Labial Fusion

A 2-year-old girl presented with a 2-day history of urinary frequency and dysuria. Physical examination revealed complete fusion of the labia minora. Urine culture showed Escherichia coli with a colony count of 108/L. The child was treated with a 10-day course of amoxicillin that resulted in complete clearance of the urinary tract infection.

Labial fusion refers to partial or complete adherence of the labia minora; it occurs most commonly in girls between ages 3 months and 4 years. Labial fusion is an acquired condition that probably develops after denudation of the superficial squamous epithelial layer of the labial mucosa. During the healing process, fibrous tissue forms and agglutination develops in the apposed area. The process typically begins posteriorly, and the vaginal vestibule may ultimately be covered.

Labial fusion should be differentiated from vaginal agenesis and imperforate hymen. In labial fusion, the vulva is flat; the thin, pale line of fusion in the midvulvar area is pathognomonic. In vaginal agenesis and imperforate hymen, the labia minora are clearly visible.

Girls with labial fusion are prone to urinary tract infection, since stagnant urine retained behind the fused labia encourages the growth of bacteria. A urinalysis and urine culture should therefore be obtained in these children. Conversely, all girls with significant bacteriuria or urinary tract infection should be checked for labial fusion. If labial fusion persists beyond puberty, problems with sexual intercourse may result.

Treatment consists of topical application of an estrogen cream once or twice a day until the adhesion has lysed. After separation of the labia minora, a nonpharmacologic ointment such as petrolatum is applied daily to the labia minora for at least a month to prevent readhesion.