A simple pelvic diameter measurement can be performed with the patient in the supine position, measuring the distance from the outer edge of the anterior superior iliac spine on both sides, which under normal circumstances is 23-25 cm, and the longest distance between the outer edges of the iliac crests on both sides can be measured with the patient lying supine, which is 25-28 cm.The distance between the midpoint of the pubic symphysis and the lower end of the spinous process of the 5th lumbar vertebrae can be measured with the patient lying on his/her side, and the normal value is 28-20 cm. The distance between the medial sciatic tuberosities can be measured bilaterally and is usually 8-9.5 cm, which represents the transverse diameter of the sciatic tuberosities and the size of the pelvic outlet.