A Prospective Study to Evaluate the Changes in Vaginal Cytology and its Correlation with Bishop's Scoring to Predict the Onset of Labor

Aim To evaluate the vaginal cytological changes and its correlation with Bishop?s scoring in predicting the onset of labor. Material and Methods: In our study 100 antenatal patients admitted in the labor ward of Shri Ram Murti Smarak Institute of Medical Sciences, Bareilly in prelabor stage were enrolled and were subjected to vaginal cytology and Bishop's scoring. 50 preterm patients (less than 37 weeks) were considered as control for comparison of vaginal cytology. The prelabor subjects were followed in early labor to correlate the cytological changes at onset of labor and duration of onset and progression into labor and also to determine validity of cytological changes against Bishops scoring in predicting labor onset. Results: In preterm group, it was observed that maximum number of cells/hpf were intermediate cells with cell number greater than 30/hpf at less than 36 weeks gestation. Beyond 37 weeks there is alteration in ratio of progesterone to estrogen which reflects an increase in number of superficial cells decrease in intermediate cells and cluster cells. At onset of labor cervical changes leads to increase in Bishop's score, hence Bishop's score increases from prelabor to early labor group. The comparison between superficial cells on Pap smear and Bishop's score was statistically significant and had 83.83 % predictive value compared to bishop score in predicting labor onset within 3 days if superficial cells were greater than 30/hpf. Conclusion: Vaginal cytology and Bishop?s score both can predict labor independently but Pap smear being an objective test has higher sensitivity and specificity compared to Bishop?s score which is more a subjective test.