What are the prevalence, characteristics and significance of fetal lateral neck cysts detected in an early anatomical scan?

PURPOSE: This study evaluated the association of fetal lateral neck cysts (FLNC) with adverse pregnancy outcomes, in relation to specific sonographic characteristics and co-existing findings.

METHODS: Pregnancies in which FLNC were detected by a single examiner in early anatomical scans (14-16 weeks) were included. Data regarding the pregnancy and its outcome were retrieved from telephone-based questionnaires, patient charts and from the examiner's reports.

RESULTS: 654 cases of FLNC were detected among 9446 early anatomical scans (6.9%). Complete data regarding 219 pregnancies were available. FLNC were significantly more prevalent in males (65.2%). The prevalence of heart malformations was 3.2% [all were non-isolated cases or with abnormal nuchal translucency (NT) and/or nuchal fold (NF)]. Amniocentesis performed in 165 pregnancies was abnormal in 1.2%. Among 206 children born from this cohort, adverse medical outcomes were reported in 5.3%. The likelihood of adverse pregnancy outcomes was significantly higher in non-isolated cases and in cases with abnormal NT or NF. Sonographic characteristics such as cyst size and bilateral findings were not linked to adverse pregnancy outcomes.

CONCLUSION: Isolated FLNC are benign findings which do not require additional work up. FLNC with additional sonographic abnormalities are associated with a significantly increased risk for adverse pregnancy outcomes.