Diaper dermatitis is caused by overhydration of the skin, maceration, prolonged contact with urine and feces, retained diaper soaps, and topical preparations and is a prototypical example of irritant contact dermatitis.

Pathophysiology

Diaper rash affects the areas within the confines of the diaper. Increased wetness in the diaper area makes the skin more susceptible to damage by physical, chemical, and enzymatic mechanisms. Wet skin increases the penetration of irritant substances. Superhydration urease enzyme found in the stratum corneum liberates ammonia from cutaneous bacteria. Urease has a mild irritant effect on nonintact skin. Lipases and proteases in feces mix with urine on nonintact skin and cause an alkaline surface pH, adding to the irritation. (Feces in breastfed infants have a lower pH, and breastfed infants are less susceptible to diaper dermatitis.) The bile salts in the stools enhance the activity of fecal enzymes, adding to the effect.

Age

Diaper dermatitis commonly affects infants, with peak incidence occurring when the individual is aged 9-12 months. One study determined that at any given time, diaper dermatitis is prevalent in 7-35% of the infant population.

Diaper dermatitis can affect persons of any age who wear diapers, in particular, elderly people.

Physical Examination

Patients with diaper dermatitis present with an erythematous scaly diaper area often with papulovesicular or bullous lesions, fissures, and erosions.

The eruption may be patchy or confluent, affecting the abdomen from the umbilicus down to the thighs and encompassing the genitalia, perineum, and buttocks. Genitocrural folds are spared in irritant dermatitis, but often involved in primary candidal dermatitis.

Children with diaper dermatitis have marked discomfort from intense inflammation.

Rule out a secondary yeast or bacterial infection, which may occur in the area.

Management

Ideally, the first-line therapy for individuals with diaper dermatitis is zinc oxide ointment or various products containing zinc oxide.

If candidiasis is suspected or proven by potassium hydroxide (KOH) preparation or culture, an antifungal agent effective against yeast is indicated.

The safest OTC emollient available for newborns is pure white petrolatum ointment, which acts by trapping water beneath the epidermis.

Prevention

Prevention of diaper dermatitis can be summarized with the acronym ABCDE (air, barrier, cleansing, diaper, and education).

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