Advanced sperm selection techniques for assisted reproduction
Abstract
Background
Assisted reproductive technologies (ART) such as in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI) bring together gametes outside of the body to enhance the probability of fertilisation and pregnancy. Advanced sperm selection techniques are increasingly being employed in ART, most commonly in cycles utilising ICSI. Advanced sperm selection techniques are thought to improve the chance that structurally intact and mature sperm with high DNA integrity are selected for fertilisation. Advanced sperm selection strategies include selection according to surface charge; sperm apoptosis; sperm birefringence; ability to bind to hyaluronic acid; and sperm morphology under ultra‐high magnification. These techniques theoretically improve ART outcomes.
Objectives
To evaluate the impact of advanced sperm selection techniques on ART outcomes.
Search methods
Systematic search of electronic databases (Cochrane Menstrual Disorders and Subfertility Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Latin American and Caribbean Health Science Information Database (LILACS)), trials registers (ClinicalTrials.gov, Current Controlled Trials, World Health Organization International Clinical Trials Registry Platform), conference abstracts (Web of Knowledge) and grey literature (OpenGrey) for relevant randomised controlled trials. We handsearched the reference lists of included studies and similar reviews. The search was conducted in May 2014.
Selection criteria
We included randomised controlled trials (RCTs) comparing an advanced sperm selection technique versus standard IVF or ICSI or versus another advanced sperm selection technique. We excluded studies of sperm selection using ultra‐high magnification (intracytoplasmic morphologically selected sperm injection, or IMSI), as they are the subject of a separate Cochrane review. Quasi‐randomised and pseudo‐randomised trials were excluded. Our primary outcome measure was live birth rate per woman randomly assigned. Secondary outcome measures included clinical pregnancy per woman randomly assigned, miscarriage per clinical pregnancy and fetal abnormality per clinical pregnancy.
Data collection and analysis
Two review authors independently assessed eligibility of studies and risk of bias, and performed data extraction. Disagreements were resolved by consultation with a third review author. Study investigators were consulted to resolve other queries that arose. Risk ratios (RRs) were calculated with 95% confidence intervals (CIs). We planned to combine studies using a fixed‐effect model, if sufficient data were available. The quality of the evidence was evaluated using Grades of Recommendation, Assessment, Development and Evaluation (GRADE) methods.
Main results
Two RCTs were included in the review. Both evaluated sperm selection by hyaluronanic acid binding for ICSI, but only one reported live births. No studies were identified that were related to surface charge selection, sperm apoptosis or sperm birefringence.
One RCT compared hyaluronanic acid binding versus conventional ICSI. Live birth was not reported. Evidence was insufficient to show whether there was a difference between groups in clinical pregnancy rates (RR 1.01, 95% CI 0.84 to 1.22, one RCT, 482 women). This evidence was deemed to be of low quality, mainly as the result of poor reporting of methods and findings. Miscarriage data were unclear, and fetal abnormality rates were not reported.
The other RCT compared two different hyaluronanic acid binding techniques, SpermSlow and physiological intracytoplasmic sperm injection (PISCI). Evidence was insufficient to indicate whether there was a difference between groups in rates of live birth (RR 1.16, 95% CI 0.65 to 2.05, one RCT, 99 women), clinical pregnancy (RR 1.07, 95% CI 0.67 to 1.71, one RCT, 99 women) or miscarriage (RR 0.76, 95% CI 0.24 to 2.44, one RCT, 41 women). The evidence for these comparisons was deemed to be of low quality, as it was limited by imprecision and poor reporting of study methods. Fetal abnormality rates were not reported.
Authors' conclusions
Evidence was insufficient to allow review authors to determine whether sperm selected by hyaluronanic acid binding improve live birth or pregnancy outcomes in ART, and no clear data on adverse effects were available. Evidence was also insufficient to show whether there is a difference in efficacy between the hyaluronic acid binding methods SpermSlow and PICSI. No randomised evidence evaluating sperm selection by sperm apoptosis, sperm birefringence or surface charge was found.
Further studies of suitable quality are required to evaluate whether any of these advanced sperm selection techniques can be recommended for use in clinical practice.
PICOs
Plain language summary
Advanced sperm selection techniques for assisted reproduction
Review question
Cochrane review authors reviewed the evidence on advanced sperm selection techniques for assisted reproduction. We sought studies of all advanced sperm techniques apart from ultra‐high magnification, which is the subject of a separate Cochrane review. Our outcomes of interest included live birth, clinical pregnancy, miscarriage and fetal abnormalities.
