Optimal reproductive competence of oocytes retrieved through follicular flushing in minimal stimulation IVF

Follicular flushing increases the number of oocytes retrieved: a randomized controlled trial

STUDY QUESTION

Does follicular flushing increase the number of cumulus-oocyte complexes (COCs) retrieved compared to single aspiration?

SUMMARY ANSWER

Follicular flushing significantly increases the number of COCs retrieved compared to single aspiration.

WHAT IS KNOWN ALREADY

On the basis of published meta-analyses, follicular flushing does not seem to increase the number of oocytes retrieved, the probability of clinical pregnancy, or that of live birth and has been associated with an increase in the duration of oocyte retrieval. It should be noted, however, that all the eligible randomized controlled trials (RCTs) in these meta-analyses have randomized patients into either single aspiration or follicular flushing. This study design might not allow the detection of the true effect of follicular flushing. Despite randomization, this might still be obscured, to an extent, by heterogeneity in patients, stimulation characteristics, and differences in the oocyte retrieval procedure.

STUDY DESIGN, SIZE, DURATION

A prospective, single centre, RCT, including 105 patients was performed between July and December 2022.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Eligible patients were those undergoing oocyte retrieval for ICSI, aged <43 years, with BMI 18-35 kg/m2. Patients with all types of ovarian response (low-normal-high), as assessed on the day of triggering final oocyte maturation, were included. Random allocation of the ovaries of each patient to either single aspiration or follicular flushing was performed on the day of oocyte retrieval, using a computer-generated randomization list. Patients could enter the study only once. All follicles from ovaries allocated to either follicular flushing or single aspiration, were aspirated by the same 16G double lumen needle, with a constant aspiration pressure of 190 mmHg, resulting in flow rate of 0.42 ml/s. In the ovaries allocated to the follicular flushing group, if a COC was not recovered in the initial aspirate of each follicle, follicular flushing was performed until a COC was retrieved, up to a maximum of five times. The primary outcome measure was the number of COCs retrieved. Secondary outcomes were oocyte recovery rate, oocyte maturation rate, fertilization rate, and rate of good quality embryos on Day 2. Values are expressed as a median (inter-quartile range).

MAIN RESULTS AND THE ROLE OF CHANCE

Significantly more COCs were retrieved in the follicular flushing as compared to the single aspiration group in all patients [5 (7) vs 2 (3), P < 0.001, respectively], as well as in patients with high [9 (3) vs 5 (4), P < 0.001, respectively], normal [5 (2) vs 2 (3), P < 0.001, respectively] and low [1 (1) vs 1 (1), P < 0.001, respectively] ovarian response. In patients with low ovarian response, no COCs were retrieved in 5.7% of the ovaries in the flushing group vs 42.8% of the ovaries in the single aspiration group (P < 0.001). The oocyte retrieval rate was significantly higher in the follicular flushing vs the single aspiration group, in all patients [88.9% (25.0) vs 45.5% (37.5), P < 0.001, respectively], as well as in patients with high [81.8% (15.9) vs 45.5% (22.2), P < 0.001, respectively], normal [85.7% (28.6) vs 40.0% (30.0), P < 0.001, respectively], and low [100% (0) vs 50.0% (100), P < 0.001, respectively] ovarian response. No significant difference was observed regarding maturation rate [85.2% (30.8) vs 100% (33.3), P = 0.78], fertilization rate [76.4% (50) vs 83.3% (50) P = 0.42], and the proportion of good quality embryos on Day 2 [83.3% (40) vs 100% (50), P = 0.62]. Similarly, no differences in the above variables were observed in patients with different types of ovarian response. Follicular flushing as compared to single aspiration was associated with a significant increase in the duration of oocyte retrieval in all patients [248 s (332) vs 135 s (164), respectively], as well as in patients with high [464 s (225) vs 237 s (89), P < 0.001, respectively], normal [248 s (108) vs 141 s (95), P < 0.001, respectively], and low [64 s (59) vs 48 s (10), P < 0.001, respectively] ovarian response.

