A retrospective study was undertaken to investigate whether viscosity alter
s sperm chromatin integrity. Semen samples were obtained from 269 men atten
ding the infertility clinic. The viscosity was measured quantitatively by n
eedle and syringe method and the viscosity ratio was calculated against dis
tilled water. The chromatin integrity was evaluated by in vitro decondensat
ion test using 1% SDS and 6 mM EDTA. According to the viscosity ratios the
samples were divided into 2 groups: I, normal (ratio < 9, n = 239); and II,
abnormal (ratio > 9, n = 30) viscosity. Chromatin integrity was significan
tly lower in the group with higher viscosity. Significant decrease in sperm
count and motility were seen in group II as compared to group I. Thus, hyp
erviscosity of seminal fluid alters the sperm chromatin integrity.