IMSI procedure improves clinical outcomes and embryo morphokinetics in patients with different aetiologies of male infertility

A new cryotop vial device system provides an aseptic cryoprotectant-free and centrifuge-free cryopreservation of human spermatozoa (a closed system)

Single sperm cryopreservation is a new method to preserve small numbers of spermatozoa in small droplets. So far, several devices have been introduced for this technique, but more studies are needed for its optimization. The aim of this study was optimizing the previous device for low number of spermatozoa and low volume semen, which led to design of Cryotop Vial device. Normal semen samples from 25 patients were prepared by swim-up method and divided into four groups: Fresh (F), Rapid freezing (R) and ultra-rapid freezing with Cryotop Device (CD) and Cryotop Vial Device (CVD). In R group, the diluted sperm suspension with sperm freezing medium was cooled in the vapor phase and then immersed in liquid nitrogen. Ultra rapid freezing was performed with sucrose in small volume using the Cryotop Device (CD) or Cryotop Vial Device (CVD). Sperm viability, motility, fine morphology, mitochondrial activity and DNA fragmentation were assessed in all samples. All sperm parameters decreased significantly in all the cryo groups compared to the fresh group. The comparison between the cryo groups showed that progressive motility (69.28 ± 6.82 vs. 55.68 ± 9.04, and 54.76 ± 5.34, p < 0.001) and viability (77.36 ± 5.48 vs.68.84 ± 8.51, p < 0.001, and 70.04 ± 7.44, P = 0.002) were significantly higher in the CVD compared to the CD and R groups respectively. DNA fragmentation was also significantly lower in both ultra-rapid freezing groups (CD and CVD) compared to the R group. Fine morphology and mitochondrial activity were not different between the cryo groups. The CVD as a cryoprotectant and centrifuge-free technique preserved sperm motility, viability and DNA integrity after cryopreservation better than other groups.

Pentoxifylline treatment had no detrimental effect on sperm DNA integrity and clinical characteristics in cases with non-obstructive azoospermia

The aim of this study was to assess the consequences of treatment with pentoxifylline (PTX), an inducer of sperm motility, on sperm DNA fragmentation (SDF) and clinical characteristics in non-obstructive azoospermia (NOA) patients. The pilot study included 15 NOA patients. Half of each sperm sample before and after rapid freezing, was treated with PTX (3.6 mM /l, 30 min) as the PTX group and the remaining samples were considered as the control. SDF and sperm motility were assessed in each group. The clinical study comprised 30 fresh testicular sperm extractions (TESE) and 22 post-thawed TESE intracytoplasmic sperm injection cycles. Half of the mature oocytes from each patient were injected with PTX-treated spermatozoa and the remaining oocytes were injected with non-treated spermatozoa. Fertilization was assessed at 16 h post injection. Embryo transfer was carried out on day 2 after fertilization. Chemical pregnancy was assessed 2 weeks after transfer. PTX was found to significantly increase (P < 0.05) sperm motility. There was an insignificant difference in SDF rates between the groups (P > 0.05). In patient ovaries given fresh TESE, there was not any significant difference in clinical characteristics (P > 0.05). In patient ovaries given post-thawed TESE, there was a significant difference in the number of 2PN and in embryo formation (P < 0.05). Differences in the results of chemical pregnancy were insignificant (P > 0.05) between the groups. In addition, there was not any correlation between DNA fragmentation index and sperm motility and laboratory outcomes. Therefore, obtaining viable spermatozoa using PTX was more effective in post-thawed TESE regime patients in terms of 2PN and in embryo formation, deprived of damaging effects on sperm DNA integrity.

