BEst Size for Ovulation Triggering in Poseidon 4 Patients (BEST 4 Study) (BEST)

What Should Be The Optimal Ovulation Triggering Size in Poseidon Group 4 Patients Undergoing Ovarian Stimulation?

This observational clinical study aims to determine the optimal timing of ovulation triggering in women aged 35 and above with poor ovarian reserve.

For this purpose, cases undergoing ovarian stimulation for assisted reproductive treatment and planned final oocyte triggering will be evaluated in two separate groups:

1. **Experimental Group**: Final oocyte triggering will be performed when the follicle or follicles measure between 13-16 mm.
2. **Control Group**: Final oocyte triggering will be performed when the follicle or follicles measure greater than 17 mm.

All triggers will be administered uniformly with 6500 units of recombinant hCG and 0,2 mg triptorelin injections.

The primary outcome of the study will be the number of mature oocytes. Secondary outcomes will include fertilization rates, embryo counts, and implantation rates.

Primary and secondary outcomes will be compared between the two groups.

Study Overview

• Status: Recruiting
• Conditions: Fertilization; Fertilization in Vitro
• Intervention / Treatment: Other: Ovulation Trigger Timing Based on Leading Follicle Size in POSEIDON Group 4 IVF Patients

Detailed Description

The timing of final oocyte maturation in assisted reproductive techniques is critically important. If serum steroid hormone levels are appropriate during the late follicular phase, ovulation triggering can be performed using various agents. There are numerous comparative studies in the literature on this topic.

However, a key issue is determining the most optimal timing for this trigger. In standard practice, the final triggering is performed when the follicle size reaches 17 mm or more.

The purpose of this is to obtain mature eggs from these follicles during the oocyte aspiration process.

However, in some special cases, to maximize the desired yield, this size threshold may be adjusted.

A prime example of this is in older patients with poor ovarian reserve, as the expected egg yield may not be achieved with standard practices.

During the oocyte collection process, fewer mature oocytes (M2) may be retrieved, or no oocytes may be retrieved at all, despite proper ovarian stimulation. Therefore, the optimal follicle size for these cases has not been definitively established in the literature. Thus, there is a need to determine other follicular thresholds specifically for older women with poor ovarian reserves to enhance egg and mature egg yields.

For this purpose, cases undergoing ovarian stimulation for assisted reproductive treatment and planned final oocyte triggering will be evaluated in two separate groups:

1. **Experimental Group**: Final oocyte triggering will be performed when the follicle or follicles measure between 13-16 mm.
2. **Control Group**: Final oocyte triggering will be performed when the follicle or follicles measure greater than 17 mm.

All triggers will be administered uniformly with 6500 units of recombinant hCG and 0,2 mg triptorelin injections.

The primary outcome of the study will be the number of mature oocytes. Secondary outcomes will include fertilization rates, embryo counts, and implantation rates.

Primary and secondary outcomes will be compared between the two groups.

• Study Type: Observational
• Enrollment (Estimated): 200

Contacts and Locations

• Study Contact: Name: Emre G Pabuccu, Professor; Phone Number: +90 532 4147844; Email: emregpabuccu@gmail.com
• Study Contact Backup: Name: Recai Pabuccu, Professor; Phone Number: +90 532 6160086; Email: pabuccu@hotmail.com

Study Locations

• Turkey (Türkiye)
  • Ankara
    • Ankara, Ankara, Turkey (Türkiye), 06800
      • Recruiting
      • Centrum Clinic IVF Center
      • Contact: Emre Pabuccu; Phone Number: 05324147844

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

A group of women defined as Poseidon Group 4, who will apply to the infertility clinic to be scheduled for ovarian stimulation and assisted conception treatments during the study period.

Description

Inclusion Criteria:

• Women age equal to or greater than 35 years
• Women with low serum AMH (<1,2 ng/ml),
• women with low AFC (<5)
• women Undergoing assisted reproduction with Short antagonist protocol or long -agonist protocol
• women who used Max daily gonadotropin dose of 300 IU

Exclusion Criteria:

• Age <35 years.
• Ovarian reserve parameters not meeting the POSEIDON group 4 definition.
• Natural or modified natural cycles without controlled ovarian stimulation.
• In vitro maturation (IVM) cycles.
• Luteal-phase stimulation or DuoStim protocols.
• Preimplantation genetic testing (PGT-A, PGT-M, or PGT-SR) cycles, unless prespecified for stratified analyses.
• Major untreated uterine cavity pathology (e.g., submucosal fibroids, significant intrauterine adhesions, congenital uterine anomalies) or untreated hydrosalpinx.
• Cycles with missing or incomplete follicular measurement data on the trigger day.
• Cycles with non-standardized or undocumented trigger-to-oocyte retrieval intervals.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

Women defined as poor responders according to POSEIDON criteria group 4 undergoing IVF; This group of women, who have low serum AMH levels and low antral follicle count obviusly reveal unfavorable ovarian stimulation and reproductive outcomes in daily practice. Since the most important outcome measure is the live birth rate in assisted reproduction, rates have been reportedly very low for this cohort. Depending from the reports, live birth rates particularly cumulative rates directly correlated with collected numbers of oocytes. Therefore, studies should focus on this entity.

Other: Ovulation Trigger Timing Based on Leading Follicle Size in POSEIDON Group 4 IVF Patients; In this study, ovulation trigger timing is determined according to the diameter of the leading follicle measured by transvaginal ultrasound during ovarian stimulation in women classified as POSEIDON group 4. Patients undergoing controlled ovarian stimulation are monitored with serial ultrasound examinations and serum hormone measurements. Ovulation triggering is performed when the leading follicle reaches predefined size categories. The study evaluates the association between the diameter of the leading follicle at the time of trigger and reproductive outcomes. The primary outcome measure is the number of metaphase II (MII) oocytes retrieved, while secondary outcomes include blastocyst formation and pregnancy outcomes.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in the Mean Mature Oocytes between two triggering strategies	Mean numbers of oocytes, mature oocytes, fertilization rates, embryos and pregnancy rates will be compared between two different triggering sizes.	From enrollment to the end of treatment at 6-8 months.

Collaborators and Investigators

• Sponsor: Centrum Clinic IVF Center
• Investigators: Study Director: Emre Pabuccu, Prof., Ufuk University

Study record dates

Study Major Dates

• Study Start (Actual): March 15, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): December 30, 2026

Study Registration Dates

• First Submitted: May 23, 2024
• First Submitted That Met QC Criteria: May 23, 2024
• First Posted (Actual): May 29, 2024

Study Record Updates

• Last Update Posted (Actual): March 19, 2026
• Last Update Submitted That Met QC Criteria: March 17, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: IVF; ovarian stimulation; oocyte; poor responder
• Other Study ID Numbers: 2024-3-1

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No