Answers

Short answers

1 Women who have had a caesarean section should be reviewed by a consultant obstetrician early in the antenatal period and have a thorough discussion about the problems related to mode of delivery.

2 Uterine rupture is the most likely diagnosis; it can cause death of the baby from asphyxiation and death of the mother from haemorrhage and blood loss.

3 The patient should be prepared for immediate delivery by caesarean section and the consultant obstetrician, anaesthetist, and paediatrician should be summoned.

Long answers
1 Advice
Women who have had a caesarean section should see a consultant obstetrician early in the antenatal period and have a frank discussion about the problems that may arise in relation to mode of delivery. Risks and benefits should cover success rates, uterine rupture, perinatal mortality, and surgical complications. Absolute and relative risks should be presented. Written information or decision aids should supplement the discussions.^{1 2} In the event of an adverse outcome, many of these cases will result in litigation. Clear documentation of all discussions and decisions is essential.

Women with a history of one uncomplicated lower segment transverse caesarean section, with no contraindication to vaginal delivery, in an otherwise uncomplicated pregnancy at term, should discuss the advantages and disadvantages of planned vaginal birth after caesarean and elective repeat caesarean section.³ The operative notes from the previous delivery should be reviewed (or a summary requested if performed elsewhere) and should help inform the advice given. An ultrasound scan should be performed to document the placental location. The final decision on mode of delivery should be agreed before the expected date of delivery (ideally by 36 weeks’ gestation).³ If the woman decides on an elective caesarean section, this should be performed at 39 weeks’ gestation, with a contingency plan in place in the event of spontaneous labour before this date.³ Infants born by elective caesarean section before 39 weeks’ gestation are at increased risk of neonatal respiratory morbidity.⁴ Women should be informed that 72-76% of those who undergo a trial of labour after a previous caesarean section will achieve a successful vaginal delivery.^{5 6 7} This proportion rises to 87-90% if the woman had a previous vaginal delivery and 90-95% if she had a previous vaginal birth after a caesarean.^{8 9 10}

Contraindications to vaginal birth after caesarean include having had a classic caesarean section, uterine rupture, or three or more caesarean deliveries.³

The specific risks and benefits of vaginal birth after a caesarean should be discussed. Planned vaginal birth after a caesarean is associated with a risk of uterine rupture of 22-74 per 10 000.^{5 11} In contrast, elective repeat caesarean section carries almost no risk of uterine rupture.⁵ Compared with elective repeat caesarean section, vaginal birth after caesarean carries about a 1% extra risk of endometritis or needing a blood transfusion.⁵ Women considering vaginal birth after a caesarean should also be informed that the risk of intrapartum death is higher than for elective repeat caesarean section (10 per 10 000 v 1 per 10 000).⁶ The absolute risk of birth related death in this situation is comparable to that seen for the first birth.^{6 12} The risk of hypoxic ischaemic encephalopathy is 8 per 10 000 and 0 per 10 000 for vaginal birth after a caesarean and elective repeat caesarean section, respectively,⁵ although the risk of neonatal respiratory problems is higher for the elective repeat caesarean section (3-4% v 2-3%).^{4 13 14} Women should be informed that the risk of anaesthetic complications is very low, irrespective of mode of delivery.¹⁵ It is important to discuss future potential pregnancies with the woman and alert her to the potential increase in risk of serious complications, including placenta percreta or placenta accreta; damage to the bladder, bowel, ureter, or blood vessels; and the need for a blood transfusion, admission to the intensive care unit, or a hysterectomy.¹⁶

Intrapartum management should be conducted in a suitably staffed and equipped delivery suite, with continuous intrapartum care and electronic fetal monitoring, and recourse to immediate caesarean section and advanced neonatal resuscitation.³ Epidural anaesthesia is not contraindicated in planned vaginal birth after a caesarean.¹⁵

Women with a previous caesarean delivery should also be advised about induction of labour and oxytocin augmentation. The incidence of uterine rupture increases twofold to threefold, and the risk of caesarean section rises 1.5-fold in induced or augmented labours compared with spontaneous labours.⁵ Induction with prostaglandin further increases the risk of uterine rupture.¹⁷ If induction or augmentation are proposed, discussion with the consultant obstetrician is essential.³

2 Diagnosis
The most likely diagnosis is uterine rupture. Uterine rupture may be defined as a disruption of the uterine muscle, extending to and affecting the uterine serosa, or disruption of the uterine muscle, with extension to the bladder or broad ligament.⁵

Uterine dehisence is defined as disruption of the uterine muscle with an intact serosa.⁵ Intrapartum uterine rupture is a life threatening emergency that can result in death or serious morbidity for both the mother and her baby.¹⁸

It is important to have a high index of suspicion in patients at risk of uterine rupture and to anticipate the clinical warning signs. The most consistent finding is an abnormal cardiotocograph (usually late decelerations or fetal bradycardia), which is seen in 55-87% of cases.^{18 19} Other symptoms and signs of uterine rupture include severe abdominal pain which persists between contractions.²⁰ The woman may have chest pain, shoulder tip pain, or shortness of breath.²⁰ An acute onset of scar tenderness, vaginal bleeding, or haematuria may occur.²⁰ Previously efficient uterine activity may cease.²⁰ The woman may have tachycardia or be hypotensive or shocked.²⁰ Vaginal examination may show loss of station of the presenting part.²⁰

Although uterine rupture occurs most commonly in women who have had a previous caesarean section it can occur after any type of uterine instrumentation, including dilatation and curettage, hysteroscopy, and forceps delivery.²¹ Risk factors for rupture of an unscarred uterus include grand multiparity, cephalopelvic disproportion, malpresentation, administration of oxytocin, fetal macrosomia, placenta praevia, placenta percreta, external cephalic version, and uterine abnormalities.²²

3 Management
The patient should be prepared for immediate delivery by caesarean section and the most senior available obstetrician, anaesthetist, and paediatrician should be directly involved in her management pending the arrival of consultant personnel. Emergency management includes securing adequate intravenous access and maintaining the woman’s airway, breathing, and circulation. The operation should be performed under general anaesthetic. Massive blood loss is likely and the local major obstetric haemorrhage protocol should be implemented. A complex surgical procedure should be anticipated, often involving repair of the uterus and bladder, and in some cases hysterectomy may be required. Advanced resuscitation of the newborn is likely to be required, and sometimes difficult end of life decisions need to be made in the neonatal period.²³ The parents will need careful debriefing at a later stage about the nature of these dramatic events and any adverse outcomes.

Cite this as: BMJ 2009;339:b2979