Middle pelvic stenosis

Introduction The diameters of the pelvic entrance are in the normal range. The entrance can be without the head basin. However, because the pelvis is funnel-shaped, the smaller the downward (the middle pelvis and the pelvic outlet are narrow), the formation of the fetal position is not correct and the dystocia is caused.

Cause

Caused by congenital dysplasia and acquired diseases.

an examination

Related inspection

Pelvic measurement outside the pelvis

The middle pelvis-outlet stenosis, also known as the funnel-type stenosis, is divided into three types:

1 The pelvis and the exit surface are narrow in diameter: the two sides of the pelvis are cohesive and are common in the apes-like pelvis.

2 The posterior diameter of the pelvis and the exit is narrow: the anterior and posterior walls of the pelvis are cohesive, and the multi-system tibia is a straight simple flat pelvis.

3 mixed type: the transverse diameter and anteroposterior diameter of the middle pelvis and the outlet surface are narrow, and both sides of the pelvis and the front and rear walls are cohesive, which is common in the male pelvis. The middle pelvic stenosis can be divided into 3 grades according to the diameter of the ischial spine, the diameter of the ischial spine + the posterior sagittal diameter and the length of the anterior and posterior diameter of the middle pelvis. The ischial spine diameter and the posterior sagittal diameter were measured by X-ray film, while the anterior and posterior diameter of the middle pelvis was measured by vaginal examination (internal measurement).

Differential diagnosis

Abnormal shape of the pelvis or short diameter of the pelvis will hinder the decline of the fetus and mechanical obstructive dystocia. The common stenosis has the following types:

1. Small pelvis: The pelvis is like a women's pelvis, but each diameter is smaller than the normal female pelvis by 2 cm or more, which can hinder the decline of the fetal head. It is more common in women with short stature. If the fetus is small, the fetal position is normal, the uterus contracts. Well, the fetal head is commensurate with the pelvis and may still be delivered from the vagina.

2, flat pelvis: there are two common types:

Simple flat pelvis: only the pelvic population has short diameter before and after, and other diameters are normal.

The rickety flat pelvis: due to rickets in childhood, the pelvis is deformed, mainly by the bones of the bones, the anterior and posterior diameter of the population is shortened, the lower part of the medulla is tilted backward, the deformation of the humerus loses normal curvature, and the transverse diameter of the pelvic outlet is widened.

If the flat pelvis is not called a fetal head, it can only enter the transverse diameter of the pelvic population with the occipital transverse position. Sometimes the fetal position is uneven before and after. Simple flat pelvis as long as the fetal head can enter the pelvic entrance, other pelvic diameters are normal.

3, funnel pelvis: the pelvic entrance of each diameter line is in the normal range, the entrance can be no head basin, but because the pelvis is funnel-shaped, the lower the smaller the lower (the middle pelvis and pelvis outlet is narrow), the formation of fetal position is not correct and cause dystocia .

4, the transverse diameter of the pelvis: this type is less common, similar to the anthropoid pelvis type, the three planes of the transverse diameter are short, if the transverse diameter is a little short, easy to produce fetal position is not correct, resulting in prolonged labor, vaginal surgery for midwifery. If the transverse diameter is significantly shortened, the vaginal delivery cannot be performed, and the cesarean section is required to end the delivery.

The middle pelvis-outlet stenosis, also known as the funnel-type stenosis, is divided into three types:

1 The pelvis and the exit surface are narrow in diameter: the two sides of the pelvis are cohesive, commonly found in apes-like pelvis

2 middle pelvis and outlet in front of the narrow diameter: pelvic anterior and posterior wall cohesive, multi-line tibia is a straight simple flat pelvis

3 mixed type: the transverse diameter and anteroposterior diameter of the middle pelvis and the outlet surface are narrow, and both sides of the pelvis and the front and rear walls are cohesive, which is common in the male pelvis. The middle pelvic stenosis can be divided into 3 grades according to the diameter of the ischial spine, the diameter of the ischial spine + the posterior sagittal diameter and the length of the anterior and posterior diameter of the middle pelvis. The ischial spine diameter and the posterior sagittal diameter were measured by X-ray film, while the anterior and posterior diameter of the middle pelvis was measured by vaginal examination (internal measurement).

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