Most commonly seen in infants and young children under age three years, labial fusion is the adherence of adjacent mucosal surfaces of the labia minora at any point along the structures, resulting in a partial or complete membranous covering of or near the vaginal opening. The fusion is the co-joining of the labia; breakdown in the labial surface can lead to the sealing of the membranous structures, much like a healing wound. Tissue breakdown occurs due to chronic inflammation, irritation, or trauma, related to factors such as low estrogen levels, various pathologic or disease states, sexual abuse, or poor hygiene. Correcting the underlying cause is the recommended treatment method. Topical estrogen creams are most commonly used, and surgical intervention is rarely necessary.

Variations: labial adhesion, labial fusion