Background
In vitro fertilisation (IVF) with or without intracytoplasmic sperm injection (ICSI) is a commonly used treatment for subfertile couples. It is thought that selection of high‐quality sperm may improve live birth rates for these couples. Advanced sperm selection techniques use complex methods to select healthy, mature and structurally sound sperm for fertilisation. Despite use of these techniques in many centres worldwide, their effectiveness is unclear.
Study characteristics
Two randomised controlled trials (with a total of 581 women) were included in the review. Both studies evaluated sperm selection by hyaluronanic acid binding for ICSI, but only one reported live birth. One study compared hyaluronanic acid binding versus conventional ICSI and reported clinical pregnancy. The other study compared two different hyaluronanic acid binding techniques, SpermSlow and physiological intracytoplasmic sperm injection (PICSI), and reported live birth, clinical pregnancy and miscarriage rates. No studies were found on other techniques. Evidence is current to May 2014.
Key results
Current evidence was insufficient to permit evaluation of the effectiveness of advanced sperm selection strategies in assisted reproductive technologist (ART). No evidence showed a difference between the groups in terms of any of the reported outcomes. Further studies of suitable quality are required before any of these advanced sperm selection techniques can be recommended for use in clinical practice.
Evidence quality
The evidence gathered was of low quality. The main limitations were imprecision, discrepancies in the data and poor reporting of study methods. Data on important clinical outcomes such as live births and adverse effects were scant.
Authors' conclusions
Summary of findings
| Conventional sperm selection (ICSI) versus hyaluronan selected sperm (HA‐ICSI) for assisted reproduction | ||||||
| Population: women with infertility requiring assisted reproductive technology | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No. of participants | Quality of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| Conventional sperm selection (ICSI) | Hyaluronan sperm selection (HA‐ICSI) | |||||
| Clinical pregnancy per woman randomly assigned | 47 per 100 | 48 per 100 | RR 0.99 | 482 | ⊕⊕⊝⊝ | |
| *The basis for the assumed risk is the median control group risk across studies. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). | ||||||
| GRADE Working Group grades of evidence. | ||||||
| aSerious risk of bias: discrepancy in reporting of pregnancy losses. bSerious imprecision: confidence intervals compatible with substantial benefit or harm from the intervention, or with no effect. | ||||||
| HA culture dish (PICSI) compared with viscous medium containing HA (SpermSlow) for infertility requiring intracytoplasmic sperm injection | ||||||
| Population: women with infertility requiring intracytoplasmic sperm injection | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No. of participants | Quality of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| Viscous medium containing HA (SpermSlow) | HA culture dish (PICSI) | |||||
| Live birth per woman randomly assigned | 30 per 100 | 35 per 100 | RR 1.16 | 99 | ⊕⊕⊝⊝a,b | |
| Clinical pregnancy per woman randomly assigned | 40 per 100 | 43 per 100 | RR 1.07 | 99 | ⊕⊕⊝⊝a,b | |
| Miscarriage per clinical pregnancy | 25 per 100 | 19 per 100 | RR 0.76 | 41 | ⊕⊕⊝⊝a,b | |
| *The basis for the assumed risk is the median control group risk across studies. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). | ||||||
| GRADE Working Group grades of evidence. | ||||||
| aSerious risk of bias: study methods not reported in adequate detail. bSerious imprecision: confidence intervals compatible with substantial benefit or harm from the intervention, or with no effect. | ||||||
Background
Description of the condition
In vitro fertilisation (IVF) is a form of assisted reproductive technology (ART) that is used for treating infertility—a condition affecting an estimated 15% of the population. IVF usually involves controlled ovarian hyperstimulation, surgical oocyte retrieval, in vitro fertilisation and embryo transfer. Intracytoplasmic sperm injection (ICSI) involves injecting a single sperm into the cytoplasm of each oocyte to achieve fertilisation. ICSI is commonly used as treatment for male factor infertility when semen parameters are poor, when sperm have been surgically retrieved or when repeated fertilisation with standard IVF has failed (Palermo 1992).
Successful embryo development and subsequent pregnancy outcome are likely to be impacted by the quality of the sperm that fertilise an oocyte (Sakkas 2000). Ideally only sperm with a high chance of successful fertilisation and subsequent embryo growth would be used for ART. These sperm would be viable and mature, would have high DNA integrity and would be structurally sound.
Sperm preparation and selection in IVF are limited to semen washing, density gradient centrifugation and use of swim‐up techniques (Boomsma 2007). In ICSI, routine sperm selection is based on motility and gross morphology (sperm are examined under a microscope at 200× to 400× magnification) after one or more of the above methods of semen preparation has been applied. Advanced sperm selection techniques based on alternative characteristics might enable further selection of the most appropriate sperm for use in ART.
