The type of pelvis

The type of pelvis

(1) Female type: normal pelvis for women, the most common. The entrance is transversely oval in shape, and the entrance diameter is slightly longer than the front and rear diameters. The lateral wall of the pelvis is straight, the ischial spines are not prominent, the pubic arch is wide, and the diameter between the ischial spines is ≥ 10 cm. Women account for 52.0%~58.9% in China.

(2) Flat type: more common. The entrance is flat-oval in shape and has a transverse diameter greater than the anterior and posterior diameters. The pubic arch is wide, the sacrum loses its normal curvature, and becomes straight backward or deeply curved, so the pelvis is shallow. Women account for about 23.2%~29.0% in China.

(3) Great ape type: the pelvic entrance is oblong, and the anterior and posterior diameter of the entrance is greater than the transverse diameter. The walls of the pelvis are slightly cohesive, the ischial spines are more prominent, the ischial notch is wider, the pubic arch is narrower, and the sacrum is tilted backward, so the anterior part of the pelvis is narrower and the posterior part is wider. The sacrum tends to have 6 segments , and the great ape pelvis is deeper than other types. Women account for about 14.2%~18.0% in China.

(4) Male type: rare. The entrance is slightly triangular, the walls on both sides are cohesive, the ischial spines are prominent, the pubic arch is narrower, the ischial notch is narrow and highly arched, the sacrum is straight and anteriorly inclined, and the sagittal diameter is shorter posterior to the exit. The pelvic cavity is funnel-shaped. Women account for only 1.0%~3.7% in China.

The above four basic pelvic types are theoretically classified, and most of the clinical observations are mixed pelvis.