Comparing Decidual Inclusion vs. Exclusion in Uterine Suture Techniques During Cesarean Section to Improve Scar Thickness and Reduce Isthmocele Risk in Primiparous Women (DISSUC)

The Impact of Decidual Inclusion or Sparing in a Single Unlocked Closure of a Cesarean Uterine Incision: Randomized Controlled Trial

This study compares two ways of closing the uterus during cesarean delivery. In one group, the decidual layer near the uterine cavity is included in the suture. In the other group, this layer is left out. The study will examine whether these two methods differ in how well the uterine scar heals 6 to 9 months after surgery.

Women having an elective cesarean delivery will be randomly assigned to one of the two closure methods. Scar healing will be assessed by ultrasound after delivery. The goal is to determine whether one method is associated with better cesarean scar healing and fewer scar defects.

Study Overview

• Status: Not yet recruiting
• Conditions: Cesarean Scar Diverticula; Isthmocele
• Intervention / Treatment: Procedure: Single-Layered Non-Locked Closure with Decidual Inclusion; Procedure: Single-Layered Non-Locked Closure with Decidual Sparing

Detailed Description

Cesarean scar defects, also referred to as niches or isthmoceles, are associated with gynecologic symptoms and adverse outcomes in subsequent pregnancies. The effect of uterine closure technique on scar healing remains uncertain, particularly with regard to whether the cavum-near decidual layer should be included in or excluded from the suture during cesarean closure.

This study is a prospective, randomized, controlled trial comparing two approaches to single-layer, non-locked uterine closure during elective cesarean delivery: decidual inclusion and decidual sparing. In both study groups, all operative steps are standardized except for the handling of the cavum-near decidual layer at the uterotomy margin.

Participants will be followed 6 to 9 months after cesarean delivery, including blinded ultrasound assessment of cesarean scar healing. The objective is to determine whether decidual inclusion or decidual sparing is associated with differences in postoperative uterine scar healing and cesarean scar defect formation.

• Study Type: Interventional
• Enrollment (Estimated): 374
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Amr S. Hamza, Assoc. Prof.; Phone Number: +41564863513; Email: amr.hamza@ksb.ch
• Study Contact Backup: Name: Leonhard Schaeffer, Prof.; Phone Number: +41564863506; Email: leonhard.schaeffer@ksb.ch

Study Locations

• Switzerland
  • Canton of Aargau
    • Baden, Canton of Aargau, Switzerland, 5400
      • Kantonsspital Baden
      • Contact: Amr S. Hamza, Assoc. Prof.; Phone Number: +41564863513; Email: amr.hamza@ksb.ch
      • Contact: Leonhard Schaeffer, Prof.; Phone Number: +41564863506; Email: leonhard.schaeffer@ksb.ch

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Singleton, term pregnancy
• Elective cesarean section before labor onset or membrane rupture
• Maternal age >18 years
• Ability to provide informed consent

Exclusion Criteria:

• Placenta previa
• Maternal substance abuse or infection
• Suspected placenta accreta
• Diabetes
• one or more prior cesarean section
• Vulnerable participants (e.g., mental health conditions)
• Emergency cesarean sections

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Decidual Inclusion Closure; Participants randomized to this arm will undergo elective cesarean delivery with single-layer, non-locked uterine closure in which the cavum-near decidual layer at the uterotomy margin is included in the suture. All other operative steps will be performed according to the standardized study protocol.	Procedure: Single-Layered Non-Locked Closure with Decidual Inclusion; During the cesarean section, the uterine incision is closed with a single-layered, non-locked suture. In this technique, the decidua (the uterine lining) is included in the closure. This means that the endometrial cells are part of the suture, potentially influencing the healing process of the uterine scar. Goal: The idea is that including the decidua may promote better healing and scar formation, reducing the risk of complications such as isthmocele and improving long-term uterine health.
Experimental: Decidual Sparing Closure; Participants randomized to this arm will undergo elective cesarean delivery with single-layer, non-locked uterine closure in which the cavum-near decidual layer at the uterotomy margin is excluded from the suture. All other operative steps will be performed according to the standardized study protocol.	Procedure: Single-Layered Non-Locked Closure with Decidual Sparing; Procedure: In this technique, the uterine incision is also closed using a single-layered non-locked suture, but the decidua is excluded from the closure. The suture is placed only through the myometrium (muscle layer) of the uterus, leaving the decidua out of the scar tissue. Goal: The intent is to observe if sparing the decidua results in better scar healing and a lower risk of isthmocele formation, as well as fewer long-term complications.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of participants with a cesarean scar niche measured by ultrasound	Presence of a cesarean scar niche, defined as a myometrial indentation at the cesarean scar site with a depth of at least 2 mm, assessed by postoperative ultrasound. The outcome will be reported as the proportion of participants with a niche in each treatment group.	6 to 9 months post-operation

