Inaccuracy in cervical dilatation assessment and the progress of labour monitoring.

Cervical dilatation is an essential indicator of the progress of labour and it is assessed several times during every vaginal delivery. For a long period of time, the size of the error in cervical dilatation assessment was considered of no importance and only in the last ten years it was estimated. The hypothesis is that the estimated error of +/-1cm in cervical dilatation assessment and inaccurate values for the rate of cervical dilatation, influence decisions of obstetricians during labour. It is suggested that in labours in which the rate of cervical dilatation is 1 cm/h the possibility of drawing incorrect conclusions upon progress of these labours is 11 and 33% for time intervals between assessments of 4 and 2 h.