What Does Intracytoplasmic Sperm Injection Change in Embryonic Development? The Spermatozoon Contribution

The intracytoplasmic sperm injection (ICSI) technique was invented to solve severe male infertility due to altered sperm parameters. Nowadays, it is applied worldwide for the treatment of couple infertility. ICSI is performed with any available spermatozoon from surgery or ejaculated samples, whatever are the sperm motility, morphology or quantity. The aim of the present review was to study if embryo development and kinetics would be modified by (1) ICSI under the technical aspects, (2) the micro-injected spermatozoa in connection with male infertility. From published data, it can be seen that ICSI anticipates the zygote kinetics Furthermore, because fertilization rate is higher in ICSI compared to conventional in vitro fertilization (IVF), more blastocysts are obtained for clinical use in ICSI. Sperm and spermatozoa characteristics, such as sperm parameters, morphology and vitality, DNA content (levels of sperm DNA fragmentation, microdeletions, and chromosomal abnormalities), RNA content, epigenetics, and sperm recovery site (testicular, epididymis, and ejaculated), have an impact on fertilization and blastocyst rates and embryo kinetics in different ways. Even though ICSI is the most common solution to solve couples' infertility, the causes of male infertility are crucial in building a competent spermatozoa that will contribute to normal embryonic development and healthy offspring.

Evaluation Of The Clinical Results Of Using Microfluidic Channel System For Sperm Selection In IVF Cycles In Patients With Low Sperm Concentration

Objective: Microfluidic channel system (MAC), a new generation method, gives the chance to select better quality spermatozoa with lower DNA fragmentation indices. This study evaluated the treatment results in patients who underwent ICSI-ET due to the MAC technique's male factors. Methods: Sakarya University ART Center carried out this retrospective study. Patients with 35 male factor indications were included in our study. In these patients, swim-up (SU) was used in the first of two consecutive IVF cycles, and the MAC sperm preparation technique was used in the second. Our study compared fertilization, quality embryo counts, implantation after fresh embryo transfer, pregnancy rates, fifth-day embryo, and frozen embryo numbers. Results: Fertilization rate was higher in the MAC group than in the SU group (P=0.009). The number of 3rd and 5th Day Grade 1 embryo in the MAC group was statistically higher than in the SU group (p=0.000 for both parameters). The number of quality embryos frozen on day 5 was higher in the MAC group than in the SU group (P=0.000). Conclusions: It is thought that MAC application does not make a statistically significant contribution on implantation and pregnancy in IVF cycles performed due to the malefactor. However, it may positively affect fertilization rate and embryo quality. In addition, we think that it increases the number of embryos frozen at the end of the cycle, and for this reason, the MAC technique may provide positive benefits to IVF treatments.

Outcome reporting across randomized controlled trials evaluating potential treatments for male infertility: a systematic review

STUDY QUESTION

What are the primary outcomes and outcome measures used in randomized controlled trials (RCTs) evaluating potential treatments for male infertility in the last 10 years?

SUMMARY ANSWER

Outcome reporting across male infertility trials is heterogeneous with numerous definitions and measures used to define similar outcomes.

WHAT IS KNOWN ALREADY

No core outcome set for male infertility trials has been developed. Male infertility trials are unique in that they have potentially three participants, a man, a female partner and their offspring and this will likely lead to significant variation in outcome reporting in randomized trials.

STUDY DESIGN SIZE DURATION

A systematic review of RCTs mapping outcomes and outcome measures evaluating potential treatments for men with infertility registered in the Cochrane Register of Controlled Trials (CENTRAL) between January 2010 and July 2021.

PARTICIPANTS/MATERIALS SETTING METHODS

Abstract screening and study selection was undertaken in duplicate using a review protocol that was developed prior to commencing the review. No risk of bias assessment was undertaken as this review aims to report on outcome reporting only.

