Aims and objectives We aim to investigate the antenatal course and subsequent neonatal outcome of isolated mild to moderate (10-15mm) ventriculomegaly (VM) at mid-trimester scan or subsequently in pregnancy.

Material and methods We did a retrospective review of all cases of mild to moderate VM diagnosed at our hospital within the fetal medicine unit from 1 January 2006 to 31 May 2011. Data was collected from electronic databases from clinical notes. All mothers with initial diagnosis of isolated mild to moderate VM in the fetus had infection screen (toxoplasma, CMV and Parvo), invasive testing was offered based on serum screening results. MRI was offered if other CNS abnormalities were suspected or imaging was found to be inadequate.

Observations Isolated mild to moderate VM was found in 33 (77%) fetuses at mid-trimester and in 10(23%) fetuses at subsequent scans. Two (4.5%) women had abnormal karyotype. None had abnormal infection screen. Isolated mild VM progressed to severe VM in 6 (14%) fetuses, was stable in 23 (53%) fetuses and resolved in 14 (33%) fetuses.

There was one intrauterine fetal demise, 3 MTOP and 2NND. Three (8%) babies had other abnormalities. Two babies had global development delay. All other babies had normal neurological outcome.

Conclusions In conclusion 2 (5%) of the livebirths had abnormal neurological outcome at 6 months- 5 year (Mean 20 months) follow up. Total perinatal loss including TOP was 7(18%). Thus truly normal outcome was seen in 29 (77%) fetuses with initial diagnosis of isolated mild to moderateVM.