Pattern of cervical dilatation in women with a previous cesarean section

OBJECTIVE(S) : To examine the role of intrapartum cervicogram in vaginal birth after cesarean section (VBAC). METHOD(S) : Prospective partographic analysis of 81 women who had one previous cesarean section was done. Duration of labor, initial dilatation rate (IDR) and average dilatation rate (ADR) were calculated. Statistical analysis was done with 'Z' test. RESULTS : Vaginal birth was successfully achieved in 74%. The mean duration of first stage and of second stage of labor were 10.93 +/- 5.86 hours and 23.44 +/- 16.23 minutes respectively. The mean duration of first and of second stage were shorter in women with previous vaginal birth compared to those who had no previous vaginal birth. The mean IDR and ADR of vaginally delivered women were 0.74 cm/hour and 1.14 cm/hour respectively. The women requiring repeat cesarean section had significantly slower dilatation rate (mean IDR 0.4 cm/hour, mean ADR 0.29 cm/hour). Ninety-five percent of the women with IDR >= 1 cm/hour and 97% women with ADR > 0.5 cm/hour delivered vaginally while 67% women with IDR < 0.5 cm/hour and 87% women with ADR < 0.5 cm/hour required repeat cesarean section. Alert line was crossed in 25 women and 21 of them required repeat cesarean section. CONCLUSION(S) : IDR > 1 cm/hour and ADR > 0.5 cm/hour have 95% and 97% positive predictive value respectively for VBAC. Alert line is helpful in identifying cases requiring intervention.