Description of the intervention
Advanced sperm selection techniques have developed as a means of improving ART outcomes in certain clinical scenarios. Techniques can be categorised as follows.
Surface charge selection
Electrophorectic sperm selection and sperm zeta potential are surface charge selection protocols utilised in both IVF and ICSI. The zeta potential of the sperm is the electrical potential between the sperm membrane and its surroundings. The zeta potential decreases with capacitation, and normally differentiated sperm are charged electronegatively. Semen is placed into an electrophoretic device and a current applied. Normally differentiated negatively charged sperm are rapidly separated and collected from an adjacent chamber (Ainsworth 2005).
Sperm apoptosis
Selection of non‐apoptotic sperm for use in ART is based on the presence of phosphatidylserine on the external surface of the sperm membrane in the early stages of apoptosis. Magnetic activated cell sorting (MACS) and glass wool separation columns utilise the magnetic properties of phosphatidylserine to separate apoptotic sperm from non‐apoptotic sperm (Grunewald 2001).
Hyaluronic acid binding
Hyaluronic acid (HA) is the main component of the extracellular matrix of the cumulus oophorus. Hyaluronic acid binding sites on the sperm plasma membrane indicate sperm maturity. Mature sperm bind to and digest HA and thus have a better chance of reaching the oocyte for fertilisation. In vitro, HA is utilised as a 'physiological selector' of mature intact sperm.
Two systems for HA sperm selection are currently available. Physiological intracytoplasmic sperm injection (PICSI; Origio, Måløv, Denmark) is a plastic culture dish with spots of HA attached to its base. Sperm are bound by the head to HA and are selected for microinjection (Huszar 2007). SpermSlow is a viscous medium containing HA. Appropriate sperm appear 'slowed' and are selected.
Sperm birefringence
The mature sperm nucleus has high intrinsic birefringence due to longitudinally orientated subacrosomal protein filaments. With the use of polarised light microscopy, sperm birefringence can be evaluated and a mature sperm selected (Gianaroli 2008).
Sperm morphology (intracytoplasmic morphologically selected sperm injection, IMSI)
Subtle defects in sperm morphology (acrosome, nucleus, mitochondria, tail, postacrosoma lamina and neck) can be observed using ultra‐high magnification (6000×) microscopy (motile sperm organelle morphology examination, MSOME) (Bartoov 2002). Intracytoplasmic morphologically selected sperm injection (IMSI) is a modification of ICSI that uses this technique (Bartoov 2003). This review does not evaluate IMSI, as it is the subject of another Cochrane review (Teixeira 2013).
How the intervention might work
Each sperm selection modality utilises different characteristics of sperm structure, physiology or function to promote selection of the most normal sperm. Selection of the most appropriate sperm for fertilisation in vitro may help improve fertilisation and the quality of embryos created. Advanced sperm selection protocols aim to improve ART outcomes and may limit possible deleterious effects on offspring of using sperm with defective DNA (Aitken 2007).
Why it is important to do this review
Advanced sperm selection techniques are hypothesised to improve ART outcome through the selection of sperm with a variety of 'beneficial characteristics.' Although individual small studies have suggested that these techniques have clinical benefit, there remains no comprehensive review of randomised controlled trials (RCTs) in this area. The current review includes only RCTs, so the results can better guide clinical practice and further research efforts.
Objectives
To evaluate the impact of advanced sperm selection techniques on ART outcomes.
Methods
Criteria for considering studies for this review
Types of studies
Published and unpublished RCTs investigating the impact of advanced sperm selection techniques in ART were eligible for inclusion. Non‐randomised studies were excluded because of high risk of bias. Cross‐over studies are inappropriate in this context and were excluded.
Types of participants
Women or couples undergoing ART.
Types of interventions
Trials comparing an advanced sperm selection technique with either another advanced sperm selection technique or an advanced sperm selection technique with standard sperm preparation techniques (e.g. semen washing, density gradient centrifugation, swim‐up techniques).
Advanced sperm selection techniques include the following.
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Surface charge selection.
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Sperm apoptosis.
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Hyaluronic acid binding.
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Sperm birefringence.
Sperm selection by sperm morphology using ultra‐high magnification (IMSI) was excluded, as this is the subject of another Cochrane review (Teixeira 2013).
Types of outcome measures
Primary outcomes
Effectiveness
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Live birth per woman randomly assigned.
(Live birth is defined as the delivery of a live fetus beyond 20 completed weeks' gestation.)
