Clinical and morphological features of the myometrium in patients with placental adherent and invasive pathology

BACKGROUND: The fast increase in the frequency of placental adherent and invasive pathology worldwide accounts for the growing interest in studying the pathogenesis of placenta accreta. According to the literature, the clinical and morphological features of the myometrium from the placental attachment area in placental adherent and invasive pathology are described in single articles. Study of morphological features using proteolytic markers in the myometrium from the placenta accreta area could help in understanding the pathogenesis of placental adherent and invasive pathology. For the first time in this study, the clinical and morphological features of the myometrium from the placental attachment area in patients with uterine scar and placental adherent and invasive pathology are compared with the myometrium of women with uterine scar without placenta accreta and intact myometrium.

AIM: The aim of this study was to evaluate the expression of matrix metalloproteinase 2 and tissue inhibitors of matrix metalloproteinases 1 and 2 in myometrial biopsies in placental adherent and invasive pathology.

MATERIALS AND METHODS: This study included 15 myometrial biopsies from the placental site, which were divided into three groups according to the clinical diagnosis of the patients: group 1 (main group), with a uterine scar after cesarean section and placental adherent and invasive pathology (n = 5); group 2 (comparison group), with a uterine scar after cesarean section (n = 5); group 3 (control group), with a normal pregnancy without a uterine scar (n = 5). Histological examination was carried out using the standard procedure. Immunohistochemical study was performed using antibodies to matrix metalloproteinase 2 and tissue inhibitors of matrix metalloproteinases 1 and 2 (Abcam, USA). Morphometry was carried out using the VideoTesT-Morphology 5.2 program (Videotest Ltd., Russia). The statistical analysis was performed using the IBM SPSS Statistics 26.0 software.

RESULTS: In the biopsies of the main group, we verified terminal chorionic villi with hypervascularization and uneven plethora of the vascular bed among hypertrophied muscle fibers, a basal plate with lumen ectasia of unevenly full-blooded vessels, and the absence of a decidual membrane, in contrast to groups 2 and 3. The matrix metalloproteinase 2 expression area in the main group was higher than in the comparison and control groups (p = 0.008; p_1–2 = 0.049*, p_1–3 = 0.011), the matrix metalloproteinase 2 optical density not differing between the groups (p = 0.122). The tissue inhibitors of matrix metalloproteinases 1 expression area was higher in the comparison group compared to the main group (p = 0.035; p_2–3 = 0.032), and the tissue inhibitors of matrix metalloproteinases 1 and 2 optical density was higher in the comparison group compared to control (p = 0.008; p_2–3 = 0.005).

CONCLUSIONS: In myometrial biopsies of patients with a uterine scar and placental adherent and invasive pathology, we verified pathology of the basal plate of the placenta, increased matrix metalloproteinase 2 expression and decreased tissue inhibitors of matrix metalloproteinases 1 expression, which may indicate the peculiarities of the inflammatory response in the myometrium in placental adherent and invasive pathology.