Trial of Labour after C-Section (TOLAC)

Women who have had one C-section typically have the option of trying for a vaginal birth in their next pregnancy vs. delivering by planned repeat C-section. Women with more than one prior C-section will typically deliver by repeat C-section.

The terms TOLAC (trial of labour after C-section) and VBAC (vaginal birth after C-section) are sometimes used interchangeably, but TOLAC refers to the attempt, and the term VBAC should be used after a successful vaginal delivery has taken place.

In some instances, a TOLAC is not recommended, and the OB will advise.

Women who are suitable candidate for a TOLAC will typically have a good probability of success, in the range of 60-80%. The chances of success depend on several factors, including the circumstances around the first C-section and the estimated size of the baby in the current pregnancy. The OB will review all of these factors and provide an estimate of the success rate for that particular women.

The main advantage of VBAC is that the recovery is generally much faster than with a C-section. Women with toddlers at home will not be able to carry them for 6 weeks after a C-section, and this can be a motivating factor for attempting a TOLAC.

The easiest recovery is with a spontaneous vaginal delivery. Second best is a planned C-section. The most difficult recovery is when emergency C-section occurs after many hours of labour. This is why the probability of success should be considered when a woman makes her decision.

Women who plan to have large families should seriously consider a TOLAC, because the surgical risks with C-section increase with each successive operation, due to the formation of scar tissue.

The main risk associated with TOLAC is that of uterine rupture. The scar on the uterus from the first C-section represents a weak area vulnerable to opening up during labour. In most cases, the risk of uterine rupture is about 1:200 or 0.5%. When the uterus ruptures, it is an emergency and a C-section must be done immediately. Even with rapid intervention, uterine rupture can result in a catastrophic outcome (fetal brain damage or death, hysterectomy, multiple blood transfusion) in about 10% of cases. We typically quote a 1:1,000 to 1:2,000 risk of serious complications in women attempting TOLAC.

In order to maximize safety, women doing a TOLAC will labour in hospital under continuous fetal monitoring. The safest scenario with the best outcomes is when labour starts spontaneously and progresses normally, without need for interventions. Epidurals are permitted. When medications are required to induce or increase labour, the risks increase, and an in-depth discussion regarding the pros and cons of such interventions will need to take place between the woman and the OB on-call.

Symptoms and signs of uterine rupture can include heavy vaginal bleeding, abnormalities of the fetal heart rate, and a constant pain in the area of the old incision. There is a fairly low threshold to proceed to repeat C-section when safety concerns arise.