Q&a attempts to provide balanced answers to those curly-yet-common questions in obstetrics and gynaecology for the broader O&G Magazine readership, including Diplomates, Trainees, medical students and other health professionals.
Despite the evidence, controversy still rages over the safest method to deliver a term breech. A common situation in our institution, though, is breech presentation before 37 weeks. What is the best advice for delivering a preterm baby in breech presentation?
Since the publication of the term breech trial1 the popularity of vaginal breech deliveries has sharply declined. When a woman reaches 37 weeks gestation and the presentation of the fetus remains breech, three options are usually discussed. External cephalic version (ECV) is commonly offered if there are no risk factors; elective caesarean section at 39 weeks may be offered outright, or booked if an attempt at ECV fails; and selected women may wish for a trial of vaginal delivery.
When a patient in Australia presents in preterm labour with breech presentation at a viable gestation, delivery by caesarean section is the usual outcome. It is important to recognise that there is no level one evidence to guide our management.
As practising obstetricians, the following guidelines can be drawn upon when faced with a difficult clinical question:
- The relevant RANZCOG statement
- The Cochrane database
- The Green Top Guidelines of the RCOG
- Relevant local hospital policies and guidelines.
Unfortunately, our RANZCOG statement offers no advice with respect to preterm breech presentation. Similarly, the Cochrane database offers no advice with respect to preterm breech presentation. The RCOG Green Top Guideline (no. 20b, December 2006) makes the following recommendation:
‘Routine caesarean section for the delivery of preterm breech presentation should not be advised. The mode of delivery of the preterm breech presentation should be discussed on an individual basis with a woman and her partner. Where there is head entrapment during a preterm breech delivery, lateral incisions of the cervix should be considered.’
As an example of local hospital guidelines, the Royal Women’s Hospital (Melbourne) guideline, available through the hospital website, states:
‘The optimal mode of delivery for preterm breech has not been fully evaluated in clinical trials and the relative risks for the preterm infant and mother remain unclear. Overall, decisions regarding mode of delivery will need to be made on an individual basis, however, with the evidence available to us at this time, Royal Women’s Hospital recommended practice is to perform emergency caesarean section for any woman presenting in preterm labour with breech presentation except where vaginal delivery is imminent. The medical circumstances are such that survival (and least morbidity) of the fetus is assessed to be unchanged by mode of delivery and/or the maternal morbidity of caesarean section is judged to be too great for the relative potential fetal disadvantages.’
Unfortunately, a randomised trial of planned caesarean section for preterm breech versus vaginal delivery was abandoned because of insufficient enrolments.4 A retrospective cohort study found that very low birth weight breech or malpresenting neonates delivered by a primary caesarean section had significantly lower adjusted relative risks of death compared with those delivered vaginally.3 However, the authors emphasised that a causal relationship cannot be inferred.
Retrospective studies that suggest that delivery by caesarean section confers a better outcome for the fetus are potentially subject to bias. The poor outcome for very low birth weight infants is related mainly to complications of prematurity rather than simply the mode of delivery. In the absence of good evidence that a preterm baby needs to be delivered by caesarean section, the decision about the mode of delivery should be made after close consultation with the woman and her partner.
Caesarean section for preterm breech is almost always an emergency where there has been a failure to tocolyse or where the decision has been made to deliver. As the woman is often in active labour, the procedure becomes classed as emergency, therefore increasing the risk of maternal complications compared to elective caesarean section.
With preterm breech, there is less risk of bony dystocia of the head. However, there are other significant risks such as delivery before full dilatation with consequent head entrapment. Fetal complications are obviously hypoxia and soft tissue injury related to the delivery, and maternal morbidity with lateral cervical incisions which can extend superiorly to the broad ligament. The risk of cord prolapse is always present, particularly in the footling breech.
In the extremely preterm breech (28 weeks or less) in uterus with a poorly formed lower segment, a classical incision may be required resulting in increased maternal morbidity in the short-term and increasing the risks for subsequent pregnancies. If the decision to perform a caesarean section is decided upon for an extremely preterm fetus for fetal reasons, a classical caesarean section should be performed. A lower segment incision should be resisted in a uterus in which a lower segment has not yet formed. One needs to think very carefully before offering a caesarean section at the limits of viability for fetal benefit.
Since 2000, most clinicians have not routinely performed vaginal breech deliveries. How many clinicians in 2009 feel confident to perform or supervise an elective breech delivery? The art of the vaginal breech delivery today belongs only to a lucky few. My generation of obstetricians, and probably those that follow, will not routinely perform caesarean sections for all breech deliveries because of the evidence or lack thereof, but because we do not possess or will not have the opportunity to acquire the skills to offer the option of a planned vaginal breech birth.
Thus, the optimal mode of delivery for preterm breech needs to be individualised based on gestational age, fetal condition, cervical dilatation at presentation, maternal wishes and the skill of the obstetrician.
- Hannah ME, Hannah WJ, Hewson SA, Hodnett ED, Saigol S, Willan AR. Planned caesarean section versus planned vaginal birth for breech presentation at term: a randomised multi-centre trial. Lancet 2000; 356:1375-85.
- Hofmeyr GJ, Hannah ME. Planned caesarean section for term breech delivery. Cochrane Database of Systematic Reviews, 2007, Issue 4. Art. No.: CD000166. DOI: 10.1002/14651858.CD000166.
- Muhuri PK, Macdorman MF and Menacker F. Method of delivery and neonatal mortality among very low birth weight infants in the United States. Maternal Child Health Journal 2006; 10: 47-53.
- Penn ZJ, Steer PJ, Grant A. A multicentre randomized controlled trial comparing elective and selective caesarean section for the delivery of the preterm breech infant. British Journal of Obstetrics and Gynaecology 1996; 103: 684-9.
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