Narrow Pelvis

Narrow pelvis. Distinguish an anatomically narrow pelvis and clinically (functionally) narrow pelvis.

The anatomically narrow pelvis is diagnosed if at least one of the pelvis dimensions is reduced by 2 cm. In the narrowing form, the uniformly pelvic pelvis is distinguished (all dimensions are reduced by 2 cm or more), a simple flat pelvis (reduced direct dimensions), a flat-skeletal pelvis (largest Narrowing of the direct size of the entrance to the pelvis - the true conjugate, along with significant changes in the sacrum) and the common flat pelvis (a combination of the uniformly flattened and flat pelvis). In midwifery practice, transversal pelvis, flattening of the sacral cavity became more common. The anatomically narrow pelvis has 4 degrees of constriction: 1 degree - true conjugate 11-9 cm; II degree-true conjugate 9-7.5 cm; III degree - true conjugate 7.5-6.5 cm; IV degree - true conjugate 6.5 cm or less. At 1 and 2 degrees of pelvic narrowing, births are possible, but with good labor and head configuration (at grade II, births are more prolonged, accompanied by a greater number of complications and they often have to be terminated by a caesarean section operation). At the third degree, a cesarean section is produced or the labor ends with a fruit-destroying operation (with a dead fruit). At IV degree, delivery is possible only by caesarean section. Pregnancy with a narrow pelvis in most cases occurs without any peculiarities. At the end of pregnancy, prenatal discharge of amniotic fluid, prolapse of the umbilical cord, anomalies of the presentation of the fetus, etc. are possible. In childbirth, weakness of contractions (primary and secondary) is often noted, and the frequency of hypotonic bleeding is increased.

The mechanism of childbirth. With a uniformly constricted pelvis: sharp bending of the head in the inlet of the small pelvis; Insertion of the head in one of the oblique pelvic dimensions; Prolonged passage of the head through the birth canal; At the time of the eruption, the head sharply deflects toward the perineum (therefore, the perineal ruptures are frequent). With a simple flat pelvis: moderate extension of the head (small and large fontanels are located on the same level); Asynclitic insertion of the head (first inserted the front or the back of the parietal bone); Middle and low stitching. With flat-braided pelvis: prolonged standing of the head at the entrance of the small pelvis; Extension of the head; Rapid birth of the fetus after passing the head of the plane into the pelvis (place of greatest constriction). In the case of a vented flat pelvis: extension of the head in the pelvic inlet; Asynclitic insertion of the head; Delayed passage of the head of the planes of the small pelvis.

The diagnosis is based on the data of anamnesis (indications of rickets, infantilism), external measurement of the pelvis with the help of a tachometer, X-ray and eyelid data and ultrasound, and the peculiarities of the birth mechanism characteristic for each type of anatomically narrow pelvis.

The management of labor depends on the degree of narrowing of the pelvis. At 1-II degrees of constriction during labor there may be a discrepancy between the size of the head and pelvis (see Clinically Narrow Pelvis). Perform a functional assessment of the pelvis. Prolonged finding of the head in one plane is dangerous because of the possibility of rupture of the uterus and the formation of urogenital fistulas. The fetus has intrauterine asphyxia and hemorrhages in the brain. Perinatal mortality increased. Pregnant women with a narrow pelvis for 2 weeks before delivery are hospitalized in the Department of Pregnancy Pathology.

Clinically, the narrow pelvis may be with an anatomically narrow pelvis, but also with a normal pelvic size, but with a large fetus, incorrect insertions and presentation of the head (posterior asynclitism, frontal presentation, etc.). The course of labor depends on the degree of discrepancy between the size of the head and pelvis. Complications: premature or early discharge of amniotic fluid; Prolapse of the umbilical cord; Weakness of labor activity; Protracted labor; Ascending infection in labor (chorionnionitis); Hypoxia and intracranial fetal injury; Rupture of the uterus; Urogenital fistulas; Divergence and rupture of the pubic joint.

Keeping childbirth. Perform a functional assessment of the pelvis. To prevent premature or early outflow of water, the pregnant woman is hospitalized for 2 weeks before childbirth. In childbirth a woman in bed must be in bed, which prevents early rupture of the fetal bladder. When the weakness of labor is prescribed rhodostimulating drugs. Oxytocin and other potent contractile agents are administered with caution because of the risk of uterine rupture. In childbirth follow the signs of clinical mismatch between the size of the head and pelvis (the standing of the head in one plane with full opening of the throat for 1.5-2 hours, a positive sign of Vasten). When these symptoms occur, a caesarean section is indicated. It is necessary to constantly prevent intrauterine hypoxia of the fetus.