Intra-amniotic and extra-amniotic injection of sodium chloride solution: Amniotic fluid salinity and abortifacient effect

Abstract

Damage to the decidua rather than to the trophoblast has been implicated to play a role in the induction of hypertonic saline abortion. In the present study, replacement of amniotic fluid by 5 per cent saline solution injected intra-amniotically did not result in abortion in any of 5 patients studied. In contrast, extra-amniotic injection of 20 per cent saline solution induced abortion in 16 of 19 patients despite the fact that the salinity of the amniotic fluid did not rise above 4.4 per cent. Furthermore, physiologic (0.9 per cent) saline injected extra-amniotically provoked abortion in 3 of 6 patients. These findings, together with earlier observations, may indicate that saline does not exert its effect by acting on tissues within the amniotic sac or in the fetal part of the placenta but rather by acting on extra-amniotic tissues. It is suggested that the decidua might be the target for the action of hypertonic saline.