[Vascular placental pathology in high-risk groups: definition and synopsis]

Abstract

The vascular placental pathology (VPP) is associated with many etiologies. Some are the consequence of a maternal genetic or acquired predisposition. Others are associated with a chronic maternal disease (hypertension, lupus, obesity, diabetes, ...). Finally, some others are associated with placental implantation leading to fetal ischemia (multiple pregnancy, chorioangioma, primiparity, feto-placental hydrops) or to environmental (altitude) or nutritional factors (famine and specific alimentary depressions). We classify these factors into three categories according to the risk level (moderate, significant and elevated). While any of these factors can increase the risk of VPP, no one is sufficiently sensitive or specific in predict inevitable onset of VPP. In most cases VPP results from a combination of two (or more) risk factors. The risk factors of VPP classified as moderate include age (> or = 35 years), increased blood pressure during the second trimester of pregnancy, a new paternity, dietetic factors or environmental factors, smoking and controlled diabetes (class B, C), or inactive systemic diseases. Risk is significantly elevated among obese (BMI > or = 25), primiparous women, women with a past familial history (first degree) of preeclampsia or eclampsia, cocaine use or association of tobacco and caffeine use, increased placental mass (associated with twin pregnancy, fetal hydrops or molar pregnancy), uncontrolled diabetes, lupus, active scleroderma. Risk is considered to be high among patients with chronic hypertension, women with a past history of preeclampsia, diabetes (class D, F, R), patients with active systemic disease or with antiphospholipid antibodies or women with lupus or renal lesions and/or proteinuria as well as chronic kidney disease resulting in proteinuria, hypertension and renal insufficiency. Finally, the risk of VPP is considered to be increased in the presence of acquired thrombophilia. It remains moderate in the presence of isolated genetic thrombophilia, except in forms presenting with multiple genetic mutations or associated with an hyperhomocysteinemia. A "high-risk group" is defined among women with past history of deep venous thromboembolic events outside pregnancy, or with a past history of placental vascular pathology (intra-uterine death, placental abruptio, severe and precocious placental, intra-uterine growth retardation, early and repetitive fetal loss) and who, in addition, present with acquired thrombophilia (antiphospholipid antibodies, thrombocytemia), unique homozygous genetic thrombophilia, amultiple genetic thrombophilia or unique heterozygous genetic thrombophilia associated with hyperhomocysteinemia. Prophylactic treatment of acquired thrombophilia and of the multiple genetic forms or associated with hypercysteinemia is a logical rationale, particularly among women with a past history of placental vascular pathology, or with a past history of venous thromboembolic events. On the contrary, prophylaxis using low-molecular-weight heparin in the event of asymptomatic genetic thrombophilic mutations and for women without a past history of deep venous thromboembolism or vascular placental pathology remains controversial.