الفهرس 
Anatomy of the uterus:
Physiological adaptation of the Uterine Vasculature During Pregnancy:Only 14 pages are availabe for public view
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Abstract
Hypertensive disorders commonly occur during pregnancy and are considered as three fatal factors when combined with bleeding and infection. These factors are responsible for the major part of mortalities and maternal complications including preeclampsia. (1) According to the estimation of the World Health Organization, more than one million women around the world annually die due to preeclampsia and its complication which lead to maternal deaths in developing countries. This rate is 5-10 and more than 18% in developing countries and the developed countries, respectively. (2) In addition, preeclampsia is one of the pregnancy- specific disorders in pregnancy, which is characterized by hypertension and proteinuria after 20 weeks of pregnancy. (3) The exact pathophysiology of this disease is not clear, but it is shown that preeclampsia is associated with an imbalance between the production of prostacyclin, thromboxane A2, and vascular spasm. (4) The end organ involvement in the form of heart failure, pulmonary edema, liver involvement, and coagulation system, and finally, the hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome are considered as its serious complications. Furthermore, preeclampsia is accompanied by a decline in renal function, cerebral involvement, convulsions, and even maternal deaths. On the other hand, the incidence of intrauterine growth restriction (IUGR) and intrauterine fetal death is also possible due to a problem in placental perfusion. (5) The Doppler ultrasonography, as a non-invasive technique, can be used to investigate placental blood flow. The impedance of uterine artery flow progressively reduces during the first and second trimester of normal pregnancy due to the trophoblastic invasion of the musculo-elastic membrane of uterine spiral arteries. (6) Moreover, the pathology of the placenta in pregnancies with preeclampsia indicates the failure in the normal transmission of maternal placental arteries to the vessels with low resistance. (7) Some studies expressed that an abnormal Doppler at the second trimester of pregnancy can be effective in identifying the high-risk patients in preeclampsia. (8).