McNamara M F, McCurdy C M, Reed K L, Philipps A F, Seeds J W
Department of Obstetrics and Gynecology, University of Arizona Health Sciences Center, Tucson, USA.
Obstet Gynecol. 1995 May;85(5 Pt 2):867-9. doi: 10.1016/0029-7844(94)00249-d.
Adequate amniotic fluid (AF) volume is one of several factors felt to be essential for normal lung development. Renal agenesis and urinary tract obstruction usually result in oligohydramnios and pulmonary hypoplasia.
Two sets of monoamiotic twins with discordant urinary tract anomalies were seen. One twin in each set had anomalies that in a singleton or diamiotic pregnancy would likely have resulted in fetal pulmonary hypoplasia and subsequent death. However, neither of these infants had pulmonary hypoplasia. One infant is unique in being the first case reported of normal pulmonary function and survival despite the anomaly.
Adequate AF provided by a monoamniotic twin environment may prevent pulmonary hypoplasia, which usually results from oligohydramnios due to certain fetal urinary tract anomalies.
充足的羊水（AF）量是正常肺发育所需的几个因素之一。肾缺如和尿路梗阻通常会导致羊水过少和肺发育不全。
观察到两组单羊膜囊双胎存在不一致的尿路异常。每组中的一个胎儿有异常情况，在单胎或双羊膜囊妊娠中，这些异常可能会导致胎儿肺发育不全及随后的死亡。然而，这些婴儿均未出现肺发育不全。其中一名婴儿很独特，是首例尽管存在异常但肺功能正常且存活的病例报告。
单羊膜囊双胎环境所提供的充足羊水可能会预防通常由某些胎儿尿路异常导致羊水过少引起的肺发育不全。
