A randomized double-blind controlled study on the efficacy of laser zona pellucida thinning on live birth rates in cases of advanced female age

Comparison of the impact of laser-assisted hatching on fresh cleavage and blastocyst embryo transfer and association with pregnancy outcomes

Objective:

Assisted hatching (AH) techniques can improve live birth (LB) and clinical pregnancy (CP) rates. Since there are limited data regarding this subject, we investigated the impact of laser-assisted hatching (LAH) on fresh embryo transfer (ET) and association with pregnancy outcomes in unselected patient population.

Materials and Methods:

This retrospective study included the fresh ETs performed at our center between April 2010 and April 2019. Among 3.782 fresh ETs, 3.286 underwent LAH (n=1.583 at cleavage stage and n=1.703 at blastocyst stage) while 496 underwent non-assisted hatching (NAH) (n=213 at cleavage stage and n=283 at blastocyst stage). The ETs were performed at the blastocyst or cleavage stages, and single or double embryos were transferred. LB rate was the primary outcome, while secondary outcomes were the pregnancy test, monozygotic twinning (MZT), and CP rates.

Results:

The LAH and NAH groups showed similar LB, pregnancy test, CP, and MZT rates at cleavage and blastocyst stages. On the other hand, LAH significantly affected LB rates at the blastocyst stage (20.6% at blastocyst stage vs. 16% at the cleavage stage, p=0.001).

Conclusion:

In conclusion, LAH does not improve reproductive outcomes of fresh blastocyst-stage and cleavage-stage ETs. However, LAH significant impacts LB rates in the blastocyst stage than the cleavage stage.

Laser-assisted hatching zona thinning does not improve the pregnancy outcomes of poor-quality blastocysts in frozen-thawed embryo transfer cycle: a retrospective cohort study

It had been suggested, after facilitating the hatching process, improved pregnancy outcomes could be attained in embryos with thick and hard zona. This study aimed to determine the effect of zona thinning on pregnancy outcomes in poor-quality frozen-thawed blastocysts. This retrospective study included 230 women (≤ 40 years) who underwent frozen embryo transfer of poor-quality blastocysts (scored < 3BB). In total, 105 patients were in the assisted hatching group in which the zona was thinned by laser before transfer and 125 patients were in the control group in which the blastocysts were non-manipulated. Patients' demographics, cycle characteristics, and pregnancy outcomes were compared between the assisted hatching group and the control group. Further, regression analysis was applied to test the correlation between assisted hatching and live birth. All parameters in the patients' demographic characteristics and the cycle's characteristics were not significantly different between two groups. As for pregnancy outcomes, the second trimester pregnancy loss was significantly higher in the assisted hatching group (P = 0.035). Other pregnancy outcomes, including implantation rate, clinical pregnancy rate, biochemical miscarriage rate, the first trimester pregnancy loss, ongoing pregnancy rate, and live birth rate were comparable between two groups. The logistic regression analysis demonstrated no association between live birth and assisted hatching (univariate, OR = 0.787, P > 0.05; multivariate, OR = 0.652, P > 0.05), and the area under the receiver operating characteristic curve of the regression model was almost 0.7. It suggested that zona thinning may not be supposed to perform on poor-quality, frozen-thawed blastocysts. The indications of assisted hatching were still needed to further investigate.

Assisted hatching on assisted conception (in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI))

BACKGROUND

Failure of implantation and conception may result from inability of the blastocyst to escape from its outer coat, which is known as the zona pellucida. Artificial disruption of this coat is known as assisted hatching and has been proposed as a method for improving the success of assisted conception by facilitating embryo implantation.

OBJECTIVES

To determine effects of assisted hatching (AH) of embryos derived from assisted conception on live birth and multiple pregnancy rates.  SEARCH METHODS: We searched the Cochrane Gynaecology and Fertility Group Specialised Register (until May 2020), the Cochrane Central Register of Controlled Trials (CENTRAL; until May 2020), in the Cochrane Library; MEDLINE (1966 to May 2020); and Embase (1980 to May 2020). We also searched trial registers for ongoing and registered trials (http://www.clinicaltrials.gov - a service of the US National Institutes of Health; http://www.who.int/trialsearch/Default.aspx - The World Health Organization International Trials Registry Platform search portal) (May 2020).

SELECTION CRITERIA

Two review authors identified and independently screened trials. We included randomised controlled trials (RCTs) of AH (mechanical, chemical, or laser disruption of the zona pellucida before embryo replacement) versus no AH that reported live birth or clinical pregnancy data.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. Two review authors independently performed quality assessments and data extraction.

