1012: Functional deterioration in fetuses with spina bifida: can we document it with ultrasound?

Abstract

To evaluate lower limb motor and bladder function in fetuses affected by open spina bifida (OSB). Single center prospective study on fetuses with isolated OSB followed-up longitudinally (2015-2019). Prenatal ultrasound was used for functional level assessment by lower limb motor function (Carreras UOG 2016). Agreement between anatomical and functional motor level was tested using the weighted kappa index. 3D-bladder volumes were acquired every 5 min for a maximum of 30 min and calculated with the VOCAL technique. The mean urinary production rate (UPR) was used as a proxy of bladder volume variation over time, and compared with reference curves generated from gestational-age matched controls (matching 1:3). The upper anatomical level was thoracic in 7(13%), lumbar in 37(67%) and sacral in 11(20%) fetuses. In all cases S1 was involved. The prevalence of lower limb motor function deterioration increased with gestational age, from 0% before 20 weeks to 80% after 32 weeks. The correlation between prenatal functional level and anatomical level increased over time (Fig 1A). In fetuses where postnatal follow up was available (n=19), there was a good correlation between the postnatal functional and the prenatal functional level as determined after 32 weeks. The gestational age of first occurrence of motor dysfunction ranged from 21.3 to 31.5 weeks, and did not correlate with the level of the lesion. However, motor impairment was more common and more severe in fetuses with higher lesions (Fig 1B). Even at early gestational ages, the mean UPR was reduced in fetuses with OSB (Fig 1C). Mean UPR did not correlate with the anatomical level. On average, bladder volumes were lower in OSB fetuses as compared to controls (Fig 1D). In fetuses with OSB, impairment in lower limb motor function and bladder function can be documented by ultrasound. While deterioration in motor function is progressive over gestation and more severe in fetuses with higher lesions, impairment in bladder function is already present at early gestational ages and does not correlate with the anatomical level.