Secondary outcomes
Effectiveness
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Clinical pregnancy per woman randomly assigned.
(Clinical pregnancy is defined as identification of a gestational sac on ultrasound at ≥ seven weeks' gestation.)
Adverse events
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Miscarriage, fetal abnormalities per clinical pregnancy.
(Miscarriage is defined as pregnancy loss at < 20 completed weeks' gestation, or when the fetus weighs < 500 grams. Miscarriage must be confirmed by ultrasound and pregnancy test or histology and includes partial loss of multiple pregnancies.)
Fertilisation rates, implantation rates and outcomes related to embryo development and quality are of importance to this review and are described under Characteristics of included studies. These outcomes were not included in the meta‐analysis because standardised grading systems for morphology are lacking, and denominators for fertilisation and implantation rates differ.
Search methods for identification of studies
We searched for all published and unpublished RCTs using the search terms 'IVF,' 'ICSI,' 'ART,' 'sperm selection,' 'sperm preparation,' 'sperm parameter,' 'Hyaluronic acid,' 'PICSI,' 'apoptosis,' 'DNA,' 'membrane maturity,' 'magnetic cell sorting,' 'morphology,' 'intracytoplasmic morphologically selected sperm injection,' 'polarization microscopy,' 'polscope' and 'sperm birefringence.'
The search included no language restriction and was designed and conducted by SM and BK, in consultation with the Menstrual Disorders and Subfertility Group (MDSG) Trials Search Co‐ordinator. The search was conducted in May 2014.
Electronic searches
We searched the following electronic databases, trial registers and websites.
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Menstrual Disorders and Subfertility Group (MDSG) Specialised Register
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Cochrane Central Register of Controlled Trials (CENTRAL)
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MEDLINE
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EMBASE
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PsycINFO
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Cumulative Index to Nursing and Allied Health Literature (CINAHL)
Other electronic sources of trials included the following.
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Trial registers for ongoing and registered trials: http://www.controlled‐trials.com, http://clinicaltrials.gov/ct2/home, http://www.who.int/trialsearch/Default.aspx.
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Citation indexes: http://scientific.thomson.com/products/sci/.
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Conference abstracts in the Web of Knowledge: http://wokinfo.com/
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Latin American and Caribbean Health Science Information Database (LILACS), for trials from the Portuguese and Spanish‐speaking world: http://bases.bireme.br/cgi‐bin/wxislind.exe/iah/online/?IsisScript=iah/iah.xis&base=LILACS&lang=i&form=F.
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PubMed: http://www.ncbi.nlm.nih.gov/pubmed/.
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Open System for Information on Grey Literature in Europe (OpenSIGLE) database (http://opensigle.inist.fr/) and Google Scholar for grey literature.
Searching other resources
We searched the reference lists of articles retrieved by the search.
Data collection and analysis
Selection of studies
After an initial screen of titles and abstracts retrieved by the search, we retrieved the full texts of all potentially eligible studies. Two review authors (SM and BK) independently examined these full‐text articles for compliance with the inclusion criteria and selected studies eligible for inclusion in the review. We corresponded with study investigators as required to clarify study eligibility. Disagreements as to study eligibility were resolved by discussion or by discussion with a third review author (AY). We documented the selection process by using a Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) flow chart.
Data extraction and management
Two review authors independently extracted data from eligible studies. Disagreements were resolved by discussion or by consultation with a third review author. Data extracted included study characteristics and outcome data and details of methods, participants, setting, context, interventions (sperm selection protocols), outcomes, results and publications. We attempted to contact study investigators via email to obtain additional information. No replies were received from any of the study authors.
Assessment of risk of bias in included studies
Two review authors (SM and BK) independently assessed the included studies for risk of bias using the Risk of bias assessment tool of The Cochrane Collaboration (Higgins 2011). This instrument assessed random sequence generation and allocation concealment (selection bias); blinding of participants and personnel; blinding of outcome assessors; incomplete outcome data; selective reporting; and other bias. Disagreements were resolved by discussion or by consultation with a third review author (AY). We have fully described all judgements and have presented our conclusions in the Risk of bias table, which we planned to incorporate into the interpretation of review findings by means of sensitivity analyses.
We took care to search for within‐trial selective reporting, such as trials failing to report obvious outcomes, or trials reporting outcomes in insufficient detail to allow inclusion. We sought published protocols and compared outcomes between the protocol and the final published study.
