Acrosome index is not an absolute predictor of the outcome following conventional in vitro fertilization and intracytoplasmic sperm injection

Acrosome reaction and chromatin integrity as additional parameters of semen analysis to predict fertilization and blastocyst rates

BACKGROUND

Traditional semen parameters have shown little to none predictive value for fertilization and blastocyst viability for a successful pregnancy. Therefore, the purpose of this study was to explore the usefulness of incorporating the acrosome reaction (AR) and chromatin integrity to conventional semen analysis to individually predict the fertile potential of sperm samples.

METHODS

A cross-sectional study was conducted in 69 participants undergoing IVF using oocyte donation. Semen samples were collected and evaluated for: AR [spontaneous (sAR) and induced (iAR)] by flow cytometry using anti-CD46-FITC, Acrosome Response to an Ionophore Challenge (ARIC), chromatin integrity by Sperm Chromatin Structure Assay (DNA Fragmentation Index-%DFI and High DNA Stainability-%HDS), WHO semen analysis, fertilization and blastocyst rates.

RESULTS

The participant age was 40.0 ± 6.1 years (66% were normozoospermic). Sperm morphology, sAR, iAR, and ARIC were associated with the fertilization (β = 3.56, R² = 0.054; β = - 5.92, R² = 0.276; β = 1.83, R² = 0.150; and β = 2.10, R² = 0.270, respectively, p < 0.05). A logit model was developed to calculate the probability of fertilization (≥ 60%) for each participant, using the sperm morphology and ARIC as independent variables, followed by ROC analysis to determine a cutoff probability of 0.65 (specificity = 80.6%, sensitivity = 63.2%). %DFI was inversely associated with the viable blastocyst rate (β = - 1.77, R² = 0.057, p = 0.003), by the logit model and ROC analysis, a cutoff probability of 0.70 (specificity = 80.6%, sensitivity = 72.3%) was obtained to predict blastocyst viability (≥ 40%). There was no difference in the results with normozoospermic samples (n = 46).

CONCLUSIONS

The incorporation of ARIC and %DFI allowed to obtain predictive models for high fertilization and blastocyst rates in an individualized way, being promising tools to improve the diagnosis of male fertility potential for research or assisted reproduction, even in men with unknown infertility.

Prediction of outcomes of assisted reproduction treatment using the calcium ionophore-induced acrosome reaction

BACKGROUND

Sperm concentration and motility are poor predictors of the outcome of intrauterine insemination (IUI), hysteroscopic intratubal insemination (HIT), or complete fertilization failure (CFF) in conventional IVF. We investigated whether the calcium ionophore-induced acrosome reaction (AR) constitutes an additional indicator of CFF and pregnancy that is independent of these semen parameters.

METHODS

Infertile couples with no female factor (n=388) and women with tubal obstruction (n=32) were studied: IVF (n=133), ICSI (n=72), HIT (n=245) and IUI (n=61). The percentage of acrosome-reacted sperm in relation to viable sperm was calculated. Receiver operating characteristic curve and multiple logistic regression analyses were used to determine threshold values and the best predictor for CFF and pregnancy.

RESULTS

Threshold values of AR for predicting CFF in IVF and pregnancy in IVF and HIT + IUI were 21, 26 and 22% respectively. These values were independent of the conventional semen analysis parameters. CFF was lower (2 versus 20%; P<0.01) and the pregnancy rate was higher (46 versus 24% P<0.05) for those with AR >21% in IVF. CFF and pregnancy rate in ICSI did not differ according to AR. Pregnancy rate was higher for those with an AR >22% for HIT + IUI (23 versus 11% P<0.01).

CONCLUSIONS

Ionophore-induced AR appears to be a useful indicator in addition to routine semen analysis for selection of patients for treatment with appropriate assisted reproduction procedure.

The human sperm head: a key for successful fertilization

In order to examine the predictive value of determining the sperm head shape, the acrosomal size, the presence of acrosomal vacuoles, and the challenged acrosome reaction (AR) on the outcome of a standard in vitro fertilization (IVF) program, a prospective study was conducted that included 75 couples undergoing IVF treatment. An assessment of sperm morphology was performed using the Hobson Sperm Tracker (Hobson Tracker Limited, Sheffield, United Kingdom). The assessment of the AR was performed before and after adding pooled undiluted human follicular fluid (FF). The outcome measure was an IVF rate of inseminated oocytes. A positive correlation was found between the fertilization rate (FR%) and the proportion of the sperm with a normal (oval) head shape (P <.001), the sperm exhibiting acrosomal vacuoles (P <.003), the sperm with a normal acrosomal size (40%-70% of total head area, P <.025), and the sperm undergoing AR after adding FF (P <.001). Multiple logistic regression analysis revealed that by incorporating the above 4 parameters, the sensitivity of prediction of IVF FR% values was 79%, and the specificity was 93%, with a positive predictive value of 96%. This study shows that the multiparametric assessment of the sperm head is useful in predicting the FR% values of a standard IVF treatment. The automated analysis used in this study is shown to maintain a level of precision and accuracy acceptable for application in a routine semen analysis situation.