Diameter of engagement In face presentation/ diameter In face presentation:
High-Yield Explanation
The engaging diameter is submentobregmatic (9.4cm).In face presentation,the biparietal diameter is 7cm behind the face unlike in veex,where it is only 3-4cm distant.The biparietal diameter will pass through the inlet only when the face is low down in the perineum (refer pgno:372 sheila textbook of obstetrics 2 nd edition)