What Is A Good Size Follicle For Fertilization

Aim: To evaluate the result of big follicular size (≥24 mm) at solar day of oocyte retrieval on oocyte/embryo quality. Patients and Methods: A cohort study was conducted in a single tertiary medical center between July 2018 and May 2019. Before ultrasound-guided follicular aspiration, follicles were measured and divided into 2 groups according to their maximal dimensional size: large: ≥24 mm and normal: <24 mm. Microscopic exam of the follicular aspirates was performed past an embryologist. Each follicle aspirated was evaluated for oocyte maturation, oocyte fertilization, and embryo quality. Results: 428 follicles were measured, including 383 (62.81%) in the normal and 45 (14.06%) in the big follicle groups. Oocytes were achieved during aspiration from 297 (75.5%) and 29 (64.4%) of the normal and large follicle groups, respectively (p = 0.05). No in-between group differences were observed in mature oocyte (MII), fertilization, and peak-quality embryo (TQE) rates. Notwithstanding, one time a zygote (2PN) was achieved, a trend toward a higher TQE rate/2PN was establish in the large follicle group (xvi/nineteen [84.2%] vs. 115/171 [67.3%]; p = 0.062). Determination: While a nonsignificant subtract in oocyte recovery charge per unit was found in follicles ≥24 mm, the zygote and TQE per follicle were comparable.

Background

Controlled ovarian hyperstimulation (COH) is a crucial step in assisted reproduction, aiming to increase the number of growing follicles that will yield competent oocytes. Ovarian follicles abound at dissimilar rates, and COH monitoring is usually guided by follicular size rather than their competence [one]. Studies have shown that follicles with greater diameter were most likely to reveal mature oocytes, which are capable of fertilization and best suited for evolution into high-quality embryos [2-4].

Information exist, both in homo and animal models, on the optimal follicular size on the 24-hour interval of oocyte retrieval that are most likely to yield a mature oocyte [five]. Follicles of 16–22 mm are more likely to yield mature oocytes than smaller follicles, while larger follicles would more probable yield "postal service-mature" oocytes that are not competent for fertilization [6]. Nonetheless, while Dubey et al. [seven] observed comparable fertilization rates in oocytes from 16- to 22-mm follicles to those from 22- to 26-mm follicles, Ectors et al. [vi] observed that follicles of xvi–23 mm on the twenty-four hours of oocyte retrieval had higher fertilization rates than those >23 mm. Withal, the % of expert scored oocyte was demonstrated to increase from 55.4% of follicle size of sixteen–23 mm to 64.6% of follicles >23 mm [6].

Recently, nosotros demonstrated in a cohort prospective study [8] evaluating the association between follicle size (maximal dimensional size: large: ≥16 mm, medium: fifteen–13 mm, and pocket-sized: <xiii mm) and oocyte/embryo quality that mature oocyte (MII) rate was significantly higher in the large and medium compared to the modest follicle size groups. Yet, no in-between group differences were observed in fertilization nor in summit-quality embryo (TQE) rates amongst the mature oocytes regardless of the follicular diameter they originated.

Prompted past the aforementioned observations, we wanted to evaluate the clan between big follicle size (≥24 mm) and oocyte development and quality. For this purpose, nosotros reanalyzed the data from our previously published cohort prospective study (Mohr-Sasson et al. [viii]).

Materials and Methods

The data used in this study were nerveless in a cohort prospective study that has been reported elsewhere (Mohr-Sasson et al. [viii]). Women undergoing COH using the multiple-dose GnRH antagonist protocol between July 2018 and May 2019, in a single academy affiliated 3rd medical middle, were included. But those <43 years old, without a history of endometriosis or Delicate X cistron mutation, were included. The written report protocol was approved by our IRB (ID 4689-17-SMC) and was registered by the National Institutes of Health (NCT02821702).

Data on patient age, infertility handling-related variables, and ovarian stimulation characteristics were retrieved from women'southward medical files. Decision of final follicular maturation triggering was based on physician judgment [nine]. The timing was based on the lead follicular cohort, usually with at least 2 leading follicles measuring ≥17 mm for maximal bore. A transvaginal sonography-guided follicular aspiration was conducted 36 h later triggering administration.

