Which plane is most impoant in obstructed labour :

Ans. is d i.e. Plane of least pelvic dimension The plane of least pelvic dimension which lies at the level of ischial spines is the most impoant plane of pelvis. as the cardinal movements of engagement and internal rotation occur here. "it is of paicular impoance following engagement of head in obstructed labour." Plane of least pelvic dimension : It is bounded by the 4'" and 5th sacral veebrae. the white line, the ischial spines, sacrospinous ligaments and the pubic symphysis. Also know Plane of greater pelvic dimension : This is the roomiest pa of the pelvis and is almost circular. It is bounded posteriorly by the junction of the second and third sacral veebrae, laterally by the obturator foramina and anteriorly by the posterior surface of the pubis. It does not have much obstetric significance.