P-674 Rescue oocyte collection: a strategy to reduce cycle cancellations in natural/natural modified IVF/ ICSI cycles with luteinising hormone (LH) surge among poor responder patients
Authors: Ranganathan A , Singh J , Datta A , Campbell S , Nargund G 
Published: July 2024

Study question

Can an early oocyte collection (OC) avoid cycle cancellation due to spontaneous ovulation in poor responders undergoing natural/ natural modified (N/NM) cycle-IVF?

Summary answer

Rescue OC may prevent premature ovulation following spontaneous LH surge in N/NM-IVF cycles allowing retrieval of mature oocytes, high-grade embryos that may result in livebirths.

What is known already

Natural IVF cycles carry an inherent higher risk of spontaneous LH surge and ovulation before OC. The introduction of gonadotropin releasing hormone antagonist with low-dose gonadotropin add-back has reduced these risks.Timing of ovulation trigger and trigger to OC interval are important to balance the risks of spontaneous ovulation with the chance of retrieving mature oocyte(s). In the absence of LH surge, the trigger to OC interval is normally 35 hours. However, it is challenging to schedule OC once LH surge has occurred.The effectiveness of rescue OC following LH surge has not been well explored.

Study design, size, duration

This is a retrospective analysis of all NC/NM-IVF/ICSI cycles in poor responders who had spontaneous urinary LH surge from over a period of 3 years, across five Fertility Centres under one company sharing the same treatment protocol.

Participants/materials, setting, methods

All women fulfilling the Bologna criteria for poor ovarian response underwent IVF/ICSI cycles with NC/ NM protocol. The study population included those who had a positive urinary LH surge without or despite the use of antagonist. A rescue OC scheduled 18 to 24 hours after a spontaneous urinary LH surge. Choriogonadotropin alfa (Ovitrelle) 250 micg was administered as soon as the surge was detected. Patients were also given indomethacin 8 hourly until OC.

Main results and the role of chance

Amongst 735 NC/NM-IVF/ ICSI cycles in poor responder women during the study period, 54 cycles (7.3%) had spontaneous urinary LH surge. Twenty-eight cycles were with NC-IVF and 26 NM-IVF protocol.

Only 8 (14.8%) cycles did not progress to OC due to spontaneous ovulation. In 46 (85.2%) of cycles, at least one oocyte was successfully retrieved, with a total of59 retrieved oocytes. ICSI cycles identified at least one mature oocyte in 82% of the cycles. Fertilisation rate with IVF and ICSI cycles combined was 49.1% and at least one cleavage-stage embryo was created from 24 (44.4%) of all cycles (52.2% of retrieved cycles). High-grade embryo(s) was obtained in 42.5% of all cycles. Clinical pregnancy rate (CPR) and live birth rate (LBR) per embryo transfer were 18.7% and12.5%, respectively.

Limitations, reasons for caution

This study was retrospective in nature, without a comparator group. Combination of both NC-IVF and NM-IVF might not have implications in practical terms. Use ofindomethacin also could have delayed ovulation. Although population size was as expected for a rare event, it may not be adequate for a precise LBR.

Wider implications of the findings

An early scheduling of OC in the event of LH surge is an effective way to reduce cycle cancellation rate which is a risk in NC/NM-IVF cycles. It also can potentially result in livebirths. This approach may encourage clinicians practising NC/NM-IVF to test and validate our findings.

Trial registration number

not applicable