Small and narrow

When the pelvic entrance, middle pelvis, and exit planes are narrow, they are said to be small and narrow. It can be divided into 3 types: ① The shape of the pelvis still maintains the shape of the female-type pelvis, only each face diameter is less than the normal value of 1 to 3 cm. All small pelvis are more common in women with poor development and short stature; ② simple flat pelvis, but the anterior and posterior diameters of the three faces are shortened; ③ anthropoid pelvis, the transverse diameter of all three faces is small. It is a symptom of abnormal dystocia of the bone canal.