MAIN RESULTS AND THE ROLE OF CHANCE

One hundred and seventy-five RCTs were identified, and given the large number of studies we limited our review to the 100 largest trials. Seventy-nine different treatments were reported across the 100 largest RCTs including vitamin and dietary supplements (18 trials), surgical treatments (18 trials) and sperm selection techniques (22 trials). When considering the largest 100 trials (range: 80-2772 participants), 36 primary and 89 secondary outcomes were reported. Forty-seven trials reported a primary outcome and 36 trials clearly defined their primary outcome. Pregnancy outcomes were inconsistently reported and included pregnancy rate (51 trials), pregnancy loss including miscarriage, ectopic pregnancy, stillbirth (9 trials) and live birth (13 trials). Trials consistently reporting the same outcome frequently used different definitions. For example, semen quality was reported by 75 trials and was defined in 7 different ways, including; the World Health Organization (WHO) 2010 criteria (32 trials), WHO 1999 criteria (18 trials), WHO 1992 criteria (3 trials), WHO 1999 and 1992 criteria (1 trial) and the Kruger strict morphology criteria (1 trial).

LIMITATIONS REASONS FOR CAUTION

We only evaluated the 100 largest trials published in the last 10 years and did not report outcomes on the remaining 75. An outcome was included as a primary outcome only if clearly stated in the manuscript and we did not contact authors to clarify this. As our review mapped outcomes and outcome measures, we did not undertake an integrity assessment of the trials included in our review.

WIDER IMPLICATIONS OF THE FINDINGS

Most randomized trials evaluating treatments for male infertility report different outcomes. Only half of the RCTs reported pregnancy rate and even fewer reported live birth; furthermore, the definitions of these outcomes varies across trials. Developing, disseminating and implementing a minimum data set, known as a core outcome set, for male infertility research could help to improve outcome selection, collection and reporting.

STUDY FUNDING/COMPETING INTERESTS

A.P.-chairman of external scientific advisory committee of Cryos International Denmark ApS, member of the scientific advisory board for Cytoswim LDT and ExSeed Health. Guest lecture at the 'Insights for Fertility Conference', funded by MERK SERONO Limited. M.v.W.-holds a ZON-MW research grant. No external funding was obtained for this study.

Early and late paternal contribution to cell division of embryos in a time-lapse imaging incubation system

The objective of this study was to investigate the impact of male age, semen quality and days of ejaculatory abstinence on embryo morphokinetics. A total of 1,220 zygotes obtained from 139 couples in a private in vitro fertilisation centre were analysed. The timing of specific events from the point of insemination, such as timings to pronuclei appearance and fading, to two, three, four, five, six, seven and eight cells and to blastulation were recorded. Multivariate linear regression analysis was used to evaluate the influence of paternal factors on embryo morphokinetic events. Paternal age was positively correlated with delayed cell cleavage and blastulation, and negatively associated with implantation rate, and clinical pregnancy and live-birth chances. The ejaculatory abstinence was inversely correlated with the implantation rate. Inverse relationships were observed between semen parameters (sperm count, progressive sperm motility, total motile sperm count and morphology) and the timing of specific events during embryo development. Sperm morphology was also positively associated with implantation rate and pregnancy and live-birth chances. Increased paternal age and ejaculatory abstinence, and poor semen quality correlate with delayed cell cleavage and blastulation and negatively impact intracytoplasmic sperm injection outcomes.

Importance of real-time measurement of sperm head morphology in intracytoplasmic sperm injection

Intracytoplasmic sperm injection (ICSI) is an important technique in male infertility treatment. Currently, sperm selection for ICSI in human assisted reproductive technology (ART) is subjective, based on a visual assessment by the operator. Therefore, it is desirable to develop methods that can objectively provide an accurate assessment of the shape and size of sperm heads that use low-magnification microscopy available in most standard fertility clinics. Recent studies have shown a correlation between sperm head size and shape and chromosomal abnormalities, and fertilization rate, and various attempts have been made to establish automated computer-based measurement of the sperm head itself. For example, a dictionary-learning technique and a deep-learning-based method have both been developed. Recently, an automatic algorithm was reported that detects sperm head malformations in real time for selection of the best sperm for ICSI. These data suggest that a real-time sperm selection system for use in ICSI is necessary. Moreover, these systems should incorporate inverted microscopes (×400-600 magnification) but not the fluorescence microscopy techniques often used for a dictionary-learning technique and a deep-learning-based method. These advances are expected to improve future success rates of ARTs. In this review, we summarize recent reports on the assessment of sperm head shape, size, and acrosome status in relation to fertility, and propose further improvements that can be made to the ARTs used in infertility treatments.

