Hello A nuchal hygroma is commonly called a cystic hygroma. It is a cyst on the area of the jaw line. It commonly happens due to blockage of the lymphatic vessels in the area. Commonly small cystic hygromas disappear and resolve on their own. Small ones are generally followed up with monthly ultrasound scans. In some cases, cystic hygromas are part of a larger group of chromosomal abnormalities, or syndromes such as Turners syndrome etc. Hence, you should have a detailed anomaly scan. Also, amniocentesis can be done to know whether there is any chromosomal defect. If chromosomes are normal, do not worry. The cyst can be cured by surgery or sclerotherapy. If the hygroma is part of a chromosomal disorder, then the prognosis is not that good. SO only further workup and amniocentesis will give you a more clear picture. Take daily folic acid supplements and do not stress out. All the best. Take care.