LIMITATIONS, REASONS FOR CAUTION

Although the current study design allows for a more accurate evaluation of the true effect of follicular flushing on the number of COCs retrieved, it does not permit the evaluation of its role on the probability of pregnancy.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first RCT to suggest that follicular flushing increases the number of COCs retrieved compared to single aspiration, independently of ovarian response. This implies that follicular flushing plays an important role in the optimization of oocyte retrieval. These results, however, need to be confirmed in future studies, in which an equal flow rate should be used during oocyte retrieval.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was obtained for this study. There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

NCT05473455.

TRIAL REGISTRATION DATE

15 July 2022.

DATE OF FIRST PATIENT’S ENROLMENT

27 July 2022.

Does Oocyte Retrieval Performance in Mono-follicular Cycles Differ by Physician Experience?

Oocyte pick-up (OPU) is considered as a minor surgical procedure and complications are very rare when performed by trained physicians. However, data on training standards are limited and assessment of proficiency is challenging. The aim of this study was to show the impact of physician experience on OPU performance in mono-follicular in vitro fertilization (IVF) cycles, using two measurable outcome parameters: successful oocyte retrieval and operative time. Senior physicians (n = 6) had over 15 years of experience and novice physicians (n = 4) had at least 30 procedures under supervision. The study population included 226 mono-follicular cycles. Oocyte retrieval was successful in 179 out 226 procedures (79.2%); seniors and novices achieved similar oocyte retrieval rates (74.1%, 43/58 vs 80.9%, 136/168, p = 0.270). The mean duration of the procedure was 513.4 ± 163.1 (126-769) s. It was significantly shorter with a mean difference of - 117.9 s (95% CI: - 164.4 to - 71.3, p = 0.0001, Hedges g = 1.3) for senior physicians when compared to novices (425.8 ± 146.2 versus 543.7 ± 157.9 s). Novices who start performing OPU independently after 30 supervised procedures perform well in collecting the single oocyte grown in mono-follicular cycles; however, the mean duration of the procedure is relatively longer compared to seniors. After initial training period, physicians have few opportunities to compare themselves with their seniors and peers; periodical reassessment of the technique-which should also cover managing the operation time-would help confirm their own practices.

What is the optimum number of follicular flushes in mono-follicular in-vitro fertilization cycles in a poor responder population?

Objective:

Assessment of the optimal number of follicular flushes on retrieval rate and quality of oocytes in mono-follicular in-vitro fertilization (IVF) cycles.

Material and Methods:

A retrospective analysis of 246 oocyte pick-up procedures in mono-follicular IVF cycles of 226 poor responder women was performed. The primary endpoint was oocyte retrieval rate in the initial aspirate versus subsequent flushing episodes. The secondary endpoints were oocyte maturity, fertilization rates and embryo cleavage.

Results:

The procedure was successful in 187 cycles (76%), of which 160 metaphase-II oocytes were retrieved. Retrieval rates were similar for natural and modified natural cycles (p=0.595). The initial aspirate provided 54% of the total yield and the rest was obtained from up to four episodes of flushing. Follicular flushing increased oocyte recovery rate from 41.1% to 76%. None of the oocytes retrieved after three flushes fertilized. Oocyte maturity, fertilization and embryo cleavage rates were comparable for oocytes from the initial aspirate and one or two episodes of flushing. Oocytes obtained after the third flushing episode developed into poor quality embryos.

Conclusion:

Flushing confers a benefit for oocyte recover rates in mono-follicular IVF cycles in poor responder women. However, more than three attempts at flushing were not associated with good outcome.

Evaluation of follicular flushing with double lumen needle in patients undergoing assisted reproductive technology treatments

OBJECTIVE

The purpose of this study was to investigate the possible impact of follicular flushing on the number of oocytes retrieved and oocytes in metaphase II in patients with poor ovarian response (POR) compared to direct aspiration.

