Funnel pelvis

The values ​​of the pelvic inlet plane are normal, but the middle pelvic and outlet planes are narrow, and the sides of the pelvis are inclined inward like a funnel, so they are called funnel-shaped pelvis. The diameter of the ischial spine <10cm, the diameter of the ischial tuberosity <8cm, the sum of the diameter of the ischial tuberosity and the posterior sagittal diameter <15cm, the pubic arch angle <90 °, and the width of the ischial notch narrowed. In general, the female pelvis is large and short in shape, the pelvic wall is smooth and thin, the bone is light, the upper pelvis is round or oval, wide front and back, the pelvic cavity is wide and shallow, has a barrel shape, and the pelvic mouth is wide. The pubic symphysis is short and low in width, flexible, and has a large pubic arch angle of 90-100 °. The obturator is approximately triangular and the acetabulum is small. The funnel pelvis is a clinical manifestation of a narrow pelvis. The pelvic diameter is too short or the shape is abnormal, causing the pelvic cavity to be smaller than the limit of the exposed part of the fetus, which prevents the exposed part of the fetus from falling and affects the smooth progress of the labor process. It is called stenosis pelvis. The narrow pelvis can be too short in one radial line or too short in multiple radial lines, or narrowed in one plane or narrowed in multiple planes at the same time. When a radial line is narrow, the size of other radial lines in the same plane should be observed, and then the size and shape of the entire pelvis should be comprehensively analyzed to make a correct judgment.