At retrieval, up to 4 leading follicles were measured before aspiration from each adult female. Follicles were divided into 2 follicular groups co-ordinate to their maximal dimensional size: normal: <24 mm and large ≥24 mm. Retrieval was done separately for each follicle measured. Microscopic examination of the follicular aspirates was performed by the embryologist. In case where no oocyte was detected, flushing of the system was performed using 0.five–1 cc of medium with Hepes (Quinn's Advantage®, Sage, United states of america).

Routine IVF or intracytoplasmic sperm injection (ICSI) was and so performed, as appropriate. Each embryo was cultured separately until transvaginal ET, which was performed 48–72 h after OPU. All patients received luteal support with progesterone.

Embryo classification was based on the individual embryo scoring parameters, where TQEs were defined equally day-2 or -3 embryos with 3–4 or vii–viii cells (respectively) and ≤10% fragmentation rate. The information for each oocyte, starting from the follicular size, was followed through all the laboratory procedures including insemination, oocyte stripping for ICSI, ICSI, fertilization, and embryo civilization.

Chief outcome was divers as the number of oocytes retrieved from each of the follicular groups (oocyte recovery charge per unit). Secondary outcomes included oocytes undergone nuclear maturation (MII), fertilization rate, and TQE rate. The subgroup analysis which we present hither was not planned in the original protocol. The cutoff to exist analyzed was called after completion of the original trial [8].

Statistical Assay

Comparison between unrelated variables was conducted with Student's t test and Isle of man-Whitney U exam, as appropriate. The χ² and Fisher's exact tests were used for comparison betwixt chiselled variables. Significance was accustomed at p < 0.05. Statistical analyses were conducted using the IBM Statistical Package for the Social Sciences (IBM SPSS v.nineteen; IBM Corporation Inc., Armonk, NY, USA).

Results

During the study menses, 199 women met the inclusion criteria, from whom 428 follicles were measured, including 383 (89.v%) in the normal and 45 (ten.5%) in the large follicle groups. No in-between grouping differences were observed in patients' body mass index or COH characteristics. Oocytes were accomplished during aspiration from 297 (77.five%) and 29 (64.4%) of the normal and large follicle groups, respectively (p = 0.051). No in-between group differences were observed in fertilization and TQE rates per follicle (Table ane). Notwithstanding, once a zygote (2PN) was accomplished, a trend toward a higher TQE rate/2PN was constitute in the large follicle group (16/19 [84.2%] vs. 115/171 [67.3%]; p = 0.062).

Table 1.

Embryological outcome according to follicular size

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Give-and-take

In the present analysis, while oocyte recovery charge per unit was nonsignificantly decreased in follicles ≥24 mm, the ratios of 2PN and TQE per follicle were comparable. Moreover, zygotes derived from a big follicle (≥24 mm) yielded a nonsignificantly higher TQE charge per unit.

The association between follicular size and oocyte maturity has been studied already 3 decades ago, and information technology dictated the timing of final follicular maturation trigger, whenever several follicles reach a diameter of >17–20 mm [6, seven, 10, xi]. In our previous study [viii], we demonstrated higher oocyte recovery rate in large (≥16 mm) and medium big (13–15 mm) compared to the modest (<13 mm) follicle groups, finding which is consequent with previous studies [two, eleven-13]. Moreover, MII oocytes were more ordinarily found in the medium and large follicle groups [viii, 11, 14].

In a prospective study conducted by Triwitayakorn et al. [thirteen], including 991 follicles, fertilization rate of mature oocytes, every bit well every bit the rate of good-quality embryos, showed a trend to increase from the small follicle group to the large follicle group; notwithstanding, this finding was not significant. Dubey et al. [7] reported that oocyte fertilization rate had a positive linear correlation as follicle diameter increased, while Nogueira et al. [fifteen] demonstrated that matured oocytes retrieved from small follicles generated embryos of lower developmental potential than oocytes derived from larger follicles.

