The hymen is a thin fold or flap of skin around the opening of the vagina. Most girls are born with a hymen, but it doesn’t serve any particular purpose. Typically, the hymen is a membrane that encircles the vaginal opening or only partially covers the vaginal opening in a crescent moon or half-moon shape. In some cases, however, babies are born with a hymen that fully covers the vaginal opening. This anomaly is called an imperforate hymen.
Imperforate hymens can affect anywhere between 1 in 1,000 and 1 in 10,000 girls. Often, doctors will notice an imperforate hymen when they’re examining newborn babies. If the imperforate hymen goes undetected, it can cause some uncomfortable symptoms as the girl ages and starts to go through puberty. The only way to correct an imperforate hymen is with minor surgery. The procedure is very common and shouldn’t cause any long-term health complications.