If the tumor is situated higher up, delivery may be more difficult, and may necessitate interference with. the forceps or even with the cephalo tribe. But these cases are rare, and such tumors are usually not perceived until after delivery. Then they manifest their presence by hemorrhages and pain, and they are either expelled spontaneously, or are removed artificially. But, if the tumors are interstitial, and occupy the lower segment of the uterus, they may resemble sub-serous growths of the cervix, and may cause serious difficulties.
When, on the contrary, they are higher still, they usually affect the delivery but slightly. If they are at first pushed into the pelvis in front of the child, they often ascend above the foetal part after the rupture of the membranes, under the influence of the uterine contraction, and thus allow its passage; or they are so softened that they are flattened out by the foetal part, and delivery takes place spontaneously, although it is retarded. This delay in labor has been observed by all authorities, who, aside from the difficulty which is inherent in the obstacle to be over come, attribute it in great part to the feebleness of the uterine contrac tions. Lefour believes that this feebleness is due to uterine inertia, following ineffectual attempts to overcome the obstacle. Sub-peritoneal fibroids complicate labor when they are situated at the inferior segment, and especially at the cervix. If there is a long pedicle, the tumor may descend into Douglass' pouch, and become impacted. When interstitial or sub-peritoneal fibroids are situated at the inferior segment or at the cervix, and thus more or less completely fill the pelvis, they oppose an enormous obstacle to delivery; however, this should not necessarily be regarded as insurmountable, because, in this case, delivery may be effected either spontaneously or artificially. Here the size of the tumor, although it is an important element, is not the principal one, since it is rather the situation of the growth with reference to the pelvis; small tumors in a bad situation may be relatively more dangerous than those of much larger size.
Delivery occurs in these cases by a special mechanism, which has been thoroughly studied by Depaul and Ganiot and more recently by Lefour. The tumor is not only compressed and softened, but it is displaced upwards into the abdominal cavity, so as to allow the passage of the foetus. Lefour affirms that this ascension may take place during preg nancy, during the latter days of pregnancy, and at the beginning of labor, or during labor.
1. During Pregnancy.—As the lower segment of the uterus develops at the expense of the anterior, rather than of the posterior wall, the latter extends upwards, carrying with it the sessile fibroid which is commonly attached here, or the ascent of the uterus as a whole tends to displace the tumor upwards.
2. During the latter Days of Pregnancy, and at the beginning of Labor. —The tumor may be carried upwards by reason of the contraction of the longitudinal muscular fibres of the uterus; but these contractions are not enough in themselves to elevate a large tumor above the superior strait; they merely dislodge it and render it somewhat movable, the eleva tion being accomplished during the period of dilatation or expulsion. Fibromata often become adherent to the neighboring parts, and if these adhesions are firm, all the efforts of the uterus will be unavailing; if. on the contrary, these are loose, they will yield during the stage of dilata tion.
3. During Labor.—Large, sessile, sub-peritoneal tumors, with broad bases, are especially apt to ascend during labor, this ascension being due to three causes, the uterine contraction, the dilatation of the cervix, and the escape of the amniotic fluid. As the longitudinal fibres contract, they exert traction simultaneously upon the os uteri and the tumor; as the former dilates the latter is displaced upwards. When the membranes rupture the uterine walls retract, and consequently the lower segment is slightly elevated. Unfortunately, this ascension or displacement of the tumor, does not always take place, whence arise insurmountable obstacles, which may render Ciesarian section necessary. But, aside from the difficulties attributable to fibroid tumors, there are others that come from mal-presentations of the foetus, which are much more frequent in preg nancies complicated with fibroids; thus, in 22 cases obseived by Tarnier, 9 were breech-presentations; in 86 reported by Nauss, 18 were shoulder and 22 breech-presentations; in 48 reported by Toloczinow, in 10 the trunk presented, in 13 the breech; in 68 by Susserott, there were 12 of the former and 16 of the latter; in 102 by Lefour, 17 of the former and 33 of the latter. According to the statistics of Dubois and Depaul, the average number of presentations of the trunk in normal labors is 0.04, of the breech, 4.2. Breech-presentations are regarded as the most favora ble in cases of fibroid tumors, and vertex-presentations the most serious.