Measures of treatment effect
The data extracted were dichotomous (e.g. live birth rate, miscarriage rate). Using RevMan software (RevMan 2011), we entered the numbers of events in control and intervention groups of each study to calculate Mantel‐Haenszel risk ratios (RRs). We presented 95% confidence intervals (CIs) for all outcomes.
Unit of analysis issues
The primary analysis was performed per woman randomly assigned. Per‐pregnancy data were included for some miscarriage outcomes. We briefly summarised data that did not allow valid analysis (e.g. 'per cycle' data), but did not meta‐analyse these data. If studies reported only 'per‐cycle' data, we attempted to contact the study authors to obtain 'per‐woman randomised' data.
We counted multiple live births (e.g. twins, triplets) as a single live birth event.
Dealing with missing data
We analysed the data on an intention‐to‐treat basis as far as possible and made attempts to obtain missing data from the original trialists. When the data could not be obtained, we assumed that the outcome measure (e.g. live birth, clinical pregnancy) did not occur. For other outcomes, we analysed available data. We planned to subject any imputation undertaken to sensitivity analysis (see below).
Assessment of heterogeneity
We considered whether the clinical and methodological characteristics of the included studies were sufficiently similar for meta‐analysis to provide a clinically meaningful summary. We planned to assess statistical heterogeneity using the I2 statistic, with an I2 measurement greater than 50% indicating moderate heterogeneity (Higgins 2003; Higgins 2008). Substantial heterogeneity was deemed to be greater than 60%. If substantial heterogeneity was apparent, we planned to explore possible explanations using a sensitivity analysis (see below) and to consider subgroup analyses. We planned to take any statistical heterogeneity into account when interpreting the results, especially if any variation in the direction of effect was noted.
Assessment of reporting biases
Reporting bias was minimised by ensuring a comprehensive search for eligible studies. If 10 or more studies were included in an analysis, we planned to use a funnel plot to explore the possibility of small‐study effects (a tendency for estimates of the intervention effect to be more beneficial in smaller studies).
Data synthesis
If the studies were sufficiently similar, we planned to combine data using a fixed‐effect model for the following comparisons.
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IVF versus advanced sperm selection technique, stratified by individual sperm selection technique (refer to Description of the intervention above for details).
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ICSI versus advanced sperm selection technique, stratified by individual sperm selection technique.
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Advanced sperm selection technique versus another advanced sperm selection technique.
We graphically displayed an increase in the risk of a particular outcome, which may be beneficial (e.g. live birth) or detrimental (e.g. adverse effects), in the meta‐analysis to the right of the centre line and a decrease in the risk of a particular outcome to the left of the centre line.
We planned to calculate number needed to treat for an additional beneficial outcome (NNTB), if significant findings were identified.
Subgroup analysis and investigation of heterogeneity
If sufficient data were available, we planned to conduct subgroup analyses to identify separate evidence within the following subgroups.
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Sperm morphology: when the Kruger score is equal to or less than 4%.
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Increased DNA fragmentation index (according to the study cut‐off).
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Surgically retrieved sperm.
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Female participants over 38 years of age.
Sensitivity analysis
We planned to conduct sensitivity analyses for primary outcome measures to determine whether the conclusions were robust to arbitrary decisions made regarding eligibility and analysis. These analyses would include consideration of whether the review conclusions would have differed if:
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eligibility were restricted to studies without high risk of bias;
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a random‐effects model had been adopted; or
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alternative imputation strategies had been implemented.
Overall quality of the body of evidence: Summary of findings table
We generated a Summary of findings table using GRADEpro software. This table evaluated the overall quality of the body of evidence for the main review outcomes, using GRADE criteria (study limitations (i.e. risk of bias), consistency of effect, imprecision, indirectness and publication bias). We justified, documented and incorporated into the reporting of results for each outcome our judgements about the quality of evidence (high, moderate or low).
Results
Description of studies
Results of the search
The search strategy identified 1007 studies. Thirty studies were potentially eligible and were retrieved in full text. Following publication of our protocol, a Cochrane review was published regarding sperm selection by sperm morphology under ultra‐high magnification (Teixeira 2013). After discussion with the Cochrane Menstrual Disorders and Subfertility Group, the scope of our review was amended to exclude the use of ultra‐high magnification for sperm selection. Nine more studies were therefore excluded. Two studies met our inclusion criteria (Parmegiani 2012; Worrilow 2013). Eight studies were excluded (see PRISMA flow chart; Figure 1). We identified no suitable studies regarding sperm selection by apoptosis, birefringence or surface charge. The remainder of the meta‐analysis therefore pertains to hyaluronic acid binding only. See study tables Characteristics of included studies and Characteristics of excluded studies.
Study flow diagram.