MAIN RESULTS

We included 39 RCTs (7249 women). All reported clinical pregnancy data, including 2486 clinical pregnancies. Only 14 studies reported live birth data, with 834 live birth events. The quality of evidence ranged from very low to low. The main limitations were serious risk of bias associated with poor reporting of study methods, inconsistency, imprecision, and publication bias. Five trials are currently ongoing. We are uncertain whether assisted hatching improved live birth rates compared to no assisted hatching (odds ratio (OR) 1.09, 95% confidence interval (CI) 0.92 to 1.29; 14 RCTs, N = 2849; I² = 20%; low-quality evidence). This analysis suggests that if the live birth rate in women not using assisted hatching is about 28%, the rate in those using assisted hatching will be between 27% and 34%. Analysis of multiple pregnancy rates per woman showed that in women who were randomised to AH compared with women randomised to no AH, there may have been a slight increase in multiple pregnancy rates (OR 1.38, 95% CI 1.13 to 1.68; 18 RCTs, N = 4308; I² = 48%; low-quality evidence). This suggests that if the multiple pregnancy rate in women not using assisted hatching is about 9%, the rate in those using assisted hatching will be between 10% and 14%. When all of the included studies (39) are pooled, the clinical pregnancy rate in women who underwent AH may improve slightly in comparison to no AH (OR 1.20, 95% CI 1.09 to 1.33; 39 RCTs, N = 7249; I² = 55%; low-quality evidence). However, when a random-effects model is used due to high heterogeneity, there may be little to no difference in clinical pregnancy rate (P = 0.04). All 14 RCTs that reported live birth rates also reported clinical pregnancy rates, and analysis of these studies illustrates that AH may make little to no difference in clinical pregnancy rates when compared to no AH (OR 1.07, 95% CI 0.92 to 1.25; 14 RCTs, N = 2848; I² = 45%). We are uncertain about whether AH affects miscarriage rates due to the quality of the evidence (OR 1.13, 95% CI 0.82 to 1.56; 17 RCTs, N = 2810; I² = 0%; very low-quality evidence).

AUTHORS' CONCLUSIONS

This update suggests that we are uncertain of the effects of assisted hatching (AH) on live birth rates. AH may lead to increased risk of multiple pregnancy. The risks of complications associated with multiple pregnancy may be increased without evidence to demonstrate an increase in live birth rate, warranting careful consideration of the routine use of AH for couples undergoing in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI). AH may offer a slightly increased chance of achieving a clinical pregnancy, but data quality was of low grade. We are uncertain about whether AH influences miscarriage rates.

Effects of laser-assisted thinning versus opening on clinical outcomes according to maternal age in patients with repeated implantation failure

Laser-assisted thinning (LAT) and laser-assisted opening (LAO) are performed as part of human in vitro fertilization (IVF) to increase the implantation rate in patients with a poor prognosis and in cases of repeated implantation failure. However, an insufficient number of studies have directly compared LAT and LAO using the same methods. Therefore, we compared the effects of LAT and LAO on clinical outcomes according to maternal age in patients with repeated implantation failure. This retrospective study was performed in 509 IVF cycles (458 patients). The cycles were divided based on maternal age and the method used (< 38 years LAT, n = 119 vs. LAO, n = 179 and ≥ 38 years LAT, n = 72 vs. LAO, n = 139). Cleavage-stage embryos before transfer were either thinned or opened using a 1.46-μm noncontact diode laser. We compared the implantation rates and pregnancy outcomes of cycles between LAT and LAO according to maternal age. The characteristics of patients did not differ significantly among the groups (p > 0.05), with the exception of mixed factor infertility, which was more common in the LAT group than in the LAO group among patients < 38 years of age (10.1% vs. 2.8%, p = 0.008). The LAT and LAO groups showed similar rates of biochemical pregnancy, clinical pregnancy, ongoing pregnancy, abortion, implantation, singleton pregnancy, and twin pregnancy (p > 0.05). In conclusion, LAT and LAO had similar clinical outcomes. Therefore, we did not find any evidence that LAT is superior to LAO. In fact, the patients ≥ 38 years of age who underwent LAO tended to have a lower abortion rate. Further study is necessary to confirm these results in a larger population.

The Effect of Assisted Hatching on Live Birth Rate Following Fresh Embryo Transfer in Advanced Maternal Age

OBJECTIVE

Assisted hatching (AH) was introduced 3 decades ago as an adjunct method to in vitro fertilization (IVF) and embryo transfer (ET) to improve embryo implantation rate. Limited data are available on the effect of AH on live birth rate (LBR) in advanced maternal age. The objective of this study is to investigate the effect of AH on LBR in women aged 40 years and older.

