A prospective randomized comparison of single- and double-lumen needles for transvaginal follicular aspiration

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.

Follicle flushing does not improve live birth and increases procedure time: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To determine whether follicle flushing during oocyte retrieval improves live birth or secondary outcomes in assisted reproductive technology (ART).

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S)

Women undergoing ART using autologous gametes.

INTERVENTION(S)

A systematic search of PubMed, EMBASE, Cochrane Database, and Web of Science for randomized controlled trials comparing follicle flushing to direct aspiration during oocyte retrieval published in English between 1989 to 2020.

MAIN OUTCOME MEASURE(S)

Live birth as primary outcome, and clinical and ongoing pregnancy, total and mature metaphase II (MII) oocytes retrieved, and operating time as secondary outcomes.

RESULT(S)

Eleven studies were included totaling 1,178 cases. No difference in live birth was demonstrated between follicle flushing and direct aspiration. Clinical pregnancy and ongoing pregnancy were not improved with flushing. Total oocyte and MII yield were lower with flushing compared with direct aspiration. Procedure time was increased with flushing by 2 minutes in poor responders and 9 minutes in normal responders. Other sensitivity analyses did not demonstrate any changes, except the difference in MII yield was no longer statistically significant.

CONCLUSION(S)

Follicle flushing during oocyte retrieval increases procedure time and does not improve live birth or secondary ART outcomes. Randomized data do not support the use of follicle flushing as an intervention in ART.

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 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.

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.

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.

A pilot trial of large versus small diameter needles for oocyte retrieval

BACKGROUND

This study was designed to determine whether small diameter needles for oocyte retrieval alter oocyte yields in patients undergoing IVF in comparison to standard large diameter needles.

METHODS

We conducted a prospective pilot study of 21 consecutive favorable prognosis patients. In each patient one ovary was randomly allocated to retrieval with either a 20 G/ 35 mm (thin) or 17 G/ 35 mm (standard) needle, the other ovary was then retrieved with the opposite needle.

RESULTS

The standard diameter needle was used to collect a total of 215 oocytes from 355 aspirated follicles (60.6%) compared to 203 oocytes from 352 aspirated follicles (57.7%) with the thinner needle (p = 0.23). Stratifying outcomes by anti-Müllerian hormone (AMH), as indicator of ovarian reserve, and by body mass index (BMI) the oocyte yields, still, did not differ (AMH, r (17) = -0.20, p = 0.44; BMI, r (17) =0.02, p = 0.96). Outcomes also did not vary among women with diminished ovarian reserve (p = 0.17) and in women with normal ovarian reserve (p = 1.00). Operating time was, however, significantly increased by 3.3 minutes per ovary (z = -3.08, p = 0.002) with the thinner needle.

CONCLUSIONS

Needle diameter does not affect oocyte yield, including in obese patients and patients with diminished ovarian reserve. Thinner needles appear to significantly prolong operating time.

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.

Follicular flushing during oocyte retrieval in assisted reproductive techniques

BACKGROUND

Ultrasound guided transvaginal aspiration of oocytes has replaced other methods of oocyte retrieval for in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). However, there is controversy over whether flushing yields a larger number of oocytes and a higher potential for pregnancy than aspiration only.

OBJECTIVES

To determine whether follicular aspiration and flushing increases live birth or ongoing pregnancy rates and the number of oocytes over aspiration alone in women undergoing IVF and ICSI.

SEARCH STRATEGY

We searched the Menstrual Disorders and Subfertility Group Specialised Register of controlled trials, MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), PsycINFO and the citation lists of relevant publications (to April 2010).

SELECTION CRITERIA

Randomised controlled trials that compared follicular aspiration and flushing with aspiration alone were included. Trials were excluded if the flushing method comparison was confounded by comparisons of other methods.

DATA COLLECTION AND ANALYSIS

Eligible studies were assessed for methodological quality. For dichotomous data, odds ratios (OR) and 95% confidence intervals (CI) were calculated. For continuous data, mean differences were reported. The heterogeneity of the studies was examined by using statistical tests of homogeneity and the I(2) statistic.

MAIN RESULTS

No studies reported on the primary outcome of live birth. There was no evidence (3 studies, 164 patients) to suggest an association between follicular aspiration and flushing and ongoing or clinical pregnancy per woman randomised (OR 1.17, 95% CI 0.57 to 2.38). There was no evidence of a difference in adverse events reported between follicular aspiration and flushing and aspiration only. There was no evidence of significant differences in increased oocyte yield per woman randomised (1 study, 44 patients). Without flushing the operative time was significantly shorter, by 3 to 15 minutes (3 studies, P < 0.001) and the dose of pethidine required was significantly less (50 mg versus 100 mg, P < 0.00001).

