Advanced sperm selection techniques for assisted reproduction

Assisted reproductive technologies (ART) including in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI), combine gametes to enhance the probability of fertilisation and pregnancy. Advanced sperm selection techniques are increasingly employed in ART, most commonly in cycles utilising ICSI. Advanced sperm selection techniques are proposed to improve the chance that structurally intact and mature sperm with high DNA integrity are selected for fertilisation. 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 are intended to improve ART outcomes.

To evaluate the effectiveness and safety of advanced sperm selection techniques on ART outcomes.

We conducted a systematic search of electronic databases (Cochrane Gynaecology and Fertility Group Specialised Register, CENTRAL via the Cochrane Register of Studies Online, MEDLINE, Embase, PsycINFO, Cumulative Index to Nursing and Allied Health Literature (CINAHL); trials registers (ClinicalTrials.gov, Current Controlled Trials, and the World Health Organization International Clinical Trials Registry Platform); conference abstracts (Web of Knowledge); and grey literature (OpenGrey) for relevant randomised controlled trials (RCTs). We handsearched the reference lists of included studies and similar reviews. The search was conducted in June 2018.

We included RCTs comparing advanced sperm selection techniques versus standard IVF, ICSI, or another technique. We excluded studies of intracytoplasmic morphologically selected sperm injection (IMSI), as they are subject to a separate Cochrane Review. Primary outcomes measured were live birth and miscarriage per woman randomly assigned. Secondary outcome measures included clinical pregnancy per woman randomly assigned. Secondary adverse events measured included miscarriage per clinical pregnancy and foetal abnormality.

Two review authors independently assessed study eligibility and risk of bias and extracted data. Any disagreements were resolved by consultation with a third review author. We consulted study investigators to resolve queries. Risk ratios (RRs) were calculated with 95% confidence intervals (CIs). We combined studies using a fixed-effect model. We evaluated the quality of the evidence using GRADE methods.

We included eight RCTs (4147 women). The quality of evidence ranged from very low to low. The main limitations were imprecision, performance bias, and attrition bias.Hyaluronic acid selected sperm-intracytoplasmic sperm injection (HA-ICSI) compared to ICSITwo RCTs compared the effects of HA-ICSI versus ICSI on live birth. The quality of the evidence was low. There may be little or no difference between groups: 25% chance of live birth with ICSI versus 24.5% to 31% with HA-ICSI (RR 1.09, 95% CI 0.97 to 1.23, 2903 women, I² = 0%, low-quality evidence). Three RCTs reported on miscarriage. HA-ICSI may decrease miscarriage per woman randomly assigned: 7% chance of miscarriage with ICSI versus 3% to 6% chance with HA-ICSI (RR 0.61, 95% CI 0.45 to 0.83, 3005 women, I² = 0%, low-quality evidence) and per clinical pregnancy: 20% chance of miscarriage with ICSI compared to 9% to 16% chance with HA-ICSI (RR 0.62, 95% CI 0.46 to 0.82, 1065 women, I² = 0%, low-quality evidence). Four RCTs reported on clinical pregnancy. There may be little or no difference between groups: 37% chance of pregnancy with ICSI versus 34% to 40% chance with HA-ICSI (RR 1.00, 95% CI 0.92 to 1.09, 3492 women, I² = 0%, low-quality evidence).HA-ICSI compared to SpermSlowOne RCT compared HA-ICSI to SpermSlow. The quality of the evidence was very low. We are uncertain whether HA-ICSI improves live birth compared to SpermSlow (RR 1.13, 95% CI 0.64 to 2.01, 100 women) or clinical pregnancy (RR 1.05, 95% CI 0.66 to 1.68, 100 women). We are uncertain whether HA-ICSI reduces miscarriage per woman (RR 0.80, 95% CI 0.23 to 2.81, 100 women) or per clinical pregnancy (RR 0.76, 95% CI 0.24 to 2.44, 41 women).Magnetic-activated cell sorting (MACS) compared to ICSIOne RCT compared MACS to ICSI for live birth; three reported clinical pregnancy; and two reported miscarriage. The quality of the evidence was very low. We are uncertain whether MACS improves live birth (RR 1.95, 95% CI 0.89 to 4.29, 62 women) or clinical pregnancy (RR 1.05, 95% CI 0.84 to 1.31, 413 women, I² = 81%). We are also uncertain if MACS reduces miscarriage per woman (RR 0.95, 95% CI 0.16 to 5.63, 150 women, I² = 0%) or per clinical pregnancy (RR 0.51, 95%CI 0.09 to 2.82, 53 women, I²=0)Zeta sperm selection compared to ICSIOne RCT evaluated Zeta sperm selection. The quality of the evidence was very low. We are uncertain of the effect of Zeta sperm selection on live birth (RR 2.48, 95% CI 1.34 to 4.56, 203 women) or clinical pregnancy (RR 1.82, 95% CI 1.20 to 2.75, 203 women). We are also uncertain if Zeta sperm selection reduces miscarriage per woman (RR 0.73, 95% CI 0.16 to 3.37, 203 women) or per clinical pregnancy (RR 0.41, 95% CI 0.10 to 1.68, 1 RCT, 62 women).MACS compared to HA-ICSIOne RCT compared MACS to HA-ICSI. This study did not report on live birth. The quality of the evidence was very low. We are uncertain of the effect on miscarriage per woman (RR 1.52, 95% CI 0.10 to 23.35, 78 women) or per clinical pregnancy (RR 1.06, 95% CI 0.07 to 15.64, 37 women). We are also uncertain of the effect on clinical pregnancy (RR 1.44, 95% CI 0.91 to 2.27, 78 women).

The evidence suggests that sperm selected by hyaluronic acid binding may have little or no effect on live birth or clinical pregnancy but may reduce miscarriage. We are uncertain of the effect of Zeta sperm selection on live birth, clinical pregnancy, and miscarriage due principally to the very low quality of the evidence for this intervention. We are uncertain of the effect of the other selection techniques on live birth, miscarriage, or pregnancy.Further high-quality studies, including the awaited data from the identified ongoing studies, are required to evaluate whether any of these advanced sperm selection techniques can be recommended for use in routine practice.