In 1834 I placed a ligature of strong dentists’ silk on the right common iliac artery of a lady of middle age for a swelling in the hip, supposed to be a gluteal aneurism, which, after commencing the operation, was found to occupy a considerable part of the iliac region. The lady died a year afterward, and it was then found that the ligature had been applied at the distance of five-eighths of an inch from the bifurcation of the aorta, and three-eighths of an inch above the origin of the internal iliac, independently of the line of separation between the parts of the iliac divided by the ligature, which did not seem to be wider than the ligature itself. The separated ends were united at the point of separation by new matter, the orifice or end of each being closed by a very narrow barrier, the inner coat of the artery being redder than natural, somewhat irregular and contracted, and containing hardly any coagulum. _The fact was thus proved in the largest artery in the body save one, that a coagulum is not necessary for the safety of the union, while the immediate vicinity of so large a vessel as the internal iliac, to say nothing of the aorta itself, also proves that the danger hitherto expected from the neighborhood of a collateral branch is more imaginary than real_--two great facts the practice of the Peninsular war led me to declare, and which ought no longer to be doubted.
The preparation exemplifying these points is in the museum of the Royal College of Surgeons, together with the ligature still carrying in its noose the portion of the artery it strangulated and brought away with it.
187. A ligature should always be round and small, provided it be sufficiently strong. The strength of a ligature is variously estimated; some surgeons trying it by the strength of their own fingers, others by what they conceive to be the resisting power of the coats of the artery, in which perhaps they may err. The only way in which a surgeon can hope to acquire correct information on this point is by trying on the dead body what force of fingers is required to cut the inner coats of arteries of various sizes; and then taking the least force required for this purpose, to ascertain whether he can easily pull the ligature over or off the divided end of the artery. If a surgeon will take the trouble to do this, he will find that he has estimated the necessary force much too highly, and that he is in more danger of breaking his ligature than of failing to secure the artery. Hemorrhage has, however, been known to occur from the ligature having slipped off the end of an artery, which had been divided in the operation for aneurism, although I have never seen it happen after amputation, where the vessels were tied with a small, firm ligature. It constitutes a valid objection to the division of the artery between the ligatures, when two are applied.