MATERIALS AND METHODS

A retrospective study conducted at a single academic reproductive center. Women aged ≥40 years, who were undergoing their first IVF cycle were included. Laser-assisted hatching was the method used for AH and single or double embryos were transferred. Embryo transfer was performed at the cleavage or blastocyst stage. Separate analysis was performed on each ET stage. Live birth rate was the primary outcome.

RESULTS

A total of 892 patients were included. Of these, 681 women underwent cleavage ET and 211 underwent blastocyst ET. The clinical pregnancy rate in the entire group was 15.3% and the LBR was 10.2%. Baseline and cycle parameters between the AH group and the control group were comparable. Assisted hatching in the cleavage stage was associated with lower clinical pregnancy rate (odds ratio [OR], 0.52; confidence interval [CI], 0.31-0.86; P = .012) and lower LBR (OR, 0.36; CI, 0.19-0.68; P = .001). Assisted hatching did not have any effect on outcomes in blastocyst ET.

CONCLUSION

Assisted hatching does not improve the reproductive outcomes in advanced maternal age. Performing routine AH for the sole indication of advanced maternal age is not clinically justified.

Assisted Hatching in Couples with Advanced Maternal Age: A Systematic Review and Meta-analysis

This systematic review aimed to evaluate the efficacy and safety of assisted hatching (AH) performed in couples with advanced maternal age. We searched for randomized controlled trials (RCTs) in electronic databases, including MEDLINE, EMBASE and CENTRAL (from inception to January 2018); in addition, we hand-searched the reference lists of included studies and similar reviews. We included RCTs comparing AH versus no treatment (control). The meta-analysis was performed by RevMan 5.3 software. The search retrieved 943 records and 8 RCTs were included, comprising 870 cycles (n=440 for AH, and n=430 for control). There was no significant difference in the rates of live birth (RR 0.88, 95% CI 0.65 to 1.18, 3 RCTs, n=427, I²=0%), clinical pregnancy (RR 1.00, 95% CI 0.83 to 1.19, 8 RCTs, n=870, I²=22%), implantation (RR 1.07, 95% CI 0.83 to 1.39, 4 RCTs, n=1359, I²=0%), miscarriage (RR 1.13, 95% CI 0.66 to 1.94, 2 RCTs, n=116, I²=0%) and multiple pregnancy (RR 0.89, 95% CI 0.31 to 2.52, 1 RCT, n=97, I²=not applicable) between the treatment group and control group. No reasonable conclusions could be drawn regarding reproductive outcomes after AH in patients with advanced maternal age due to the small sample pooled in meta-analyses. Studies of high methodological quality and with adequate power are necessary to further investigate the value of AH in assisted conception of those patients.

Revisiting embryo assisted hatching approaches: a systematic review of the current protocols

Zona pellucida (ZP) manipulation, termed "assisted hatching" (AH), has been introduced in order to favor embryo hatching and ultimately improve assisted reproductive technology success but with poor proofs of safety and biological plausibility. We herein provide a systematic review of clinical outcomes following the application of different methods of ZP manipulation on fresh or frozen/thawed embryos at different developmental stages in different groups of patients. Out of the 69 papers that compared the clinical outcomes deriving from hatched versus non-hatched embryos, only 11 considered blastocysts while the rest referred to cleavage stage embryos. The ZP thinning of fresh embryos either by chemical or laser approach was shown to provide very limited benefit in terms of clinical outcomes. Better results were observed with procedures implying a higher degree of zona manipulation, including zona removal. Studies comparing the mechanical or chemical procedures to those laser-mediated consistently reported a superiority of the latter ones over the former. Literature is consistent for a benefit of ZP breaching in thawed blastocysts. This review provides the current knowledge on the AH procedure in order to improve its efficacy in the appropriate context. Embryologists might benefit from the approaches presented herein in order to improve Assisted Reproduction Technologies (ART) outcomes.

