While a cystic hygroma, a fluid-filled cyst in the head or neck area, can sometimes be detected during a pregnancy ultrasound, it cannot be treated until after the baby is born. If the cystic hygroma is small and does not affect neighboring tissues, it can usually be removed with ease. Full removal of the abnormal tissues is necessary to prevent regrowth, but larger cystic hygromas may be impossible to remove completely.
This is when other treatment methods, such as chemotherapy, radiation, and sclerosing medications, are used to shrink the cyst to a size that is conducive to successful surgical removal. Without complete removal of the cystic hygroma, the baby may experience a number of complications, including recurrent growths, bleeding, and infections.