The influence of the bony pelvis in persistent occiput posterior position.

Roentgenologic pelvimetry has been performed in 68 consecutive cases of occiput posterior position. The results point to an influence from a transverse narrowing of the pelvis or a tendency towards large dimensions. In many cases, however, no clear correlation to pelvic dimensions is found. A significant difference exists in the rate of obstetrical complications between nulliparous and parous women. The reasons for this and for the persistent OP position are discussed.