_Accumulations of fluid, and tumours in the chest or abdomen._ It is very rare that the chest is distended by any accumulation of fluid or morbid growth, although this is not unfrequently met with in the abdomen. La Motte has given three cases of ascites which, by the distention of the abdomen, produced considerable obstruction to the delivery of the child. (Cases 331, 332, and 333.) In other cases the liver or the kidneys have been enormously enlarged. A case is described by Dr. Hemmer, where the child was born as far as the shoulders, and there stuck; finding it impossible to extract the child, he perforated the abdomen in two places, but could not extract it; in a few minutes after it came away of itself. The abdomen had been distended with small hydatids; these gradually escaped, and thus diminished the size of the abdomen. (_Neue Zeitschrift für Geburtshülfe_, band iv. heft 1, 1836.) Where the child has been dead some time in the uterus, the abdomen is frequently tympanic, and thus retards its expulsion. _Monsters._ Certain cases of monstrous formation may produce very serious obstacles to the progress of labour: the most considerable is of twins united by the breast. It is difficult to conceive how so large a mass can be forced through the pelvis: we can only suppose it possible where the children have been dead some time before birth, or where they were premature: to this latter circumstance only we can attribute the fact of their having been born alive, as in the celebrated case of the Siamese twins. Where the children have been united by one pelvis, &c., the chances here of the foetus being dead before birth would be even still greater. M. Rath, of Zetterfeld, has lately described a case of extremely difficult labour, in consequence of twins united by the breast. "The children (two girls) weighed 15lbs.; they were 17 inches long. The part by which they were united was 9 inches broad and 3 long, and extended from the upper extremity of the sternum to the navel, into which one umbilical cord, which was common to both, entered. The diameter of the two children when laid together was between 7 and 8 inches from one back to the other. One child had two thumbs on the right hand. The cord was 19 inches long, and unusually thick. After suffering some time from peritonitis, &c., the patient recovered." (Siebold's _Journal_, band xvii. heft 2. 1833.)