Labial Fusion

The mother of this 11-month-old girl was concerned that her infant’s vagina was almost obscured by a membrane. This was noted incidentally a few days earlier. The mother was sure that the membrane was not there in the immediate neonatal period. Urination was unimpaired, and the infant was asymptomatic. She had no history of trauma to the genital area. Her past health was unremarkable. In particular, she had no history of unexplained fever, foul-smelling urine, or an overt urinary tract infection.

On examination, the vulva was flat. The edges of the labia minora were sealed in the midline by a thin, translucent membrane that extended from the posterior fourchette to just below the clitoris.

Labial fusion refers to partial or complete adherence of the labia minora. The condition is rare at birth and occurs most commonly in girls between 3 months and 4 years of age. The peak incidence is between 13 and 23 months, during which about 3.3% of girls are affected.

Labial fusion probably develops after denudation of the superficial squamous epithelial layer of the labial mucosa. Denudation occurs with inflammatory conditions of the labia minora, such as vulvitis or vulvovaginitis, most often secondary to poor perineal hygiene. Estrogen deficiency is associated with a reduction in the thickness of the labial epithelial cells and is a possible pathogenic factor.

Most girls with labial fusion are asymptomatic. The condition is usually discovered incidentally by a physician during a routine examination or by the mother while she is bathing the child. Labial fusion may predispose the child to asymptomatic bacteriuria or to urinary tract infection. Occasionally, the labial fusion causes urinary outflow obstruction with resultant bladder distention and hydronephrosis.

Treatment consists of precise application of a topical estrogen cream to the fused area twice a day until lysis of the adhesion is complete. Most cases resolve within 2 to 3 months. As the labia minora separate, petroleum jelly should be applied to the edges to prevent readhesion.

FOR MORE INFORMATION:
• Leung AK, Robson WL. Labial fusion. Consultant for Pediatricians. 2004;3:31-35.
• Leung AK, Robson WL, Kao CP, et al. Treatment of labial fusion with topical estrogen therapy. Clin Pediatr (Phila). 2005;44:245-247.
• Leung AK, Robson WL, Tay-Uyboco J. The incidence of labial fusion in children. J Paediatr Child Health. 1993;29:235-236.