PRESENTATIONS OF THE PELVIC EXTREMITY.
The presentation of the pelvic extremity may be complete or incom plete, and may present the two following varieties: 1. Complete Pelvic Presentation.—That is to say where the breech presents, accompanied by the inferior extremities, which are in the fol lowing relative positions: The thighs flexed upon the pelvis, the legs upon the thighs, the heels in contact with the buttocks and the feet crossed (tailor-fashion). (Fig. 215).
2. Incomplete Presentation. And then: cr. The breech alone presents, the lower limbs are extended and point upward on the anterior plane of the foetus, which appears bent double ; this constitutes the breech presentation (Fig. 214).
fi. The lower limbs are totally extended. The feet first present in the pelvic excavation and at the vulva : footling presentation (Fig. 216).
y. The lower limbs are but partly flexed, so that the knees first pre sent at the os uteri and at the orifice of the vulva: knee presentation (Fig. 21-1.) 6. Finally it may happen that but one foot or one knee alone is flexed, the other inferior extremity remaining extended on the anterior plane of the foetus; this constitutes a sub-division of either footling or knee pre sentation.
This state of affairs is of no importance as regards the mechanism, for whatever the variety of presentation, whether the pelvic extremity be complete or incomplete, the mechanism remains the same.
Whether complete or incomplete, the pelvic extremity may occupy the two fundamental positions, L or R, with their varieties—anterior, trans verse, and posterior ; and, the sacrum being taken as the starting-point, we will have to examine the mechanism of labor in S.I.L.A., S.I. L. P., S. I. R. A. , S. I. R. P.
The presentations of the pelvic extremity are next in frequency to those of the vertex.
Mine. Lachapelle gives the frequency at 1,390 among 37,895 labors; Dubois 85 among 2,022 ; Hecker 99 among 8,472 ; Depaul 633 among 16,233 ; Pinard 3,301' among 100,000 ; and Mme. Boivin 611 among 20,157.
But the varieties of breech presentations, are not equally frequent.
Thus Dubois found among his 85 pelvic presentations : Breech present ing 54 times. Feet presenting 26 times.
Madame Boivin found among her 611 cases : Breech presenting 373 times. Feet presenting 234 times. Knees presenting 4 times.
Madame Lachapelle encountered only 11 knee presentations among her 37,895 cases of labor, or one in 3,445 deliveries.
As to the positions, the left sacroiliac arc more frequent than the right ; thus : Mme. Lachapelle found among 1,390 pelvic presentations : S.I.L. 756 ; S.I.R. 494. Besides, she found the sacrum directed straight forward 13 times ; backward, 26 times.
Dubois, on the other hand, among 85: S.I.L. 41; S.I.R. 44. Ntsege16, among 163: S. I. L. A. 121; S. I. R. P. 40.
Hence, we see, that the left positions are more frequent than the right, and the anterior more common than the posterior.
If the reader will bear in mind what has been said with reference to presentations, the causes of breech presentation can be summarized in a few words: all those which prevent the fcetus from freely accomo dating itself to the uterus—in other words, such as prevent vertex pre eentation (hydrocephalus, twin pregnancy, distention of the uterus, small ness of fetus, mobility, hydramnios, etc.).
The diagnosis must be made before and during labor; but the variety of presentation, some rare cases excepted, can only be ascertained during labor.
Before Labor.
first sign which attracts attention is, that when the hvpogastric region is palpated, the excavation is felt to be empty, and, consequently, that the presentation is elevated. Again, on palpating at or above the level of the superior strait, we find some large fetal part, and near it we often feel small extremities. On examining the superior portion of the uterus, we find very frequently on one side or the other, about the level of the ribs, a hard, round, prominent tumor presenting the charac teristics of the cephalic extremity, and the mobility of which is consid erable—this constitutes cephalic ballottement. A resistant surface occu pying one of the sides of the uterus, and absent on the other side, indi cates the back, and thus the right or left position.