In the bulk of the studies, big follicles relate to those ≥16 mm in diameter. Only few considered larger (≥24 mm) diameters. In the present analysis, nosotros observed a nonsignificant decrease in oocyte recovery rate in follicles ≥24 mm, with comparable 2PN and TQE per follicle ratios. Still, in one case a zygote was recovered from a big follicle (≥24 mm), a nonsignificantly higher TQE charge per unit was observed. In accordance with our observation, Ectors et al. [6] observed that follicles of >23 mm on the day of oocyte retrieval had higher maturation rate compared to those <23 mm. Moreover, the % of good scored embryos was demonstrated to increase from 55.4% of follicle size of 16–23 mm to 64.half-dozen% of follicles >23 mm (Ectors et al. [half dozen]).

In virtually centers, final follicular maturation is triggered once 2–3 follicles reach at to the lowest degree 17–eighteen mm in diameter, actually 2 days prior to oocyte retrieval. Sometimes, few follicles achieve the required size while others are still small or medium size, and information technology is common to "sacrifice" the larger on behalf of allowing the development of the smaller cohort of follicles. In the nowadays study, we demonstrated that by letting follicles to develop to larger diameter (≥24 mm), non only are they not sacrificed, merely they as well accept good probability to yield MII oocytes, and in one case recovered, to develop to TQEs.

Strengths and Limitations

The study has several limitations. Women included in the study were treated for infertility due to various reasons. Furthermore, handling protocols were not homogeneous to all study population; therefore, follicles exposed to unlike gonadotropins and trigger modes were included. Moreover, since we analyzed only 383 follicles in the normal and 45 in the large follicle groups, the chance of type 2 error is still possible.

Although diverse studies exist apropos the association between follicular size to oocyte recovery rate at retrieval, data relating to large (≥24 mm) follicles are scarce. This report strength is in its beingness conducted in a single center past a professional person consistent squad on a big study grouping.

Conclusions

In summary, the results of this study indicate that while oocyte recovery rate was nonsignificantly decreased in follicles ≥24 mm, the zygote and TQE per follicle are comparable. Moreover, zygotes derived from a large follicle (≥24 mm) yielded a nonsignificantly higher TQE rate. This information should be of value to physicians and patients alike. Further investigation is required to strengthen this finding.

Acknowledgements

We acknowledge the Embryological Laboratory Squad of Sheba Medical Center for their cooperation.

Statement of Ideals

The written report protocol was approved past the "Sheba Medical Center" Institutional Review Board (ID 4689-17-SMC) on December 21, 2017, and was supported by the National Institutes of Wellness (NCT02821702).

Disharmonize of Involvement Statement

The authors have nothing to declare.

Funding Sources

This manuscript was not supported by specific funding.

Author Contributions

R.O. was the chief investigator, designed the study, wrote the paper, and edited it in all its revisions. A.Grand.S. participated in designing the study, retrieved the data, performed the statistical evaluations, proofread the newspaper, and took part in discussions regarding the results. S.B., R.N., and A.A. retrieved the data, proofread the paper, and took part in discussions regarding the results. J.H. participated in designing the study, assisted in writing the paper and edited it, proofread the newspaper, and took part in discussions regarding the results.

Availability of Data and Material

Data will be made available from the corresponding author on request.

Author Contacts

Jigal Haas

Department of Obstetrics and Gynecology, Sheba Medical Center

TAU, Derech Sheba 2, Tel-Hashomer

Ramat Gan 52621 (State of israel)

jigalh@hotmail.com

Commodity / Publication Details

First-Page Preview

Abstract of Original Article

Received: June 05, 2020
Accustomed: July xxx, 2020
Published online: September 23, 2020
Outcome release date: December 2020

Number of Print Pages: four
Number of Figures: 0
Number of Tables: ane

ISSN: 0378-7346 (Print)
eISSN: 1423-002X (Online)

For boosted data: https://www.karger.com/GOI

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