Objective: To evaluate sperm preincubation in tes and tris (TEST)-yolk buffer as a potential enhancing agent of fertilizing capacity of sperm during human in vitro fertilization (IVF).
Design: Oocytes obtained during IVF were divided into two groups: one group fertilized with TEST-yolk buffer-treated sperm and the other group with standard-prepared sperm.
Setting: The University of Southern California IVF Program.
Patients: Thirty-nine couples with suspected male factor infertility undergoing IVF.
Interventions: Preinsemination incubation of sperm in TEST-yolk buffer for 24 hours.
Main outcome measures: Fertilization rates in vitro.
Results: TEST-yolk buffer-treated sperm fertilized 140 of 241 oocytes (58%), whereas control sperm fertilized 108 of 251 oocytes (43%). Of four couples who had previously failed to fertilize during IVF, one fertilized with both specimens and three fertilized with TEST-yolk buffer-treated sperm only.
Conclusions: TEST-yolk buffer pretreatment of sperm for 24 hours results in higher fertilization rates during IVF among suspected male factor patients.