A Prospective Randomized Controlled Study of Laser-Assisted Hatching on the Outcome of First Fresh IVF-ET Cycle in Advanced Age Women

There is no sufficient data to conclude the benefit of assisted hatching (AH) for advanced age patients. However, AH is routinely performed for advanced age patients undergoing in vitro fertilization (IVF) in China based on some retrospective evidence. It is important to assess the benefit of AH procedure for advanced age patients, especially by analyzing the data from China. This is a prospective randomized controlled trial to evaluate the effect of laser AH in the advanced age patients undergoing IVF. A total of 256 patients conformed to the inclusion criteria, and 78 were excluded by exclusion criteria. A total of 178 patients were eligible and randomized to 2 groups (82 AH group and 96 control group). Laser AH (zona thinning) was performed in the AH group. There were no statistical significance in basic clinical parameters between the 2 groups. No difference was found in implantation rate (AH vs control, 32.45% vs 39.29%) and clinical pregnancy rate (AH vs control, 48.78% vs 59.38%). Our data did not find any benefit of laser AH in improving implantation or pregnancy rates in advanced age women. Due to the potential risk and increasing financial burden, AH should not be routinely performed in first fresh IVF embryo transfer cycle for advanced age women.

The impact of laser-assisted hatching on the outcome of frozen human embryo transfer cycles

Biochemical modifications of zona pellucida (ZP) result in zona hardening. Zona hardening (ZH) is induced by several factors such as advancing maternal age, in vitro culture conditions and cryopreservation and adversely effects implantation. The objective of the clinical study was to determine whether or not laser-assisted hatching (LAH) applied on day 3 frozen embryos improves the outcome of frozen embryo transfer (FET) cycles in patients with recurrent implantation failure and/or advanced female age. In total, 413 patients of different ages with recurrent implantation failure (maximum three cycles) were involved into the study. Patients were allocated randomly into LAH and control groups. On the day of FET, after thawing and just before FET, the ZP was thinned using a laser system. In the control group no treatment was applied on frozen embryo before transfer. The main outcome measures were clinical pregnancy rate. Overall, the results indicate a tendency that LAH increased (P = 0.08) clinical pregnancy. However, for patients older than 37 years, LAH increased pregnancy rates significantly (P = 0.03). In the LAH and control groups, the age of patients and the number of transferred embryos influenced pregnancy rates (P = 0.01). For patients older than 37 years, no effect of number of transferred embryos was detected (P = 0.14). The incidence of multiple pregnancies also increased in the LAH group (P = 0.01). In conclusion, in older woman, to overcome the negative effect of zona hardening, LAH could be performed on frozen embryos as a routine strategy before FET in frozen cycles in order to increase the possibility of pregnancy formation.

Laser-assisted hatching improves clinical outcomes of vitrified-warmed blastocysts developed from low-grade cleavage-stage embryos: a prospective randomized study

The aim of this study was to evaluate the effects of quarter zona-pellucida (ZP) opening by laser-assisted hatching (QLAH) on the clinical outcomes following transfer of vitrified-warmed blastocysts developed from low-grade cleavage-stage embryos in patients with all high-grade and fair-grade cleavage-stage embryos transferred without achieving pregnancy. Patients were randomized into two groups: QLAH (n=101) and control (n=102). The implantation and clinical pregnancy rates were significantly higher in the QLAH group compared with the control group (P=0.021 and P=0.034, respectively). The live birth rate of the QLAH group was also higher, although not significantly. When the clinical outcomes according to the day of blastocyst vitrification were compared between the groups, the implantation, clinical pregnancy and live birth rates of the QLAH group were significantly higher (P<0.05) than those of the control group for day 6 blastocysts, but not for day 5 or day 5/day 6 blastocysts. These results suggest that QLAH improves the clinical outcomes of vitrified-warmed blastocysts, especially of day 6 vitrified blastocysts, developed from low-grade cleavage-stage embryos.

Effects of partial or complete laser-assisted hatching on the hatching of mouse blastocysts and their cell numbers

BACKGROUND

It is still debatable whether a full-thickness assisted hatching (AH) is better than the partial zona thinning. In this research, we used a mouse model to study the effect of partial and complete laser-AH on the rate of completely hatched blastocyst and their cell numbers.

METHODS

In experiment 1, mouse morulae had 0, 1, 2 or 3 full-thickness openings of 10 microns created in the zona pellucida with an infrared laser beam. In the second experiment, 0, 1 and 2 openings of 20 microns were studied. In the third experiment, a full-thickness opening of 20 microns or quarter-thinning of the zonal circumference to a depth of 90% was compared with non-AH controls.

RESULTS

No difference in blastocyst formation was found in laser-treated groups and in the controls. In experiment 1, the rate of completely hatched blastocysts was significantly lower than the controls. In experiment 2 when the size of the opening was increased, blastocysts completely hatched at a significantly higher rate than that in the controls. In experiment 3, the rate of completely hatched blastocysts was the highest in the full-thickness group. Cell numbers in completely hatched blastocysts from both AH groups were significantly fewer than those in the controls.