Morphokinetics of embryos after IMSI versus ICSI in couples with sub-optimal sperm quality: A time-lapse study

An investigation was conducted to determine the influence of two sperm selection modalities, IMSI and ICSI, on the morphokinetics, dynamic development and ploidy status of embryos derived from males with sub-optimal sperm profiles during IVF program. A total of 209 PGTA-tested top-quality blastocysts (IMSI = 129, ICSI = 80) from 84 couples (IMSI = 51, ICSI = 33) were assessed retrospectively. This study found that both IMSI and ICSI yielded comparable embryo morphokinetics, except for the T7, TEB and CC3 parameters (p < 0.05). A significant lower incidence of multinucleation was observed in the IMSI group when compared to the ICSI group (48.8% vs. 71.3%, p = 0.002), while other parameters of embryo development such as direct cleavage, distorted cytoplasmic movement, reverse cleavage and vacuole(s) appearance did not differ (p > 0.05). No differences were noticed in the proportion of generating chromosomally euploid embryos (44.2% vs. 51.3%, p = 0.394, respectively, for IMSI and ICSI). The implementation of IMSI or ICSI in couples with sub-optimal sperm profiles resulted in embryos with comparatively similar morphokinetics. Furthermore, the incidence of multinucleation at the two- to four-cell stage was lower following the practice of IMSI, although the method did not improve the proportion of gaining euploid embryos.

Competence of embryos showing transient developmental arrest during in vitro culture

PURPOSE

In vitro developing embryos may apparently show no developmental progress during 24 h and resume their development up to the blastocyst stage. The present study was conducted to assess their ability to implant and to give rise to a live birth when replaced at day 5 (fresh or vitrified/warmed) as compared to continuously developing embryos.

METHODS

Embryo development follow-up and grade were prospectively recorded in a photo database. The studied period was from April 2011 to July 2017. The studied embryos included transient arrested embryos (TAE) that showed the same developmental stage at two subsequent observations, i.e. between day 2 and day 3 (d2 and d3), between day 3 and day 4 (d3 and d4) and between day 4 and day 5 (d4 and d5). TAE were compared to continuously developing embryos (CDE). Elective day 5 embryo transfers were performed.

RESULTS

Woman age was higher in TAE (34.3±3.9) than in CDE (32.9±4.8) (p<0.01). TAE were more frequently (63.1%) observed after ICSI than after conventional IVF (55.9%) (p<0.01). Implantation rate was reduced in TAE as compared to CDE, after both fresh (10.0% vs 23.8% [p<0.01]) and vitrified/warmed (12.9% vs 19.0% [p<0.01]) embryo transfers. Delivery rate was also lower after the transfer of fresh (8.3% vs 19.4% [p<0.01]) and vitrified/warmed (8.5% vs 14.1% [p<0.01]) TAE as compared to CDE. Implantation and delivery rates were not statistically different whether embryo arrested between day 2 and day 3 (d2 and d3), between day 3 and day 4 (d3 and d4) or between day 4 and day 5 (d4 and d5).

CONCLUSION

TAE may be considered for transfer at a lower priority than CDE and associated with inferior prognosis than CDE.

