Widening of foetal cerebral ventricles is one of the most commonly diagnosed anomalies of the foetal brain and one of the most common reason, why pregnant women are referred to the referral centre. This abnormal finding very often is misdiagnosed as the hydrocephalus, but it is not the hydrocephalus according to the classical definition. Extended cerebral fluid accommodation in foetus may be an isolated finding, but it may also coexist with other anomalies of the brain, other congenital anomalies and also with genetic syndromes – in each case of the cerebral ventricles widening, other abnormalities should be excluded. Presence of other anomalies changes the prognosis for the foetus/neonate and determines further parental counselling. In the case of hydrocephalus prenatal intervention may be considered, whereas other foetal brain anomalies (e.g. holoprosencephaly) may be lethal conditions, so appropriate diagnosis of the anomaly is crucial for planning of the perinatal care. Here we present foetal brain anomalies coexisting with extended cerebral fluid accommodation or suggesting foetal hydrocephalus, and their characteristic features, which should be considered in differential diagnosis.

foetal central nervous system, foetal brain anomalies, prenatal diagnosis, ventriculomegaly, hydrocephalus