CONCLUSIONS

Full-thickness opening resulted in a higher rate of completely hatched blastocysts than quarter zonal-thinning and controls, but the cell numbers were significantly decreased.

Assisted hatching on assisted conception (in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI)

BACKGROUND

Failure of implantation and conception may result from an inability of the blastocyst to escape from its outer coat, which is known as the zona pellucida. Artificial disruption of this coat is known as assisted hatching and has been proposed as a method for improving the success of assisted conception by facilitating embryo implantation.

OBJECTIVES

To determine the effect of assisted hatching (AH) of embryos from assisted conception on live birth and multiple pregnancy rates. 

SEARCH METHODS

We searched the Cochrane Menstrual Disorders and Subfertility Group Specialised Register (August 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (August 2012), MEDLINE (1966 to August 2012) and EMBASE (1980 to August 2012).

SELECTION CRITERIA

Three authors identified and independently screened trials. We included randomised controlled trials (RCTs) of AH (mechanical, chemical or laser disruption of the zona pellucida prior to embryo replacement) versus no AH that reported live birth or clinical pregnancy.

DATA COLLECTION AND ANALYSIS

Three authors independently performed quality assessments and data extraction.

MAIN RESULTS

Thirty-one trials reported clinical pregnancy data, including 1992 clinical pregnancies in 5728 women. There was no significant difference in the odds of live birth in the AH group compared with the control group (9 RCTs; odds ratio (OR) 1.03, 95% confidence interval (CI) 0.85 to 1.26, moderate quality evidence), with no evidence of significant heterogeneity (P = 0.38) or inconsistency (I(2) = 6%). Analysis of the clinical pregnancy rates from the nine studies which reported live birth showed a non-significant result (OR 1.03, 95% CI 0.85 to 1.25 ).Analysis of all of the studies included in this update (31 RCTs) showed that the clinical pregnancy rate in women who underwent AH was slightly improved, but the level only just reached statistical significance (OR 1.13, 95% CI 1.01 to 1.27, moderate quality evidence). However, it is important to note that the heterogeneity for this combined analysis for clinical pregnancy rate was statistically significant (P = 0.001) and the I(2) was 49%. Subgroup analysis of women who had had a previous failed attempt at IVF found improved clinical pregnancy rates in the women undergoing AH compared with the women in the control group (9 RCTs, n = 1365; OR 1.42, 95% CI 1.11 to 1.81) with I(2) = 20%. Miscarriage rates per woman were similar in both groups (14 RCTs; OR 1.03, 95% CI 0.69 to 1.54, P = 0.90, moderate quality evidence). Multiple pregnancy rates per woman were significantly increased in women who were randomised to AH compared with women in the control groups (14 RCTs, 3447 women; OR 1.38, 95% CI 1.11 to 1.70, P = 0.004, low quality evidence).

AUTHORS' CONCLUSIONS

This update has demonstrated that whilst assisted hatching (AH) does appear to offer a significantly increased chance of achieving a clinical pregnancy, the extent to which it may do so only just reaches statistical significance. The 'take home' baby rate was still not proven to be increased by AH. The included trials provided insufficient data to investigate the impact of AH on several important outcomes. Most trials still failed to report on live birth rates.

Assisted hatching in assisted reproduction: a state of the art

The World Health Organization estimates that one in six couples experience some delay in conception and an increasing number require treatment by the assisted conception (AC) procedures of in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI).The implantation rate of embryos resulting from in vitro fertilization cycles is generally less than 20%. The exposure of oocytes and embryos to the artificial conditions of in vitro culture may have negative effects on the embryo's ability to undergo normal hatching, resulting in low rates of implantation following IVF and embryo transfer. Human embryos resulting from superovulation develop more slowly in vitro compared to embryos in vivo, manifest a relatively high degree of cytogenetic abnormalities and undergo cellular fragmentation. Artificially disrupting the zona pellucida is known as assisted hatching (AH) and there is some evidence that embryos that have undergone zona manipulation for assisted hatching tend to implant one day earlier than unhatched embryos. A variety of techniques have since been employed to assist embryo hatching, including partial mechanical zona dissection, zona drilling and zona thinning, making use of acid tyrodes, proteinases, piezon vibrator manipulators and lasers. This review will consider the impact of IVF conditions on zona pellucida physiology, zona hardening, different techniques of assisted hatching, who may benefit from assisted hatching and potential hazards.