Microfluidic sperm selection yields higher sperm quality compared to conventional method in ICSI program: A pilot study

An appropriate preparation technique, should be capable of isolating highquality spermatozoa for intracytoplasmic sperm injection (ICSI). The aim was to assess sperm quality parameters, DNA integrity, embryo development, and clinical outcomes using a practical and accessible Microfluidic Sperm Sorting (MSS) technique. A total of 95 ICSI cases performed using sperm samples were prepared with our MSS (group 1) or by Direct Swim Up (DSU; control) method (group 2). Both sperm quality parameters and sperm DNA fragmentation (SDF) were compared between the groups. DNA fragmentation was assessed using Sperm Chromatin Dispersion (SCD) test and fine morphology was assessed using Motile Sperm Organelle Morphology Examination (MSOME). Embryo development and clinical outcomes were compared between the groups. In the MSS group, progressive motility and the fraction of Class I sperm morphology sperm were significantly higher compared to DSU group (P < 0.01 and P < 0.001, respectively). Moreover, the rates of DNA fragmentation and immotile spermatozoa were significantly lower in MSS when compared to DSU group (P < 0.001). Also, higher rates of high-quality embryo formation (P < 0.001), implantation (P = 0.04) and pregnancy (P = 0.05) were achieved in the MSS compared to DSU groups. The MSS technique proved to be a noninvasive, disposable, easy to use, and inexpensive method for separation of high-quality spermatozoa. Both laboratory parameters and clinical outcomes were improved with application of MSS for neat sperm collection in ICSI.AbbreviationsICSI: Intracytoplasmic Sperm Injection; MSS: Microfluidic Sperm Sorting; Sperm DNA Fragmentation (SDF); SCD: Sperm Chromatin Dispersion; MSOME: Motile Sperm Organelle Morphology Examination; DGC: Density Gradient Centrifugation; DSU: Direct Swim Up; ROS: Reactive Oxygen Species; ART: Assisted Reproducetive Technology.

Does sperm origin-Ejaculated or testicular-Affect embryo morphokinetic parameters?

BACKGROUND

It is unclear whether sperm origin, either ejaculated or testicular, in couples diagnosed with male factor infertility, affects the timing of the embryo's developmental events evaluated by time-lapse monitoring and implantation rates.

OBJECTIVE

To examine the effect of sperm origin on embryo morphokinetics in couples diagnosed with male factor infertility.

MATERIALS AND METHODS

This study included a retrospective analysis of morphokinetic parameters performed by time-lapse monitoring between 2013 and 2017. The developmental processes and morphokinetic parameters of 419 embryos obtained from couples with male factor infertility attributed to oligo-astheno-teratozoospermia, 158 embryos derived from surgically extracted testicular spermatozoa from couples diagnosed with non-obstructive azoospermia, and 190 embryos from couples with normal ejaculated spermatozoa and female mechanical factor-related infertility, were evaluated. A comparison of morphokinetic parameters, implantation, and clinical pregnancy rates was performed between the groups with additional analysis in accordance with implantation status.

RESULTS

Embryos from the normal ejaculated spermatozoa and oligo-astheno-teratozoospermia patients reached the later morphokinetic milestones-synchronous division (S3) and time to morula (tM)-faster than embryos obtained from testicular spermatozoa. Implantation rate was similar in the normal ejaculated spermatozoa and oligo-astheno-teratozoospermia groups (41.9% vs. 45.8%, NS), with higher implantation rate in the oligo-astheno-teratozoospermia group compared to the testicular spermatozoa group (45.8% vs. 33.6%, p = 0.02). Comparison of Known Implantation Data (KID) positive (KIDp) and KID negative (KIDn) embryos in each group revealed more rapid development in KIDp embryos in the normal ejaculated spermatozoa and the oligo-astheno-teratozoospermia groups, while in the testicular spermatozoa group implanted embryos reached the late morphokinetic milestones (time to 8 cell stage-t8, ECC3, S3, and tM) significantly faster than embryos that failed to implant. In a multivariate logistic regression analysis of the male factor infertility population, (oligo-astheno-teratospermia) (OR = 2.54, p = 0.003) and t8 (OR = 0.95, p = 0.027) were predictive of successful implantation. Male factor infertility embryos that reached the t8 milestone within 48-56 h had favorable implantation rates (p < 0.001).

