Ovarian hyperstimulation syndrome


  • Fertility treatments causing development of multiple follicles at once
    • Exaggerated ovarian response to ovulation induction (esp in IVF when HCG is used to stimulate)
  • Fluid shifts out of vasculature (third spacing)
  • Typically 5-10d after 1st dose
  • Ranges in severity from mild to severe multiorgan dysfunction, relating in part to massive intravascular fluid shifts

Clinical Features

Differential Diagnosis

Pelvic Pain

Pelvic origin

Abdominal origin


Pelvic ultrasound (sagittal) in woman with OHSS showing ascites and enlarged ovary (diameter = 6.5mm)



Classification Clinical features Lab findings
Mild Normal
Moderate Above plus:
  • Ultrasonographic evidence of ascites
  • Elevated hematocrit (>41%)
  • Elevated WBC (>15,000/mL)
  • Hypoproteinemia
Severe Above plus:
  • Hemoconcentration (hematocrit >55%)
  • WBC >25,000/mL
  • Serum creatinine >1.6mg/dL
  • Creatinine clearance <50 mL/min
  • Hyponatremia (Na+ <135 mEq/L)
  • Hyperkalemia (K+ >5 mEq/L)
  • Elevated liver enzymes
Critical Above plus: Worsening findings


Pregnant patients must be followed very closely, as they are likely to worsen

  • Urgent GYN consultation for all


  • Pain control
  • Encourage oral fluids (1-2 liters/day)
  • Ambulate, but avoid other physical activity. Avoid sexual intercourse


  • IV fluids (e.g normal saline)
  • Therapeutic paracentesis if ascites (aspirate 0.5-4 L)
  • Thromboembolic prophylaxis (e.g. LMWH)
    • All hospitalized patients
    • Outpatients with 2-3 risk factors:
      • Age >35 years
      • Obesity
      • Immobility
      • Personal or family history of thrombosis
      • Thrombophilias
      • Pregnancy



  • As above + resuscitative care


  • Mild: outpatient
    • Avoid heavy physical activity
    • Return for
      • Worsening abdominal pain
      • Weight gain (>1 kg/day)
      • Increasing abdominal girth
  • Moderate: outpatient if close follow-up (discuss with GYN)
  • Severe: admit
  • Critical: ICU


See Also


  1. Norris DL, Young JD. UTI. EM Clin N Am. 2008; 26:413-30.
  2. Norris DL, Young JD. UTI. EM Clin N Am. 2008; 26:413-30.
  3. Navot D, Bergh PA, Laufer N. Ovarian hyperstimulation syndrome in novel reproductive technologies: prevention and treatment. Fertil steril 1992; 58:249. From: Fiedler K, Ezcurra D. Predicting and preventing ovarian hyperstimulation syndrome (OHSS): the need for individualized not standardized treatment. Reprod Biol Endocrinol 2012; 10:32. Copyright © 2012 Fiedler and Ezcurra. Reproduced from BioMed Central Ltd