METHODS

This prospective, comparative, randomized single center study included 208 punctures of patients with POR, submitted to assisted reproduction technology (ART) treatments. Two groups were compared; one in which double lumen needles were used (Wallace DNS1733) for follicular flushing (n=105), and one in which single lumen needles were used (Wallace ONS1733) for direct aspiration (n=103), upon the observation of ≤ 5 follicles between 15-17 mm, ≤ 4 follicles with sizes greater than 18 mm on hCG day, and ≤ 7 recovered oocytes.

RESULTS

There were no differences in age (39.07±3.88 vs. 38.11±3.43); weight (61.73±17.53 vs. 65.96±15.44); AMH (0.63±0.59 vs. 0.94±0.97); stimulation days (9.57±1.87 vs. 10.29±2.82); estradiol levels (788.94±670.82 vs. 940.16±694.69); progesterone (617.29±319.76 vs. 561.18±486.78); or number of follicles with sizes ≥18 mm (1.84±0.95 vs. 2.07±1.09). Although gonadotropin totals (1678.28±798.52 vs. 2080.45±852.36; p=0.0008), number of aspirated oocytes (3.00±2.11 vs. 3.69±2.20; p=0.02), and number of metaphase II oocytes (2.20±1.64 vs. 2.99±1.88; p=0.02) were significantly different, oocyte / follicle ratio ≥15 mm (0.93 vs. 0.98) and metaphase II oocytes / follicles ≥15 mm (0.68 vs. 0.79) were similar in both groups. The failure to capture was 16% vs. 9.8%.

CONCLUSIONS

Considering that there was no difference in the oocyte per follicle ratio, follicular flushing did not increase the number of oocytes recovered from poor responders.

Follicular flushing increases the number of oocytes retrieved in poor ovarian responders undergoing in vitro fertilization: a retrospective cohort study

Background

To investigate the impact of follicular flushing on the number of oocytes retrieved and embryo quality and to determine the optimal number of flushings for poor ovarian responders (PORs) undergoing in vitro fertilization (IVF).

Methods

This retrospective study included 291 IVF cycles in 224 patients who were PORs and had no more than three dominant follicles on retrieval day. During oocyte retrieval, follicular fluid was aspirated and examined for an oocyte. If no oocyte was identified, follicular flushing was repeated until an oocyte was retrieved or up to a maximum of nine times.

Results

The mean number of oocytes retrieved by aspiration and subsequent flushes was significantly higher than the number retrieved from the initial aspirate (1.73 ± 0.96 VS. 1.23 ± 1.00, P = 0.000). The total recovery rate was 83.7% (503/601), which was significantly higher than the 59.6% recovery rate for direct aspiration (P = 0.000). Before the 4th follicular flushing, the cumulative recovery rate increased significantly as flushing was repeated, but after the 4th flushing, the ascending trend was mitigated; and the risk ratio of recovering fewer oocytes after 4 flushes compared with after 9 flushes was 0.765 (95%CI, 0.570–1.026, P = 0.074). Significant differences were not observed in maturation rate, fertilization rate, cleavage rate or high-quality embryo rate (P > 0.05).

Conclusions

Follicular flushing may increase the number of oocytes retrieved and does not have adverse effects on oocyte or embryo quality in PORs undergoing IVF. Four times may be an optimal number of follicular flushings.

Follicular flushing during oocyte retrieval in assisted reproductive techniques

BACKGROUND

Follicular aspiration under transvaginal ultrasound guidance is routinely performed as part of assisted reproductive technology (ART) to retrieve oocytes for in vitro fertilisation (IVF). However, controversy as to whether follicular flushing following aspiration yields a larger number of oocytes and hence is associated with greater potential for pregnancy than aspiration only is ongoing.

OBJECTIVES

To assess the safety and efficacy of follicular flushing as compared with aspiration only performed in women undergoing ART.

