Ovarian Hyperstimulation Syndrome (OHSS) following IVF treatment.

Ali Abbara, Rumana Islam, George Christopoulos, Waljit S Dhillo, Geoff H Trew.


A 35 year old woman and her partner presented for IVF treatment. An ultrasound scan revealed polycystic ovarian morphology and an antral follicle count of 40, although she had no clinical features of polycystic ovarian syndrome (PCOS) with regular menstrual cycles and no features of androgen excess. Her serum AMH was 26.6 pmol/L (AMH >25 pmol/L has a 90.5% sensitivity and 81.3% specificity for subsequent OHSS following IVF treatment) and a hysterosalpingogram (HSG) confirmed tubal patency. The semen analysis and ‘swim up’ test for her partner were normal. In view of her increased risk for ovarian hyperstimulation syndrome (OHSS), she was treated with a recombinant FSH / GnRH antagonist IVF cycle. She had 27 follicles of 11mm or greater in diameter on the day of trigger administration (>15 follicles suggests high risk and >25 follicles suggests very high risk of OHSS) and oocyte maturation was triggered using a GnRH agonist. On the day of egg collection, 36 hours following trigger administration, she collapsed in the waiting room and was admitted to hospital. She reported severe abdominal pain requiring opiate analgesia and nausea, but no vomiting, abdominal bloating or diarrhoea. An ultrasound scan revealed large ovaries (left 154 mls and right 612 mls) and 165mls of free fluid in the abdomen. There was no evidence of haemoconcentration,  nor of renal or hepatic dysfunction on blood analysis. She was carefully observed throughout her admission, supported conservatively for OHSS and discharged after a 3 day admission.

A month later she reported continuation of her abdominal pain and a scan revealed a persistently enlarged right ovary of 314mls. A laparoscopy revealed a necrotic right ovary secondary to torsion which required surgical removal.


OHSS can occur in high risk patients with high antral follicle count and AMH levels. Complications of OHSS can include ascites, renal failure, pleural effusions and even death. Ovarian torsion is an uncommon, but recognised complication of large ovaries in the context of OHSS.