When the perineum or Vulva remains rigid and hard, so that the opening cannot be enlarged sufficiently for the child to pass, it may also be necessary to operate with the knife. But this should never be done till after every means of relaxation has been tried, and the head has been kept back as long as prudent. It is however, always better to open a passage than to let one be _torn_, because it may be made in the most favorable place. When the perineum is allowed to be torn, the most serious consequences often ensue, and the patient is made a miserable sufferer for life. The Vagina and Rectum may be torn into one, or the power of retaining the contents of the intestine, or bladder, may be for ever lost. When an incision is made none of these evils follow; the wound speedily heals, and in a little time no trace of it can be seen. It has even been necessary _to cut the neck of the Womb_, when it would not open, to prevent the organ from being ruptured; and this has been done with perfect safety. A celebrated practitioner in this city had to perform such an operation very recently, on a female who had injured herself, and made the mouth of the Womb grow together, by violent attempts to produce abortion. The delivery took place with comparative ease, and no unpleasant results whatever followed, either to the mother or the child. CHAPTER XX. CAUSES CONNECTED WITH THE CHILD, OR CHILDREN, WHICH MAY IMPEDE DELIVERY, OR MAKE IT DIFFICULT AND DANGEROUS. PROCIDENTIA OF THE UMBILICAL CORD. This means the escape of a portion of the cord before the child itself. It is most frequent in the irregular presentations, as they do not so fully close up the mouth of the Womb, and it is most likely to occur at the commencement of labor, though not impossible at a later stage. Very often the cord descends when the membranes break, being carried down by the rush of the waters; and sometimes it is already in the sack, or bag, before the rupture takes place. This accident is comparatively frequent, being found to occur as often as once in about three hundred cases. The causes which produce procidentia of the cord, are most likely these:--A large quantity of liquor amnii, and its sudden discharge,--Unnatural presentations,--Deformities of the superior strait of the Pelvis,--A very long cord,--and rupturing the membranes too early. But it may also happen from other causes with which we are unacquainted. There is seldom much difficulty in detecting this accident, because if the membranes are broken it protrudes into the Vagina, and if they remain whole it can be felt within the sack, and its pulsation will be quite distinct. Sometimes, it is true, it may be so firmly compressed, between the fœtus and the walls of the pelvis, that its pulsation may be very indistinct, or even totally suspended for a time; but this only necessitates a little extra care.