Ben-Chaim J, Docimo S G, Jeffs R D, Gearhart J P
Department of Urology, Johns Hopkins Hospital and University School of Medicine, Baltimore, MD 21287-2101, USA.
J R Soc Med. 1996 Jan;89(1):39P-46P. doi: 10.1177/014107689608900112.
Exstrophy of the bladder is rare and the incidence of bladder exstrophy is calculated to be from 1 per 30,000 to 50,000 live births with male to female ratio ranging from 1.5-5 to 1(1-4). It was found that persistence or overgrowth of the cloacal membrane on the lower anterior abdominal area, prevents normal mesenchymal ingrowth. This causes divergence of the lower abdominal muscular structures and forces the genital ridges to fuse caudal to the cloacal membrane. The stage of ingrowth of the urorectal septum at the time of rupture determines whether one will produce an exstrophic urinary tract alone (classic bladder exstrophy or epispadias) or cloacal exstrophy with the hindgut interposed between the hemibladders.
膀胱外翻很少见，据计算膀胱外翻的发病率为每30000至50000例活产中有1例，男女比例为1.5 - 5比1（1 - 4）。研究发现，下腹部前侧区域泄殖腔膜的持续存在或过度生长会阻止正常的间充质向内生长。这会导致下腹部肌肉结构出现分歧，并迫使生殖嵴在泄殖腔膜尾侧融合。尿直肠隔破裂时的向内生长阶段决定了是单独产生一个外翻性尿路（典型膀胱外翻或尿道上裂）还是产生泄殖腔外翻，即后肠介于两半膀胱之间。