AUTHORS' CONCLUSIONS

There is no evidence that follicular aspiration and flushing is associated with improved clinical or ongoing pregnancy rates, nor an increase in oocyte yield. The operative time is significantly longer and more opiate analgesia is required for pain relief during oocyte retrieval. There is a lack of evidence regarding the effect of follicular aspiration and flushing on live birth rates in the identified data.

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.

Is there a benefit from routine follicular flushing for oocyte retrieval?

The object of this study was to determine the optimum number of follicular flushing for a maximum number of oocytes to be retrieved. This was a prospective study, based at a private in vitro fertilization centre (Brentwood Fertility Centre, The Essex Nuffield Hospital, Brentwood, Essex UK). Patients attending the IVF centre for assisted reproductive technology were studied. We counted the number of oocytes obtained with each flushing after primary aspiration of the follicle. Some 40% of the oocytes were retrieved with primary aspiration without follicular flushing, while up to 82% of oocytes were retrieved with two flushes and 97% of oocytes were retrieved in up to four flushes. Only 3% of the remaining oocytes were retrieved with 5th and 6th flush. The optimum number of follicular flushing was four times, in order to achieve maximum number of oocytes without compromising the duration of retrieval and number of oocytes retrieved.

Follicle curetting at the time of oocyte retrieval increases the oocyte yield

PURPOSE

To determine whether follicle curetting at the time of oocyte retrieval increases oocyte yield.

METHODS

Retrospective review of all patients who underwent oocyte retrieval from July 1, 2003 to June 30, 2005.

MAIN OUTCOME MEASURE

Number of oocytes retrieved.

SECONDARY OUTCOME MEASURES

retrieval time, number of cryopreserved embryos, pregnancy rates, and incidence of ovarian hyperstimulation syndrome.

RESULTS

There were no differences in patient demographics, antral follicle count, cycle stimulation characteristics, fertilization rates, embryo quantity or quality, embryo cryopreservation rates, clinical pregnancy rates, live birth rates, or ovarian hyperstimulation syndrome between the groups. Retrievals that utilized curetting took three minutes longer. Follicle curetting significantly increased the number of oocytes retrieved, 13.9 +/- 0.6 compared to 11.4 +/- 0.6 oocytes without curetting (P = 0.003). The quantity of mature oocytes was also increased with curetting (10.3 +/- 0.5 versus 8.4 +/- 0.5, P = 0.006).

CONCLUSIONS

This study demonstrated that follicle curetting significantly increased oocyte yield. While it did not increase live birth rates, this increase in oocyte yield should lead to increased numbers of embryos for selection at transfer and increased embryos for cryopreservation.

Ovarian follicular flushing among low-responding patients undergoing assisted reproductive technology

A randomized comparison trial was performed to evaluate whether follicular reaspiration with use of a double-lumen retrieval needle improves oocyte recovery when compared with direct follicular aspiration among low-responding patients undergoing ART. There were no differences observed in the number of oocytes retrieved (single lumen: 6.5 +/- 2.2 oocytes, double lumen: 7.2 +/- 2.3 oocytes) whereas follicular reaspiration with the double-lumen retrieval needle resulted in a twofold increase in procedure time.

[The follicular flushing duplicate the pregnancy rate on semi natural cycle IVF]

OBJECTIVE

To evaluate the importance of follicular flushing on semi natural cycle IVF.

MATERIAL AND METHODS

We have compared prospectively the reproductive potential of oocytes obtained from follicular fluid (LF, N = 79) to those obtained from follicular flushing (R, N = 47) in 146 oocyte pick ups.

RESULTS

The group LF and R were similar with regard to fertilization rate (79.7 versus 88.1%, respectively), percentage of superior grade embryos (28.8 versus 37.8%) and implantation rate (24.1 versus 44.1%).

CONCLUSION

The practice of follicular flushing on semi natural IVF cycle improves the pregnancy rate. The oocytes obtained by follicular flushing had the same reproductive potential than those obtained on follicular fluid.

A new follicle aspiration needle set is equally effective and as well tolerated as the standard needle when used in a prospective randomized trial in a large in vitro fertilization program

OBJECTIVE

To compare the effectiveness and tolerability of two different 17-gauge follicle aspiration needles used in a large in vitro fertilization (IVF) program.

DESIGN

Prospective, randomized single blinded study.

SETTING

Private IVF center.

PATIENT(S)

Three hundred women undergoing IVF were randomly allocated at the time of oocyte retrieval to either the study needle (n = 151; follicle aspiration set [FAS] set) or the standard needle (n = 149; Echotip) used in the practice. Patients were blinded to the needle used.

