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

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.

The importance of follicular flushing in optimizing oocyte retrieval

PURPOSE OF REVIEW

To critically evaluate the use of follicular flushing during oocyte retrieval.

RECENT FINDINGS

The latest meta-analysis evaluating follicular flushing does not favour its use over single aspiration. The randomized controlled trials (RCTs) included, however, are characterized by significant heterogeneity regarding the population analysed, the needle type and lumen used, the aspiration pressure applied and the number of flushing attempts performed. More importantly, information regarding the flow rate used for aspiration is scarce. The only RCT employing a constant flow rate between single aspiration and follicular flushing in women with monofollicular development, suggests that a higher number of oocytes is retrieved after follicular flushing.

SUMMARY

In order to eliminate clinical heterogeneity that might obscure the detection of the true effect of follicular flushing, randomization to single aspiration and follicular flushing should occur within the same patient. This can be achieved by randomly allocating each patient's ovary to either single aspiration or follicular flushing, maintaining similar flow rates between the groups compared.Given the importance of maximizing the number of oocytes retrieved from a given number of follicles developed, the conduction of properly designed RCTs evaluating follicular flushing is certainly required.

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). The process involves aspiration of the follicular fluid followed by the introduction of flush, typically culture media, back into the follicle followed by re-aspiration. However, there is a degree of controversy as to whether this intervention yields a larger number of oocytes and is hence associated with greater potential for pregnancy than aspiration only.

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 13 July 2021: the Cochrane Gynaecology and Fertility Specialised Register of Controlled Trials, CENTRAL (containing output from two trial registries and CINAHL), MEDLINE, Embase, and PsycINFO. We also searched LILACS, Google Scholar, and Epistemonikos. We reviewed the reference lists of relevant papers and contacted experts in the field to identify further 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 review authors independently assessed studies identified by search against the inclusion criteria, extracted data, and assessed risk of bias. A third review author was consulted if required. We contacted study authors as needed. 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 certainty of evidence using the GRADE approach.

MAIN RESULTS

We included 15 studies with a total of 1643 women. Fourteen studies reported outcomes per woman randomised, and one study reported outcomes per ovary. No studies were at low risk of bias across all domains; the main limitation was lack of blinding. The certainty of the evidence ranged from moderate to very low, and was downgraded for risk of bias, imprecision, and inconsistency. We are uncertain of the effect of follicular flushing on live birth rate compared to aspiration alone (OR 0.93, 95% CI 0.59 to 1.46; 4 RCTs; n = 467; I2 = 0%; moderate-certainty evidence). This suggests that with a live birth rate of approximately 30% with aspiration alone, the equivalent live birth rate with follicular flushing lies between 20% and 39%.  We are uncertain of the effect of follicular flushing on miscarriage rate compared to aspiration alone (OR 1.98, 95% CI 0.18 to 22.22; 1 RCT; n = 164; low-certainty evidence). This suggests that with a miscarriage rate of approximately 1% with aspiration alone, the equivalent miscarriage rate with follicular flushing lies between 0% and 22%. We are uncertain of the effect of follicular flushing on oocyte yield (MD -0.47 oocytes, 95% CI -0.72 to -0.22; 9 RCTs; n = 1239; I2 = 61%; very low-certainty evidence); total number of embryos (MD -0.10 embryos, 95% CI -0.34 to 0.15; 2 RCTs; n = 160; I2 = 58%; low-certainty evidence); and clinical pregnancy rate (OR 1.12, 95% CI 0.85 to 1.51; 7 RCTs; n = 939; I2 = 46%; low-certainty evidence). The duration of the retrieval process may be longer with flushing (MD 175.44 seconds, 95% CI 152.57 to 198.30; 7 RCTs; n = 785; I2 = 87%; low-certainty evidence). It was not possible to perform a meta-analysis for adverse events, although individual studies reported on outcomes ranging from depression and anxiety to pain and pelvic organ injury.

AUTHORS' CONCLUSIONS

The effect of follicular flushing on both live birth and miscarriage rates compared with aspiration alone is uncertain. Although the evidence does not permit any firm conclusions on the impact of follicular flushing on oocyte yield, total number of embryos, number of cryopreserved embryos, or clinical pregnancy rate, it may be that the procedure itself takes longer than aspiration alone. The evidence was insufficient to permit any firm conclusions with respect to adverse events or safety.

