Abnormal labour (dystocia)

What it is

Normal labour is defined as progressive cervical effacement and dilatation resulting from regular uterine contractions of sufficient frequency, intensity and duration, and this is preceded by the descent of the fetal presenting part.

Abnormal labour, dystocia or dysfunctional labour is defined as difficult labour or child birth. And the page states its weight in one line: abnormal labour or dystocia is the number one cause of primary caesarean section.

The four causes

Power — uterine contractions and maternal expulsive efforts. Passage — the pelvis, meaning its size, shape and joint mobility; and tumour. Passenger — size and shape of the head, and fetal position and size. Psyche — stress and pain.

The phases, and what each is called

Labour has a latent phase and an active phase, and the active phase holds the first, second, third and fourth stages. On the curve the active phase is drawn as acceleration, then the phase of maximum slope, then deceleration — this is Friedman's curve.

Each phase has a name for what it does: the latent phase is the preparatory division, where the changes are in the cervix; the active phase is the dilatational division, with rapid dilatation of the cervix; and the second stage is the pelvic division, where the cardinal fetal movements occur — flexion, descent, rotation and the rest.