INTERVENTION(S)

Transvaginal ultrasound-guided oocyte aspiration.

MAIN OUTCOME MEASURE(S)

Number of eggs retrieved/follicles visualized, retrieval time, mean amount of blood in the aspirate, egg damage, patient tolerance, physician acceptability, implantation, and pregnancy rate.

RESULT(S)

No differences were found in the number of eggs retrieved normalized to follicles visualized. Egg damage (4% vs. 4.2%), average blood in the aspirate (2.2 vs. 2.2), and retrieval time per egg (38 vs. 36 seconds) were similar with both needles. There were also no differences in pain or cramping scores (at 30 minutes and 24 hours after retrieval) or in the physicians' ratings of the two needles. The percentage of patients receiving an embryo transfer (ET), the implantation rate per embryo transfer, and the clinical pregnancy rate per embryo transfer were comparable for both needles.

CONCLUSION(S)

The FASs are equivalent.

Follicular flushing at oocyte retrieval: a reappraisal

A survey of Australian assisted reproduction technique (ART) units revealed many (> 50%) use flushing of the follicle in addition to direct aspiration of the fluid during oocyte retrieval. The rationale is that flushing offers an advantage to the patient, with a larger number of oocytes being collected and thus a higher potential for pregnancy Following a complication in a patient, the medical staff determined that flushing might have been implicated. While this was later shown to be unfounded, the unit changed the method of oocyte collection, thus providing an opportunity historically to evaluate the differences between aspiration of follicular fluid alone or with additional flushing of each follicle. Thus the aim of this analysis was to test the hypothesis that aspiration alone does not effect the outcomes of ART with respect to oocyte numbers collected, their quality and subsequent fertilisation, or ultimate pregnancy rate in a large patient group (n = 2378). During the review period (1991-1993) the manufacturer of the aspiration needles; the pump and pressure used for aspiration; the staff involved in all procedures; and the premises, equipment and media used for oocyte collection and culture remained constant. Similarly the two patient groups did not differ in their demographics and physical characteristics. There was no difference (p > 0.5) in the number of oocytes collected, the number of embryos created or the pregnancy rate for that treatment cycle. There was also no significant difference between the two groups in fertilisation rates, irrespective of the type of treatment being used in vitro fertilisation (IVF), gamete intrafallopian transfer (GIFT) or intracytoplasmic sperm injection (ICSI)). The data presented in this paper are not prospective. They use historical comparison and are confounded by minor changes in ovarian stimulation protocols, but the conclusions are still valid. These data suggest there is no difference in the outcome of ART (from oocyte collection through to pregnancy rate) whether or not aspiration of follicles is accompanied by flushing. First principles of surgery advocate the shortest possible operating time, the simplest procedure and minimum amount of tissue handling as maxims for reducing complication. Therefore, as a routine, flushing would seem superfluous in ART.

The collection of oocytes from bovine ovaries

Various needle sizes (17- and 20-g) and aspiration pressures (25, 50, 75 and 100 mmHg) were used to aspirate a total of 5,827 ovarian follicles from bovine ovaries from a slaughterhouse source to assess the impact on the quantity and quality of recovered immature oocytes. The cumulus oocyte complexes (COC's) were graded according to the presence and consistency of cumulus cells surrounding the oocyte and the data analyzed using general linear models. Overall recovery rates and the recovery of oocytes considered viable for IVM/IVF procedures (Classes A, B and C) were both significantly higher using a 17-g needle than a 20-g needle (P < 0.01). As the vacuum pressure increased so did the recovery rate of the total number of oocytes, although the number of viable oocytes reached a maximum at a calculated vacuum pressure of 55 mmHg for the 17-g needle and 77 mmHg for the 20-g needle, with an increased incidence of denuded oocytes at higher vacuum pressures. In a second experiment conducted on 1, 473 follicles, no significant difference was found between 17-g double (flushing) and 17-g single lumen needles in the recovery rate of either the total number or number of viable oocytes when using a vacuum pressure of 50 mmHg.

A prospective study comparing the outcome of oocytes retrieved in the aspirate with those retrieved in the flush during transvaginal ultrasound directed oocyte recovery for in-vitro fertilization

OBJECTIVE

To study prospectively the fate of oocytes collected from the follicular aspirate and subsequent flushes during transvaginal ultrasound directed oocyte recovery for in-vitro fertilization (IVF).

SETTING

A tertiary referral assisted conception centre.

SUBJECTS

100 consecutive patients undergoing 100 cycles of IVF. Four patients were withdrawn because their embryos were electively cryopreserved. Therefore 96 cycles were studied.

