Ultrasound assessment of bladder and motor function in fetuses with open spina bifida: cohort study

Open spina bifida (OSB) is associated with lower limb and bladder dysfunction. We documented bladder function and lower limb motor function on ultrasound throughout gestation in a cohort of fetuses with OSB. The association of the prenatal findings with postnatal dysfunction was investigated, along with the impact of talipes on pre- and postnatal motor function.

A prospective cross-sectional cohort study was performed including all fetuses with isolated OSB, which were assessed at the University Hospitals Leuven between July 2015 and December 2019. The anatomical level of the lesion was determined on three-dimensional ultrasound. Bladder volumes were also measured on three-dimensional ultrasound and filling-voiding changes (flow) were calculated and compared to gestational-age-matched control fetuses imaged for this study (matched 1:1). The fetal motor function level was determined on ultrasound based on joint movement of the hip, knee, ankle and toes. Postnatal bladder function was assessed by questionnaire and cystography at 1 year of age. The predictive ability of prenatal anatomical and functional levels for postnatal lower limb function was assessed. Lastly, the presence of talipes was assessed as a prognostic factor.

We included 122 examinations from 69 OSB fetuses. Bladder volumes were smaller in fetuses with OSB compared to controls and the difference increased with advancing gestational age. There was no association of bladder volume and urinary flow with the level of the lesion, nor was there a measurable effect of prenatal surgery on fetal bladder volume. Postnatal urinary reflux was more likely in children with a smaller bladder volume and lower urinary flow rate at 24 weeks' gestation. Lower limb motor dysfunction was more frequent at higher gestational ages. In-utero motor function was a better predictor of postnatal motor function than the anatomical level of the lesion in fetuses that underwent surgery. Fetuses with talipes performed four levels worse postnatally compared to fetuses without talipes, despite a similar anatomical level of the lesion.

In OSB, prior to fetal surgery, bladder volume and urinary flow are already abnormal from early in gestation, independent of the level of the lesion, and may be predictive of postnatal urinary reflux. Motor function impairment can be demonstrated prenatally and is a better predictor of postnatal motor dysfunction than the prenatal anatomical level of the lesion. The presence of talipes adversely impacts postnatal motor function. © 2025 International Society of Ultrasound in Obstetrics and Gynecology.