Authors’ Response to the Letter to the Editor: Single- vs. Double-Layer Closure of Hysterotomy at the Time of Cesarean Delivery
14 June 2017 (eFirst)
We would like to thank the authors for taking a keen interest in our recently published RCT to examine the outcome of a single- versus double-layer hysterotomy closure at cesarean delivery using ultrasound to assess uterine scar thickness . Our results suggest that the residual myometrium thickness (RMT) at least six months after surgery was significantly increased after double-layer closure compared with single-layer unlocked suturing of the low transverse uterine incision in women with primary or elective cesarean delivery.
Despite the fact that this is the largest randomized trial in this field to date, further statistical comparisons between the subgroups of women in each arm were difficult due to a limited sample size after lost to follow-up. Regarding women who underwent a primary cesarean in labor, we were able to perform scar assessment (intention to treat) at least six months after birth in 13 participants with a single-layer unlocked suture, 18 women after single-layer locked suture and 10 women with double-layer closure.
As mentioned by Roberge and Bujold , including the inner side of the uterine wall (decidua) in the suture may lead to impaired scar healing, isthmocele and placenta accreta  in a subsequent pregnancy. This is in agreement with your results, showing a 2.4 mm thicker RMT of the cesarean scar after double-layer closure excluding the decidua in comparison to women with a locked single-layer suture including the endometrium.
Therefore, we decided that in all closure types the first layer suture should penetrate the full thickness of the myometrium, including a narrow band of the endometrial layer avoiding the involvement of large segments of the decidua within the stitch.
We are not able to ensure that this technique was performed in all participants, in particular in women who were delivered by an in labor cesarean section at the second stage and in whom the lower uterine segment was thin. However, due to randomization and intention to treat as well as treated analyses, we may argue that this bias did not significantly influence our results.