EP21.22: First trimester cystic hygroma: genetic determinacy

Cystic hygroma represents fluid accumulation often cephalic on the left side, with incidence of 1/6000-1/16000. Genetic anomalies are found in 20-75% cases, most frequent Turner, Down's, Klinefelter, Edwards and Patau syndromes, but also subchromosomal – Noonan, Fryns, multiple pterygium syndrome and achondroplasia. This report aims to identify the correlation between cystic hygroma and genetic anomalies in our practice. We report a small series of cases diagnosed during January 2022–December 2022 in our Department in the first trimester with cystic hygroma and their genetic determinacy. Out of 23 patients diagnosed with cystic hygroma, 5 underwent genetic testing and are presented below, the others choosing TOP. First patient was diagnosed at 11.6 weeks of gestation with a large generalised cystic lesion, omphalocele, AVSD and arthrogryposis. Patient decided TOP and the karyotype confirmed Down's syndrome. Second patient with a term birth followed by 5 miscarriages, presented at 8.5 weeks of gestation a large hygroma suggestive for fetal hydrops and no fetal heartbeat. Abortion product karyotype revealed Turner syndrome. Couple karyotyping and genetic counselling showed a 46,XX/47,XXX mosaicism in the mother, respectively an addition in the 9th pair of chromosomes in the father – 46,XY,add(9)(p12). Third patient with history of 2 early miscarriages and 2 failed IVF procedures, presented with a spontaneous 11.6 weeks pregnancy with cystic hygroma, omphalocele, micrognathia and hypoplastic nasal bone. Couple decided TOP and karyotype revealed Trisomy 18. Fourth patient was diagnosed in the first trimester with a large left cervical cystic mass, consistent with lymphangioma. Follow-up showed normal development and amniocentesis normal karyotype. Appropriate weight neonate was born at 38 weeks by Caesarean section, expecting removal surgery of the cervical lymphatic cyst sized 12 cm. Our small series of cases suggests significant association between cystic hygroma and karyotype anomalies, stronger in patients with obstetrical failure history, validated by invasive genetic testing.