Mechanically expanding the zona pellucida of human frozen thawed embryos: a new method of assisted hatching

OBJECTIVE

To determine whether a new assisted hatching (AH) method increases the implantation and clinical pregnancy rates of frozen-thawed day-3 (D3) embryos.

DESIGN

Prospective study.

SETTING

A university hospital in vitro fertilization (IVF) program.

PATIENT(S)

Patients who had their first IVF/intracytoplasmic sperm injection (ICSI) cycles between June 1, 2006, and December 31, 2008, with fresh IVF-embryo transfer failures or without fresh embryo transfer.

INTERVENTION(S)

The couples were randomized into thawed embryo transfer after AH versus no AH. In the AH group, the zona pellucida (ZP) of D3 frozen-thawed embryos was expanded by injected hydrostatic pressure after thawing. In the control group, embryos were pierced by ICSI needles without expanding the ZP.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy and implantation rates.

RESULT(S)

The morphologic features of the blastomeres were carefully monitored and recorded. In the AH group, 244 embryos were thawed, and 178 (73.0%) survived; in the control group, 259 embryos were thawed, and 190 (73.4%) survived. Despite the transfer of a similar number of embryos, the AH group resulted in statistically significantly higher implantation and clinical pregnancy rates compared with the no AH group.

CONCLUSION(S)

Mechanically expanding the ZP of frozen-thawed D3 embryos with injected hydrostatic pressure after thawing increases the implantation rate compared with control embryos.

Intracytoplasmic sperm injection outcome of women over 39: an analysis of 668 cycles

PURPOSE

To evaluate intracytoplasmic sperm injection (ICSI) outcome of women over age 39 and to determine when to discourage such couples to undergo IVF using their own oocytes.

METHODS

Four hundred ninety-five consecutive women (n=668 cycles) over age 39 were evaluated by year-by-year age increments to discriminate the independent prognostic factors for the achievement of pregnancy.

RESULTS

Although the ovarian hyperstimulation performance (COH) and embryological data were not too diverse, the clinical pregnancy rates per embryo transfer decreased from 26 to 13% from age 40 to 44. According to logistic regression, the female age seems to be the only variable in order to predict an ongoing pregnancy. The miscarriage rate increased with advancing female age. It was 33% at age 40 but increased to 100% by age 45.

CONCLUSIONS

The performance of COH and embryological data is not discouraging among women over 39 years in ICSI cycles. However, increased miscarriages as well as decreased implantation rate are mainly responsible for the poor performance of patients with advanced female age. Irrespective of the ovarian reserve testing, ICSI may be refused at age 45 and thereafter.

Assisted hatching on assisted conception (IVF and ICSI)

BACKGROUND

Failure of implantation and conception may result from an inability of the blastocyst to escape from its outer coat, known as the zona pellucida. Artificial disruption of this coat is known as assisted hatching (AH) and has been proposed as a method for improving the success of assisted conception.

OBJECTIVES

To determine whether assisted hatching (AH) of embryos facilitates live births and clinical pregnancy.

SEARCH STRATEGY

We previously searched the Cochrane Menstrual Disorders and Subfertility Group Specialsed Register (February 2007), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2007), MEDLINE (1966 to February 2007) and EMBASE (1980 to February 2007).

SELECTION CRITERIA

Two authors identified and independently screened trials. We included randomised controlled trials (RCTs) of AH (mechanical, chemical or laser disruption of the zona pellucida prior to embryo replacement) versus no AH, which reported live birth or clinical pregnancy rates.

DATA COLLECTION AND ANALYSIS

Two authors independently performed qualitative assessments and data extraction.

MAIN RESULTS

Twenty-eight trials reported clinical pregnancy data, including 1228 clinical pregnancies in 3646 women. There was no significant difference in the odds of live births in the AH compared with control groups (seven RCTs; OR 1.13, 95% CI 0.83 to 1.55; 255 births from 719 women, with no heterogeneity (P = 0.37) or inconsistency I(2) = 8%)). We also analysed the clinical pregnancy rate from the seven studies that reported live births, which was non-significant (OR 1.13, 95% CI 0.83 to 1.54). Inclusion of studies which were more robust in methodology showed an increase in clinical pregnancy rate which was just statistically significant (16 RCTs; OR 1.20, 95% CI 1.00 to 1.45, P = 0.05). Analysis of all the studies included in this update (28 RCTs) showed a marked increase in clinical pregnancy rate (OR 1.29, 95% CI 1.12 to 1.49).Miscarriage rates per women were similar in both groups (14 RCTs; OR 1.13, 95% CI 0.74 to 1.73). Multiple pregnancy rates per woman were significantly increased in women who were randomised to AH compared with women in control groups (12 RCTs; OR 1.67, 95% CI 1.24 to 2.26).

