Nonobstructive hydrocolpos: sonographic appearance and differential diagnosis.

Hydrocolpos in the pediatric patient almost invariably occurs secondary to fluid distending the vaginal canal proximal to an obstructive lesion, usually an imperforate hymen. There are, however, other causes for fluid filling and sometimes markedly distending the vagina; many of these are not pathologic. Sonographically, fluid in the vaginal canal often has a confusing appearance and may be mistaken for a pathologic mass. Ways of differentiating hydrocolpos from other normal and abnormal pelvic fluid collections are described. Five adult patients are presented who showed a varied sonographic spectrum of nonobstructive hydrocolpos.