MAIN OUTCOME MEASURES

The oocyte recovery rate, viability, fertilization and cleavage rates and outcome of embryos generated from oocytes that were obtained from either the initial aspirate (A1), dead space in the collecting system (A2) or the first two 2 ml flushes (F1 and F2) were compared.

RESULTS

The overall oocyte recovery rate was 87.8%. Of the 1046 oocytes collected, 40.3% were from A1, 41.3% from A2, 13.7% from F1 and 4.7% from F2. There were comparable numbers of viable and fertilized oocytes and cleaved, transferred and frozen embryos in tubes A1 and A2 but all these parameters were significantly lower in tubes F1 and F2 (P < 0.0001). All these parameters were also significantly higher in F1 compared with F2 (P < 0.001), except for the number of embryos frozen, in which there was no difference. The overall pregnancy rate per cycle was 28.1% and the pregnancy rate per embryo transfer was 31.0%. There were no pregnancies in any of the cycles in which embryos originating from F2 were transferred, nor were there pregnancies in cycles in which only embryos from F1 were transferred.

CONCLUSION

Follicular aspiration together with one 2 ml flush maximises the recovery of oocytes that will result in pregnancies.

A prospective randomized study comparing aspiration only with aspiration and flushing for transvaginal ultrasound-directed oocyte recovery

OBJECTIVE

To compare aspiration only with aspiration and flushing of ovarian follicles during transvaginal ultrasound (US)-directed oocyte recovery.

DESIGN

Prospective randomized study.

PATIENTS

One hundred patients who were undergoing an in vitro fertilization (IVF) treatment cycle.

INTERVENTIONS

All patients underwent pituitary desensitization before the administration of gonadotropins. Monitoring of ovarian stimulation and the criteria for the administration of human chorionic gonadotropin were similar in both groups. In patients in whom aspiration alone was used, each follicle was aspirated until it was empty. The US probe was then rotated until every drop of follicular fluid had been aspirated before the next follicle was aspirated and the procedure repeated. For patients who had aspiration and flushing, each follicle was aspirated and then flushed up to a maximum of six times before moving to the next follicle. In both groups, all follicles greater than 10 mm were aspirated.

RESULTS

The indication for IVF and mean age of the patients were comparable in the two groups. There were no significant differences between the aspiration and the aspiration and flushing groups in terms of the number of oocytes retrieved (11 versus 9), the oocyte recovery rates (77.5% versus 77.0%), the fertilization rates (55.6% versus 60.0%), the number of embryos transferred (2 versus 2), or the number of clinical pregnancies (12 versus 13). The time taken for oocyte recovery was significantly shorter (15 versus 30 minutes, P less than 0.00001), and the dose of pethidine required significantly less (50 mg versus 100 mg, P less than 0.00001) in the aspiration only group.

CONCLUSIONS

Aspiration alone produces comparable oocyte recovery rates as aspiration and flushing while significantly reducing the length of the procedure and the dose of analgesia required. Aspiration alone suffices for virtually all cases during transvaginal US-directed oocyte recovery.

Transport in vitro fertilization--a novel scheme for community-based treatment

OBJECTIVE

To provide an inexpensive and extensive in vitro fertilization (IVF) service for the Mersey Region, United Kingdom.

DESIGN

Twenty-four transport IVF patients treated in two district general hospitals using the central university laboratory as co-ordination point for treatment schedule and embryology. Outcomes were compared with 26 control patients treated in the central unit.

SETTING

Royal Liverpool University Hospital, a central IVF unit, and two district general hospitals in the Mersey Region.

PATIENTS

Fifty patients under 35 years of age with irreversible tubal damage selected and treated by IVF, half in the central unit and the other half in two district general hospitals.

MAIN OUTCOME MEASURES

Pregnancy rate (PR) in the different centers.

RESULTS

A PR of 42.3% per cycle in the peripheral hospitals compared with 30.7% per cycle in the central unit.

CONCLUSION

Transport IVF is an inexpensive and feasible alternative to standard IVF in a central unit for patients without access to central units.

A prospective study to investigate the value of flushing follicles during transvaginal ultrasound-directed follicle aspiration

In this study, 50 transvaginal US-directed follicle aspiration procedures were performed with follicle flushing using a double-channel needle. The origin of each oocyte was established according to whether it had been obtained in the initial part of the aspirate, in the dead space aspirate, in the first to third flushes, or in the fourth to sixth flushes. Seventeen percent of total oocytes were found in follicle flushes. Only 3.2% of total oocytes were found in the fourth to sixth flushes, and their fertilization rate was reduced. Flushing follicles with a double-channel needle may result in the recovery of 20% more oocytes than would be obtained by aspiration alone.