Caesarean section scar: Histological analysis on hysterectomy specimen. A pilot study

In recent years, caesarean section (CS) rate has risen worldwide. Complications associated with CS scars have risen too, such as scar dehiscences and uterine ruptures. Uterine healing is a complex phenomenon still poorly understood. The aim of this study is to carry out a comparative histological analysis of healthy and scarred uterus.

Women who underwent hysterectomy for benign pathology were included prospectively and divided into two groups: previous CS (group 1) versus control (group 2). Hysterectomy specimen were analyzed histologically and immunohistochemically.

Sixty women were included: 30 women per group. In group 1, only 19 women could be analyzed. Median total thickness at the thinnest site of the scar is significantly thinner (4.34 mm; IQR [2.76-9.45]) than that of adjacent healthy isthmus (12.70 mm; IQR [10.45-14.95]) (p < 0.001). It is also thinner than in group 2 (13.45 mm; IQR [11.03-16.90]) (p < 0.001). Median myometrial thickness within the scar in group 1 was also thinner (1.14 mm; IQR [0.30-2.69]) than that of the adjacent healthy isthmus (8.90 mm; IQR [8.18-10.08]) (p < 0.001) and that in group 2 (10.00 mm; IQR [8.38-13.35]) (p < 0.001). There was a significant increase in fibrosis in the scar (55.01 %; IQR [35.71-63.46]) compared with adjacent tissue (17.41 %; IQR [15.08-24.78]) (p < 0.001) and with healthy uterus (33.91 %; IQR [18.93-46.53]) (p = 0.006).

In uterus with previous CS scar, total thickness of the wall and thickness of the myometrium are reduced and proportion of fibrosis is significantly increased. This study shows that the thickness of the wall remains reduced in scarred uterus, even very long after CS. Further studies are currently in progress to understand its pathophysiology within the uterus using animal models.