Niche In CEsarean Scar Trial (NICEST)

Rationale: Cesarean delivery (CD) rates are increasing rapidly worldwide. The consequences of cesarean section not only affect the next pregnancies such as uterine rupture or malplacentation but also cause many gynecological complications or infertility due to the formation of cesarean scar defect (CSD) or Niche. One of the major factors for Niche formation is the techniques of hysterotomy closure at the time of cesarean delivery. Most common hysterotomy closures include single and double layers closure. However, there is limited literature to prove which technique decreases niche creation and associated gynecological complications.

Objective: To compare the effect of uterine closure techniques during CD on the formation of Niche evaluated on transvaginal ultrasound and gynecological complications.

Study design: a double-blinded, single-center, randomized clinical trial. Setting: Hanoi Obstetrics \& Gynecology Hospital (HOGH), Viet Nam. Study population: All women at gestational age ≥ 37 0/7 weeks who undergo a primary CD (planned or unplanned).

Intervention: After informed consent, women will be randomized to either unlocked single layer closure or unlocked double-layer closures of cesarean uterine scar in a 1:1 ratio Primary outcome: The proportion of Niche over time (at 6, 12, 18, 24 months after CD) in the two groups.

Power calculation: A sample size of 389 women is needed for each group. Nature and extent of the burden and risks associated with participation, benefit, and group relatedness: Both uterine closure methods followed by the Vietnam Ministry of Health (VN-MOH), transvaginal ultrasound is also not harmful. It is believed that there are no potential increased risks to patients taking part in this trial because of the standard care and management they receive.