Uterine rupture

What it is

Uterine rupture is one of the obstetric emergencies, the one of the uterus itself, next to the placenta (abruption, previa) and the fetus (vasa previa, cord prolapse, shoulder dystocia). It shows up in three lists at once, and that is the whole of it: it is a cause of antepartum hemorrhage, which is bleeding after 24 wks of gestation; it is a cause of shock in obstetrics; and it is the maternal risk that sets who may labour after a previous Cesarean section and who may not.

Causes and risk

The uterus that has been cut before is the uterus that ruptures:

• Previous classical or T shape incision
• Previous uterine rupture
• Previous myomectomy, or any transmural uterine incision, including metroplasty

Uterine rupture is a long term complication of Cesarean section, along with abnormal placenta, adhesions and subfertility. Labour itself adds to the risk:

• Shoulder presentation, whose cause is a transverse or oblique lie, and whose risks are cord prolapse, shoulder dystocia, uterine rupture and prolonged labour
• Induction of labour, where rupture or cervical tear is a named complication, along with hyperstimulation, cord prolapse and compression, infection and fetal death
• Augmentation or IOL, which raise the failure rate of a trial of labour
• Grand multiparity and uterine overdistension, as in polyhydramnios or multiple pregnancy
• Fundal pressure in shoulder dystocia, which is why it is avoided

The numbers are given for induction and augmentation: a 2-3 fold increased risk of uterine rupture, and a 1.5 fold increased risk of cesarean section in induced or augmented labours compared with spontaneous labour, with a higher risk of rupture when the induction uses prostaglandin. Misoprostol is contraindicated in a woman with a prior cesarean section for this reason.