AUTHORS' CONCLUSIONS

The improvement in clinical pregnancy rate (CPR) with AH means that a clinic with a success rate of 25% could anticipate improving the CPR to between 29% and 49%, all things being equal. The included trials provided insufficient data to investigate the impact of assisted hatching on several important outcomes.

[Laser assisted hatching: Rouen University Hospital outcomes]

OBJECTIVE

Despite technical progress in In Vitro Fertilisation (IVF) procedure, embryo implantation rate remains low. Assisted hatching has been proposed to facilitate natural embryo hatching and implantation.

PATIENTS AND METHODS

Our study has evaluated whether laser assisted hatching improves implantation, pregnancy and live birth rates in different cases. We studied retrospectively 143 IVF cycles concerning more than 38 years old women, 166 IVF cycles after two previous implantation failures and 180 frozen-thawed embryo transfers.

RESULTS

Population characteristics were comparable in hatched and control groups. Implantation, pregnancy and live birth rates in women more than 38 years old were comparable with or without assisted hatching. Concerning repeated implantation failures, even if implantation, pregnancy and live birth rates were higher in assisted hatching group (FIV or ICSI), the differences were not significant. After frozen-thawed embryo transfers, implantation rate was significantly better with assisted hatching (19.14% vs 8.84% [p=0.02]).

DISCUSSION AND CONCLUSION

Assisted hatching improves embryo implantation rate after frozen-thawed embryo transfer.

The effect of condition/state of testicular spermatozoa injected to the outcome of TESE-ICSI-ET cycles

OBJECTIVE

The effect of state/condition of spermatozoa (fresh/motile, fresh/immotile, frozen/motile and frozen/immotile) to fertilization, embryo formation/development, implantation and pregnancy/delivery and abortion rates were studied.

STUDY DESIGN

The data of a total of 167 TESE-ICSI-ET cycles with fresh and cryopreserved, motile and immotile testicular spermatozoa collected with testicular biopsy from patients suffering from non-obstructive azoospermia were analyzed retrospectively. Analysis of variance (ANOVA) was used to distinguish the group effects in fertilization, embryo formation, and implantation ratio. The group effect was evaluated by using non-parametric statistics and the independent grouping variable was also the "semen state/condition". "Semen state/condition" groups were created according to fresh or frozen, and motile or non-motile (immotile) characteristics. For comparing the four groups, Kruskal-Wallis ANOVA and Median-test was applied. The analysis was carried out using Statistica for Windows (StatSoft, Inc., Chicago, USA).

RESULTS

Independently of state/condition of testicular spermatozoa injected into oocytes, no differences were found in fertilization and implantation/pregnancy rates. No difference was obtained in embryo development of oocytes injected with fresh/immotile or frozen/motile spermatozoa. However, difference was found in embryo development of oocytes injected with fresh/motile or frozen/immotile testicular spermatozoa (87% vs. 73%; P<0.04). Comparing embryo development of oocytes injected with fresh vs. frozen spermatozoa difference was also found (83% vs. 74%; P<0.01). No difference was found in the abortion rates between the groups. Differences were observed in the implantation rates, however, these differences could not be verified statistically.

CONCLUSION

The presented data show that condition of injected testicular spermatozoa has influence to embryo development and even frozen/immotile testicular spermatozoa is able to induce/support fertilization and early embryo development.

Impact of assisted hatching on fresh and frozen-thawed embryo transfer cycles: a prospective, randomized study

The aim of this study was to determine if assisted hatching (AH) could improve the rates of pregnancy and implantation for both fresh and frozen-thawed embryo transfer cycles. A total of 760 fresh embryo transfer cycles and 200 frozen-thawed embryo transfer cycles were randomly assigned to either the treatment group (AH) or the control group (no AH). Zona thinning by laser was performed just before embryo transfer. In fresh embryo transfer cycles, the AH group and control group results were comparable. There were no significant differences in the rates of positive human chorionic gonadotrophin (HCG; 47.5 versus 48.8%), clinical pregnancy (42.4 versus 42.6%), or implantation (26.3 versus 25.2%) between the two groups. However, in frozen-thawed embryo transfer cycles, the rates of positive HCG (32.0 versus 17.0%), clinical pregnancy (25.0 versus 14.0%) and implantation (16.7 versus 7.3%) were significantly greater in the AH group than in the control group (P &lt: 0.05). The results of this investigation show that in the fresh embryo transfer cycles, laser-assisted hatching by zona thinning has no impact on the rates of positive HCG, clinical pregnancy and implantation, whereas in frozen-thawed cycles, assisted hatching by zona thinning significantly increases all three of these rates.

