Purpose or Case Report: Genitourinary abnormalities are frequently detected on prenatal imaging. Though many anomalies are easily diagnosed on ultrasound and MR imaging, those that lead to hydrocolpos are not always as easy to distinguish. The purpose of this educational poster is to review the causes of prenatal hydrocolpos and provide an organized approach to differentiate these entities on prenatal imaging.

Several examples of ultrasound and fetal MR imaging are provided to illustrate multiple abnormalities that can produce hydrocolpos (e.g., cloacal malformations, persistent urogenital sinus, congenital adrenal hyperplasia, transverse vaginal septum, imperforate hymen, vaginal atresia) and to distinguish other lesions that may mimic hydrocolpos (e.g., sacrococcygeal teratoma, ovarian cyst).

A diagnostic approach is provided for differentiating the various causes of hydrocolpos on prenatal imaging. When available, postnatal imaging, physical examination, and endoscopic correlations are provided for diagnostic confirmation or clarification. Complications and associated abnormalities are discussed to provide additional considerations for prenatal evaluation and treatment planning. At the end of this module, viewers will better understand and differentiate the various entities that lead to hydrocolpos on prenatal imaging.
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