Unilateral follicular aspiration and in-vitro maturation before contralateral oocyte retrieval: A method to prevent ovarian hyperstimulation syndrome

Background: Five women undergoing intracytoplasmatic sperm injection (ICSI) considered to be at high risk of developing an ovarian hyperstimulation syndrome (OHSS) from March to July 2002 underwent unilateral follicular aspiration. Methods: When ≥15 follicles of 12-15mm diameter in each ovary and a serum estrodial level ≥2500pg/ml was present, follicular aspiration was performed unilaterally without hCG administration. Ovarian stimulation was continued for 1-3 days in four women before human chorionic gonadotrophin (hCG) was given. In one woman hCG injection was administered at the evening after unilateral follicular aspiration. The oocyte retrieval from the contralateral ovary was performed 36h after hCG injection. By unilateral follicular aspiration two to six germinal vesicle (GV) oocytes could be retrieved. After in-vitro maturation of those oocytes ICSI was performed. Results: In four women one to two oocytes were fertilized and cryopreserved. In one case only one triploid pronucleus (3PN) was observed. At the contralateral ovum-pick up after hCG injection a median of 10 could be retrieved. After transfer of a median of 3 embryos, no pregnancy was achieved. Four of five patients developed a severe OHSS and were hospitalized for a median of 3 days. Conclusion: Unilateral follicular aspiration and continuation of stimulation therefore can not be recommended for the prevention of OHSS.