Despite the fact that caesareans are far more common than most people realise, the operation is still surrounded by a considerable amount of mystery. It is often difficult to distinguish between reliable up-to-date research-based information and the considerably larger bulk of accepted 'knowledge', much of which is based on opinions and practices that medical research calls into question.
Individual women are often in a position where 'informed choice' is impossible, since there appears to be only one sensible course of action - any alternatives remain hidden from consideration due to inadequate availability of information. For some women this may not be a problem, since they may be happy to trust to the experience of their health professionals and may welcome the freedom from responsibility that this can bring.
However, without full information, a mother may feel that she has no option but to accept the course deemed most appropriate by others. One of the main contributing factors to post-caesarean emotional trauma is a woman's loss of control. Many caesarean mothers feel that they had no alternative but to put themselves fully in the hands of the medical professionals. Good information can go a long way to enabling women to take part in the decision-making process, thus reducing such trauma.
A diagnosis of CPD is where the baby's head is thought to be too large to pass through the woman's pelvis. In the 18th and 19th centuries, poor nutrition, rickets and illnesses such as polio caused pelvic anomalies, which resulted in loss of life during childbirth. Indeed initially CPD was the most common reason for carrying out a caesarean. In modern times, however, CPD is rare, since our general standard of living is so much higher and true CPD is more likely to be caused by pelvic fracture due to road traffic accidents or congenital abnormalities.
Often CPD is implied rather than diagnosed. In cases where labour has failed to progress or the baby has become distressed, medical staff commonly assume that this is due to physical inadequacies in the mother rather than look towards circumstances of the mother's care. These problems frequently occur when CPD is not suspected and there are many other causes such as fear and uncertainty, difficulty adjusting to a medical environment, lack of emotional support and non-continuity of carer.
Many women worry about how something as big as a baby will come down such a narrow vaginal passage, so implications of pelvic inadequacy can confirm personal fears, lower self-esteem, affect the progress of any subsequent labour and add greatly to feelings of failure.
CPD is also sometimes suspected when the baby's head fails to engage, although both this and failure to progress have proved unreliable indicators.
When CPD is suspected, x-ray pelvimetry may be suggested, either antenatally or postnatally. This is when the mother's pelvis is measured by taking x-rays to assess pelvic adequacy. Quite apart from the health risks of x-rays,3,4 this method of pelvic assessment has been criticised since it has been shown to be inaccurate and because often the results do not influence the way that the delivery is managed.5 Due to concerns over x-ray exposure of women and babies, some hospitals offer pelvimetry by computed tomography (CT) scan which uses a much lower dose of radiation. However, there is no reason to believe that the resulting measurements will provide a more accurate diagnosis of CPD than conventional x-rays for the same reasons.
A woman's degree of motivation to achieve a vaginal delivery along with the level of support she receives are likely to be more influential on the outcome than her pelvic measurements. Even in undisputed cases of CPD, it should still be possible for a mother to go into labour without compromising the safety of her baby. In fact, a period of labour prior to caesarean section is believed to reduce the occurrence of respiratory distress and can therefore be beneficial for the baby.
In any case, CPD is difficult to diagnose accurately since there are no less than four variables that cannot be measured:
When a diagnosis of CPD has been made, many people still believe that this constitutes a reason for elective repeat caesarean section in future pregnancies, despite the wealth of evidence to the contrary. Indeed, there have been many documented cases where women have been diagnosed as having CPD and then gone on to deliver vaginally a larger infant than the one that was delivered surgically.
Karen, whose first baby remained high and was caesarean born due to failure to progress in labour, was diagnosed as having CPD following a CT scan. She went on to deliver a healthy 9lb 7oz baby vaginally.The Guide to Effective Care in Pregnancy and Childbirth'The likelihood of vaginal birth is not significantly altered by the indication for the first caesarean section (including "cephalopelvic disproportion" or "failure to progress").'
Some women will be able to accept and concur with a diagnosis of CPD, perhaps even preferring the caesarean way of birth, whereas others will want to be able to come to their own independent conclusions, and some of these may wish to labour again under more conducive circumstances, to have the chance to give labour their 'best shot'.
After one caesarean section, VBAC (pronounced vee-back - vaginal birth after caesarean) is widely accepted as appropriate and safe. However, after two or more caesareans, it is common policy for a mother to be automatically scheduled for an elective (planned) caesarean since it is believed that the risks of caesarean scar rupture increase with the number of caesarean operations.
Lack of evidence supporting this theory has led some researchers and obstetricians to question the basis for this accepted practice.8,9 Indeed, the highly respected Guide to Effective Care in Pregnancy and Childbirth concludes that: '...the available evidence does not suggest that a woman that has had more than one previous caesarean section should be treated any differently from the woman who has had only one caesarean section'.10
While the number of obstetricians willing to support a mother through labour after two caesareans is believed to be small, that number does appear to be increasing, leading the authors to believe that the tide may be turning in this respect. However, it is rare to hear of a vaginal delivery after three sections and the authors know of no cases in this country following four or more caesareans, although cases have been documented in the United States.
One reason for such low numbers of vaginal deliveries after multiple caesareans is the low parity in this country and it is known that women who undergo caesarean operations tend to have fewer children than average, although the reasons for this are not clear.
It must also be accepted that many women who have had multiple caesareans will have no desire to embark on a labour, having come to terms with the caesarean section as a mode of delivery, and who may well have come to prefer the caesarean way of birth. Others may well take the attitude 'better the devil you know'.