DISCUSSION

The study results may highlight another pathophysiology by means of which sperm origin affects embryo developmental kinetics. Selecting embryos demonstrating a faster developmental rate at t8 and specifically the 48- to 56 h interval following time of pronuclei fading (tPNf) may improve implantation rates in cases of male factor infertility.

CONCLUSION

This study showed that ejaculated spermatozoa is associated with faster late cell divisions, more rapid compaction, and higher implantation rates compared to testicular spermatozoa. Additionally, t8 is an important predictor for implantation in the male factor infertility population.

Does sperm DNA fragmentation have negative impact on embryo morphology and morphokinetics in IVF programme?

Evaluation of sperm integrity may predict the in vitro fertilisation (IVF) outcomes. The aim was to evaluate the relationship between the sperm DNA fragmentation (sDNAf) with embryo morphology and morphokinetic using time-laps monitoring (TLM) and to select the best time points for normalisation in IVF setting. After evaluating the fertilisation and pronuclei (Z) scoring, 328 normally fertilised oocytes were assessed to time of pronuclei fading, time of 2 to 8 discrete cells (t2-t8) and abnormal cleavage patterns, such as multinucleation, direct cleavage, reverse cleavage and fragmentation. Sperm chromatin dispersion (SCD) assay was used for assessment of prepared sperm chromatin status. SCD was categorised into 4 groups of <6.5, 6.5-10.7, 10.7-20.1 and >20.1. The finding showed significant differences in t6 (p = .012), t7 (p = .045), t8 (p = .013) and s1 (p = .001) between 4 SCD groups. When morphokinetic variables were normalised to tPNf, this difference was observed in t2 (p = .003) and t6 (p = .017). Subsequently, the percentage of top quality embryos and Z₁ scoring were dependent to the sDNAf rate. In conclusion, tPNf was the best reference time point in IVF cycles. Also, we found high sDNAf rate had no negative impact on embryo morphology and morphokinetics in conventional IVF.

Association between early embryo morphokinetics plus transcript levels of sperm apoptotic genes and clinical outcomes in IMSI and ICSI cycles of male factor patients

PURPOSE

The aim was to assess the correlation of sperm apoptotic transcript levels with cleavage stage embryokinetic and pregnancy outcomes of intracytoplasmic morphologically selected sperm injection (IMSI) and ICSI methods in patients with male factor infertility.

MATERIAL AND METHODS

Eighty male factor cases were divided into ICSI and IMSI groups. ICSI was done routinely, and for IMSI, sperm was selected at high magnification and injected. On day 3, time-lapse parameters were evaluated, and the best embryos were transferred and followed to delivery. In addition, sperm DNA fragmentation and apoptotic transcript levels were quantified using reverse transcription Q-PCR between the groups.

RESULTS

IMSI selected spermatozoa had lower DNA fragmentation and apoptotic transcript levels compared with ICSI (p < 0.0001). Moreover, all cytokinetic variables and cleavage abnormalities were noticeably different between groups (p < 0.0001); the rates of clinical outcomes were higher in the IMSI group. The transcript levels of Caspase 3 showed a moderate negative correlation with s2 and s3 (rs = - 0.57, P = 0.008 and rs = - 0.51, p = 0.021, respectively) in the IMSI group. However, there was no relationship between sperm apoptotic transcript levels and clinical outcomes in two groups.

CONCLUSIONS

Sperms selected at high magnification showed lower DNA fragmentation and apoptosis genes transcript. Also, better embryo kinetics and clinical outcomes were confirmed in IMSI than ICSI groups. Some time-lapse parameters may be associated with transcript levels of apoptosis genes. Therefore, these noninvasive techniques may be unique in assisting couples with male factor infertility.

TRIAL REGISTRATION

This trial retrospectively registered on 4 July 2020 (IRCT20180130038561N1).

