Constipation can have various reasons. How old is she? If she has associated gas, bloating and abdominal pain it can indicate a simple condition like Irritable bowel. Sometimes it can be due to intolerance to certain foods which have a constipating effect. Rarely it can be due to hormonal disorders. The important thing to understand is that all these causes of constipation are treatable if the diagnosis is right. Constipation is also preventable by eating high fibre foods, doing regular exercise and drinking plenty of water. Enema is absolutely not the way to go about it.