Uterine rupture is a complication of labor in which the myometrium, the muscular layer of the uterus, ruptures. Doctors characterize the condition as an incomplete rupture or an incomplete rupture. In an incomplete rupture, which is also called uterine dehiscence, the outer layer of tissue surrounding uterus —called the serosa or the perimetrium— does not rupture, so the contents of the uterus remain separate from the surrounding peritoneal cavity. Complete uterine rupture is when the rupture goes through the myometrium and the perimetrium too. This releases the contents of the uterus, which can include the fetus and the placenta being released into the peritoneal cavity. As may imagine, this situation is a severe threat to the health and life of both the mother and the fetus (high morbidity and high mortality).
There are several factors that put you at elevated risk for uterine rupture. One major risk factor is a previous cesarean section (C-section), because the scar in the uterus is a weak point. Normally, cesarean birth is routine and extremely safe. This is true, whether you undergo an emergency C-section for complications like preeclampsia or failure of labor to progress, or whether it’s a planned, elective C-section. You have no reason to worry. But like any operation, or for that matter like vaginal delivery, there always is the possibility of complications. As with any surgical procedure, bleeding, pain, and infection are high on the list of possible complications. There also are various complications that can occur with the wound subsequent to the operation, plus there is a risk of endometritis and damage to local structures, such as the ureters, bladder, blood vessels, and bowel. Problems with the bowel include ileus, which is a temporary lack of normal contractions of the intestines. Additionally, there is a possibility of adhesions, meaning that scar tissue grows, potentially disrupting organs. Cesarean also increases the risk of future need for cesarean, uterine rupture, placenta previa, and stillbirth, plus there is the very rare possibility of later rupture, due to the weakened area along the scar.
This risk is particularly high in women undergoing vaginal birth after cesarean section (VBAC). This is because, in addition to having a weak area in the myometrium, the myometrium is contracting, putting a lot of pressure on that scar tissue. Use of oxytocin to induce labor by stimulating uterine contraction is also a risk factor. If oxytocin is given during a VBAC, the risks add together, making the risk particularly high. Oxytocin is a hormone that is produced in your brain, by cells in a part of the brain called the hypothalamus and is released by the pituitary gland into the blood. Various situations cause oxytocin to be released. These include sexual activity and breastfeeding, but they also include labor. Oxytocin stimulates uterine contractions and when your own oxytocin and the naturally occurring uterine contractions are not enough, doctors administer oxytocin from the outside to help labor along. So it is used in labor induction, but this can also lead to trouble.
Uterine rupture is extremely rare in women giving birth for the first time, but the risk increases for those who have given birth multiple times. Another risk factor is previous uterine surgery other than a C-section. Other risk factors include high BMI (obesity) and increased age.
A woman who develops uterine rupture will become extremely sick for a variant of reasons. One big reason is that the rupture causes hemorrhage, so there’s a dramatic drop in blood pressure, which can lead to shock. Typical symptoms of uterine rupture include abdominal pain and vaginal bleeding. Signs of uterine rupture include the cessation of uterine contractions that previously were underway, hypotension (low blood pressure) and tachycardia (rapid heartbeat) in the mother and various other indications of maternal collapse.
Uterine rupture is an emergency to which the medical team will respond rapidly. Doctors will initiate fluid resuscitation in which the woman is given fluids, and if needed blood products, to raise her blood pressure and compensate for blood loss. An emergency C-section will be performed to get the fetus out. This procedure may turn into a cesarean hysterectomy in which the damaged uterus is removed as well, but in some cases the uterus may be repaired.