Table 1. Classification of OHSS
Grade	Symptom
Mild OHSS	Abdominal bloating
	Mild abdominal pain
	Ovarian size usually <8 cm
Moderate OHSS	Moderate abdominal pain
	Nausea ± vomiting
	Ultrasound evidence of ascites
	Ovarian size usually 8 to 12 cm
Severe OHSS	Clinical ascites (occasionally pleural effusion)
	Oliguria
	Hematocrit (>45%)
	Hypoproteinemia
	Ovarian size usually >12 cm