Objective To examine the impact of introduction of the mid-trimester scan on pregnancy outcome in cases of open spina bifida in two regions of The Netherlands. Methods This was a retrospective cohort study of 190 cases of open spina bifida diagnosed pre- or postnatally, with an estimated date of delivery between 2003 and 2011. Results With implementation of the mid-trimester scan the percentage of cases of open spina bifida detected before the 24th week of pregnancy increased from 43% to 88%. The rise in prenatal detection rate was associated with a significant increase in the number of terminated pregnancies and a decrease in the rate of perinatal loss; the percentage of children born alive did not change significantly. In the subgroup that underwent a scan between 18 and 24 weeks of pregnancy, cranial signs were present in 94.4% of cases. Conclusion Introduction of the mid-trimester scan has led to an increase in early identification of pregnancies complicated by open spina bifida. Pregnancies previously destined to end in perinatal loss are now terminated whilst pregnancies with a relatively good prognosis are frequently continued; the number of children with open spina bifida who are born alive has not changed significantly. Our study confirms that prenatal diagnosis is usually triggered by visualization of a lemon-shaped skull or a banana-shaped cerebellum.