Fetal cystic hygroma

What it means

The presence during the prenatal period of a cystic mass with multiple septa with multiple, asymmetric, thin-walled cysts near the posterior aspect of the neck. Fetal cystic hygroma can be defined as nuchal translucency with or without septations measuring greater than 3.0 mm. Increased NT refers to a measurement above the 95th centile, and the term is used irrespective of whether the collection of fluid is septated or not, and whether it is confined to the neck or envelopes the whole fetus. After 14 weeks, increased NT usually resolves, but in some cases it evolves into nuchal edema or cystic hygromas.

Upon ultrasound examination, fetal cystic hygroma presents as a cystic mass with multiple septa with multiple, asymmetric, thin-walled cysts related to the posterior aspect of the neck. Cystic hygromas can range from increased nuchal translucency to thin-walled cystic masses that may become larger than the fetal head. The cysts may result from a lymphatic abnormality, possibly one caused by absent or inefficient connections between the lymphatic and venous systems. Depending on the site, the cut off may vary from site to site. Lowest would be 2.5 mm and highest 3.5 mm.

Rare diseases that can present with this1

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Foetal cystic hygroma