A half moon of thin membrane normally surrounds a young girl's vagina. Sometimes, the hymenal membrane extends all the way across the hymenal area with only a very small hole in the center. This is called a microperforate hymen.
Menstrual blood and mucus may still be able to escape the vagina, but since it's flowing through such a small hole, the period may last longer than the normal four- to seven-day cycle.
Your daughter may not be able to insert a tampon, or she may have pain when she tries to fit it in.
Sometimes a microperforate hymen resolves spontaneously as the girl grows older, or it may tear away with some pain when she inserts a tampon or when she has sexual intercourse. There is also a minor surgery than can remove the extra tissue and create a normal sized vaginal opening.