Follicular flushing leads to higher oocyte yield in monofollicular IVF: a randomized controlled trial

STUDY QUESTION

Does follicular flushing increase the number of mature oocytes in monofollicular IVF?

SUMMARY ANSWER

Follicular flushing increases the number of mature oocytes in monofollicular IVF.

WHAT IS KNOWN ALREADY

Flushing increases neither the oocyte yield nor the pregnancy rate in polyfollicular IVF or in poor responder patients. In monofollicular IVF, the effect of flushing has so far been addressed by two studies: (i) a prospective study with minimal stimulation IVF demonstrated an increased oocyte yield, and (ii) a retrospective study with natural cycle (NC)-IVF showed an increased oocyte yield and an increased transfer rate.

STUDY DESIGN, SIZE, DURATION

Randomized controlled trial including 164 women who were randomized for either aspiration with or without flushing from 2016 to 2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Infertile women 18–42 years of age with an indication for IVF treatment at a university-based infertility unit. Women undergoing monofollicular IVF were randomized to either follicular aspiration only or follicular aspiration directly followed by five follicular flushes at a 1:1 ratio. The intervention was done without anaesthesia, using a gauge 19 single-lumen needle. Flushing volume was calculated (sphere formula) based on the size of the follicle.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 164 women were included; 81 were allocated to ‘aspiration only’ and 83 to additional ‘flushing’. Primary analysis was based on the intention-to-treat: oocyte yield, defined as the collected mature oocyte rate, was higher (n = 64/83, 77.1%) in the flushing group compared to the aspiration only group (n = 48/81, 59.3%, adjusted risk difference (RD): 18.2% (95% CI 3.9–31.7%), P-value = 0.02). In the flushing group, most oocytes were retrieved within the first three flushes (63/83, 75.8%). Fertilization rate was higher in the flushing group (n = 53/83, 63.9% vs n = 38/81, 46.9%; adjusted RD: 16.8% (96% CI 1.5–31.4%), P = 0.045). Transfer rate was also higher in the flushing group (n = 52/83, 62.7% vs n = 38/81, 46.9%; RD: 15.71 (95% CI 0.3–30.3%)), but the difference was not significant (P = 0.06). The clinical pregnancy rate n = 9/83 versus n = 9/81 (RD: −0.3% (95% CI −9.9% to 9.5%)) and live birth rate n = 7/83 versus n = 8/81 (RD: −1.5% (95% CI −10.4% to 7.1%)) were not significantly different between the flushing and the aspiration group. The median duration of the intervention was significantly longer with flushing (2.38 min; quartiles 2.0, 2.7) versus aspiration only (0.43 min; quartiles 0.3, 0.5) (P < 0.01). There was no significant difference in the mean (±SD) visual analogue scales pain score between the follicular flushing (3.4 ± 1.8) and the aspiration group (3.1 ± 1.89).

LIMITATIONS, REASONS FOR CAUTION

Blinding of the procedure was not possible.

WIDER IMPLICATIONS OF THE FINDINGS

Our study proved that flushing of single follicles in NC-IVF increases the oocyte yield. In contrast to polyfollicular IVF flushing seems to be beneficial in a monofollicular setting if the technique used in our study (single-lumen needle, 5 flushings with flushing volume adaptation) is applied.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by the financial sources of the division and in part by a research grant provided by NMS Biomedical SA, Switzerland. The company did not have any roles in design or conduct of the study or in the preparation of the manuscript. The authors have no other conflicts of interest.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov NCT 02641808.

TRIAL REGISTRATION DATE

29 December 2015

DATE OF FIRST PATIENT’S ENROLMENT

22 August 2016

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 using double lumen needle yields more oocytes in mono-follicular poor responders

OBJECTIVE

To compare the efficacy of follicular flushing (FF) with double lumen needle and direct follicular aspiration with single lumen needle in terms of oocyte yield in mono-follicular responder patients undergoing assisted reproduction techniques (ART).

MATERIALS AND METHODS

Prospective 'quasi-experimental' study was carried out in an IVF center. Infertile women 18-42 years of age with diminished ovarian reserve who revealed a single follicle >17 mm on the day of oocyte retrieval were included in the study. Follicular flushing up to 8 times was performed in FF group using an 17-G double lumen needle. Direct follicular aspiration using a 17-G single lumen needle without FF was performed in direct aspiration group. Total numbers of collected oocytes, metaphase 2 oocytes, fertilization and pregnancy rates were compared among groups.