Effect of laser zona pellucida opening on clinical outcome of assisted reproduction technology in patients with advanced female age, recurrent implantation failure, or frozen-thawed embryos

OBJECTIVE

To determine whether laser-assisted hatching can improve clinical outcome of assisted reproductive techniques in patients with advanced female age, with recurrent implantation failure, or who are using frozen-thawed embryos.

DESIGN

A prospective randomized study.

SETTING

The infertility and IVF unit at a research facility in Iran.

PATIENT(S)

Four hundred ten patients with advanced female age (> or =37 y), 796 patients with recurrent implantation failure (for > or =2 cycles), and 180 patients with frozen-thawed embryos.

INTERVENTION(S)

Patients were divided equally into test and control groups. On the day of embryo transfer, the zona pellucida of the selected embryos in the test group were opened about 40 mum by using an infrared optical laser system, whereas in the control group they were all intact.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy rates and implantation rates.

RESULT(S)

In the patients with advanced female age or recurrent implantation failure, the clinical pregnancy and implantation rates were similar for the test and control groups. However, in the patients with frozen-thawed embryos, the rates were statistically significantly higher in the test group as compared with those of the control group (31.2% and 12.8% vs. 11.1% and 4.2%, respectively).

CONCLUSION(S)

The laser-assisted hatching improved the pregnancy and implantation rates in patients with frozen-thawed embryos but had no effect in patients with advanced female age or recurrent implantation failure.

Assisted hatching on assisted conception (IVF & ICSI)

BACKGROUND

Failure of implantation and conception may result from an inability of the blastocyst to escape from its outer coat, know as the zona pellucida. In vitro culture conditions and/or advancing maternal age may alter the architecture of the zona pellucida and result in hatching difficulties. Artificial disruption of this coat is known as assisted hatching (AH) has been proposed as a method of improving the success of assisted conception.

OBJECTIVES

To determine whether assisted hatching (AH) of embryos facilitates live births and clinical pregnancy and whether it impacts on negative outcomes (such as multiple pregnancy and miscarriage).

SEARCH STRATEGY

We searched the Cochrane Menstrual Disorders and Subfertility Group trials register (1 June 2005), the Cochrane Controlled Trials Register (Cochrane Library Issue 2, 2005), MEDLINE (1996 to June 2003), EMBASE (1980 to June 2005) and reference lists of articles. Authors were contacted for missing and/or unpublished data.

SELECTION CRITERIA

Trials were identified and independently screened by two reviewers. Randomised controlled trials of AH (mechanical, chemical or laser disruption of the zona pellucida prior to embryo replacement) versus no AH that reported live birth, clinical pregnancy or implantation rates were included.

DATA COLLECTION AND ANALYSIS

Qualitative assessments and data extraction were performed independently by two reviewers. Outcomes were extracted as rates and combined using random effects meta-analysis, sensitivity analysis, sub grouping and meta-regression where appropriate.

MAIN RESULTS

Twenty-three randomised controlled trials consisting of 2668 women reported on 849 pregnancy outcomes. There was no significant difference in the odds of live births in the AH compared with control groups (6 RCTs; OR 1.19 95% CI 0.81 to 1.73; 163 births from 516 women). Women undergoing assisted hatching were significantly more likely to achieve clinical pregnancy (23 RCTs, OR 1.33, 95% CI 1.12 to 1.57). Miscarriage rates per woman were similar in both groups (12 RCTs OR 1.23 (95% CI 0.73 to 2.05). Multiple pregnancy rates per woman was increased in women who were randomised to AH compared with control women (9 RCTs OR 1.83 (95% CI 1.19 to 2.83). The improvement in clinical pregnancy rate means for a clinic with a success rate of 25% could anticipate improving the CPR to between 28 and 39%, all things being equal. The trials provided insufficient data to investigate the impact of assisted hatching on several important outcomes, including monozygotic twinning, embryo damage, congenital and chromosomal abnormalities, and in vitro blastocyst development.

AUTHORS' CONCLUSIONS

Despite significantly improved odds of clinical pregnancy, there is insufficient evidence to determine any effect of AH on live birth rates. The increased multiple pregnancy rate is of concern although it likely that with a policy of single embryo transfer this may be lowered. Currently, there is insufficient evidence to recommend assisted hatching.