The First World Congress On: Controversies in Obstetrics, Gynecology & InfertilityPrague, Czech Republic - 1999
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Vaginal delivery after previous caesarean section (CS) raises an important issue in obstetric care.As we enter the new millennium the answers remain largely controversial. Vaginal delivery is safer for both the mother and the baby, is associated with lower morbidity and saves money for all concerned. A rise of 1% in the CS rate costs the National Health Service an extra five million pounds per year in the U.K.1 A normal vaginal delivery amounts to a saving of £760 compared to a CS delivery. These costs relate to an easy delivery and a failed trial of labour resulting in an emergency CS would greatly narrow these cost estimate differences.
There are many studies, mostly case-controlled, reporting trial of labour following previous CS. Rosen et al2 published a meta-analysis in 1990 of six studies which included a total of 1015 women. 75% of these women had a successful trial of labour, however those with two previous sections had a 30% lower probability of a vaginal delivery. Similar results were noted by Miller et al3. Over a 10 year period they showed that a policy of trial of labour lowered the CS rate by 6.4%. The major benefit was seen in the group who had undergone one section in the past. They constituted 5.5% of the over-all figure of 6.4%. There was however a three-fold increased risk of uterine scar rupture in women with two previous CS. A recent prospective study, which analyzed 130 women with two previous sections, reported two cases of uterine scar rupture4. Overall these studies report vaginal delivery to be successful in 50-75% of cases of two previous sections, however there is a more than 1% risk of uterine tear.4At present this is not a reducible complication as there are no reliable methods to predict the strength of the uterine scar following a CS.
Uterine rupture carries a real risk of hypoxia to the fetus and serious damage occurs 18 minutes after the onset of a hypoxic insult.5The actual reported morbidity and mortality following a trial of labour is low .The morbidity associated with a failed trial of labour is however greater than that associated with an elective CS. In a well designed study involving 6,138 women, McMahon et al 6 have reported an increased morbidity amongst women who chose a trial of labour following a previous CS, but were unsuccessful and needed a CS later. There was an increased incidence of uterine rupture, operative injury and hysterectomy in this group. The total complications were increased almost two fold with major complications rising by a value of nearly five times. There are no reliable tests at present to predict outcome following a trial of labour . Any such test would need to have a high sensitivity and specificity in order to obtain a reasonable balance between the reduction in morbidity and the total rate of caesarean deliveries.7
Central to the debate of a vaginal delivery following a previous section centers around the prospective mother herself. Women are less likely to accept any risk to their babies when compared with their treating physicians.8 They are no longer a passive recipient of care as is evident from the fact that maternal wish figures more and more as an indication for a repeat caesarean section. Patient demand was the third commonest reason for a repeat section in a recent study from a District hospital in the United Kingdom.9 An anonymous postal survey found that knowledge of the effects of normal labour on the pelvic floor, influences the mode of delivery women choose.10 31.1% of female obstetricians requested an elective CS for an uncomplicated full term singleton pregnancy. The bottom line is that a well informed consumer’s choice may still be a repeat section regardless of the advocated benefits of a trial of vaginal delivery.
At this moment efforts to reduce CS with its associated morbidity and its implications to a woman’s obstetric future will have to focus on ways and means to reduce primary sections while offering trial of labour to those with one uterine scar.
1 AUDIT COMMISION First class delivery: improving maternity services in England and Wales. Abington: Audit Commission Publications, 1997.
2 ROSEN MG, DICKINSON JC, WESTHOFF CL. Vaginal birth after caesarean: a meta-analysis of morbidity and mortality. Obstet Gynecol 77:465-70, 1991.
3 MILLER DA, DIAZ FG, PAUL RH. Vaginal birth after caesarean: a 10 year experience. Obstet Gynecol 76:255-8,1994.
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6 McMAHON MJ, LUTHER ER, BOWES WA Jr.,OLSHAN AF. Comparison of a trial of labour with an elective second caesarean section. N Eng J Med 335:689-95, 1996.
7 MACONES GA. The utility of clinical tests of eligibility for a trial of labour following a caesarean section: a decision analysis. Br J Obstet Gynecol 106:642-46, 1999.
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9 ATIBA EO, ADEGHE AJ, MURRAY PJ, FLEMINGHAM JE, SCOTT GI. Patient’s expectations and caesarean section rate. Lancet 341: 246,1996.
10 AL-MUFTI R, McCARTHY A, FISK NM. Obstetricians’ personal choice and mode of delivery. Lancet 347:544,1996.