Familial occurrence of isolated nonseptated nuchal cystic hygromata in midtrimester of pregnancy

Objective: Nonseptated cystic hygromata of the fetal neck in midtrimester of pregnancy have been associated with chromosomal and structural malformations. Consequently, fetal karyotyping is frequently offered. We describe 18 families in which 18 pairs of siblings were affected by transient nonseptated cystic hygromata in utero. Methods: Over a seven-year period, 18 families came to our attention, with a recurrent diagnosis of fetal nonseptated cystic hygromata in two subsequent pregnancies. Detailed anatomic surveys by transvaginal ultrasound were performed between 14 to 16 weeks' gestation on the basis of self-referral. Sonographic markers for fetal aneuploidy were specifically looked for. Nonseptated cystic hygroma was diagnosed when unilateral or bilateral cystic dilations in the anterolateral aspect of the fetal neck were present, as described by Bronshtein et al. (1989). All patients underwent amniocentesis, fetal echocardiography, and transabdominal follow-up ultrasound scan at 22 to 24 weeks' gestation. Results: Thirty-six sibling fetuses with isolated nonseptated hygromata (unilateral n = 5; bilateral n = 31) were identified. Amniocentesis revealed normal karyotypes in all 36 fetuses, including 20 males and 16 females. Fetal echocardiograms and neonatal pediatric examinations were normal. Sonographic resolution of the cystic hygromata was noted in all cases at the 22 to 24 weeks' follow-up scan. One pregnancy, producing a female newborn, was conceived by a remarried mother. All others were reportedly conceived by the same partners. Probability calculations suggest that if our findings were explained by chance alone, a population base of 367 000 pregnancies would have to be scanned in order to find 18 pairs of siblings with nonseptated cystic hygromata. Conclusion: The familial occurrence and identical natural history of the cystic lesions in utero suggest the presence of an inheritable developmental syndrome affecting the lymphatic system in utero, but without long-term sequelae.