Three years after the Term Breech Trial

A sea change in perceptions of risk and
acceptance of cesarean delivery

By Susan Usher

In October 2000, the results of Dr Mary Hannah's Term Breech Trial (TBT) were published in The Lancet and put an abrupt end to vaginal breech deliveries across Canada and in most of the developed world. Physicians who had been uncomfortable with breech deliveries before were relieved of the nagging uncertainty about their choice. Those who had always felt confident were confronted with a very careful calculation of the real risks involved. Even with an obstetrician experienced in vaginal breech deliveries, even with careful selection, even with all the right skills and tools, the rate of serious morbidity was 5%, while the risk with a planned cesarean section was under 2%.

That 3% additional risk came as a surprise to many obstetricians who had performed breech deliveries for years without complications. "As an obstetrician providing that option," says Dr David Young, Head of Obstetrics and Gynecology at the IWK Health Centre, "you would only be delivering five to 15 a year, so you could go five to 10 years before having a bad outcome." Dr Erika Eason performed vaginal breech deliveries for years without complication. But the study convinced her that it was just a matter of time. "I'm just not sure we can do better than what the study results showed," she admits. She has not delivered a breech vaginally since the TBT was published. A survey Dr Hannah undertook six months after the TBT found an abrupt change in practice. "Of the 84% of clinicians who had routinely recommended vaginal breech births before they became aware of the trial," says Dr Hannah, who is Director of the University of Toronto Maternal, Infant and Reproductive Health Research Unit at the Centre for Research in Women's Health, "only 14% made the same recommendation afterwards." Practice has changed in other countries as well, even such stalwart supporters of vaginal births as Holland and Ireland. "The Dutch study published in October 2003 showed that the TBT had an immediate amplifying impact on top of the already existing trend of rising cesarean section rates for term singleton breech presentation, but also for pre-term and twin breeches."

MAINTAINING SKILLS
"The skills needed to deliver a breech baby vaginally had been disappearing for a while before the TBT," says Dr Robert Liston, Chief of the Department of Obstetrics at the British Columbia Women's Hospital and Health Centre. "The acceptance of this trial result put the coup de grace on the few practitioners who were doing term breech deliveries."

However, the end to planned vaginal breech deliveries does not spell the end to vaginal breech deliveries themselves. "Some babies are faster than we are," says Dr Dan Farine, Director of Perinatology at Mount Sinai Hospital. "Right now, there are still enough of us with some experience to deal with emergencies, but that won't last long."

He and other obstetricians who used to perform vaginal breech deliveries are now trying to pass that skill set on to residents, taking them through breech cesarean sections as though they were vaginal deliveries to give them some idea of how to approach a vaginal delivery if they had to. But they acknowledge that this training does little to impart the subtle instincts that made them comfortable with the procedure in the first place. "The fact remains," says Dr Eason, "that when you have a difficult delivery of a head in a cesarean, you can just pick up the scissors and open the uterus and get it out, whereas you don't have that option vaginally."

While no one advocates continuing a practice that presents additional risk just to maintain obstetrical skills, there is growing concern about the ability to cope with emergencies. "We need to remain prepared for the patient who arrives fully dilated and on the perineum with a breech presentation," says Dr Young.

The direct impact of the TBT on cesarean section rates would be no more than 2% if the 50% of breeches that used to be delivered vaginally were all sectioned. But the indirect impact has been much greater. The decision to do a cesarean used to weigh the benefits to the baby against risks for the mother. "The TBT emphasized that the risks to the mother with cesarean were not high," says Dr Hannah, "and that there were even some benefits: the three-month follow-up of women who participated in the TBT showed a lower incidence of incontinence in the elective cesarean group."

The trial also supported a risk-averse culture among both obstetricians and their patients. "There are all sorts of risks to the baby that we can get rid of by doing sections," says Dr Farine. Convincing studies have shown benefits of elective cesarean for obese women, vaginal births after cesarean have been shown to be riskier than initially thought and the increased risk of going post-term has been documented.

Dr Young regards increasing the number of cesareans when there is good evidence that it reduces risk as moving ahead. "In a number of situations, the risk of complications with vaginal delivery has been shown to go up just a bit, but it's enough to scare doctors and patients." More formally, the 3% risk of complications found in the TBT has been used in court to assess the wisdom of a course of action in other situations. The real impact of that trial was to show that neither women nor their doctors are willing to take a 3% risk with the health of a baby. "Women today are looking at the end, not the means," says Dr Farine. He has had only a couple of women persist with a planned vaginal breech delivery after being informed of the trial results. Dr Eason has not had one. "Women are pushing for planned cesarean sections even when there is no medical indication," she says.

Concern for the baby's safety is now being joined by concerns over maternal factors, especially incontinence. Dr Hannah's two-month follow-up showed a decrease in incontinence among women in the elective cesarean group. "About 12% of women suffer some injury to the perineum with vaginal births," says Dr Farine. This is set to become a further consideration in the choice of delivery methods. In a large trial started this month by Dr John Barret at Sunnybrook and Women's Hospital looking at twin deliveries, the primary measure is the outcome of the babies, but the secondary outcome is incontinence in the mother two years post-partum.

ACCEPTING CESAREANS
Where does that leave the cesarean rate? "Eight different bodies, from Canada, the US to the World Health Organization came up with the figure of 15%," says Dr Farine. "Two years ago, the actual rate in Canada, the US, the UK and Australia was around 22%. Is this something we're determined to fix, to bring in line with the 15%?" The short answer would be no.

"The cesarean rate is going up and people are less concerned about that than before," says Dr Hannah. "We need to focus on the best outcomes for the mother and the baby, and not on the rate of a procedure." Results from her two-year follow-up of mothers and babies in the TBT will be presented at the American Society for Maternal-Fetal Medicine annual meeting in February.