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40. Rupture Uterus
Keywords
Scarred uterusRupture uterusSpontaneous ruptureObstructed laborVBACPrior cesarean section40.1 Introduction
Rupture uterus is an acute catastrophic event occurring during pregnancy and labor resulting in grave complications to mother and the baby constituting obstetric emergency. High degree of suspicion and clinical skills are required to tackle this complication; failure to do so causes high rate of stillbirths and maternal morbidity and even mortality. The signs and symptoms associated with this acute obstetric emergency are usually nonspecific, causing delay in diagnosis and initiation of definitive management. The short time for instituting definitive therapeutic action makes uterine rupture in pregnancy a much feared event for medical practitioners.
40.2 Definition
Rupture uterus is defined as disruption of all the layers of uterus including visceral peritoneum (serosa) after 28 weeks of gestation with or without the baby lying in the peritoneal cavity. At times it may cause massive hemorrhage from edges of the disruption leading to hemoperitoneum and shock.
40.3 Incidence
The incidence of uterine rupture differs in scarred and unscarred uterus, common in former than latter. The incidence of uterine rupture is approximately 1 in 1536 pregnancies (0.07%). In modern industrialized countries, the uterine rupture rate during pregnancy for a woman with a normal, unscarred uterus is 1 in 8434 pregnancies (0.012%) [1]. The incidence of scar rupture as found out in a retrospective analysis of 7 years study in a tertiary hospital in India was 1 in 1633 deliveries (0.061%) [2]. The prevalence more or less has remained constant over a period of time. Due to improved obstetric care in case of complicated obstructed labor and institutional deliveries, the rate of rupture uterus has decreased, but at the same time, there is increased incidence of uterine rupture in previous cesarean section cases.
40.4 Risk Factors
- 1.
Scarred uterus—Scarred uterus of previous cesarean section is more prone for rupture as uterus is actively contracting in postpartum period, resulting in weakening of the scar [3, 4]. The occurrence of scar rupture is determined by number of previous cesarean section, previous myomectomy, previous metroplasty, inter conceptional period and type of uterine incision like low transverse, low vertical, classical in upper segment, high transverse, T-shaped. Likewise, vaginal delivery after previous cesarean section, post operative period like postpartum sepsis or wound infection, or resuturing and obstetric complication in present pregnancy like grand multipara, elderly, big baby, abnormal presentation, multiple pregnancy, contracted pelvis, dystocia, abnormal placentation and accidental hemorrhage, use of oxytocics to augment or induce labor all determine the occurrence of the scar rupture.
- 2.
Multiparity—There is thinning of uterine wall due to repeated childbirths, resulting in increased chances of spontaneous rupture [5]. If the pregnancy is complicated by previous scar, the chances of rupture uterus are doubled.
- 3.
Maternal age—Advanced maternal age is directly proportional to the incidence of rupture uterus as often the baby is macrosomic causing uterine dystocia [6].
- 4.
Placentation—Abnormal placentation like accrete, percreta, increta, previa, and abruption all weaken the uterine wall musculature and cause abnormal uterine activity and increased chances of uterine rupture.
- 5.
Injudicious use of oxytocics—Oxytocics like oxytocin and prostaglandins when used inadvertently can lead to uterine rupture especially in grand multipara and previous cesarean section patients [7–10].
- 6.
Multiple gestations—Overdistension due to multiple gestations or polyhydramnios in unscarred uterus is rarely responsible for uterine rupture, but when it is complicated by previous cesarean scar or pregnancy, complication mentioned earlier leads to increased chances of scar rupture. The ACOG 2010 guidelines for VBAC recommend that women with one previous cesarean delivery with a low transverse incision, who are otherwise appropriate candidates for twin vaginal delivery, may be considered candidates for TOLAC [11].
- 7.
- 8.
Dystocia and uncoordinated uterine action and hyperstimulation of uterus leading to obstructed labor can result in uterine rupture.
- 9.
Trophoblastic invasion of the myometrium by weakening the uterine musculature.
