In young children, it is normal not to be able to pull back the foreskin at all. Over 90% of cases resolve by the age of seven, although full retraction is still prevented by preputial adhesions in over half at this age. 99% of cases resolve by age 16. Occasionally, phimosis may be caused by an underlying condition such as scarring due to balanitis or balanitis xerotica obliterans. This can typically be diagnosed by seeing scarring of the opening of the foreskin.