Fertilization and early embryology: Ongoing pregnancies and birth after intracytoplasmic sperm injection with frozen--thawed epididymal spermatozoa

In seven patients who did not become pregnant following microsurgicalepididymal sperm aspiration (MESA) and intracytoplasmic sperminjection (ICSI), a subsequent ICSI was performed using previouslycryopreserved supernumerary epididymal spermatozoa without re-operatingon the husband. During the original MESA procedure a mean spermconcentration of 12.3x10⁶/ml was achieved. The supernumeraryspermatozoa were cryopreserved for later use. After thawingfrozen epididymal spermatozoa a mean concentration of 1.9x10⁶spermatozoa/ml was obtained in straws containing a total volumeof sperm suspension of 250 µl. From 68 intact oocytesinjected with frozen—thawed epididymal spermatozoa, atwo pronuclear fertilization rate of 45% and a cleavage rateof 82% were obtained. A total of 17 embryos were replaced inthe seven patients, resulting in two ongoing singleton pregnanciesand one twin delivery. Six embryos were cryopreserved. In conclusion,it would appear mandatory to cryopreserve supernumerary spermatozoaduring a MESA in order to avoid subsequent further scrotal surgery.