Cesarean operations are one of the most common obsetric operations and have an increasing trend in all over the world. However unfortunately the operation techniques have not been standardized yet. It is well known that different uterine closure techniques result in differences with respect to wound healing on the uterus; however, the ideal uterine closure technique is yet not known. The aim of this study is to assess the results of different uterine closure techniques during cesarean section with respect to the development of cesarean scar defects.

Patients were randomized into three groups using a computer-based program (ratio 1:1:1), and the assigned surgical technique was disclosed just before surgery. At the time of surgery, the sealed opaque envelope, numbered consecutively and containing the description of the suturation technique, was given to the operator. Suturing techniques varied between groups: double layer continuous, non-locking suturing with endometrial inclusion, second layer imbricating the first layer (Group 1), double layer, continuous, non-locking suturing without endometrial inclusion second layer imbricating the first layer (Group 2) and double layer continuous with the first layer unlocked, including the endometrium and the deep part of the myometrium, and the second layer continuous unlocked including the remaining part of the myometrium (Group 3) (Figure 2). Size 1 polyglycolic acid 910 (Vicryl ® Ethicon Inc. Somerville, NJ) was used as suture material in all groups.

Patients were re-evaluated at the sixth month as uterine scar healing is reported to be completed within six months and preoperative assessments were repeated. Transvaginal ultrasonography was performed by an investigator blinded to suturing techniques. Measurements included RMT, and CSD assessment (as the primary outcomes) (including the depth and width of the CSD), as well as other routine ultrasonographic evaluations. Transvaginal sonography was performed by the same investigator with a Toshiba Applio 500 device using a PMW-621VT 6 Mhz R13 probe. CSD was considered when myometrial continuity in the previous caesarean incision site was lost, and an anechoic defective area towards the myometrium was noted. In patients who did not develop CSD, the incision line was measured anteriorly, and the symmetrical posterior uterine wall thickness was measured. In patients with CSD, the myometrium tissue above the anechoic defective area was evaluated as residual myometrial thickness. The CSD sac's depth and its base's width were measured. The full-thickness myometrium adjacent to the defect area was measured, and recovery rates were calculated by taking the percentage of the residual myometrial thickness over the defect to the full-thickness myometrium.

Inclusion Criteria:

1. being nulliparous
2. having singleton fetus
3. not having diabetes and or hypertension
4. not having an intrauterine infection
5. body mass index <35 kg/m2
6. not having any placental insertion anomalies
7. not having Mullerian anomalies
8. active phase of labor is not started.
9. no previous uterine surgeries

Exclusion Criteria:

1. being multiparous
2. having multiple pregnancies
3. having diabetes and or hypertension
4. having an intrauterine infection
5. body mass index >=35 kg/m2
6. having any placental insertion anomalies
7. having Mullerian anomalies
8. in active phase of labor
9. having previous uterine surgeries