SEARCH METHODS

We searched the following electronic databases up to 18 July 2017: Cochrane Gynaecology and Fertility Group (CGF) Specialised Register of Controlled Trials, the CENTRAL Register of Studies Online (CRSO), MEDLINE, Embase, PsycINFO, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL). We also searched the trial registries ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform to identify ongoing and registered trials up to 4 July 2017. We reviewed the reference lists of reviews and retrieved studies to identify further potentially relevant studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared follicular aspiration and flushing with aspiration alone in women undergoing ART using their own gametes. Primary outcomes were live birth rate and miscarriage rate per woman randomised.

DATA COLLECTION AND ANALYSIS

Two independent review authors assessed studies against the inclusion criteria, extracted data, and assessed risk of bias. A third review author was consulted if required. We contacted study authors as required. We analysed dichotomous outcomes using Mantel-Haenszel odds ratios (ORs), 95% confidence intervals (CIs), and a fixed-effect model, and we analysed continuous outcomes using mean differences (MDs) between groups presented with 95% CIs. We examined the heterogeneity of studies via the I² statistic. We assessed the quality of evidence by using GRADE (Grades of Recommendation, Assessment, Development and Evaluation) criteria.

MAIN RESULTS

We included ten studies, with a total of 928 women. All included studies reported outcomes per woman randomised. We assessed no studies as being at low risk of bias across all domains and found that the main limitation was lack of blinding. Using the GRADE method, we determined that the quality of the evidence ranged from moderate to very low, and we identified issues arising from risk of bias, imprecision, and inconsistency.Comparing follicular flushing to aspiration alone revealed probably little or no difference in the live birth rate (OR 0.95, 95% CI 0.58 to 1.56; three RCTs; n = 303; I² = 30%; moderate-quality evidence). This suggests that with a live birth rate of approximately 41% with aspiration alone, the equivalent live birth rate with follicular flushing is likely to lie between 29% and 52%. None of the included studies reported on the primary outcome of miscarriage rate.Data show probably little or no difference in oocyte yield (MD -0.28 oocytes, 95% CI -0.64 to 0.09; six RCTs; n = 708; I² = 0%; moderate-quality evidence). Very low-quality evidence suggests that the duration of oocyte retrieval was longer in the follicular flushing group than in the aspiration only group (MD 166.01 seconds, 95% CI 141.96 to 190.06; six RCTs; n = 714; I² = 88%). We found no evidence of a difference in the total number of embryos per woman randomised (MD -0.10 embryos, 95% CI -0.34 to 0.15; two RCTs; n = 160; I² = 58%; low-quality evidence) and no evidence of a difference in the number of embryos cryopreserved (meta-analysis not possible). Data show probably little or no difference in the clinical pregnancy rate (OR 1.07, 95% CI 0.78 to 1.46; five RCTs; n = 704; I² = 49%; moderate-quality evidence). Only two studies reported on adverse outcomes: One reported no differences in patient-reported adverse outcomes (depression, anxiety, and stress), and the other reported no differences in needle blockage, vomiting, and hypotension. No studies reported on safety.

AUTHORS' CONCLUSIONS

This review suggests that follicular flushing probably has little or no effect on live birth rates compared with aspiration alone. None of the included trials reported on effects of follicular aspiration and flushing on the miscarriage rate. Data suggest little or no difference between follicular flushing and aspiration alone with respect to oocyte yield, total embryo number, or number of cryopreserved embryos. In addition, follicular flushing probably makes little or no difference in the clinical pregnancy rate. Evidence was insufficient to allow any firm conclusions with respect to adverse events or safety.

