The diagonal conjugate diameter, which assesses the pelvic inlet, is the most important pelvic measurement to be made. First, the fingers of the examining hand must reach the promontory of the sacrum. At this point, the hand is lifted to the inferior aspect of the symphysis, and the distance from the tip of the middle finger and the symphysis is noted. Under 12 cm. This assesses the mid-pelvis.
Prominent spines can narrow the mid-pelvis and cause deep transverse arrest.
Distance between ischial spines is under 10 cm. After you complete the physical examination, review the key findings with the patient. If possible problem areas are noted, explain what measures may be necessary. This also assesses the mid-pelvis. Identify women with an unusual angulation of the sacrum.