[Clinical and morphological characteristics of the atypical placentation spectrum in the uterus].

Background: The concern of the global community of gynecologists and obstetricians (FIGO) regarding the increase in the number of caesarean sections has resulted in the creation of a new classification, Placenta Accreta Spectrum (PAS), which presents degrees of villus invasion into the uterine wall.

Objective: Compare the main types of atypical placentation (AP) with the stages of PAS, to supplement and unify the clinical and morphological criteria AP.

Material and methods: Surgical material was examined from 73 women after metroplasty (n=61) and hysterectomies (n=12) from the regions of Russia, Moscow and the Moscow region for ingrown villi and from 10 women with a typical placenta location during the first cesarean section. A targeted cutting of material from the uteroplacental region was used, at least 10-12 pieces, with further H&E and Mallory staining.

Results: In the classification of AP, the terms «placenta accreta», «increta», «percreta» should be retained. It is necessary to single out pl. previa as a separate type. Attention is focused on the need to assess the depth of villi invasion accompanied by a layer of fibrinoid, the volume of scar tissue and the degree of disorganization of the myometrial bundles, the state of the vessels in the serous membrane. A new type of AP has been proposed - a sharp thinning of the lower segment of the uterus, due to the scar failure and the pressure of the growing amniotic sac, leading to atrophy and necrosis of the myometrium.

Conclusion: An integrated approach should be used to classify atypical placentation, taking into account not only the depth of villus invasion, but also anatomical and pathogenic factors in order to develop targeted methods of surgical treatment.