Effect of vaginal douching with normal saline before insertion of dinoprostone vaginal insert for labor induction

Vaginal pH has been suggested to be one of the causative factors, responsible for variation in prostaglandin efficacy for induction of labour. The purpose of this study was to analyse the effect of vaginal douching with normal saline before insertion of dinoprostone vaginal insert for induction of labour.

This randomised controlled study was done in the Department of Obstetrics and Gynaecology for a period of 1 year. Using a computer-generated random number table, subjects were allocated in two groups. In group A (study group), vaginal douching was done with 20 cc of sterile 0.9% NaCl and vaginal pH was again measured with pH paper strips just before inserting dinoprostone pessary. Dinoprostone pessary was inserted without douching in group B (control group).

There was a significant increase in the vaginal pH after douching with normal saline (4.91 vs 5.52, P < 0.001). Mean intrinsic vaginal pH (pH before inserting dinoprostone insert) in women who delivered vaginally was significantly higher than that of the women who had a caesarean section (5.10 vs 4.63, P < 0.001). Time interval between dinoprostone insertion to active phase of labour, duration of active phase of labour, time interval between dinoprostone insertion, and complete cervical dilatation and mode of delivery were not significantly different between the two groups.

Although douching with normal saline increases vaginal pH, douching does not help in increasing the chances of vaginal delivery because it gives a transient effect. Rather, it is intrinsic vaginal pH, which is a better decisive factor for successful vaginal delivery.