The third case supposed that the fetus is not viable but the symptoms of maternal hemorrhage are slight. The danger to the mother in waiting is greater here than in case one, and the decision must be made in keeping with evidences in the particular case. The surgeon who assumes responsibility is obliged to remain ready for instant operation.
Where there are symptoms of grave hemorrhage in the mother at any stage of ectopic gestation the surgeon must operate at once, and ligate the bleeding vessels to save the woman's life. The ligation will shut off the blood supply to the fetus, and thus indirectly, permissively, the fetus must be unavoidably allowed to die. This is a clear case of double effect immediately issuing from the same cause, and the operation is morally licit. No matter how young the fetus is, the surgeon or an assistant is to baptize it; if it is very young it may be necessary to split the envelopes to get at the fetus.
In the cesarean delivery (_partus cesareus_, celiohysterotomy) the infant is brought out through an opening made in the abdominal and uterine walls. The chief indications for this operation may be a contracted maternal pelvis, an abnormally large fetal head or body, death of the pregnant mother before delivery, certain forms of rigidity of the cervix uteri, some cases of stenosis of the vagina, relative vaginal narrowness, blocking tumors, or a ventrofixed uterus. Sometimes abruptio placentae, eclampsia, placenta praevia, and other accidents of pregnancy are taken as indications for cesarean delivery.
An abnormal bony pelvic girdle is the most frequent obstruction to delivery of the fetus. The lower part of the pelvis, called the pelvis minor or true pelvis, supports the muscles of the pelvic floor, and gives shape and trend to the parturient canal. The inlet and outlet of the true pelvis are narrower than its middle portion and are called the superior and inferior straits. The inlet is somewhat cordate in outline, and normally from front to back, at its so-called conjugata vera, it averages 11 centimetres (4-5/16 inches) in depth; from side to side it measures 13 centimetres (5-1/8 inches); obliquely from the right posteriorly to the left anteriorly it is 12-1/2 centimetres (nearly 5 inches), and the other oblique conjugate is 12 centimetres (4-3/4 inches) long. The transverse diameter of the outlet, from right to left, is 11 centimetres; the diameter from front to back, because the coccyx can be pushed back in labor, is from 9-1/2 (3-3/4 inches) to 12 cm. Normal fetal head measurements average from side to side at the widest part, 9-1/2 cm. (3-3/4 inches); from the root of the nose to the occiput, 11 cm.; from the chin to the occiput, 13 cm.; from the vertex to the neck behind, 9-1/2 cm. The size of the fetal head is the most important factor in delivery, so far as the child is concerned, because, as a rule, when the head is delivered the compressible trunk follows readily. Normally the child presents in delivery with the vertex of the head first; other presentations are transitional, abnormal or pathologic. In 48,499 cases Karl Braun found vertex presentations in 95.9 per cent., and Schroeder in 250,000 cases found an average of 95 per cent. The child's head is "engaged" when its largest diameter has passed the plane of the inlet.