Sperm selection strategies and their impact on assisted reproductive technology outcomes

The application of assisted reproductive technologies (ART) has revolutionised the treatment of human infertility, giving hope to the patients previously considered incapable of establishing pregnancy. While semen analysis is performed to access whether a sample has an adequate number of viable, motile and morphologically normal sperm cells able to achieve fertilisation, sperm selection techniques for ART aim to isolate the most competent spermatozoon which is characterised by the highest fertilising potential. Based on the semen analysis results, the correct sperm selection technique must be chosen and applied. In this review, different sperm selection strategies for retrieving spermatozoa with the highest fertilising potential and their impact on ART outcomes are discussed. In addition, advantages and disadvantages of each method and the best suited techniques for each clinical scenario are described.

Regular (ICSI) versus ultra-high magnification (IMSI) sperm selection for assisted reproduction

BACKGROUND

Subfertility is a condition found in up to 15% of couples of reproductive age. Gamete micromanipulation, such as intracytoplasmic sperm injection (ICSI), is very useful for treating couples with compromised sperm parameters. An alternative method of sperm selection has been described; the spermatozoa are selected under high magnification (over 6000x) and used for ICSI. This technique, named intracytoplasmic morphologically selected sperm injection (IMSI), has a theoretical potential to improve reproductive outcomes among couples undergoing assisted reproduction techniques (ART). However, our previous version of this Cochrane Review was unable to find evidence that supported this possible beneficial effect. This is an update of Teixeira 2013.

OBJECTIVES

To identify, appraise, and summarise the available evidence regarding efficacy and safety of IMSI compared to ICSI in couples undergoing ART.

SEARCH METHODS

We searched for randomised controlled trials (RCTs) in these electronic databases: the Cochrane Gynaecology and Fertility Group Specialised Register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, LILACS, and in these trial registers: ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform. We also handsearched the reference lists of included studies and similar reviews. We performed the last electronic search on 18 November 2019.

SELECTION CRITERIA

We only considered RCTs that compared ICSI and IMSI; we did not include quasi-randomised trials. We considered studies that permitted the inclusion of the same participant more than once (cross-over or per cycle trials) only if data regarding the first treatment of each participant were available.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, data extraction, and assessment of the risk of bias and quality of the evidence; we solved disagreements by consulting a third review author. We corresponded with study investigators to resolve any queries, as required.

MAIN RESULTS

The updated search retrieved 535 records; we included 13 parallel-designed RCTs comparing IMSI and ICSI (four studies were added since the previous version), comprising 2775 couples (IMSI = 1256; ICSI = 1519). We are uncertain if IMSI improves live birth rates (risk ratio (RR) 1.11, 95% confidence interval (CI) 0.89 to 1.39; 5 studies, 929 couples; I² = 1%), miscarriage rates per couple (RR 1.07, 95% CI 0.78 to 1.48; 10 studies, 2297 couples; I² = 0%, very-low quality evidence), and miscarriage rate per pregnancy (RR 0.90, 95% CI 0.68 to 1.20; 10 studies, 783 couples; I² = 0%, very-low quality evidence). We are uncertain if IMSI improves clinical pregnancy rates (RR 1.23, 95% CI 1.11 to 1.37; 13 studies, 2775 couples; I² = 47%, very-low quality evidence). None of the included studies reported congenital abnormalities. We judged the evidence for all outcomes to be of very low-quality. We downgraded the quality of the evidence due to limitations of the included studies (risk of bias), inconsistency of results, and a strong indication of publication bias.

AUTHORS' CONCLUSIONS

The current evidence from randomised controlled trials does not support or refute the clinical use of intracytoplasmic sperm injection (intracytoplasmic morphologically selected sperm injection (IMSI). We are very uncertain of the chances of having a live birth and of the risk of having a miscarriage. We found very low-quality evidence that IMSI may increase chances of a clinical pregnancy, which means that we are still very uncertain about any real difference. We did not find any trials reporting on the risk of congenital abnormalities. Well-designed and sufficiently powered trials are still required.