When the entrance, middle and exit planes of the pelvis are narrowed, it is called homogeneous stenosis. There are three types of stenosis: (1) female pelvis, but the diameter of each plane is less than the normal value of 1 to 3 cm; (2) simple flat pelvis, but the anterior and posterior diameters of all three planes are shortened; (3) ape-like pelvis, in which the transverse diameters of all three planes are small. It is a symptom of abnormal obstructed labor in the bony birth canal. So how to diagnose even small stenosis? The following is a brief introduction for you. 1, medical history If there is a history of the following diseases, such as vitamin D deficiency disease, osteochondrosis, poliomyelitis, tuberculosis of the spine and hip, severe thoracic or spinal deformation, pelvic fracture and previous cesarean delivery, vaginal surgery assisted delivery, recurrent breech or transverse position of the transverse maternity, stillbirth, neonatal birth injury, etc., should be carefully examined for pelvic abnormalities. 2.Physical examination: women with short stature, less than 145cm, have a higher possibility of having pelvic are small stenosis. Those with a stout physique, short neck, and masculine bones tend to affect the size of the pelvic cavity not only because of their thick bones, but also easily accompanied by funnel-shaped stenosis. The unequal length of both lower limbs can lead to pelvic deformity, so it should be carefully examined for lower limb or spinal diseases affecting pelvic morphology, vitamin D deficiency or sequelae of pelvic fracture, etc.