The results of blood assays and of ultrasound evaluations will determine the proper timing of oocyte pick-up.

That is :

• when each maturing follicle has reached a diameter of 18 to 25 mm.
• When the oestradiol level corresponds to 150-300 pg/ml (pg = picogram)
  per large follicle.

Under the influence of the GnRH agonist, the ovulation LH peak cannot occur. Therefore, at optimal follicular ripeness, an injection of hCG (Pregnyl or Profasi) is given to produce this peak.

Oocyte pick-up must be carried out 36 to 38 hours after this injection, that is, 1 to 2 hours before ovulation would occur.

CHU Saint-Pierre, Université Libre de Bruxelles
UMC Sint-Pieter, Vrije Universiteit Brussel
Saint-Pierre University Hospital, Free University of Brussels