Consequently, the chances of an obstetrician encountering a woman in her fourth or subsequent pregnancy, who has had three or more caesarean sections and is well motivated to achieve a vaginal delivery, are slim at best, and he is unlikely to do so many times in his career. So few obstetricians are confronted with such a situation that knowledge of the true risks, or rather the lack of them, is sparse, and the confidence that comes with experience totally lacking. Individual mothers who wish to avoid further caesarean operations must therefore have access to information from other sources in order to facilitate truly 'informed choice'.
Those women who would like a home delivery are among those least likely to be able to labour effectively in a hospital environment and therefore among those most likely to 'end up' with a caesarean section.
Many mothers who have had a previous caesarean consider continuity of carer as a high priority. It is usually easier for a mother to ensure that she will receive continuity of care from someone she knows and trusts if she books a home delivery, although the reasons that mothers cite for booking home deliveries vary greatly.
Previous and current obstetric history do not, in fact, alter a woman's right to have a home delivery. All women, regardless of whether they are considered high or low risk, may opt for a home delivery. Area health authorities have a legal obligation to provide a competent midwife. GP and/or obstetric support is not a requirement, although there is an obligation upon the health authority to provide obstetric services, including those appropriate in the unlikely event of any emergency that should require specialist obstetric attention.
A home booking does not prevent a mother from transferring to hospital or obstetric care at any time during her pregnancy or labour. This could be because a new need has arisen or simply because the mother has changed her mind about her desired place of birth.
Mothers booking for a home delivery following a previous caesarean section are generally considered high risk, due to the remote possibility of problems with the caesarean scar. However, individual mothers will not book for home until they have satisfied themselves that the risk of this occurring is small.
The risk of rupture of a transverse lower segment scar is generally considered to be around 0.5%,11 which is one in 200 women. Although this may seem high, the majority of these cases result in minimal adverse effects on either mother or baby. The occurrence of poor outcome is considerably lower. In a review of all the VBAC studies carried out worldwide and documented in the International Childbirth Education Association (ICEA} Review published in August 1990 it was found that 'in over 21,000 planned labours after caesarean only five babies were reported to have died in association with scar rupture. This is less than one in 4,200 (0.02%). In the same sample 'twelve mothers lost their uterus due to scar rupture (0.06%). This is less than one- tenth the 0.7% hysterectomy rate reported for "obstetric hemorrhage" after caesarean section.'12
The same Review also states that 'There has been no report of a mother who has died due to rupture of a cesarean scar during planned labor after cesarean. In contrast, reports continue to document deaths of wonton due to complications of elective cesarean operations.'12
There is some debate about whether interventions such as prostaglandin gel induction and augmentation with oxytocin drip increase the risk of caesarean scar rupture.13
Many women feel that they will in fact be safer if their labour is not subject to the stresses of hospital and possible intervention. Many also believe that their labour is likely to be better monitored at home, as they are assured of care by an experienced midwife who is caring for only one mother and whose attention is free from the distractions of the hospital. The alternative is usually the share of a midwife with other labouring mothers, which can leave the mother alone for a considerable period should another labouring mother need the midwife's attention. Mothers who have had problems at home often comment on how quickly these were picked up and acted upon, as they had individual attention and there was mutual trust between the mother and midwife.
Although some mothers feel happier and safer in their home environment, others feel more relaxed in hospital where the proximity of obstetric facilities may provide reassurance. As with all mothers, place of birth is an individual decision and, regardless of obstetric history, mothers should be free to choose without the pressure of the opinions of others.
A classical caesarean is where a vertical incision is made in the main body of the uterus, which is more muscular and therefore contains more blood vessels. It is generally accepted that those women who have a classical uterine incision are not eligible for future vaginal delivery, because of the slightly higher risk of uterine rupture relative to the more usual lower transverse uterine incision (LSCS) and also because such ruptures are believed to be more likely to be of a serious nature. Mothers with other non-LSCS scars are often excluded for the same reasons.
The often quoted rupture rate of 2.2% for classical incisions is based on studies carried out more than 30 years ago. It is not known whether advances in surgical technology over recent decades will have affected this figure. Caesarean Birth in Britain points out that 'the classical incision was commonly done in days when anaesthesia was not so advanced and blood transfusions and antibiotics were not available, so that rapid surgery and wound infection led to a higher chance of a weak scar'.14
Until LSCS became common, it was not unusual for women with classical scars to go on to have vaginal deliveries. Indeed, in 1968 in Kenya, Professor Wendy Savage delivered a woman by caesarean of her 13th child. In 1946 and 1947, her first two children had been born by caesarean and she then had ten normal deliveries.'14
Even though the risk of scar rupture following a classical caesarean is acknowledged as being greater, some women will consider a 97.8% chance of having no difficulties with their previous scar as good odds. Individual mothers need to be enabled to balance their own views of the risks and benefits of vaginal or caesarean birth and come to their own supported conclusions about what is likely to be most appropriate in their individual case.
Although we need to ensure that good research-based information is available and accessible to those women who wish to make choices, it has to be acknowledged that not all mothers either want or are ready to receive such information, especially when this calls into question medical advice that they have received. However, this must not prevent us from fully supporting those mothers who are struggling to seek out sufficient information to enable them to maintain control and make their own informed choice, regardless of whether these are compatible with common obstetric practice or even research.
First published in the NCT publication NEW GENERATION DIGEST March 1997