[Echographic diagnosis of cystic hygroma. Apropos of a case]

A case of nuchal cystic hygroma associated with non immune hydrops fetalis and renal malformation in one of two twins observed at 18th week of gestation is reported. Occurrence of acute polyhydramnios and severity of the anomalies showed by serial ultrasound scans has led to termination of pregnancy induced by prostaglandin E. This rare malformation is related to an abnormality of the lymphatic system and is usually associated with monosomy 45 XO or Turner syndrome. But a review of some 191 reported cases shows that this condition may be connected with various chromosomic or congenital anomalies. This may worsen the prognosis and accurate diagnosis is mandatory to guide the genetic counseling for future pregnancy. Ultrasonography allows precise diagnosis of cystic hygroma as soon as the end of the first trimester. The potentially lethal associated malformations and anomalies of karyotype will condition the management of this malformation. The prognosis usually fatal in utero will often lead to termination of pregnancy.