Rupture during pregnancy may happen at alrnost any period, but chiefly during the latter half, although it may take place even as early as the second month, as from vo miting:I Or it may be occasioned by violent spasmodic contraction, or from contusion or sudden concussion. It is most likely to happen in the case of the imperfectly de veloped uterus, as in the uterus unicornis, of which a description has been already given (p. 679.), or in the case of gestation in the uterine portion of the Fallopian tube (gra viditas interstitialis, p. 621.).
Rupture of the uterus may occur upon only- very slight exertion, as in the act of stooping*, or even without any obvious cause, as during sleep.t Most of tile recorded cases, however, of spontaneous rupture of the uterus have occurred during labour, under violent uterine action, combined with some unusual resistance to the pa.ssage of the child, such as is occasioned by a distorted or fractured pelvis, a tumour, an unyielding state of the os and cervix uteri, or by some malposition or unusual bulk of the child. It may also occur from violence in instrumental delivery, or from injudicious efforts to turn the child.
The seat of rupture is most commonly the neighbourhood of the cervix, the laceration extending very often through the os to the vagina, or upwards, so as to involve more or less of the body of the uterus. It occurs oftenest at the sides, less frequently in the anterior or posterior walls, and least of all at the fundus.
The course of the laceration is generally oblique, rarely in the• horizontal direction. It may, however, extend round the whole circumference of the cervix, the lov.er seg ment of the uterus being forced off in a sin gle piece, before the presenting part of the child.t The length of the rupture tnay be such as to admit of the child escaping into the ab domen, among the intestines, or it may be only very slight. All the coats of the uterus are not necessarily involved. The peritoneum alone may be torn, numerous rents (40-60) occurring in this coat, without extending to the muscular tissue.§ These lacerations occur in most instances where the uterine tissues are perfectly healthy. In some cases the walls of the uterus have been apparently attenuated, the attenuation being attributed to pressure upon the spine or pelvic bones, or there has been more or less evidence of antecedent inflammation near the seat of the accident.
Perforation of the uterine walls occurs in cancer, (fig. 479.) followed by the establish
ment of fistulous communications with the bladder and rectum ; or from penetrating abscess at the surface of the uterus ; or as a consequence of adhesions formed between the uterus and an ovarian cyst, the contents of the latter being discharged through the uterine cavity.
Pathological conditions of the Uterus after Parturition.
Irregular contraction. — After tedious and exhausting labours, or those in which the uterus has been rapidly einptied, or under other circumstances which tend to the production of a general or partial atony of the organ, its post-partum contractions are often imperfect. The whole uterus may re main relaxed and undiminished in size, or a portion only of the walls may contract while the rest remain inactive. From the latter combination result the hour-glass and other irregular forms of the organ when the cavity of the uterus is partitioned into two chambers, in the upper of which a part or the whole of the placenta may be imprisoned. The seat of constriction being either near the fundus, or the centre of the uterus, or the neigh bourhood of the cervix. This condition is often attended by hmmorrhage froin the un contracted portions of the uterine walls.
In explanation of these irregular contrac tions, it has been usually assumed that the contracted portions consist of the fibres that have retained their vigour, and the relaxed parts of those that have been exhausted. Numerous observations, however, have satis fied me that this is but an imperfect and, in some respects, an erreneous interpretation of this phenomenon. It appears to depend rather upon arrested peristaltic action, which may indeed be, and probably is, the result of ex haustion ; not, however, of a particular set of fibres, but of the ganglionic nerves which especially govern this movement of the organ. So that the peristaltic contraction in travelling along the uterus from os to fundus, is stopped in some part of its course. This explanation is consistent with the fact that these constric tions are not confined to any special region, but may occur at any point between the cer vix and the fundus, and particularly with the circumstance that in some cases the con stricted part may change its seat, the contrac tion being sometimes felt to travel onwards towards the fundus, while the hand is em ployed within the uterus in removing the pla centa. See p. 673.