Resurgence of Minimal Stimulation In Vitro Fertilization with A Protocol Consisting of Gonadotropin Releasing Hormone-Agonist Trigger and Vitrified-Thawed Embryo Transfer

Minimal stimulation in vitro fertilization (mini-IVF) consists of a gentle controlled ovarian stimulation that aims to produce a maximum of five to six oocytes. There is a misbelief that mini-IVF severely compromises pregnancy and live birth rates. An appraisal of the literature pertaining to studies on mini-IVF protocols was performed. The advantages of minimal stimulation protocols are reported here with a focus on the use of clomiphene citrate (CC), gonadotropin releasing hormone (GnRH) ago- nist trigger for oocyte maturation, and freeze-all embryo strategy. Literature review and the author’s own center data suggest that minimal ovarian stimulation protocols with GnRH agonist trigger and freeze-all embryo strategy along with single embryo transfer produce a reasonable clinical pregnancy and live birth rates in both good and poor responders. Additionally, mini-IVF offers numerous advantages such as: i. Reduction in cost and stress with fewer office visits, needle sticks, and ultrasounds, and ii. Reduction in the incidence of ovarian hyperstimulation syndrome (OHSS). Mini-IVF is re-emerging as a solution for some of the problems associated with conventional IVF, such as OHSS, cost, and patient discomfort.

Follicular flushing and in vitro fertilization outcomes in the poorest responders: a randomized controlled trial

STUDY QUESTION

Does follicular flushing during oocyte retrieval improve the number of oocytes retrieved in the poorest responders?

SUMMARY ANSWER

Follicular flushing in the poorest responders does not increase the number of oocytes retrieved and may result in lower implantation and clinical pregnancy rates.

WHAT IS KNOWN ALREADY

Although previous studies have shown no beneficial effect of follicular flushing in normal responders, no study has demonstrated a detrimental effect and many IVF centers continue to perform this technique in poor responders. Data on follicular flushing in this patient group are limited, with no randomized trial to date assessing its utility in the poorest responders.

STUDY DESIGN, SIZE, DURATION

This randomized controlled trial compared the effects of follicular flushing and direct aspiration on IVF outcomes in the poorest responders, defined as having four or fewer follicles ≥12 mm on the day of hCG administration. Fifty patients were randomized during the 12-month enrollment period.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The patients were treated at an academic fertility center at Weill Cornell Medical College, New York.

MAIN RESULTS AND THE ROLE OF CHANCE

Fifty women were randomized to follicular flushing (n = 25) or direct aspiration (n = 25). One patient in the direct aspiration group was canceled prior to oocyte retrieval for premature ovulation and was included in the intent-to-treat analysis. There was no difference in the number of oocytes retrieved with a median (IQR) of 4 (2-6) in the aspiration group versus 3 (2-5) in the flushing group (95% CI: -0.78, 1.98; P = 0.41). Patients who underwent follicular flushing had significantly fewer embryos transferred {1.7 [standard deviation (SD) 0.6] versus 2.5 (SD 1.2), P = 0.03}, a lower implantation rate (5.3 versus 34.2%, P = 0.006) and a lower clinical pregnancy rate (4 versus 36%, P = 0.01). The difference in pregnancy rates remained significant after adjusting for embryos transferred.

LIMITATIONS, REASONS FOR CAUTION

Findings, including results for secondary outcome measures, may not be generalizable to natural IVF cycles as these were excluded from the study.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first randomized trial to evaluate the utility of follicular flushing in the poorest responders, and the first to demonstrate a potentially detrimental effect of flushing on IVF outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

NCT 01558141.

Follicular flushing during oocyte retrieval: a systematic review and meta-analysis

PURPOSE

The purpose of this systematic review and meta-analysis was to examine the literature and identify randomized controlled trials (RCTs), in order to answer if performing follicular flushing during the oocyte retrieval may improve the assisted reproductive technologies (ART) outcomes.

METHODS

An exhaustive electronic search was performed using MEDLINE and EMBASE databases. Only RCTs comparing follicular flushing to aspiration only during ART, were included. We included 5 trials, with a total of 482 patients randomized, with median ages ranging from 30.5 to 37.1.

RESULTS

The data analyses did not show significant differences regarding live birth rate, clinical pregnancies rates, and the number of oocytes retrieved. The duration of oocyte retrieval was significantly increased in the follicular flushing group.

