M Ajmal Department of Anaesthesia, Sligo General Hospital, Ireland Accepted 17 September 2009. DOI: 10.1111/j.1471-0528.2009.02432.x Oxytocin at caesarean section – are we giving too much? Author’s Reply Sir, I thank Muhammad Ajmal 1 for the valuable comments about the dose of oxytocin required and methods of administration at caesarean delivery. Practice regarding doses and administration of oxytocin at caesarean section varies widely. In the literature, examples of a quick, single intravenous bolus of 5–10 iu oxytocin given over a few seconds can be found, as well as an infusion with diluted oxytocin given over a few hours. Others use a bolus plus a continuing infusion of oxytocin. The risks of oxytocin, especially given by rapid injection, have been highlighted, and a slow, intravenous bolus dose of 5 iu of oxytocin following delivery of the infant at cae- sarean section is currently recommended by the National Institute for Clinical Excellence (NICE) in the UK. 2 A more detailed definition of ‘slow’ is, however, not given in this guideline. It has been shown that when oxytocin is given at a slower rate, greater haemodynamic stability will result. 3 Thomas et al. 3 administered oxytocin either as an intrave- nous bolus of 5 iu diluted to 5 ml with normal saline, given as quickly as possible (1 s), or as 5 iu diluted to 15 ml with normal saline, given over 5 minutes using an infusion pump. The slower injection of oxytocin effectively minimised the cardiovascular side effects (hypotension and tachycardia) of a bolus without compromising the therapeutic benefits. It is important for the reader to notice that the regimen in the studies where lower doses of oxytocin showed effective- ness was not that of a single intravenous bolus of oxytocin, but of a bolus followed by an oxytocin infusion. 4 An addi- tional oxytocin infusion at caesarean section may reduce blood loss, and while awaiting results of ongoing studies, giv- ing too much oxytocin too quickly should be avoided. 5 j References 1 Ajmal M. Oxytocin at caesarean section – are we giving too much? BJOG 2010;117:118–9. 2 National Collaborating Centre for Women’s and Children’s Health. Caesarean Section. Clinical Guideline. April 2004 National Collaborat- ing Centre for Women’s and Children’s Health. London: RCOG Press, 2004. 3 Thomas JS, Koh SH, Cooper GM. Haemodynamic effects of oxytocin given as i.v. bolus or infusion on women undergoing caesarean sec- tion. Br J Anaesth 2007;98:116–9. 4 Carvalho JC, Balki M, Kingdom J, Windrim R. Oxytocin requirements at elective caesarean delivery: a dose-finding study. Obstet Gynecol 2004;104(5 Pt 1):1005–10. 5 Murphy DJ, MacGregor H, Munishankar B, McLeod G. A rando- mised controlled trial of oxytocin 5IU and placebo infusion versus oxytocin 5IU and 30IU infusion for the control of blood loss at elective caesarean section – pilot study. ISRCTN 40302163. Eur J Obstet Gynecol Reprod Biol 2009;142:30–3. M Jonsson Department of Women’s and Children’s Health, Uppsala University, Uppsala, Sweden Accepted 29 September 2009. DOI: 10.1111/j.1471-0528.2009.02430.x The role of bacterial vaginosis, aerobic vaginitis, abnormal vaginal flora and the risk of preterm birth Sir, Donders et al. 1 add some insight into the role of bacterial vaginosis (BV), aerobic vaginitis (AV), abnormal vaginal flora (AVF) and the risk of preterm birth (PTB). The ear- lier in pregnancy that PTB occurs, the greater this is likely to be as a result infection. The earlier in pregnancy AVF is diagnosed, the greater is the risk of an adverse outcome, even if this resolves, suggesting that whatever infection/ inflammatory damage that occurs as a result of AVF, occurs early and persists. If antibiotics are to reduce PTB, they should be: active against organisms associated with PTB, used in women with demonstrable AVF, and used early in pregnancy before infection/inflammation can cause irreversible fetomaternal tissue damage. The study was undertaken 8–9 years ago, and women who were chlamydia-positive on the Chlamydiazyme test were excluded from the analysis. The test is only about 50% sensitive compared with current molecular techniques. Accordingly, some women regarded as chlamydia-negative, were positive and remained in the study. The authors state that in studies in which strict criteria had been applied for the diagnosis of BV, there was no correlation with PTB, yet we are aware of well-respected studies, for example Hay et al., 2 in which strict diagnostic criteria were used, and in which a five-fold increased risk of PTB was demonstrated when BV was detected early (i.e. with a maximal gesta- tional age at screening of 20 weeks). The authors state that ‘intermediate flora’ (scores of 4–6 on the Nugent Gram-stain) does not correspond with ‘inter- mediate BV’. We take ‘intermediate BV’ to mean ‘partial BV’, described by the authors as ‘patchy streaks of BV flora or sporadic clue cells mixed with other flora’. There is a dis- ª 2009 The Authors Journal compilation ª RCOG 2009 BJOG An International Journal of Obstetrics and Gynaecology 119 Correspondence