Using Z-scores to evaluate levator hiatal dimensions with four-dimensional translabial ultrasound.
Lieming WenJing ZhangShi ZengQichang ZhouPublished in: The journal of obstetrics and gynaecology research (2017)
'Normal hiatal dimension' was defined as Z-Av ≤ 1.0 or Z-Lv ≤ 1.0, and 'hiatal ballooning' was defined as Z-Av ≥ 2.0 or Z-Lv ≥ 1.5.