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Residual-to-adjacent myometrial thickness ratio	Ratio of residual myometrial thickness to adjacent myometrial thickness measured by ultrasound.	6 to 9 months post-operation
Operative time	Operative time in minutes	Periprocedural
Need for additional sutures for hemostasis	Need for additional hemostatic sutures, yes (how many: __ Number) /no	Periprocedural
Length of hospital stay	Length of postoperative hospital stay in days	Postoperative day 2
Postoperative pain intensity on the 11-point Numeric Rating Scale	Pain intensity assessed using an 11-point Numeric Rating Scale ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate worse pain.	Postoperative day 2
Postoperative bleeding	Clinically relevant postoperative bleeding, yes/no	Postoperative day 2
Wound infection	Postoperative wound infection, yes/no	Postoperative day 2
Postoperative fever	Postoperative fever, yes/no	Postoperative day 2
Abnormal uterine bleeding	Abnormal uterine bleeding reported at follow-up, yes/no	6 to 9 months post-operation
Dysmenorrhea	Dysmenorrhea reported at follow-up, yes/no	6 to 9 months post-operation
Chronic pelvic pain	Chronic pelvic pain reported at follow-up, yes/no	6 to 9 months post-operation
Dyspareunia	Dyspareunia reported at follow-up, yes/no	6 to 9 months post-operation
Cesarean scar niche length measured by ultrasound in mm	Length of cesarean scar niche in mm measured by ultrasound.	6 to 9 months post-operation
Cesarean scar niche depth measured by ultrasound in mm	Depth of cesarean scar niche in mm measured by ultrasound.	6 to 9 months post-operation
Cesarean scar niche width measured by ultrasound in mm	Width of cesarean scar niche in mm measured by ultrasound.	6 to 9 months post-operation
Residual myometrial thickness measured by ultrasound in mm	Residual myometrial thickness measured by ultrasound in mm	6 to 9 months post-operation
Presence of intrauterine fluid on ultrasound	Presence or absence of intrauterine fluid on ultrasound.	6 to 9 months post-operation

Collaborators and Investigators

• Sponsor: Kantonsspital Baden
• Investigators: Principal Investigator: Amr S. Hamza, Assoc. Prof., Kantonsspital Baden

Study record dates

Study Major Dates

• Study Start (Estimated): May 25, 2026
• Primary Completion (Estimated): May 1, 2029
• Study Completion (Estimated): May 30, 2029

Study Registration Dates

• First Submitted: August 27, 2025
• First Submitted That Met QC Criteria: May 19, 2026
• First Posted (Actual): May 27, 2026

Study Record Updates

• Last Update Posted (Actual): June 1, 2026
• Last Update Submitted That Met QC Criteria: May 28, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Cesarean section; Dyspareunia; Sonography; isthmocele; Scar thickness; Decidual sparing; Uterine closure techniques; Decidual inclusion; Niche formation
• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Mental Disorders; Genital Diseases, Male; Male Urogenital Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Genital Diseases, Female; Sexual Dysfunction, Physiological; Sexual Dysfunctions, Psychological; Dyspareunia
• Other Study ID Numbers: StudyKSBHAM001

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: De-identified individual participant data will not be shared outside the research team because no external data-sharing process has been approved by the ethics committee or institution. Aggregate study results may be shared through publication or presentation.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No