Uterine peristalsis-induced stresses within the uterine wall may sprout adenomyosis

Adenomyosis is a disease in which ectopic endometrial glands and stromal cells appear in the uterine myometrium. This pathology is common among women of reproductive age, and in addition to chronic pelvic pain and heavy periods it may also cause infertility. The 'tissue injury and repair' mechanism in response to increased intrauterine pressures was proposed as the etiology for migration of fragments of basal endometrium into the myometrial wall. In order to investigate this mechanism, a conceptual two-dimensional model of the uterine wall subjected to intrauterine pressures was implemented using ADINA commercial software. The stress field within the uterine wall was examined for a variety of intrauterine sinusoidal pressure waves with varying frequencies. The results revealed that: (1) as the wavelength of the subjected pressure wave decreased, high concentration of stresses developed near the inner uterine cavity; (2) as the pressure wave frequency increased, high gradients of the stresses were obtained; (3) at menstrual phase, the highest stresses obtained at the endometrial-myometrial interface. Therefore, increased uterine activity results in high stresses which may lead to tissue lesions and detachment of endometrial cells.