CONCLUSIONS

The results from this systematic review and meta-analysis suggest that there is no advantage to use of routine follicular flushing during OR in an unselected group of patients.

The use of follicle flushing during oocyte retrieval in assisted reproductive technologies: a systematic review and meta-analysis

STUDY QUESTION

Does follicular flushing during assisted reproductive technologies (ART) improve the number of oocytes retrieved?

SUMMARY ANSWER

Follicular flushing during ART does not result in a greater number of oocytes in normal responders.

WHAT IS KNOWN ALREADY

Despite limited evidence supporting the use of follicular flushing, it continues to be a common procedure in many ART clinics. Prior studies have provided conflicting results regarding the routine use of flushing during oocyte retrieval.

STUDY DESIGN, SIZE, DURATION

Systematic review and meta-analysis of 518 patients who participated in 6 randomized trials over 20 years.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Literature searches were conducted to retrieve randomized controlled trials on follicle or ovarian flushing in ART. Databases searched included PubMed, EMBASE, Web of Science and the Cochrane Database of Clinical Trials (CENTRAL). Six trials that included 518 subjects matched the inclusion criteria. Studies included were limited to trials that were published, randomized trials comparing oocyte retrieval with a single-lumen pick-up needle versus follicle flushing after direct aspiration with a multi-channel oocyte pick-up needle in ART patients.

MAIN RESULTS AND THE ROLE OF CHANCE

In each of the trials, measures of the oocyte yield (oocytes retrieved divided by follicles aspirated), total oocytes retrieved, fertilization or pregnancy were not different when comparing direct aspiration with follicle flushing. Four trials reported a higher operative time with follicle flushing. Results of the meta-analysis indicated no significant differences in the oocytes retrieved [weighted mean difference: 0.07, 95% confidence interval (CI): -0.13 to 0.29] or the oocyte yield (odds ratio: 1.06, 95% CI: 0.95-1.18) between the non-flushing and flushing groups.

LIMITATIONS, REASONS FOR CAUTION

All trials featured an open label design and the majority of patients in this meta-analysis were normal responders. The applications of these results to poor responders, patients undergoing natural cycle ART or minimal stimulation ART should be made with caution.

WIDER IMPLICATIONS OF THE FINDINGS

Follicle flushing does not improve ART outcomes in normal-responding patients and should not be performed. This meta-analysis should solidify this recommendation as it includes the largest trial published on the subject and is consistent with a recently published Cochrane review.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported, in part, by the Program in Reproductive and Adult Endocrinology, NICHD, NIH, Bethesda, MD. The authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

N/A.

Is there a benefit in follicular flushing in assisted reproductive technology?

PURPOSE OF REVIEW

Follicular flushing utilizing double-lumen retrieval needles attempts to increase oocyte yield during transvaginal retrieval. The original work on this topic, now more than 2 decades old, examined its utility in normal-responding assisted reproductive technologies (ART) patients. Newer studies examining its utility have focused on special populations expected to demonstrate benefit: poor responders, natural cycle and minimal stimulation ART, and in-vitro maturation cycles. This review assesses the current evidence regarding the effectiveness of ovarian follicular flushing in improving oocyte yield.

RECENT FINDINGS

Follicular flushing offers no substantive benefit in oocyte yield, fertilization rates, or pregnancy outcomes for normal and poor-responding ART patients. Patients undergoing natural cycle or minimal stimulation ART may benefit from follicular flushing resulting in more mature embryos but unclear effects on cycle outcome.

SUMMARY

Randomized controlled trials consistently demonstrate no benefit and increased procedural time with follicular flushing in both normal and poor-responding ART patients. Nonrandomized data suggest a possible role for follicular flushing in natural cycle or minimal stimulation ART and in those undergoing in-vitro maturation IVF cycles; however, randomized controlled trials are needed to verify this finding. Presently, there is insufficient evidence to recommend the routine use of follicular flushing.