Uterine Myometrial Preischemia: Yet Another Physiological Change of Pregnancy!

The uterus shows tremendous increase in size during pregnancy to nurture the fetus within it. It may show a spectrum of physiological changes or pathological lesions that may affect the pregnancy favorably or adversely. The main purpose of our study was to analyze the physiological changes in the uterus during pregnancy and the postpartum period, thereby gaining deeper knowledge.  We studied a total of 152 uterine specimens obtained from obstetric hysterectomies and maternal autopsies for the presence or absence of normal physiological changes. As a control group, an equal number of surgical uterine specimens received for abnormal uterine bleeding were studied.  Decidual change was observed from 6 weeks of gestation to 16 days postpartum. It was partially deficient to absent in four cases of placenta accreta. Myometrial hypertrophy was seen in 150 cases (98.68%) from 8 weeks of gestation till 30 days postpartum period. Vascular remodeling was partially deficient to absent in eight cases of pregnancy-induced hypertension. Preischemia of myometrial fibers was an unexpected finding noticed from 20 weeks of gestation to 16 days postpartum in 131 cases (86.18%). Cervical wall hemorrhages were seen in 84.84% cases of vaginal delivery and in only 17.64% cases of lower segment cesarean section.  Ours is the first study to describe the duration of the routine physiological uterine changes during pregnancy. The relationship between cervical wall hemorrhages and vaginal delivery as well as between myometrial preischemia and gestational age, both being normal physiologic findings, was found to be statistically significant.