P-626 Time interval between ovulation triggering and oocyte retrieval and ART outcomes: an updated meta-analysis
Authors: Gan R , Li Y 
Published: June 2023

Study question

To explore whether prolonged hCG-ovum pickup(hCG-opu) interval improves assisted reproductive technology outcomes.

Summary answer

The clinical pregnancy rates can be increased by prolonging the hCG-opu interval, which would help develop more reasonable time schedules for fertility centers and patients.

What is known already

hCG-OPU interval greatly affects ART success, which allows to obtain the maximum number of competent mature oocytes while avoiding spontaneous ovulation. There is also no consensus regarding the optimal time between hCG-OPU, which some studies had shown that ideal ART outcomes could be obtained when oocyte retrieval was done more than 36 h -39 h after hCG priming, while others have concluded that an interval of more than 36 hours does not improve ART outcomes.

Study design, size, duration

CENTRAL, CNKI, Cochrane Systematic Reviews, EMBASE, MEDLINE, PUBMED, and Web of Science up to February 7, 2022 were searched for studies reporting associations between hCG-ovum pickup intervals and assisted reproductive technology outcomes. We searched for prospective or retrospective cohort studies measuring the hCG-OPU interval, using 36 hours as the cutoff value between short and long intervals. A combination of the following key search terms was used: “oocyte retrieval,” “human chorionic gonadotropin,” and “interval.”

Participants/materials, setting, methods

Studies analyzing the relationship between the hCG-OPU interval and ART outcomes were considered eligible for abstract screening. Intervention types included short (≤36 h) and long (&gt;36 h) hCG-ovum pickup intervals in assisted reproductive technology cycles. All outcomes were based upon only fresh embryo transfers. Data were pooled using random-effects models. Heterogeneity was assessed using the I 2 statistic.

Main results and the role of chance

12 studies were included in the meta-analysis, including five retrospective cohort studies, one prospective cohort study, and six randomized or quasi-randomized controlled trials. The short and long interval groups had similar oocyte maturation rates, fertilization rate and high-quality embryo rate (OR, 0.69; 95% CI, 0.45–1.06; I2 = 91.1%, OR, 0.88; 95% CI, 0.77–1.0; I2 = 44.4% and OR, 1.05; 95% CI, 0.95–1.17; I2 = 8.6%, respectively). The clinical pregnancy rates in the long retrieval group were significantly higher than in the short retrieval group (OR, 0.66; 95% CI, 0.45–0.95; I2 = 35.4%). The groups had similar miscarriage and live birth rates (OR, 1.92; 95% CI, 0.66–5.60; I2 = 0.0% and OR, 0.50; 95% CI, 0.24–1.04; I2 = 0.0%, respectively).

Limitations, reasons for caution

Using studies without patient data represents a potential source of bias. The hCG-OPU intervals were selected based on clinical relevance, resulting in statistical heterogeneity. Despite sensitivity analysis, such heterogeneity sources call for caution when interpreting the results.

Wider implications of the findings

The clinical pregnancy rates can be increased by prolonging the hCG-OPU (&gt;36h), which would support the search for better clinical outcomes. The finding should be validated. And if validated by multicenter, randomized, controlled trials, long interval could be implemented in ART programs, resulting in better clinical pregnancy outcomes.

Trial registration number

not applicable