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Vasa praevia : ウィキペディア英語版 | Vasa praevia
Vasa praevia (vasa previa AE) is an obstetric complication in which fetal blood vessels cross or run near the external orifice of the uterus. These vessels are at risk of rupture when the supporting membranes rupture, as they are unsupported by the umbilical cord or placental tissue.The term "vasa previa" is derived from the Latin; "vasa" means vessel and "previa" comes from "pre" meaning "before" and "via" meaning "way". In other words, vessels lie before the baby in the birth canal and in the way. 〔 ''(Full text )''〕 ==Etiology/Pathophysiology== Vasa previa is present when unprotected fetal vessels traverse the fetal membranes over the internal cervical os. These vessels may be from either a velamentous insertion of the umbilical cord or may be joining an accessory (succenturiate) placental lobe to the main disk of the placenta. If these fetal vessels rupture the bleeding is from the fetoplacental circulation, and fetal exsanguination will rapidly occur, leading to fetal death. It is thought that vasa previa arises from an early placenta previa. As the pregnancy progresses, the placenta tissue surrounding the vessels over the cervix undergoes atrophy, and the placenta grows preferentially toward the upper portion of the uterus. This leaves unprotected vessels running over the cervix and in the lower uterine segment. This has been demonstrated using serial ultrasound. Oyelese et al found that 2/3 of patient with vasa previa at delivery had a low-lying placenta or placenta previa that resolved prior to the time of delivery. There are three types of vasa previa. Types 1 and 2 were described by Catanzarite et al. In Type 1, there is a velamentous insertion with vessels running over the cervix. In Type 2, unprotected vessels run between lobes of a bilobed or succenturiate lobed placenta. In Type 3, a portion of the placenta overlying the cervix undergoes atrophy. In this type, there is a normal placental cord insertion and the placenta has only one lobe. However, vessels at a margin of the placenta are exposed.
抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Vasa praevia」の詳細全文を読む
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