Use of the acrosome reaction to ionophore challenge test in managing patients in an assisted reproduction program: a prospective, double-blind, randomized controlled study.

Objective: To assess the utility of the acrosome reaction (AR) to ionophore challenge test in determining the sperm treatment protocols for patients undergoing assisted reproduction.
Design, Setting, Patients: One hundred twenty-one couples undergoing an IVF-ET or GIFT procedure from January to July 1992 were included in this prospective study. All cases had a preliminary semen analysis within the previous 3 months and an AR to ionophore challenge test was carried out unless an acceptable fertilization rate occurred on previous IVF. For those patients whose AR to ionophore challenge score was below the accepted fertile range of > or = 10%, a second AR to ionophore challenge test was performed after exposure of sperm to the stimulant pentoxifylline. Couples then were managed by assisted reproduction with randomized allocation of oocytes for fertilization with a standard sperm preparation or with added sperm stimulants, either 3.6 mM pentoxifylline alone or combined with 3.0 mM 2-deoxyadenosine. The study was double-blind with neither the patients nor the embryologist knowing the AR to ionophore challenge result at the time of the IVF procedure.
Main Outcome Measures: Data from the preliminary semen analyses and AR to ionophore challenge scores were correlated with the fertilization rates achieved using control and treated sperm preparations. The rates of total fertilization failure and the numbers of clinical pregnancies occurring in each subgroup were also recorded.
Results: All AR to ionophore challenge groups showed normal sperm counts except the groups with poor AR to ionophore challenge, which demonstrated reduced sperm counts. The group with normal AR to ionophore challenge scores or previous normal fertilization showed satisfactory fertilization rates with either control or treated sperm, although some individual cases showed reduced fertilization with treated sperm. The fertilization rate for the group with low AR to ionophore challenge scores improved significantly with pentoxifylline, and the benefit was greatest when this had been predicted from the AR to ionophore challenge studies. Cases with persisting poor AR to ionophore challenge despite pentoxifylline showed no significant improvement in fertilization rates with sperm exposed to either sperm stimulant regimens. Poor AR to ionophore challenge scores were also predictive of total fertilization failure, but this problem was reduced by sperm stimulation. The AR to ionophore challenge score at 10% cutoff level showed optimal levels of sensitivity (82.1%), highest negative predictive value (82.1%), and lowest false negative rate (17.9%).
Conclusions: The AR to ionophore challenge test is useful in the assessment and management of the male factor in assisted reproduction. It can be used to identify the majority of cases who will benefit from the use of sperm stimulants.