Assessment of lower limb trophism in fetuses with open spina bifida using fractional thigh volume of three‐dimensional ultrasound

Objective To assess the trophism of the lower limbs of fetuses with open spina bifida using fractional thigh volume (TVOL) of three‐dimensional (3D) ultrasound. Methods A prospective cross‐sectional study was carried out with normal fetuses and with open spina bifida (myelomeningocele and rachischisis) at 26 weeks' gestation. The TVOL (delimitation of five cross‐sectional areas of the middle portion of the limb) was evaluated, as well as the subjective assessment of hypotrophy and lower limb movement. Results Thirty‐one fetuses with open spina bifida, 21 with myelomeningocele and 10 with rachischisis, and 51 normal fetuses were included. There were no significant differences in the TVOL between normal and spina bifida fetuses (p = 0.623), as well as between normal fetuses, with myelomeningocele and with rachischisis (p = 0.148). There was no significant difference in the TVOL of fetuses with spina bifida with or without lower limb hypotrophy (p = 0.148). Fetuses with spina bifida and with lower limb movement had higher TVOL values than fetuses without lower limb movement (p = 0.002). Conclusion There were no significant differences in the TVOL measurement of normal and spina bifida fetuses (rachischisis and myelomeningocele). Fetuses with spina bifida without spontaneous movement of the lower limbs had lower TVOL values. There were no significant differences in the fractional thigh volume measurement of normal and spina bifida fetuses (rachischisis and myelomeningocele). Fetuses with spina bifida without spontaneous movement of the lower limbs had lower fractional thigh volume values.