An abnormal pelvis may be generally contracted, dwarfed, in all its diameters; it may be flat or narrow from front to back; it may be contracted from side to side; it may be generally contracted and flat at the same time; it may be obliquely contracted (Nägeli's pelvis); or it may be crowded together irregularly. Rachitis, osteomalacia, curvature of the spine, habit scoliosis, hip dislocation, and similar pathologic states cause these distortions and contractions.
Contraction of the pelvis affects the mother and child in parturition in proportion to the degree of the narrowing. Besides this, the prognosis depends on the size of the child, its presentation, position, and attitude, the strength of the pains, the skill and surgical cleanliness of the operator, and the presence or absence of complications. Obstruction may bring about rupture of the uterus, septicemia, exhaustion and shock, pressure narcosis, or tears of the cervix or vagina. If the child's head becomes impacted the vagina and vulva may become even gangrenous. Pressure may cause areas of necrosis resulting in fistulas into the bladder, rectum, or between the uterus and the vagina. When the contracture is sufficient to let the fetus just engage, pressure may interfere with the placental circulation and kill the child. Compression of the vagus nerve may slow the child's pulse and asphyxiate it through lack of oxygen in the blood. The cord may prolapse. The pressure on the child's head may cause fatal intracranial hemorrhage, or effect permanent injury to the brain.
Often it is extremely difficult to find out the best plan for delivering a woman who has a contracted pelvis. Where the conjugata vera is 9.5 cm. (35⁄8 inches) or above, Ludwig and Savor found that 75 per cent. were delivered without instrumental help. At 9 cm. (31⁄2 inches), 58 per cent. so end; at 8 cm. (33⁄16 inches), 25 per cent. Should the conjugata vera be less than 51⁄2 cm. (23⁄16 inches) in a flat pelvis, or 6 cm. (23⁄8 inches) in a generally contracted pelvis, this is an absolutely contracted pelvis according to the old standard, and the delivery must be by cesarean section, whether the child is living or dead. The minimal requirements have been gradually extended. In 1901 Williams of Johns Hopkins University advocated that the absolute indication for cesarean section be changed to 7 cm. in the generally contracted pelvis, and to 7.5 cm. in the simple flat pelvis. His opinion was accepted by Webster, Jewett, Edgar, and others. Now some obstetricians of authority extend the measurements to 8 cm. If the woman is seen before labor, or early in labor, cesarean delivery alone is done. When the uterus is infected it is usually necessary to remove it after taking away the child, because an infected uterus left in place causes death by sepsis, as a rule.
Text-books on obstetrics have a series of rules, based on pelvic measurements, concerning the indications for cesarean or other methods of delivery in cases of contracted pelvis, but the problems are not so simple and uniform as to be always accurately solved by the data derived from measurements. One woman with a contracted pelvis may require cesarean delivery; another woman with the same measurements may have a normal parturition because the child happens to be small or its skull compressible. The best pelvic measurement is made with the fetal head. A difficult decision as to whether a cesarean delivery is necessary or not comes up in the majority of cases in primiparae; in multiparae the physician has the experience from former births to guide him. In over 90 per cent. of primiparae the fetal head normally is found engaged in the pelvis in the last week of gestation, and can be felt by a vaginal examination. In multiparae the head usually is not engaged until labor begins. If the fetal head does not engage in a primipara, this fact at once suggests an absolutely or relatively narrow pelvis. When labor has begun, if the fetal head cannot be pushed into the true pelvis of a primipara, especially after anesthesia, the necessity for cesarean delivery may be clearly evident.
In the cases where there is doubt that the child can get through the pelvis, but good reason to think that it can, many obstetrical experts try the effect of labor for two hours or a little more, and if there is no real progress they deliver through laparotomy. There is considerable objection now to version or the application of high forceps, but many skilful men prefer these methods at times. When version has been done and it fails there is no chance to save the child's life. In the trial of labor, the expectant treatment, extraordinary watchfulness is required and a full knowledge of the special procedure that may be necessary.
In minor degrees of pelvic contraction the obstetrical practice is either to induce premature labor at the thirty-second week, or to deliver by a cesarean operation, or to delay and try labor. In the last event there may be one of the following issues: spontaneous delivery, version and delivery, extraction by high forceps, cesarean delivery, symphyseotomy, hebosteotomy, or craniotomy. Craniotomy on a living child is never to be considered under any circumstances. Symphyseotomy is a cutting of the maternal pelvic girdle through the symphysis pubis, the rigid joint at the front middle part of the pelvis, and thus letting the bony girdle dilate. Hebosteotomy or pubiotomy is a sawing through the pelvis near that joint to get the dilatation. Symphyseotomy has been replaced by hebosteotomy because the maternal mortality and morbidity are somewhat lessened by the latter method. Schläfli in 1908 reported 700 hebosteotomies with a maternal mortality of 4.96 per cent. and a fetal of 9.18 per cent. Other operators have a better average; still others a worse. This operation is done very seldom of late except in a case where the fetal head is caught low in the pelvis, or there is a chin-posterior or brow or face presentation, and the cesarean operation would not deliver the child.
The varieties of the cesarean delivery as practised at present are the classic cesarean, called also celiohysterotomy, the Porro cesarean, or celiohysterectomy, where the uterus is removed after the extraction of the child, and the two sections in the cervical end of the uterus, viz., the extraperitoneal cesarean and the transperitoneal cervical cesarean. Before the days of antiseptic surgery cesarean delivery was practically always fatal to the mother. Tarnier could not find one successful outcome for the mother in Paris during the nineteenth century up to his own time, and Spaeth said the same for Vienna up to 1877. In 1877 Porro of Pavia advised the supravaginal amputation of the uterus after the child was delivered to avoid hemorrhage and peritoneal infection. This operation replaced the classic cesarean until 1882, when Sänger invented a suture which would keep the uterine incision shut, and applied antisepsis. Sänger's operation has been improved so much that cesarean delivery, when performed by skilled obstetricians, has an extremely low mortality in cases which have not been infected. Routh, in 1910, collected the statistics of Great Britain, comprising 1282 cases, which may be taken as a standard for all civilized countries, and he found a steady decrease in the mortality until now it is near 2 per cent. in uninfected cases. The dangers in the operation increase with every hour the woman is in labor, but even then the general mortality is now down to about 8.1 per cent. This, it must be remembered, is the rate when competent men operate.
When the ordinary practitioner in small cities, towns, and country places operates the mortality is very high. Newell[106] said that in four cities of from 25,000 to 40,000 inhabitants within forty miles of Boston he collected the following data: in A no patient on whom cesarean section had been done is known to have recovered—a mortality of 100 per cent. In B the mortality is from 60 to 70 per cent. In C the operation is invariably fatal when done by the local surgeons. In D the fatality is from 10 to 20 per cent. in average cases, but since cesarean section has become popular as a method of treatment for eclampsia the mortality is over 50 per cent.
In spite of perfect technic by the best obstetricians, the operation has a high morbidity: fever, peritonitis, pneumonia, dilatation of the stomach, and other bad results are common.