Included studies
Study design and setting
Two parallel‐design RCTs were included in the review (Parmegiani 2012; Worrilow 2013). One was a single‐centre study conducted in Italy, and the other was a multi‐centre study, performed at 10 IVF programs in the USA. Two further conference abstracts were identified that contained data from the above two trials; these have been listed as secondary references.
Participants
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The first study (Parmegiani 2012) included 49 women in the PICSI group and 50 in the SpermSlow group. No study arm received standard ICSI only. Couples were included if the woman was ≤ 41 years of age, ICSI treatment was to be utilised, total sperm number was ≥ 1 million and sperm motility was ≥ 5%. Couples using sperm collected surgically or with severe oligoasthenoteratozoospermia were excluded.
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The second study (Worrilow 2013) included 240 women in the intervention group (PICSI) and 242 in the control group (standard ICSI). Couples were included if they were receiving ICSI as part of their ART treatment. Participants were excluded if the woman was > 40 years old, or if testicular sperm was used. Participants were divided into cohorts on the basis of the proportion of sperm bound to hyaluronan in the unprocessed sample. Participants were further excluded if HB binding was < 2%. Participants were divided into those with hyaluronan‐bound sperm between 2% and 65% or > 65%, and then were further divided into study groups (intervention or control).
Interventions
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1/2 studies compared PICSI versus SpermSlow.
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1/2 studies compared PICSI versus standard ICSI.
Outcomes
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1/2 studies reported live birth.
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1/2 studies reported clinical pregnancy rate.
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1/2 studies reported miscarriage rate.
Excluded studies
Eight studies were excluded from the review for the following reasons.
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4/8 were not RCTs (Berkovitz 2006; Fleming 2007; Gnosh 2007; Parmegiani 2010b).
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2/8 were pseudo‐randomised (Gianaroli 2008; Gianaroli 2010).
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1/8 did not analyse a relevant intervention (Blanchard 2010).
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1/8 analysed participants per treatment randomly assigned (Parmegiani 2010a), and despite attempts to contact the study investigators, we were unable to obtain "per‐woman" data.
Nine studies pertaining to IMSI were excluded, as this intervention is the subject of a separate Cochrane review (Teixeira 2013).
Risk of bias in included studies
See Characteristics of included studies; Figure 2; and Figure 3 for detailed information.
Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.
Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
Allocation
Random sequence allocation
One study was at low risk of bias related to sequence generation: it used computer‐generated randomisation (Worrilow 2013). The other study was at unclear risk of bias, as the method of random sequence generation was not reported (Parmegiani 2012).
Allocation concealment
One study was at low risk of bias, as the investigator performing randomisation had no involvement in the trial (Worrilow 2013). Information was insufficient to permit judgement in the other trial (Parmegiani 2012).
Blinding
One study was double‐blinded (Worrilow 2013), and the other was unblinded (Parmegiani 2012). Blinding however is unlikely to affect any of the outcome measures. Both studies were judged to be at low risk of bias for this domain.
Incomplete outcome data
In one study the risk of attrition bias was unclear, as it could not be accurately determined which study group participants with incomplete data belonged to (Worrilow 2013). Data were incomplete in 4/482; therefore the risk in this domain was not considered high. The other study was deemed to be at low risk of bias in this domain (Parmegiani 2012).
Selective reporting
One study was considered to be at high risk of selective reporting bias, as data regarding all outcome measures were not available (Worrilow 2013). The remaining study was deemed to be at low risk of selective reporting bias (Parmegiani 2012). No evidence was found to suggest that specific outcomes were reported on the basis of statistical significance.
Other potential sources of bias
One study was potentially biased, as it was stopped prematurely because of financial constraints and a slower than expected time to recruit (Worrilow 2013).
Effects of interventions
See: Summary of findings for the main comparison Conventional sperm selection (ICSI) versus hyaluronan sperm selection (HA‐ICSI) for assisted reproduction; Summary of findings 2 HA culture dish (PICSI) compared with viscous medium containing HA (SpermSlow) for infertility requiring intracytoplasmic sperm injection
See summary of findings Table for the main comparison. Conventional sperm selection (ICSI) versus hyaluronan selected sperm (HA‐ICSI); summary of findings Table 2. HA culture dish (PICSI) versus viscous medium containing HA (SpermSlow).
HA culture dish (PICSI) versus ICSI
Primary outcome
Live birth (effectiveness)
Live birth was not reported in the included study.
Secondary outcomes
Clinical pregnancy (effectiveness)
Evidence was insufficient to show whether there is a difference between the interventions (RR 0.99, 95% CI 0.82 to 1.20, one RCT, 482 women, low‐quality evidence; Analysis 1.1; Figure 4).
