Hi Henci,

Are there any studies on the risk of UR (or other complications) for a VBAC with a bicornuate uterus?  especially a VBA2C?

Thanks so much!

Christa Bartley

www.birthnetwork.org

Unfortunately, according to one review of the medical literature, you are at greater risk for the scar giving way:

Lieberman E. Risk factors for uterine rupture during a trial of labor after cesarean. Clin Obstet Gynecol 2001;44(3):609-21.

Lieberman cites a study of planned VBAC in 25 women with uteruses that were not the usual shape compared with 1,788 women with the usual upside-down pear shape. The scar gave way in 2 (8%) cases in women with bicornuate, unicornuate, didelphic, or septate uteruses versus 11 cases (0.6%)  in women with the usual shape.

The latter percentage falls in the typical range for scar problems, but 8% is quite high. Still, you have 92% odds that the scar will not be a problem. I also have no details from the cited study. For example, were the women with unusual uterine shapes all given oxytocin to stimulate stronger contractions? That would increase their risk of scar rupture. And, of course, a third cesarean surgery is not risk free, so there are trade-offs to be considered in making your decision. If you do decide to plan a VBAC, you, more than the typical woman with prior cesareans, might be wise to have it in a hospital capable of handling an urgent cesarean 24/7.

-- Henci

It does, and perhaps it was a statistical oddity like having five girls in a row, but 1 out of 13, which is the same odds as 2 out of 25, is a very different number from 1 out of 163, which is the same odds as 11 out of 1788. I think that more of a question is whether the varying uterine shapes that were lumped together in their case series have differing consequences for the scar. Unfortunately, it is unlikely that we will get better data because the condition is rare and no single institution or group of institutions is likely to have a reasonably large set of women with it who plan VBACs.

-- Henci 

So, having written the above, what should appear in my in box in International Cesarean Awareness Network's bimonthly newsletter but a link to a study of Mullerian anomalies and VBAC. Mullerian anomalies, BTW, refers to abnormal development of the embryonic tube that develops into the Fallopian tubes, uterus, and vagina. I spent an extremely frustrating half hour trying to get the actual study to no avail. Here, at least, is the citation and abstract from PubMed, but, of course, the devil is in the details. 

-- Henci

Am J Obstet Gynecol. 2007 Jun;196(6):537.e1-537.e11.

Related Articles, <script language=JavaScript1.2></script> Links

Trial of labor and vaginal birth after cesarean section in patients with uterine Müllerian anomalies: a population-based study.

Erez O, Dukler D, Novack L, Rozen A, Zolotnik L, Bashiri A, Koifman A, Mazor M.

Department of Obstetrics and Gynecology, Faculty of Health Sciences, Soroka Medical Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel.

OBJECTIVE: The aim of our study was to determine the success rate of vaginal birth after cesarean section among patients with Müllerian anomalies in comparison to the success rate of vaginal birth after cesarean section in patients with normal uterus with emphasis on the rate of uterine rupture. STUDY DESIGN: A retrospective population-based study was designed, including all patients with a previous cesarean section that attempted vaginal birth after cesarean section during the study period. Women with known Müllerian anomalies were included in the study group. The control group consisted of women with normal uterus. The rates of vaginal birth after cesarean section, uterine rupture, maternal morbidity, and perinatal outcome were compared between the groups. RESULTS: Of 5571 eligible patients, 165 (2.96%) had Müllerian anomalies. The rate of vaginal birth after cesarean section was significantly lower among patients with Müllerian anomalies than in patients with normal uterus, 37.6% (62/165) vs 50.7% (2740/5406), respectively (P = .0009). During the study period, there were 10 cases of uterine rupture, all in patients with normal uterus. The major indication for repeated cesarean delivery among Müllerian anomalies patients was malpresentation, 58.3% (60/103) vs 14.4% (385/2666) in patients with normal uterus (P < .001). CONCLUSION: A trial of vaginal birth after cesarean section in patients with uterine Müllerian malformations and cephalic presentation is not associated with a higher rate of maternal morbidity and uterine rupture.

PMID: 17547885 [PubMed - in process]