RESULTS

A total of 206 women underwent oocyte retrieval procedure; 106 women were assigned to FF and 100 women into direct aspiration arm. Overall oocyte retrieval rate was 50.4% in all cases. The total oocyte retrieval rate was higher (65/106, 61.9%) in FF group, than in direct aspiration group (39/100, 39%, p = 0.001). Metaphase 2 oocyte rate was also higher in FF group (47/106, 44.3% vs 29/100, 29% p = 0.04). Fertilization rates, total number of patients with a cleavage stage embryo and grade 1 cleavage embryo were similar among the groups (p>0.5). Numbers of positive hCG, ongoing pregnancy and miscarriage rates were similar among groups.

CONCLUSION

Follicular flushing using double lumen needle in mono-follicular responder patients with diminished ovarian reserve yields more oocytes and mature oocytes than direct aspiration of follicles.

Causes and Effects of Oocyte Retrieval Difficulties: A Retrospective Study of 10,624 Cycles

Oocyte retrieval is a routine procedure during the application of assisted reproduction technology. However, technical difficulties experienced during oocyte retrieval and the subsequent unsatisfactory number of oocytes obtained are rarely reported. The current study included 10,624 oocyte retrieval cycles from April 2015 to June 2018, and patients were followed up until February 2019. Patients were divided into two groups depending on whether the oocyte number obtained reached the >14-mm follicle number on the day of hCG administration. In the oocyte retrieval not satisfactory (ORNS) group, there were 1,294 cycles, and in the oocyte retrieval satisfactory (ORS) group, there were 9,330 cycles. ORNS patients were older, had a longer duration of infertility, had higher follicle-stimulating hormone, and were more likely to have endometriosis. The ORS group had a higher rate of the use of a follicular phase long-acting gonadotropin-releasing hormone (GnRH) agonist long ovarian stimulation protocol and a lower rate of the use of a luteal phase short-acting GnRH agonist long protocol. The ORNS group had fewer total number of days of FSH stimulation. On human chorionic gonadotropin day, the ORNS group had higher luteinizing hormone (LH), lower estradiol, and lower progesterone levels. After oocyte retrieval, the oocyte quality and fresh cycle transplantation rate were higher in the ORNS group. An unsatisfactory oocyte retrieval number did not influence the clinical pregnancy rate, miscarriage rate, or live birth rate during the fresh cycles. The cumulative pregnancy rate and the live birth rate were lower in the ORNS group. In conclusion, with a similar number of matured follicles, ORNS was more likely to occur in ovarian dysfunction patients. The follicular phase long-acting GnRH agonist long protocol had lower oocyte retrieval difficulty during IVF/ICSI. ORNS does not affect embryo quality or the fresh cycle pregnancy rate, but it significantly reduces the cumulative pregnancy rate and the live birth rate.

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.

Follicular flushing in patients with poor ovarian response: a systematic review and meta-analysis

A systematic literature review and meta-analysis was conducted to evaluate the effect of follicular flushing on clinical outcomes (primary outcome: mean number of cumulus-oocyte-complexes [COC]) in poor-response IVF patients). The bibliographic databases OvidMedline (includes Pubmed), Cochrane Library and Web of Science were searched electronically for randomized controlled trials (RCT) comparing follicular flushing with no flushing. Three RCT with a total of 210 patients could be included. The mean number of COC did not increase with flushing (weighted mean difference: -0.45 COC, 95% CI -1.14 to 0.25, I² = 70%; P = 0.21; three RCT, n = 210). Mean number of metaphase II oocytes and the proportion of randomized patients having at least one COC retrieved were no different between groups. No difference was observed between groups for mean number of embryos, the proportion of randomized patients achieving embryo transfer, clinical pregnancy and live birth rates. Procedure duration was significantly increased with flushing (P = 0.0006). A positive effect of flushing on any of the investigated outcomes could not be observed in the existing literature in patients with poor ovarian response. Flushing is unlikely to significantly increase the number of oocytes, and the routine use of follicular flushing should, therefore, be scrutinized.

Comparison of costs associated with substituting culture medium with saline solution for follicular flushing during oocyte retrieval

OBJECTIVES

To compare culture medium and saline solution for follicular flushing during oocyte retrieval with assisted reproductive technologies.

