cases. Risk of torsion is increased  even further in OHSS with subsequent pregnancy compared to OHSS alone. Distended luteal cysts may rupture.

Mild and moderate cases are usually self limiting and can be treated symptomatically. Patients can be monitored on an outpatient basis by tracking weight gain, which is one of the first signs of fluid retention. OHSS resolves with cessation of hormonal stimulation. Severe OHSS is potentially fatal, and requires immediate action to maintain intravascular fluid and correct electrolyte imbalances. In moderate to severe OHSS, aggressive early paracentesis has been shown to reduce need for hospitalization and can prevent progression of disease severity.

References


STATdx, https://app.statdx.com, accessed 12/18/14

Radiopaedia, http://radiopaedia.org, accessed 12/18/14

Fiedler, Ezcurra. Predicting and preventing ovarian hyperstimulation syndrome (OHSS): the need for individualized not standardized treatment. Reproductive Biology and Endocrinology. 2012, 10:32. http://www.rbej.com/content/pdf/1477-7827-10-32.pdf, accessed 12/18/14


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