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Rapid Responses: Rapid Responses published:
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Vaginal birth after caesarean section is not necessarily beneficial
- Paul T-Y Ayuk (26 June 2007)
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Are these results, statistically significant?
- Preetham Kodumuri (28 June 2007)
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Effects of unblinding
- Emuobonuvie J Emoghware (29 June 2007)
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Ethical issues of consent
- Suryanarayana Kakkilaya, Vasudevan Edamana Krishnan (29 June 2007)
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Paul T-Y Ayuk, Obstetrician and Gynaecologist John Radcliffe hospital, OX3 9DU
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The study by Montgomery et al. (1) and the accompanying editorial (2) are based on the premise that vaginal delivery after one caesarean section (VBAC) is necessarily a beneficial and desirable objective or outcome. This is reflected in the tendency of obstetricians and midwives to promote VBAC. However, the risks and benefits of VBAC as published in the recent RCOG guidelines (3) can be summarised as follows: Risks associated with VBAC 1) Uterine rupture ~22–74/10,000 2) 1% increase in risk of endometritis (289/10,000 versus 180/10,000) 3) 1% increase in need for blood transfusion (170/10,000 versus 100/10,000) 4) 2–3/10,000 additional risk of birth-related perinatal death when compared with planned caesarean section (C/S) 5) Increased risk of antepartum still-births after 39 weeks with an overall increase in perinatal mortality at term 6) 8/10,000 risk of hypoxic ischaemic encephalopathy which may have long-term developmental implications. Benefits of VBAC 1) Probable reduction in risk of neonatal respiratory problems: 2–3% with planned VBAC and 3–4% with C/S 2) C/S may increase the risk of serious complications in future pregnancies. Given that most women in developed countries are unlikely to have more than 2-3 babies, the value of promoting VBAC is highly questionable. Maternal choice is central to pregnancy care, and the reduction in anxiety in the computer based decision analysis approach is welcome. The potential increase in the number of women choosing to, and delivering vaginally is presented as a positive outcome. This is not the case when considered in the context of the mortality and morbidity statistics above. Given these figures, an RCT of VBAC Vs C/S is likely to find increased mortality and morbidity in the VBAC group. Women with a breech presentation are no longer offered a choice between vaginal delivery and C/S on the basis of the results of the term breech trial (4). Must we wait for such a trial to recognise that VBAC costs and C/S saves lives? Women should have a choice, but this should not come before safety. To promote a process which is known to be associated with greater mortality and morbidity, or consider such a process as beneficial or desirable seems inappropriate irrespective of the reduction in women’s anxiety. Paul Ayuk 1) Montgomery AA, Emmett CL, Fahey T, Jones C, Ricketts I, Patel RR, Peters TJ, Murphy DJ et al. Two decision aids for mode of delivery among women with previous caesarean section: randomised controlled trial BMJ 2007;334:1305-1308 2) Lauer AP, Betrán JA. Decision aids for women with a previous caesarean section BMJ 2007;334:1281-1282 3) Birth after previous caesarean birth. RCOG green-top guideline no 45. Feb 2007. 4) Hannah ME, Hannah WJ, Hewson SA, Hodnett ED, Saigal S, Willan AR. Planned caesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Term Breech Trial Collaborative Group. Lancet. 2000;356:1375-1383. Competing interests: None declared |
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Preetham Kodumuri, Clinical attachment Royal Liverpool Childrens Hospital L12 2AP
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The study done by Alan A Montgomery
describes the primary analysis of Decisional conflict and mode of
delivery in pregnant women with a previous caesarean section. The
study had good design and randomisation was effective. The 3 groups were almost
similar before the trial.
It is worth noting that there is no mention of power calculation and out of 1148 women invited to participate in the trial only 742 were randomised. The study result describes the reduction in decisional conflict and they are statistically significant but the results of mode of delivery has huge confidence intervals and they cross the unity (statistically not significant). This is usually due to the small sample size. I feel that we will need more studies on this area to confirm these findings before making changes to the practice. Competing interests: None declared |
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Emuobonuvie J Emoghware, Honorary SHO Royal Liverpool University Hospital, Liverpool, L7 8XP
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This randamised case control study (1) looks at the effects of giving relevant information in different ways to help take decision about the treatment. Blinding is important in case control studies to minimise the bias. There is no mention about the steps taken to ensure blinding. Both interventions were delivered using personal computers and obviously there was no need for blinding. But the lack of blinding could have introduced bias in the control group. The positive effect of the intervention may just be due to the lack of information provided to the control group. (1). Montgomery AA, Emmett CL, Fahey T, Jones C, Ricketts I, Patel RR, Peters TJ, Murphy DJ et al. Two decision aids for mode of delivery among women with previous caesarean section: randomised controlled trial BMJ 2007;334:1305-1308 Competing interests: None declared |
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Suryanarayana Kakkilaya, Staff Grade Psychiatrist, Peasley cross resource centre, 5 Boroughs partnership NHS trust, St Helens, WA9 3DA, Vasudevan Edamana Krishnan
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Study by Montgomery et al, demonstrates a higher rate of vaginal delivery following the use decision making aid, in women with previous caesarean section compared to the group who received extensive information and asked to make an informed choice What is not clear is what factors are responsible for this?1. In the study participants were required to consider the value they attached to possible outcomes by rating each on a visual analogue scale from 0 to 100. Percipients were aware that they were part of a study and this might have influenced the choice 2. Investigators did not ask the participants to select their choice of mode of delivery 3. Medical Decision making (1) includes the cost effectiveness and cost benefit analysis. It is not clear if this was taken in to account in decision tree. Unless the reasons for this finding are clear, it will not be ethically correct to use decision making aid in clinical practice. (1)Sox HC, Blatt MA, Higgins MC, Marton KI. Medical decision making. Boston: Butterworth-Heinemann, 1988 Competing interests: None declared |
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