Effect of amniotic sac puncture on parturition in rat.

Pregnant Charles Foster rats were subjected to amniotic sac puncture on day 15 of gestation and the effect was observed on parturition. All the control rats as expected delivered on day 22 of gestation. In the group where all the sacs were punctured, only 12.5% rats delivered on day 22 while rest either failed to deliver (62.5%) or died (25%). In the group with unpunctured sacs at vaginal ends, 75% rats delivered on day 21 while 25% on day 22. In the group with unpunctured sacs at ovarian ends, 75% rats delivered on day 23 and rest 25% failed to deliver. The resorption rates ranged between 61 to 94% in different groups. Malformations were observed only in one pup. The results suggest that amniotic sac puncture interferes with parturition in the form of either failure or delayed parturition. Nonpatency of the birth canal due to puncture induced fetal deaths and tissue adhesions were presumed to be the contributing factors.