Hi Henci,

I'm sure you have seen this new study comparing the risks of rupture for VBACers who have single- vs. double-layer sutures: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=17118738&query_hl=1&itool=pubmed_docsum . What do you think of it? They only studied 35 single-sutured women, but apparently 8% of them ruptured -- enough to really scare me (I had a single-suture c/s in Nov '04). Do you think I should still attempt VBAC with a single-suture?

Thanks,
L.S. By: MomtoAsh

I have not seen this study. I am out of the country but will be returning tomorrow. I can say, though, that an 8% scar rupture rate is much bigger than other studies have reported. I need to be home to consult my files, but as I recall, while some studies have shown an excess rate compared with double-layer suturing, the difference has been on the order of 2% vs 0.5%. Also, a study that did not find an excess with single-layer suturing raised the issue of suture material and technique potentially playing a role in scar strength.

What is shocking to me is that after reading that, I tried to find studies comparing different techniques and materials with respect to scar strength and was shocked that I could not even find any randomized controlled trials, let alone a systematic review on this topic. I would have thought this was an important issue, but apparently obstetricians do not deem determining what surgical techniques produce the strongest scar a question worthy of research.

-- Henci By: Henci Goer

"What is shocking to me is that after reading that, I tried to find studies comparing different techniques and materials with respect to scar strength and was shocked that I could not even find any randomized controlled trials, let alone a systematic review on this topic. I would have thought this was an important issue, but apparently obstetricians do not deem determining what surgical techniques produce the strongest scar a question worthy of research."

Actually they do:

One-versus two-layer closure of a low transverse cesarean: the next pregnancy. SJ Chapman, J Owen, JC Hauth - acogjnl, 1997

Trial of labor after a one-or two-layer closure of a low transverse uterine incision. JM Tucker, JC Hauth, P Hodgkins, J Owen, CL … Am J Obstet Gynecol. 1993 Feb;168(2):545-6.

Uterine rupture, perioperative and perinatal morbidity after single-layer and double-layer closure at cesarean delivery. C. Durnwald et al. American Journal of Obstetrics and Gynecology, Volume 189, Issue 4, Pages 925-929

The impact of a single-layer or double-layer closure on uterine rupture. E Bujold, C Bujold, EF Hamilton, F Harel, RJ
Am J Obstet Gynecol. 2002 Jun;186(6):1326-30.

Comparative study of single layer and conventional closure of uterine incision in cesarean section. K Lal, P Tsomo. Int J Gynaecol Obstet. 1988 Dec;27(3):349-52

Transverse uterine incision closure: one versus two layers. JC Hauth, J Owen, RO Davis. Am J Obstet Gynecol. 1992 Oct;167(4 Pt 1):1108-11.

Continuous vs interrupted sutures for single-layer closure of uterine incision at cesarean section. M Hohlagschwandtner et al. Arch Gynecol Obstet. 2003 Apr;268(1):26-8.

An evaluation of uterine scar integrity after cesarean section in rabbits. DR Dunnihoo, WN Otterson, JB Mailhes, DF Lewis, WD … acogjnl, 1989

Transverse uterine incision non-closure versus closure: an experimental study in sheep. Gul A et al. Acta Obstet Gynecol Scand. 2000 Oct;79(10):813-7.



By: ATuteur

You misread my reply. I am aware of all the studies you listed comparing single- vs double-layer suturing save the Hohlagschwandtner 2003 study, which, by the way, is not a randomized controlled trial, and the animal studies. The animal studies are not relevant for evaluating scar integrity in subsequent labor because labor in 4-footed mammals is not as strenuous as it is in humans, who are upright. Humans have a much more resistant cervix as the human uterus must hold in the baby against the forces of gravity. They also appear to be about single- vs double-layer suturing, and the human studies you listed on this topic are underpowered to detect small but important differences in scar rupture rates. To repeat, single- vs double-layer suturing is not the only variable affecting scar integrity that is dependent on the surgeon. To my knowledge, no RCTs in women compare suture materials or suturing technique. It remains a shocking failure to me that in the 25 years in which VBAC has been an issue, obs have not investigated what surgical techniques maximize safety in subsequent pregnancies in women delivered by cesarean. It is equally shocking that the Cochrane review on single- vs double-layer suturing concluded that single-layer suturing was safe with totally inadequate data on the consequences in subsequent labors.

-- Henci By: Henci Goer

"The animal studies are not relevant for evaluating scar integrity in subsequent labor because labor in 4-footed mammals is not as strenuous as it is in humans, who are upright. "

Of course they are relevant. The only way that scar integrity and tensile strength of the incision can actually be measured is in an animal model. It would be unethical to biopsy uterine scars in human beings.

"It remains a shocking failure to me that in the 25 years in which VBAC has been an issue, obs have not investigated what surgical techniques maximize safety in subsequent pregnancies in women delivered by cesarean."

I just showed you studies about single vs. double layer closure. They are not the only studies of uterine scar integrity. There are studies comparing types of uterine incisions (classical vs. transverse) and there are studies investigating the results of using different suturing materials. You may not be familiar with the studies about suturing materials because many were done by infertility specialists. They have a very keen interest in minimizing any tissue reaction in surgery on the tubes or the uterus (as in the case of repair of uterine developmental defects). If you like, I can compile a list for you. The point is, though, that those studies exist and it is wrong to suggest that no one has looked into the effects of incision type, closure type and suture material on uterine scars. All three have been investigated extensively.

By the way, as regards the previous topic we discussed, the MacDorman study, I'd like to draw your attention to the fact that one of the investigators has publically acknowledged the flaws in the study that you claimed either did not exist or were not relevant. In an interview with Medscape, Declerq, one of the principal investigators said the following:

Medscape: What are the limitations of your study?

Dr. Declerq: There are several limits. Most notably these births we have identified cannot be termed "patient choice" cesareans since there is no indication on the birth certificate concerning mother's choice or intention. Also there is the possibility that some of the cesareans were for medical reasons not covered by the birth certificate items or that those completing the forms simply failed to complete them correctly. (my emphasis)




By: ATuteur