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To VBAC or Not to VBAC?

September 23, 2017

With the advancements in surgical techniques, women with a straightforward pregnancy have a 75% chance of achieving vaginal birth following a C-section. What are some key considerations for this path?

By Emma McNerlin  

In 1916, a famous American obstetrician Edwin Cragin declared in the New York Medical Journal “Once a Caesarean always a Caesarean” (Cragin, 1916). The edict was appropriate for its time. Classical scars (vertical incisions along the abdomen) and rudimentary suturing practices of the day carried with them a risk of uterine rupture and almost certain death for mother and child of somewhere between 12-20% (Odent, 2004).

...any woman planning on a VBAC has at least a seven in ten chance of achieving this.

Advancements in surgical techniques since the 1950s--such as lower segment (bikini-line) incisions and double-layer suturing with improved suture material--have meant that alternatives to the repeat C-section could be contemplated. However, caution among the medical community persisted and it wasn’t until the 1980s that vaginal birth after C-section (VBAC) became viable for women with previous C-sections.

What are my chances of a successful VBAC?

We now know that overall, those women with a straightforward pregnancy seeking a vaginal birth following a C-section have a 75% chance of achieving this (CDC, 2015). Some factors will increase this chance even further; having had any previous vaginal delivery increases the odds of successful VBAC to 85-90% (RCOG, 2015).

...most women who are motivated for a normal birth following C-section would feel positive about their choice.

The reason for the previous C-section can also affect your chances of VBAC. For example, if you had a C-section during labor, having experienced some degree of cervical dilatation, your chances are higher than for women who had a C-section before labor began, such as in the case of a breech presentation, where baby is facing bottom first or legs first, or placenta praevia, where the placenta wholly or partially covers the exit of the womb to the cervix (Rageth et al., 1999). Some factors will also decrease your chances of a successful VBAC, such as induced labor, no previous vaginal delivery, BMI greater than 30 and previous cesarean for obstructed labor. However, even when all these factors are present, successful VBAC is achieved in 40% of cases (RCOG, 2015).[l] Presented with these odds, most women who are motivated for a normal birth following C-section would feel positive about their choice.

Why have a VBAC?

How a woman decides to birth her baby should always be a personal choice. There are a small number of cases where VBAC is contraindicated (see Table 1).

Both repeat C-section and VBAC carry their own benefits and risks. Repeat elective C-section may be preferred if the woman has experienced a traumatic emergency C-section in a previous pregnancy. The element of knowing what to expect in a repeat C-section as well as the convenience of being able to choose the birthdate may also be appealing and may outweigh possible post-operative complications such as extra risk of bleeding, infection blood clots, neonatal breathing difficulties as well as longer recovery time that C-section carries (Derrick et al., 2012). For some women, the opportunity to experience natural or vaginal birth is a rite of passage. For these women, VBAC is preferred as it offers shorter recovery time, shorter hospital stay, more opportunity for skin-to-skin and a greater chance of normal birth in future pregnancies. Attempting a VBAC carries with it a slightly increased risk of requiring an emergency C-section than a woman having her first baby: 25% as opposed to 20% (RCOG, 2015).

What about scar rupture?

Uterine rupture

Perhaps the most cited risk associated with VBAC is uterine rupture. This is a serious complication and is defined as “a separation through the thickness of the uterine wall at the site of a prior caesarean incision” (VBAC.com, 2017).

Many of the signs of uterine rupture can be monitored for in labor.

The extent of uterine rupture across the scar can vary, from a small pocket of separation to a complete separation, where the contents of the uterus spill into the peritoneum. The latter is a life-threatening emergency for both mum and baby. The overall risk of uterine rupture for women following previous C-section is 0.5%, or one in two-hundred; we do not have statistics broken down by severity of rupture.

Scar dehiscence

Scar rupture is not to be confused with scar dehiscence, which is more common but still relatively rare (2% of all pregnancies with previous C-section) and involves a thinning of the lower segment C-section (LSCS) scar but does not involve the layer to the peritoneum, hence maintaining the integrity of the uterus. Scar dehiscence seldom results in any serious adverse outcome to mum or baby. They heal on their own, requiring no medical treatment. Recent developments in ultrasound practice have allowed doctors to monitor the shape, thickness, and integrity of LSCS scars trans-vaginally, and evidence is emerging that scars measuring at least between 3.5mm and 2.4mm thickness at term indicate general suitability for VBAC, though more research is required in this area (Rama et al., 2012).

The language of risk

When contemplating a VBAC birth, finding an OB/GYN who is confident and experienced with a proven track record in successful VBAC is vital. As medical professionals, doctors are required to discuss all the risks and benefits of a proposed treatment or procedure with their patient.

How risk is described

Some may do this in a measured way, others may use threatening or emotive language when describing these risks, referring to uterine rupture as the womb ‘bursting open’ or ‘erupting’, without fully explaining the incidence of this. How the information is presented is also important. A woman hearing that 995 out of 1,000 women will not experience any scar rupture is a more positive message than 1 in 200 will; yet both are equally true. If I were to say that the risk of your baby suffering a scalp laceration during LSCS is double that of a uterine rupture, that also would be true: the risk of scalp laceration is one in one hundred babies born by LSCS (RCOG, 2016).

Monitoring for signs of uterine rupture

Many of the signs of uterine rupture can be monitored for in labor. Continuous abdominal pain and tenderness, rising maternal pulse, vaginal bleeding in labor and patterns of decelerations of fetal heart rate and fetal distress are all pre-cursors to uterine rupture, which, if present and identified, can allow the woman and doctor to discuss the situation and opt for repeat C-section if that is indicated.

Thankfully, serious complications are extremely rare and more is known on how to mitigate risk and deal with any emergencies that may occur

Proper management of labor such as avoiding induction of labor or use of oxytocic medications such as Pitocin, and monitoring for any signs of obstructed labor or stalled progress in labor also reduces the risk of scar rupture.

Truth in the evidence

When contemplating a VBAC it can feel like one is being bombarded with negative messages and horror stories about all that can possibly go wrong. This is not counteracted either by blind ignorance and trust that nothing can go wrong. The truth is to be found in the evidence, and the evidence states that any woman planning on a VBAC has at least a seven in ten chance of achieving this. As with any pregnancy, we are not in control of the outcome. Nothing is without risk nor can any risk be fully eradicated, but thankfully, serious complications are extremely rare and more is known on how to mitigate risk and deal with any emergencies that may occur, making birth now safer than it has ever been. So whichever way you choose to birth your baby after C-section, make sure that it is an informed choice, fully supported by your caregiver, and leave that which cannot be controlled to the forces of the universe.    

Acronyms

  • LSCS: lower segment C-section. The incision is made from one side of the abdomen to the other, just above the pubic hairline (bikini line).
  • VBAC: Vaginal Birth After C-section

References

Image by shorty_ox from Pixabay   

About the Author

Originally from Ireland, Emma is a UK-trained midwife who worked in the maternity unit at a busy NHS hospital just outside London. Emma moved to Bangkok with her husband in 2014; they have an 11-year-old son, Toby. Volunteering with BAMBI Bumps and Babies since August 2015, Emma regularly conducts sessions on pregnancy, birth, breastfeeding and Infant First Aid. In her spare time, she enjoys baking and Muay Thai, and is an active member of her son’s parent group at school.

The views expressed in the articles in this magazine are not necessarily those of BAMBI committee members and we assume no responsibility for them or their effects. BAMBI News welcomes volunteer contributors to our magazine. Please contact editor@bambiweb.org.