- 10.
Instrumentation like attempted forceps delivery through incompletely dilated cervix can cause uterine rupture.
- 11.
Uterine manipulation like external cephalic version, internal podalic version, and manual removal of placenta all cause increased chances of uterine rupture in scarred and unscarred uterus.
- 12.
Trauma to the uterus in the form of either direct blow to the abdomen or fall or accidents can result in traumatic rupture of the uterus.
- 13.
Couvelaire uterus as in abruption of the placenta—The blood from concealed hemorrhage is accumulated in the uterine walls causing weakening of the musculature with abnormal uncoordinated uterine action.
40.4.1 Rupture of the Unscarred Uterus
Rupture of unscarred uterus also known as spontaneous rupture is usually an uncommon occurrence. A healthy uterus is unlikely to give way in labor and less so in pregnancy. The causes are previous damage to the uterine wall due to previous dilatation and curettage or manual removal of the placenta, grand multipara due to thin uterine walls, congenital malformation of the uterus like bicornuate uterus, and weakening of walls in couvelaire changes of uterus in abruptio placenta. During labor, however, the causes of rupture of unscarred uterus include obstructed labor and grand multipara more so with the inadvertent use of oxytocics.
The rupture of the uterus is usually complete and involves the upper segment and occurs later in pregnancy. The rupture due to obstructed labor involves the thinned-out lower segment and usually extends from one lateral side of the uterus to the upper segment, whereas the nonobstructive rupture involves fundal region and usually complete.
40.4.2 Rupture of the Scarred Uterus
The rate of primary cesarean section is alarmingly increasing since the last two decades posing a major threat in rising incidence of scar rupture as the main reason of increased uterine rupture. The scar of myomectomy and metroplasty rarely gives way as these procedures are done in nonpregnant state and scar heals well due to uterine quiescence, and when they rupture, they give way in late third trimester or early in labor [13]. On the contrary, the scar of previous cesarean section and hysterotomy is of more concern especially on the latter.
The scar of classical cesarean section is likely to rupture in later months of pregnancy, whereas scar of lower-segment cesarean section gives way during labor predominantly. However, the scar of classical cesarean section, hysterotomy, and myomectomy is more at risk of rupture during labor. Rupture in previous low transverse uterine incision is increased by a subsequent trial of labor, subsequent augmentation of labor, subsequent induction of labor, the use of prostaglandins, inter-delivery interval (cesarean delivery and subsequent conception if it is <6 months), one layer versus two layer closure, more than one prior delivery, maternal age, fetal macrosomia, multiple gestations, and gestation beyond 40 weeks [14]. Previous successful vaginal delivery and subsequent successful VBAC have a protective association. Current ACOG guidelines discourage the use of prostaglandins to induce labor in most women with a previous cesarean delivery.
The incidence of scar rupture is 1–2% in lower-segment scar, whereas it is five to ten times more in classical cesarean section.
Rupture of the uterus at fundus in bicornuate uterus. The fetus was lying in the peritoneal cavity with hemoperitoneum. Uterine repair was done to conserve future childbearing (Image is from personal collection of the author)
40.5 Pathology of Uterine Rupture
40.5.1 Types
- 1.
Incomplete rupture: Incomplete rupture usually results from rupture of previous lower-segment uterine scar and may extend up to the cervix and fornix causing colporrhexis. It may result from upward extension of cervical tear during difficult instrumental delivery with or without formation of broad ligament hematoma. In incomplete rupture, the peritoneal layer is intact, and the placenta and fetus remain inside the uterine cavity, or part of the fetus may lie between the layers of broad ligament.
- 2.
Complete rupture: Complete rupture occurs when the scar of classical cesarean section gives way in upper segment or in spontaneous rupture of obstructive or nonobstructive variety. In complete rupture, the peritoneal coat is not intact resulting in fetus with or without placenta escaping out of uterus and lying in peritoneal cavity. The uterus remains contracted without much of blood loss unless a major vessel is affected.
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