Choriogonadotropin alfa

How it works

It mimics the action of luteinising hormone at LH/hCG receptors, inducing final oocyte maturation and rupture of the mature follicle after adequate follicular development.

Prescribing in practice

• It is given to trigger ovulation only once follicular development is adequate, as administering it can precipitate or worsen ovarian hyperstimulation syndrome.
• It should be withheld if there is an excessive ovarian response or an abnormally high number of follicles because of the heightened hyperstimulation risk.
• It is administered by subcutaneous injection within an assisted conception protocol under specialist supervision.

Monitoring

Ovarian response is assessed by ultrasound and hormone monitoring before the trigger, and patients are watched for signs of hyperstimulation afterwards.

Counselling the patient

• This injection is the trigger that prepares your eggs for collection or release at a precise time.
• Follow the exact timing instructions given by your fertility clinic.
• Report marked abdominal swelling, pain, breathlessness, or reduced urine output, which may indicate ovarian hyperstimulation.

Evidence & guidelines

Recombinant hCG is an established ovulation-triggering agent in controlled ovarian stimulation protocols for assisted conception.