Bone birth canal abnormalities

Introduction Abnormal bone birth canal is seen in the narrow pelvis. The pelvic diameter line is too short or abnormal in morphology, resulting in the pelvic cavity being smaller than the limit of the first exposed part of the fetus, which hinders the decline of the first exposed part of the fetus and affects the smooth progress of the labor process, which is called the narrow pelvis. A narrow pelvis can be too short or multiple short lines, or a narrow plane or multiple planes. The narrow pelvis affects the decline and internal rotation of the fetal position and the exposed part of the fetus in the delivery mechanism, and also affects contractions. The pelvis is an important factor to consider when estimating the difficulty of childbirth.

Cause

Pelvic stenosis, injury, etc. caused by various reasons. The pelvis is a constant factor during childbirth. The narrow pelvis affects the decline and internal rotation of the fetal position and the exposed part of the fetus in the delivery mechanism, and also affects contractions. The pelvis is an important factor to consider when estimating the difficulty of childbirth. When a radial line is narrow, it is necessary to observe the size of other radial lines in the same plane, and then comprehensively analyze the size and shape of the entire pelvis to make a correct judgment. During pregnancy, you should check whether the pelvis is abnormal, whether the head basin is not called, and make a diagnosis early to determine the appropriate mode of delivery.

an examination

Related inspection

Intrapelvic measurement of extrapelar measurement pelvic measurement pelvic tilt test

The pelvis is a constant factor during childbirth. The narrow pelvis affects the decline and internal rotation of the fetal position and the exposed part of the fetus in the delivery mechanism, and also affects contractions. The pelvis is an important factor to consider when estimating the difficulty of childbirth. During pregnancy, you should check whether the pelvis is abnormal, whether the head basin is not called, and make a diagnosis early to determine the appropriate mode of delivery.

History

Ask your pregnant women about rickets, polio, polio, spinal and hip tuberculosis, and traumatic history. If you are a mother, you should know whether there is a history of dystocia and its causes, whether the newborn has a birth injury or not.

2. General inspection

Measure the height. If the height of the pregnant woman is below 145cm, be alert to the small pelvis. Pay attention to the body shape of the pregnant woman, whether there is squatting in the gait, whether there is a spine or hip deformity, whether the Mie's diamond-shaped nest is symmetrical, whether there is a sharp abdomen or a drooping abdomen.

3. Abdominal examination

(1) Abdominal morphology: pay attention to the abdominal type, measure the length of the upper uterus and the abdominal circumference, and observe the relationship between the first exposure of the fetus and the pelvis by B-mode ultrasound, and also measure the double top diameter, breast diameter, abdominal diameter and femur length of the fetal head. Predict fetal weight and determine whether it can pass through the bone birth canal.

(2) abnormal fetal position: pelvic inlet stenosis often because the head basin is not called, the fetal head is not easy to enter the basin, resulting in abnormal fetal position, such as the first gluteal, the first exposed. The middle pelvic stenosis affects the rotation of the fetal head that has entered the basin, resulting in continuous occipital transverse position and posterior occipital position.

(3) Estimation of head and basin relationship: Under normal circumstances, some pregnant women should be in the basin 2 weeks before the expected date of delivery. If the birth is still in place and the fetal head is still not in the basin, the head basin relationship should be fully estimated. Check the specific method of whether the head basin is commensurate: pregnant women empty the bladder, supine, legs straight. The examiner places his hand over the pubic symphysis and pushes the floating fetal head toward the pelvic cavity. If the fetal head is lower than the plane of the pubic symphysis, it means that the fetal head can enter the basin. The head basin is symmetrical, which is called the trans-shadow sign. If the fetal head and the pubic symphysis are in the same plane, it means that the suspicious head basin is not called. Positive; if the fetal head is higher than the pubic symphysis plane, it means that the head basin is obviously not called, which is called positive across the shame. For pregnant women with positive cross-symptoms, they should take the two-leg flexion semi-recumbent position and re-examine the fetal head cross-symptom sign. If it turns negative, it indicates that the pelvic inclination is abnormal, not the head basin.

4. Pelvic measurement

(1) Measurement outside the pelvis: 1 cm of each radial line was measured as a skewed pelvis.

(2) Measurement in the pelvis: Abnormalities in the lateral pelvis are found, and intrapelvic measurements should be performed. Diagonal diameter.

Differential diagnosis

Differential diagnosis of abnormal bone birth canal:

1. The pelvic entrance plane is narrow

Women in our country are more common. The external diameter of the shame was measured <18 cm, the anteroposterior diameter of the pelvic inlet was <10 cm, and the diagonal diameter was <11.5 cm. The following two types are common:

(1) simple flat pelvis (simple flat pelvis): the entrance of the pelvis is flat and round, and the squat protrudes forward and downward, so that the anterior and posterior diameter of the pelvic entrance is shortened and the transverse diameter is normal.

(2) rickets flat pelvis: due to childhood rickets, bone softening caused the pelvis to deform, the sputum was pressed forward, the anterior and posterior diameter of the pelvic entrance was significantly shortened, the pelvic entrance was kidney-shaped, the lower part of the humerus moved backward, and the normal curvature of the humerus was lost. , straighten back to the back. The tailbone is hooked to the pelvic outlet plane. Due to the abduction of the humerus, the diameter of the iliac spine is equal to or greater than the intercondylar diameter; due to the valgus of the ischial tuberosity, the angle of the pubic arch is increased and the transverse diameter of the pelvic outlet is widened.

2. The pelvis and pelvic outlet plane is narrow

(1) Funnel shaped pelvis: The diameter of each pelvic inlet is normal. Because the pelvic walls on both sides are inclined inward and resemble a funnel, they are called funnel pelvis. The characteristics are that the middle pelvis and pelvic outlet plane are obviously narrow, which shortens the diameter of the ischial spine and the ischial tuberosity, and the pubic arch angle is <90°. The sum of the ischial tuberosity and the posterior sagittal diameter <15cm is common in the male pelvis.

(2) transversely contracted pelvis: similar to the anthropoid pelvis. The transverse diameters of the pelvic inlet, the middle pelvis and the pelvic outlet are shortened, the anterior and posterior diameters are slightly longer, and the ischial incision is wide. The external diameter of the shame was measured to be normal, but the intercondylar diameter and the intercondylar diameter were shortened.

3. Three plane stenosis of the pelvis

The shape of the pelvis is female pelvis, but the pelvic inlet, middle pelvis and pelvic outlet plane are narrow. Each plane diameter is less than the normal value of 2cm or more. It is called the general contracted pelvis. It is more common in short stature. Shapely women.

4. Malformed pelvis

The pelvis loses its normal form. The following two types are common:

(1) osteomala pelvis: now rare. Due to lack of calcium, phosphorus, vitamin D and ultraviolet radiation, the bone mineralization disorder in adulthood is replaced by bone-like tissue, and the bone is decalcified, loosened and softened. Due to the trunk gravity and the two inward compression of the two bones, the condyle forward and the pubic symphysis protrude forward. The plane of the pelvic entrance is concave and triangular, and the diameter of the trochanter and the diameter of the ischial tuberosity are obviously shortened. Hold 2 fingers.

(2) obliquely contracted pelvis (obliquely contracted pelvis): an ankle joint fixation caused by one side flap and hip bone dysplasia, and a lower limb and hip joint disease, causing a skewed pelvis with a shortened pelvic side diameter.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.