Rates of caesarean section and instrumental vaginal delivery in nulliparous women after low concentration epidural infusions or opioid analgesia: systematic review

BMJ 2004; 328 doi: http://dx.doi.org/10.1136/bmj.38097.590810.7C (Published 10 June 2004)
Cite this as: BMJ 2004;328:1410

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EDITOR-The systematic review by Liu and Sia concludes that low dose epidurals do not increase the rate of caesarean sections.[1] The results of this review will reassure the multi-disciplinary labour ward teams of the relative safety of epidural anaesthesia in providing pain relief to women in labour.

It is recommended by professional groups that the majority of caesarean sections should be performed under regional nerve block.[2] This is because there is less morbidity and mortality associated with it than with general anaesthesia.[3]

We undertook a 15-month retrospective case note review of hospital notes at a district general hospital from April 2003 to examine anaesthesia usage during caesarean sections. There were 3418 deliveries of which, 748 (21.9%) were caesarean sections. 50 (6.8%) women underwent general anaesthesia, which is comparable to the figures in the literature.[2] Of particular interest we found that 21 (42%) of the general anaesthesia cases were because the epidural, which was in-situ failed or could not be extended for surgical anaesthesia and there was no time to site a spinal. This was identified as an area for improvement by the department. After a multi-disciplinary team meeting it was agreed that midwives and anaesthetists should regularly check on the effectiveness of the sited epidural so that if an emergency arose, which necessitated either instrumentation or caesarean section the regional nerve block could still cover it. A re-audit of this is now due.

A working in-situ epidural may not continue to deliver pain relief throughout labour. Our results add to Liu and Sia’s findings by highlighting the importance of monitoring the block provided by epidurals once they are sited, especially in women who are suspected by the labour ward team to require an emergency caesarean section.


1. Liu E, Sia T. Rates of caesarean section and instrumental vaginal delivery in nulliparous women after low concentration epidural infusions or opiod analgesia: systematic review. BMJ 2004;328:1410-1412.

2. Thomas J, Paranjothy S. Royal College of Obstetricians and Gynaecologists Clinical Effectiveness Support Unit. National Sentinel Caesarean Section Audit Report. RCOG Press, 2001.

3. Morgan B, Aulakh J, Barker J, Reginald P, Goroszeniuk T, Trojanowski A. Anaesthetic morbidity following caesarean section under epidural or general anaesthesia. Lancet 1984;323:328-330.

Competing interests: None declared

Competing interests: None declared

Hitesh Patel, Medical Student

Mitesh Patel (SHO Surgery Rotation, Kings College, London), Ayaz Aleem (Medical Student, Imperial College, London)

Imperial College

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Another systematic review in a prestigious general journal showing that epidural analgesia does not increase the caesarean section rate is to be welcomed.

Unlike previous meta-analyses,[1-3] Liu and Sia have included only studies of nulliparous women receiving low concentration epidural infusions, in order to re-examine their effect on instrumental vaginal delivery, in the belief that infusions containing low concentrations of local anaesthetic are associated with a lower risk of operative delivery than are higher concentrations.

They cite the COMET trial,[4] which could not have demonstrated this, as in this trial it was only possible to compare low and high dose bolus administration. There have been at least five other randomised comparisons of low and high dose epidural boluses, two of which showed a significant difference in delivery outcome, but aggregation of all the data does indeed show a significant effect.[5]

By contrast there have also been at least six randomised trials of low and high concentration infusions, none of which demonstrated a reduction in normal delivery rates with low concentrations, despite randomising over 800 women.[5]

I would not describe an infused concentration of bupivacaine of 0.125% with opioid as low; this is overkill: such a concentration is effective when bupivacaine is infused without opioid. In the infusion studies referred to above, the usual ‘low’ concentration was 0.0625%, yet no increase in normal deliveries was achieved. Had Liu and Sia analysed comparisons of low dose bolus epidurals with systemic opioid analgesia, it is possible that they might have found no significant effect on instrumental vaginal delivery.

Liu and Sia state that neonatal outcomes may be better with epidural analgesia. In 1974 three studies demonstrated improved fetal acid-base status and protection from the adverse effects of a pronged second stage with epidural analgesia.[6-8] Since then randomised studies have appeared, and meta-analysis has shown a significant benefit to the newborn in acid- base status with epidural analgesia of all types, compared with systemic opioids.[9]

Such good news is disregarded by radical midwifery groups, who still regard epidural analgesia as undesirable interference.[10] Let us hope that this latest evidence will receives better attention.


1. Halpern SH, Leighton BL, Ohlsson A, Barrett JFR, Rice A. Effect of epidural vs parenteral opioid analgesia on the progress of labor. JAMA 1998;280:2105-10.

2. Zhang J. Klebanoff MA. DerSimonian R. Epidural analgesia in association with duration of labor and mode of delivery: a quantitative review. Am J Obstet Gynecol 1999:180:970-7.

3. Leighton BL, Halpern SH. The effects of epidural analgesia on the progress of labor, maternal and neonatal outcomes: a systematic review. Am J Obstet Gynecol 2002;186:S69-77.

4. COMET study group. Effect of low-dose mobile versus traditional epidural techniques on mode of delivery: a randomised controlled trial. Lancet 2001; 358: 19-23.

5. Reynolds F, Russell R, Porter J, Smeeton N. Does the use of low dose bupivacaine infusion increase the nornal delivery rate? International Journal of Obstetric Anesthesia 2003; 12: 156-163.

6. Thalme B, Belfrage P, Raabe N. Lumbar epidural analgesia in labour: I. Acid-base balance and clinical condition of the mother, fetus and newborn child. Acta Obstet Gynecol Scand 1974;53:27-35.

7. Pearson JF, Davies P. The effect of continuous lumbar epidural analgesia upon fetal acid-base status during the second stage of labour. J Obstet Gynaecol Br Commonw 1974;81:975-9.

8. Zador G, Nilsson BA. Low dose intermittent epidural anaesthesia with lidocaine for vaginal delivery. Acta Obstet Gynecol Scand 1974; Suppl 34:17-30.

9. Reynolds F, Sharma S, Seed PT. Analgesia in labour and funic acid-base balance: a meta-analysis comparing epidural with systemic opioid analgesia. Br J Obstet Gynaecol 2002; 109: 1344-1353.

10. Moss L. Midwives want investigation into birthing procedures. http://news.scotman.com.latest.cfm 20 May 2004

Competing interests: None declared

Competing interests: None declared

FELICITY REYNOLDS, Emeritus Professor of Obstetric Anaesthesia

St Thomas' Hospital, London SE1 7EH

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