DYSTOCIA OWING TO THE CONDITION OF TILE SOFT PARTS.
Contraction and Rigidity qf the Vulva and Vagina.—In women who be come pregnant late in life, or possess strong muscular development, the external genitals may be rigid and resist dilatation, thus retarding the progress of labor. The head succeeds in overcoming the obstacle only after violent efforts, and often after tearing the vulva and perineum. Budin has shown that the resistance is really not at the vulvar cleft, but at the lower extremity of the vagina. Olshausen has demonstrated the resistance offered by the constrictor cunni. The vulvo-vaginal opening may in some instances furnish an obstable to delivery, but Budin believes that it is at the vaginal orifice, as he proved in a case where the head had been arrested for two hours at the vulva, and was delivered in a few seconds after incising the edge of the vaginal outlet. The latter only yields by tearing, and this occurs constantly at the first labor; the lacera tion occurring at several points, one being in the median line posteriorly, and one or more on each side. The former may extend to the fourchelle, and then involve the perineum, and is caused by the passage of either the head or the shoulders. But the resistance and narrowness of the vulvar opening may constitute the real difficulty, and if the resistance is ex treme, and the perineum is excessively thinned and distended, a central rupture may occur. It is in such cases that incision of the vulvar cleft has been recommended, and authorities differ as to the point at which it should be made, Michaelis preferring the median line, while others make two lateral incisions with the scissors or bistoury, the depth of which should not exceed of an inch. Tarnier urges the following objections to lateral incisions: A large gaping wound is left on either side of the vulva, the edges of which cannot unite by first intention, and the result is long suppuration and cicatricial contraction. In a certain proportion of the cases the incisions do not prevent extensive laceration of the perineum. Tarnier recommends an incision beginning at the median and extending, not directly backwards, but obliquely outwards towards the anus. If rupture of the perineum occurs in spite of this, it will follow
the direction of the incision, and the sphincter will be saved.
Resistance and Laceration of the Perineum.—Resistance of the perine um, especially in occipito-posterior positions with non-rotation, is unques tionably the most frequent cause of dystocia in primipare, and is due either to too vigorous contraction of the muscles that constitute the perineum, or to excess of adipose tissue in it. Two results may occur: Either the contractions of the uterus, which are at first exaggerated by reason of the resistance, gradually diminish in intensity, until the organ sinks into a condition of more or less complete stony, or, on the other hand, the pains continue to increase until rupture of the uterus or death of the foetus results; again, the head may be driven through the perineum, caus ing a central rupture. It is not by any means the thinnest perinea that are most liable to tear, but those in which the tissues are soft and (edema tous. Whether the pains are weak or strong, says Cazeaux, we must ab solutely proscribe ergot, and have recourse to the forceps. Kristeller's method of expression is sometimes of value. Lacerations may be com plete, incomplete, or central.
Frequency.—These are far more frequent than is generally admitted. As Cohen and Budin have shown, many lacerations extend from within outwards, the mucous membrane tearing first, then the muscles and fascia, and lastly the skin. Olshausen distinguishes two varieties, those which are inevitable, occurring in spite of the greatest precaution, and those which are avoidable. The first (not including tears of the fourchette,) occur in 15 per cent. of primiparte. The result of his observations, ex tending over ten years, shows that the perineum is torn in 21.1 per cent. of primiparte, and in 4.7 per cent. in multiparte. Snow Beck saw 75 rup tures in 112 primiparte, Schroeder 71 in 189 primiparte, but only 9 in 100 multiparae.