OBJECTIVE We assess and clarify diagnostic features for making the prenatal diagnosis of cloacal exstrophy. METHODS We evaluated 9 patients born with cloacal exstrophy at our institutions (2 prospectively and 7 retrospectively) for diagnostic features on prenatal ultrasound studies. We also thoroughly reviewed the literature on 13 previous prenatally diagnosed cloacal exstrophy cases. Diagnostic criteria were assessed by combining the findings in our patients and those in previous reports. RESULTS Of the 22 patients with prenatal ultrasound studies and cloacal exstrophy whom we analyzed 1 of our 9 and 2 in the literature had a cloacal membrane that persisted at 22 weeks of gestation. Major ultrasound criteria for diagnosing cloacal exstrophy prenatally are nonvisualization of the bladder, a large midline infraumbilical anterior wall defect or cystic anterior wall structure (persistent cloacal membrane), omphalocele and lumbosacral anomalies. Seven less frequent or minor criteria include lower extremity defects, renal anomalies, ascites, widened pubic arches, a narrow thorax, hydrocephalus and 1 umbilical artery. CONCLUSIONS We propose major and minor criteria to assist in the prenatal diagnosis of cloacal exstrophy. Despite these major and minor criteria the certainty of establishing a prenatal diagnosis remains challenging. Persistence of the cloacal membrane beyond the first trimester in 1 patient was an exception to the classic concept of cloacal exstrophy embryogenesis. An accurate prenatal diagnosis requires validation of these criteria by further correlation of prenatal and postnatal observations.