Ovarian hyperstimulation syndrome (OHSS) in pregnancy not associated with ovulation induction

Ovarian hyperstimulation syndrome (OHSS) has gained recent interest because of various ovarian stimulation regimes used for treatment of infertility (1). Ovarian hyperstimulation syndrome is commonly associated with disorders of pregnancy with high levels of serum hCG such as gestational trophoblastic disease, fetal hydrops, multifetal gestation in late months of pregnancy, and conditions associated with large placentae such as diabetes and Rhesus isoimmunization (2). It is very rarely seen in pregnancy where ovulatory drugs or hormones have not been used (3). Oligomenorrhoic anovulation and low age and low weight are other risk factors (4). Ovarian hyperstimulation syndrome is characterized by extremely enlarged ovaries with multiple cysts, increased capillary permeability and loss of fluid and proteins from the intravascular to extravascular space. Clinically OHSS is associated with hypovolemia, oliguria, ascites, abdominal pain, pleural effusion, hemoconcentration and electrolyte imbalances, especially hyperkalemic acidosis (5).