Influence of uterotomy closure technique on uterine wall stability in subsequent pregnancies

• Applicants: Professor Dr. Thorsten Braun; Dr. Alexander Paping
• Subject Area: Gynaecology and Obstetrics
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 443517978

The rate of cesarean sections has increased to over 30% in some countries in recent decades. Especially due to the risk of a rupture of the uterine scar with possibly perilous consequences for mother and child, obstetricians increasingly recommend delivery by cesarean section in subsequent pregnancies and pregnant women are reluctant to decide in favor of a trial of labor after cesarean section. However, the increase in cesarean section rate alone cannot explain the disproportionate increase in the occurrence of uterine ruptures. It seems probable, that the worldwide adoption of the Misgav-Ladach method of cesarean section around the year 2000 has played an important role. According to this method, after extraction of the fetus, the uterotomy closure is implemented in the form of a single layer continuous suture. Until the advent of this method there was no standardized suture technique. In many hospitals worldwide, the uterus was closed with interrupted sutures. We postulate that the former use of single interrupted sutures led to less strangulation of the tissue and thus caused less tissue hypoxia. Therefore, less connective tissue was formed. As single layer interrupted sutures have rarely been used in the last two decades, there are no basic science studies that have examined the impact of this uterine closure technique on uterine tissue healing and stability. The purpose of the proposed study is to investigate and provide a comprehensive comparison of the effects on myometrial healing of the four main uterine closure techniques during cesarean sections in a sheep model. 48 sheep were delivered by cesarean section. Twelve animals (4 groups) received uterine closure with the same technique. During the planned second cesarean section, a hysterectomy will be performed and the scar tissue will be characterized with regard to its features in histology, immunohistochemistry, molecular biology and biomechanical properties. We suspect the uterine tissue after interrupted sutures to be more tear-resistant because this technique has a less constrictive effect on the myometrium than continuous sutures. Therefore, it produces less necrosis and leads to a diminished scar formation (especially compared to imbricated sutures). The comprehensive design of our translational research project clearly stands out from the existing studies in this field. It promises to provide an important contribution to the understanding of the pathways of uterine healing and it shall help to develop safer methods of uterine closure during cesarean section. We believe that a lower cesarean section rate per se can be best achieved by lowering the rate of repeat cesarean sections. The anticipated insights on potential modifications of uterotomy closures will help to lower the risk of uterine ruptures and will therefore help to restore the confidence in vaginal birth after cesarean section.

• DFG Programme: Research Grants
• Co-Investigator: Dag Wulsten