Forest plot of comparison. Hyaluronan sperm selection (HA‐ICSI) versus ICSI, outcome: 1.1 Clinical pregnancy per woman randomly assigned.
Miscarriage (adverse event)
Pregnancy loss rate was included in the reported study; however the data were not suitable for meta‐analysis. From the data provided, we were unable to accurately determine to which treatment group a miscarriage pertained.
Fetal abnormality (adverse event)
The included study did not report fetal abnormality.
HA culture dish (PICSI) versus viscous medium containing HA (SpermSlow)
Primary outcome
Live birth (effectiveness)
Evidence was insufficient to show whether there is a difference between the interventions in live birth rates (RR 1.16, 95% CI 0.65 to 2.05, one RCT, 99 women, low‐quality evidence; Analysis 2.1; Figure 5).
Forest plot of comparison: 2 HA culture dish (PICSI) versus viscous medium containing HA (SpermSlow), outcome: 2.1 Live birth per woman randomly assigned.
Secondary outcomes
Clinical pregnancy (effectiveness)
Evidence was insufficient to show whether there is a difference between the interventions in clinical pregnancy rates (RR 1.07, 95% CI 0.67 to 1.71, one RCT, 99 women, low‐quality evidence; Analysis 2.2; Figure 6).
Forest plot of comparison: 2 HA culture dish (PICSI) versus viscous medium containing HA (SpermSlow), outcome: 2.2 Clinical pregnancy per woman randomly assigned.
Miscarriage (adverse event)
Evidence was insufficient to indicate whether there is a difference between the interventions in miscarriage rates (RR 0.76, 95% CI 0.24 to 2.44, one RCT, 41 women, low‐quality evidence; Analysis 2.3; Figure 7).
Forest plot of comparison: 2 HA culture dish (PICSI) versus viscous medium containing HA (SpermSlow), outcome: 2.3 Miscarriage per woman randomly assigned.
Fetal abnormality (adverse event)
The included study did not report fetal abnormality.
Secondary analyses
Data were insufficient for review authors to conduct any subgroup or sensitivity analyses or to construct a funnel plot to assess reporting bias.
Discussion
Summary of main results
Overall, this review does not allow any conclusions to be drawn regarding the use of advanced sperm selection techniques for assisted reproduction.
Live birth rate was reported in only one included trial, and evidence was insufficient to indicate whether there is a difference in effectiveness between PICSI and SpermSlow.
Evidence was insufficient to show whether there is a difference in clinical pregnancy rates between PICSI and standard ICSI or between PICSI and SpermSlow. Congenital abnormality outcomes were not reported.
Data were insufficient to permit any conclusions with regard to miscarriage.
No suitable studies were identified that would have allowed determination of the effect of sperm selected by surface charge, sperm apoptosis or sperm birefringence. None of the included studies reported a subgroup suitable for analysis. See summary of findings Table for the main comparison and summary of findings Table 2 for further details.
Overall completeness and applicability of evidence
The objectives of this review were incompletely addressed by the studies included. No suitably controlled data were available to address the primary outcome measure (live birth per allocated couple) for any of the advanced sperm selection techniques described, and data on other important clinical outcomes such as miscarriage and fetal abnormalities were lacking.
Only one study (Worrilow 2013) provided data pertaining to clinical pregnancy per allocated couple for hyaluronanic acid binding compared with standard ICSI. The other included study (Parmegiani 2012) compared two different hyaluronanic acid binding techniques—PICSI and SpermSlow—but did not include a control population receiving standard ICSI. No study allowed a suitable subgroup analysis.
Quality of the evidence
The quality of the evidence for reported outcomes was low. The main limitations were poor reporting of study methods, discrepancies in the data and serious imprecision. The 95% confidence intervals were compatible with substantial benefit or harm from the intervention, or with no effect. Available RCT data were very sparse, and the two included studies did not address the same clinical comparison. We were unable to assess the risk of reporting bias.
The included study for the main comparison (Worrilow 2013) had several limitations. Overall the methodology was of a very poor standard. Study findings were difficult to interpret, and absolute values for outcome measures were not easily identifiable. The trial was stopped early for financial reasons and slow recruitment; this may have hindered the investigators' ability to adequately complete the stated objectives. It was unclear to which study group dropouts belonged. Attempts were made to contact the lead author to clarify several findings; however no reply was forthcoming (see summary of findings Table for the main comparison).
