Aim: To analyze the morphological features of the supravaginal part of the cervix depending on the echogenicity ratios of the cervix to the body of the uterus. Materials and Methods: In 87 reproductive-age patients (30–40 years) with uterine leiomyoma (>14 weeks gestation), morphological features of the supravaginal cervix were analyzed in 23 hysterectomy specimens based on echogenicity ratios: Group I (n = 10): Cervical echogenicity > uterine body. Group II (n = 8): Cervical echogenicity = uterine body. Group III (n = 5): Cervical echogenicity < uterine body. Results: Histological analysis revealed that increased cervical echogenicity corresponded to a predominance of collagen fibers over smooth muscle bundles. Conversely, when cervical echogenicity was equal to or lower than the uterine body, smooth muscle bundles dominated. These specimens also exhibited destructive changes, connective tissue disorganization, and dystrophic alterations, which are pathognomonic signs of potential lower uterine segment failure during pregnancy. Conclusions: 1. Comparative studies show that in cases of excess echogenicity of the cervix over the body of the uterus, pathomorphological changes in the supravaginal part of the cervix were not detected. 2. Equal or reduced cervical echogenicity was associated with connective tissue disorganization and dystrophic changes in smooth muscle, indicating structural inferiority. 3. A change in the ratio of echogenicity of the cervix to the body, which is closely related to the morphological structure of the isthmus of the uterus, can serve as one of the criteria for predicting the failure of the lower segment of the uterus in women.