METHODS

The present retrospective study analyzed data collected at Galway Fertility Clinic, Galway, Ireland, between January 1, 2015 and August 31, 2016; all patients attending the clinic for in vitro fertilization/intracytoplasmic sperm injection during this period were included. Data were stratified by whether follicular flushing was performed with culture medium or saline, and the oocyte yield rate, fertilization rate, embryo utilization rate, and biochemical and clinical pregnancy rates were compared between the groups.

RESULTS

In total, 422 oocyte retrieval procedures with culture medium and 277 with normal saline were analyzed. The fertilization (P=0.676) and clinical pregnancy rates (P=0.593) did not differ between the groups. Using normal saline resulted in an approximately 41-fold per-patient cost saving compared with culture medium.

CONCLUSION

Switching from culture medium to normal saline for follicular flushing significantly reduced oocyte-retrieval costs without adversely affecting reproductive outcomes.

Effect of follicular flushing on reproductive outcomes in patients with poor ovarian response undergoing assisted reproductive technology

PURPOSE

The purpose of this study is to investigate the impact of follicular flushing on the number of oocytes retrieved, oocyte maturity, fertilization rate, embryo development, and pregnancy rate of poor ovarian responders (POR).

METHODS

Retrospective study of 524 cycles of 384 patients with POR submitted to assisted reproductive technology (ART) and who had follicular flushing during oocyte retrieval was used in the study. We included patients with <5 oocytes at oocyte retrieval (POR group) and matching the Bologna criteria.

RESULTS

POR patients had a mean age of 38.2 ± 4.2 years. A total of 1355 follicles (mean = 3.5 ± 1.6) were aspirated and 1040 oocytes recovered, with 709 (68.2%) obtained by direct aspiration and 331 (31.8%) by follicular flushing. We found a difference between the total number of oocytes and the number of aspirated oocytes. Overall pregnancy rate was 22%. Association was observed between pregnancy rate and the number of oocytes retrieved, the number of MII oocytes, and the number of embryos transferred. The patients matching the Bologna criteria had a mean age of 38.9 ± 3.9 years. A total of 309 follicles were aspirated (mean = 3.1 ± 1.5) and 242 oocytes recovered, with 156 (64.5%) obtained by direct aspiration and 86 (35.5%) by follicular flushing. There was a significant difference between the total number of oocytes and the number of aspirated oocytes. Overall pregnancy rate was 12.1%. There was no association between the pregnancy rate and the number of oocytes retrieved, the number of MII, and the number of embryos.

CONCLUSIONS

Follicular flushing might be a suitable alternative to increase the number of oocytes and pregnancy rates in patients with POR.

Direct aspiration versus follicular flushing in poor responders undergoing intracytoplasmic sperm injection: a randomised controlled trial

OBJECTIVE

To compare follicle flushing three times with direct follicular aspiration in poor responders. Our hypothesis was that follicle flushing three times in poor responders would result in similar oocyte yield compared with direct aspiration in poor responders.

DESIGN

A randomised controlled trial performed between January 2015 and June 2015.

SETTING

University hospital.

POPULATION OR SAMPLE

Eighty eligible poor responders, who were defined as having five or fewer follicles ≥13 mm in average diameter with at least two follicles having maximum diameters >17 mm on the day of human chorionic gonadotrophin administration. Monofollicular cycles, including natural cycles, were excluded from the current trial.

METHODS

In the double-lumen needle group, oocyte retrieval was performed by flushing three times with 2 ml in each follicle and in the single-lumen group direct follicle aspiration was performed.

MAIN OUTCOME MEASURE

Number of metaphase II oocytes retrieved.

RESULTS

The mean number of metaphase II oocytes was similar in both groups (1.9 ± 0.1 versus 2.1 ± 0.1, respectively). The clinical pregnancy and live birth rates were similar in both groups (32.5% versus 25% and 25% versus 22.5%, respectively). The only significant difference between the two groups was the duration of oocyte retrieval (178.4 ± 13.4 versus 236.3 ± 24.1 seconds, respectively, P = 0.01).

CONCLUSION

Follicular flushing is time consuming and has similar results compared with direct follicle aspiration in poor responders.

TWEETABLE ABSTRACT

Direct follicle aspiration versus flushing in poor responders yields similar metaphase II oocytes.