Evidence on the comparison of two different hyaluronic acid binding methods for sperm selection (Parmegiani 2012) was similarly limited by imprecision and by poor reporting of study methods (see summary of findings Table 2).
Potential biases in the review process
No potential biases were identified in the review process.
Agreements and disagreements with other studies or reviews
Another systematic review (Said 2007) has addressed effects of advanced sperm selection on sperm quality and ART outcomes. Sperm selection techniques similar to those described in this review were investigated. A total of 44 studies were identified, but few were strictly randomised, and nearly all were deemed unsuitable for inclusion in this review. However, the authors' conclusions were in concordance with our findings. Further clinical trials are required before advanced sperm selection techniques can be recommended in routine practice.
Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.
Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
Forest plot of comparison. Hyaluronan sperm selection (HA‐ICSI) versus ICSI, outcome: 1.1 Clinical pregnancy per woman randomly assigned.
Forest plot of comparison: 2 HA culture dish (PICSI) versus viscous medium containing HA (SpermSlow), outcome: 2.1 Live birth per woman randomly assigned.
Forest plot of comparison: 2 HA culture dish (PICSI) versus viscous medium containing HA (SpermSlow), outcome: 2.2 Clinical pregnancy per woman randomly assigned.
Forest plot of comparison: 2 HA culture dish (PICSI) versus viscous medium containing HA (SpermSlow), outcome: 2.3 Miscarriage per woman randomly assigned.
Comparison 1 Hyaluronan sperm selection (HA‐ICSI) versus ICSI, Outcome 1 Clinical pregnancy per woman randomly assigned.
Comparison 2 HA culture dish (PICSI) versus viscous medium containing HA (SpermSlow), Outcome 1 Live birth per woman randomly assigned.
Comparison 2 HA culture dish (PICSI) versus viscous medium containing HA (SpermSlow), Outcome 2 Clinical pregnancy per woman randomly assigned.
Comparison 2 HA culture dish (PICSI) versus viscous medium containing HA (SpermSlow), Outcome 3 Miscarriage per woman randomly assigned.
| Conventional sperm selection (ICSI) versus hyaluronan selected sperm (HA‐ICSI) for assisted reproduction | ||||||
| Population: women with infertility requiring assisted reproductive technology | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No. of participants | Quality of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| Conventional sperm selection (ICSI) | Hyaluronan sperm selection (HA‐ICSI) | |||||
| Clinical pregnancy per woman randomly assigned | 47 per 100 | 48 per 100 | RR 0.99 | 482 | ⊕⊕⊝⊝ | |
| *The basis for the assumed risk is the median control group risk across studies. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). | ||||||
| GRADE Working Group grades of evidence. | ||||||
| aSerious risk of bias: discrepancy in reporting of pregnancy losses. bSerious imprecision: confidence intervals compatible with substantial benefit or harm from the intervention, or with no effect. | ||||||
| HA culture dish (PICSI) compared with viscous medium containing HA (SpermSlow) for infertility requiring intracytoplasmic sperm injection | ||||||
| Population: women with infertility requiring intracytoplasmic sperm injection | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No. of participants | Quality of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| Viscous medium containing HA (SpermSlow) | HA culture dish (PICSI) | |||||
| Live birth per woman randomly assigned | 30 per 100 | 35 per 100 | RR 1.16 | 99 | ⊕⊕⊝⊝a,b | |
| Clinical pregnancy per woman randomly assigned | 40 per 100 | 43 per 100 | RR 1.07 | 99 | ⊕⊕⊝⊝a,b | |
| Miscarriage per clinical pregnancy | 25 per 100 | 19 per 100 | RR 0.76 | 41 | ⊕⊕⊝⊝a,b | |
| *The basis for the assumed risk is the median control group risk across studies. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). | ||||||
| GRADE Working Group grades of evidence. | ||||||
| aSerious risk of bias: study methods not reported in adequate detail. bSerious imprecision: confidence intervals compatible with substantial benefit or harm from the intervention, or with no effect. | ||||||
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Clinical pregnancy per woman randomly assigned Show forest plot | 1 | 482 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.99 [0.82, 1.20] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Live birth per woman randomly assigned Show forest plot | 1 | 99 | Risk Ratio (M‐H, Fixed, 95% CI) | 1.16 [0.65, 2.05] |
| 2 Clinical pregnancy per woman randomly assigned Show forest plot | 1 | 99 | Risk Ratio (M‐H, Fixed, 95% CI) | 1.07 [0.67, 1.71] |
| 3 Miscarriage per woman randomly assigned Show forest plot | 1 | 41 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.76 [0.24, 2.44] |
