Pregnancy outcome after intracytoplasmic sperm injection with strontium oocyte activation in a globozoospermic patient.

Dear Editor, I am Dr Xiao-Yu Yang, from the Center of Clinical Reproductive Medicine in the First Affiliated Hospital at the NanJing Medical University, Nanjing, China. We present here a case report of a globozoospermic patient whose partner became pregnant after intracytoplasmic sperm injection (ICSI) with assisted oocyte activation (AOA). Globozoospermia is characterized by the presence of 100% roundheaded spermatozoa lacking an acrosome. The lack of the acrosome, which renders spermatozoa unable to bind to the zona pellucida or fuse with the oocyte oolemma, is considered to be the cause of infertility in these patients. The introduction of ICSI provided a possible solution for patients suffering from globozoospermia. Since then, many cases of successful pregnancies after ICSI with globozoospermic sperm have been reported; however, the fertilisation rate after ICSI in these cases has been low, and some patients failed ICSI treatment because of limited or failed fertilisation. Fertilisation failure was initially attributed to the reduced ability of globozoospermic sperm to activate the oocyte. Rybouchkin et al. demonstrated that the fertilisation rate was improved by the addition of a calcium ionophore. After that, ICSI combined with AOA was effectively used in many studies to improve the fertilisation rate and embryo development and to achieve live births from globozoospermic sperm from men with previously failed fertilisation attempts. Various methods of AOA, including the use of a calcium ionophore and electrical and mechanical stimuli, have been reported to be effective for fertilisation in men with globozoospermia. Strontium treatment, which is proven to induce calcium oscillations in mice, was found to be an effective method for AOA in cases of low or absent fertilisation after ICSI. Whether strontium is effective at improving fertilisation by globozoospermic sperm has not been reported. We report a successful case of a twin pregnancy resulting in live births following ICSI and strontium oocyte activation with round-headed sperm. A couple with primary infertility of 5 years’ duration visited our centre. Both members of the couple were 27 years old and healthy, with no physical problems other than the husband’s semen parameters. The wife had no fertility problems. Analysis of a semen sample showed normal values for volume (3.3 ml), sperm concentration (56310 ml) and motility (45%). The Diff–Quik staining method revealed that 100% of the spermatozoa were round-headed and lacking an acrosome (Figure 1). Assessment of the acrosome with fluorescent Pisum sativum agglutinin staining of the human spermatozoa was also conducted (Figure 1). Ultrastructural characteristics of the round-headed sperm were evaluated using a scanning electron microscope (JEOL Technics Ltd, Akishima-Shi, Tokyo, Japan) (Figure 1). Spherical heads without acrosomes are shown. The karyotypes of the couple were obtained from peripheral lymphocytes and were 46,XX in the wife and 46,XY in the husband. A conventional long protocol was used to stimulate follicular development. Two cycle attempts were conducted. In the first cycle, the couple decided to undergo the conventional ICSI procedure. ICSI was performed on 20 metaphase II oocytes. Following ICSI, four oocytes were normally fertilized. Three days after insemination, two embryos reached the four-cell stage and one reached the three-cell stage without fragmentation; one did not cleave. Two embryos in the four-cell stage were transferred; however, pregnancy did not occur. After the failure of the first ICSI cycle, the couple decided to conduct SrCl2 oocyte activation on the retrieved oocytes as part of the next attempt. Only three reports involving four patients undergoing SrCl2 for human oocyte activation have been published, making SrCl2 oocyte activation highly experimental. The risks of the treatment were explained in detail, and informed consent was obtained from the couple. The study protocol was approved by the local ethics committee of the First Affiliated Hospital of NanJing Medical University. The second attempt was conducted 10 months after the first one using the same long ovarian stimulation protocol. Fifteen metaphase II oocytes were obtained and were randomly divided into two groups. Ten oocytes (Group B) underwent ICSI treatment combined with