Another danger threatening the infant is the extension of the arms, owing to the difficulties their disengagement causes. For it must not be forgotten that, while we are engaged in freeing the arms, the trunk is delivered, the foetus will make inspiratory efforts, and as the head is still within the uterus, blood and liquor amnii mixed with meconium will enter the respiratory pasPages instead of air, thus exposing the fcetus to the gravest dangers. (See Podalic version.) Tarnier and Chantreuil also assign an important part to detachment of the placenta, which may result from uterine retraction, that manifests itself as soon as the head has passed the orifice, and becomes the more dangerous in proportion to the length of time the head is arrested at the level of the perineum. We think these authors attach too much impor tance to detachment of the placenta; for, if the head is on the perineum, or if it arrives there under favorable conditions, and then emerges soon, the fcetus is safe; if it is there less favorably situated for delivery, the intervention of the obstetrician is imperatively demanded; in either case, if promptly successful, the infant will have escaped the threatening dan ger, whereas the accoucheur finds himself in the presence of serious diffi culties, when the trunk being delivered, the child makes inspiratory efforts, and thereby draws into the air-passages blood or liquor amnii, which seems to us of much greater importance than detachment of the placenta.
This accident, however, may be effected in two ways; eithet by uterine retraction, or by the traction exercised on the cord by the foetus; for owing to the not infrequent premature descent of the Tunis, the fcetus may drive the cord before it, or the cord may be between the foetal limbs, and espe cially if naturally rather short, will be pulled the harder the farther the fcetus descends.
Depaul correctly emphasizes another danger to the fcetus: retraction of the cervix uteri upon the neck of the infant; not that the cervix strangles the neck, thus as it were choking the fcetus and killing it by compression of the vessels and congestion of the head, but because " in this engage ment of the pelvic extremity, the os uteri need not be dilated ad maxi mum for the passage of the trunk, and, when the neck arrives, the dila tation effected cannot persist, as this part of the fcetus does not suffice to maintain it. The head is, therefore, held back by the cervix envelop ing the foetal neck, in a similar way as a button-hole retains a collar button." Of course, this accident is the more likely to occur when the uterine contractions are insufficient to maintain the full flexion of the head.
Hence we see that the prognosis of pelvic presentations is always very grave for the child, and, therefore, the rate of foetal mortality in this de livery must not surprise us.
Mme. Lachapelle had among 804 pelvic presentations: Feeble infants, 102; still-born, 115.
Paul Dubois gives the average as one death to eleven deliveries.
We will see hereafter how the extraction causes lesions in the foetus, which render the prognosis of pelvic presentations still worse.