10.2.3 Inappropriate use of uterotonic agents
Whenever you use a uterotonic drug (drugs that cause uterine contraction, e.g. misoprostol, oxytocin or ergometrine) for active management of the third stage of labour (recall Study Session 6), you must first check that there is no other fetus in the uterus. This is because if you mistakenly administer a uterotonic agent when there is still a fetus in the uterus, it will contract so powerfully that it can easily rupture, especially in the case of multiparous women. Also it is likely to asphyxiate the baby.
Why are multiparous mothers at greater risk of a ruptured uterus than primiparous women?
Scarring of the uterus is a major risk factor in uterine rupture, because scar tissue is less flexible and may tear open during contractions. A multiparous woman may have scars from a caesarean, or from a complicated earlier delivery which damaged the birth canal. Also, her uterus will go on contracting for a long time without developing uterine inertia, even if the labour is obstructed.