Oocyte retrieval at 140-mmHg negative aspiration pressure: A promising alternative to flushing and aspiration in assisted reproduction in women with low ovarian reserve

BACKGROUND:

Oocyte retrieval in women with low ovarian reserve is challenging and often results in poor pregnancy outcomes.

AIM:

The aim was to compare outcomes of oocyte retrieval using three aspiration methods in women with normal and low antral follicle counts (AFCs).

STUDY DESIGN:

Retrospective cohort study.

SETTING:

Tertiary care hospital.

MATERIALS AND METHODS:

Data from 172 women who underwent in-vitro fertilization/intracytoplasmic sperm injection over 3 years was studied after dividing into three groups: Group A (96) - normal AFC (≥10), direct oocyte retrieval at 120 mmHg, Group B (41) - low AFC (<10), direct retrieval at 140-mmHg, Group C (35) - low AFC, follicular flushing, and aspiration at 120-mmHg. In each group, oocyte yield, embryo quality, and pregnancy out comes were assessed.

RESULTS:

The oocyte and embryo yield in Groups A and B were comparable (P > 0.05) but were significantly less in Group C (P < 0.05). The pregnancy rates in Groups A and B were similar (35.4%, 39%) but were significantly less (17.1%) in Group C (P < 0.05). The live birth rate was 76% in Group A, 69% in Group B, and 50% in Group C. The miscarriage rates in the three groups were 21%, 31%, and 50%, respectively.

CONCLUSION:

Direct oocyte retrieval with 140-mmHg showed significantly better oocyte yield and pregnancy outcomes compared to flushing and aspiration in women with low AFC.

Approaches to oocyte retrieval for advanced reproductive technology cycles planning to utilize in vitro maturation: a review of the many choices to be made

PURPOSE

To evaluate the minutiae associated with oocyte retrieval for use in human in vitro maturation IVF cycles. Many of the relevant features of oocyte retrieval were identified by the Trounson group in the first publication on successful in vitro maturation using transvaginal oocyte harvesting and these were a major focus of this review.

METHODS

Published human and animal studies, together with topics from mathematics and mechanics, were used to try to understand the importance of different choices that could be made in structuring a transvaginal oocyte retrieval procedure in humans.

RESULTS

The published literature suggests that the highest oocyte recovery rate occurs using higher pressures and thicker needles, but this comes at the cost of damaging the cumulus oocyte complex. It is likely that this damage is caused by the sheer stress forces exerted on the cumulus oocyte complex due to parabolic forces associated with laminar flow within the needle and is likely worsened by irregular forces during intervals of turbulent flow occurring with entry into the needle. Larger needles also cause more pain and may be associated with more blood loss. Higher velocity entry into the follicle, needle rotation to prevent premature blockage of the lumen, and carefully timed applications of aspiration pressure theoretically optimize oocyte retrieval technique.

CONCLUSIONS

Oocyte retrieval for in vitro maturation is effected by the interaction of the many choices that need to be made in planning for the procedure. The most difficult decision involves aspiration pressure or fluid flow rate and needle size.

Failure of intrauterine insemination as rescue treatment in low responders with adequate HCG timing with no oocytes retrieved

In this retrospective study, the efficiency of carrying out rescue intrauterine insemination (IUI) in low-responder patients undergoing IVF when no oocytes were retrieved after follicular aspiration and when HCG timing was adequate was analysed. A historical control group was used. Over 13 years, women undergoing IVF with failure to obtain oocytes at follicular aspiration underwent rescue IUI if the following criteria were met: adequate HCG timing; one normal tube; motile sperm count after preparation over 3 million/ml; and ultrasound visualization of one to six follicles over 13 mm. The rescue IUI was carried out 1 h after follicular aspiration. Results were compared with those of a standard IUI population (5394 cycles) in the same period. Confidence intervals were calculated using Poisson 97.5% confidence upper tail limits when no event was observed in the study sample. No pregnancies were achieved among the 54 cases who underwent rescue IUI (confidence interval: 0 to 6.8%). This pregnancy rate was lower than that observed in the general IUI population (17.5%) (relative risk, 19.2). After adjusting for age and endometriosis, the relative risk was 11.7. The rescue IUI is an inefficient procedure. Its efficacy is unlikely to exceed 7% pregnancy rate per IUI.