Repeat cesarean delivery with hysterectomy: a sheep model to examine uterine scars

Abstract

Cesarean delivery (CD) is one of the most common surgical procedures worldwide, with rising rates leading to an increasing impact of complications, such as uterine rupture during a trial of labor in a subsequent pregnancy. To date, only little information on uterine wound healing is available. The current challenge is to establish a suitable model and to define quantifiable outcome parameters of uterine scar tissue with the aim of comparing the effect of different surgical techniques on uterine scarring. This study presents a sheep model to examine the effects of different hysterotomy closure techniques. A total of 48 Merino ewes underwent planned CD. After one year, 40 ewes were mated again following estrus synchronization and received planned repeat CD with peripartum supracervical hysterectomy and sampling of uterine scar tissue without any major complications. Survival rates at repeat CD were 95.0 and 91.4% for ewes and lambs, respectively. Due to placement of non-absorbable sutures around the hysterotomy closure during the first CD, all scarred uterine wall segments could be identified. Of 80 uterine scars, 16 (20%) showed dehiscences with a macroscopic thinning of the uterine wall. A full-thickness uterine rupture was not found. Gomori trichrome staining was used to assess the collagen content histomorphometrically. It revealed a markedly scarred uterine wall. This translational model can be used to evaluate intraoperative approaches to optimize uterine wound healing, such as suturing techniques, pharmacological agents, or biomaterials, with the aim of reducing the risk of uterine rupture in humans and improving maternal outcomes in pregnancies after previous CD.