Ligature of Common Iliac.—Anatomical Note.—This short thick trunk varies slightly in its relations on the two sides of the body. As the aorta bifurcates on the left side of the body of the fourth lumbar vertebra, the common iliac of the right side would have a longer course to pursue than that on the left, if both ended at corresponding points. However, this is not always the case, as has been pointed out by Mr. Adams of Dublin, as the right common iliac often bifurcates sooner than the left does. With this slight difference, the position of the two vessels is precisely similar, each extending along the brim of the pelvis from the bifurcation of the aorta towards the sacro-iliac synchondrosis for about two inches. Sometimes the division takes place a little higher, even at the junction of the last lumbar vertebra and the sacrum. This variation depends chiefly on the length of the artery, which, as Quain has shown, varies from one inch and a half to more than three inches.
The anterior surface of both arteries is covered by the peritoneum, and each is crossed by the ureter just as it bifurcates into its branches.
The artery of the right side is in close contact behind with its corresponding vein, which at its upper part projects to the outside, and below to the inner side. The artery of the left side is less involved with its vein, which lies below it, and to the inside. The right is in contact with a coil of ileum, the left with the colon. The inferior mesenteric artery crosses the left one, while to the outside of both, and behind them, lie the sympathetic and obdurator nerves.
There are no named branches from the common iliac.
Operation.—The chief difficulties to be encountered are—1. The close proximity of the peritoneum, and specially the risk there is that it has become adherent to the sac of the aneurism; 2. The depth of the parts, and tendency of the intestines to roll into the wound; 3. Specially on the right side, the proximity of the great veins. With these exceptions the passing of the ligature is not so difficult as in some situations, the lax cellular tissue in which the vessel lies generally yielding much more easily than the tough sheath which elsewhere, as in the femoral, requires accurate dissection.
Incision.—([Plate I.] fig. 3.)—From a point about half an inch above the centre of Poupart's ligament, a crescentic incision should be made, at first extending upwards and outwards, so as to pass about one inch inside of the anterior superior spine of the ilium, and then prolonged upwards and inwards, as far as may be rendered necessary by the size of the aneurism or the depth of parts. It must extend through skin and superficial fascia, exposing the tendon of the external oblique, which must then be slit up to the full extent visible. The spermatic cord may then be easily exposed under the edge of the internal oblique, and the forefinger of the left hand inserted on the cord, and thus beneath the internal oblique and transversalis muscles, the peritoneum being quite safe below.
On the finger these muscles may be safely divided to the full extent of the external incision. The deep circumflex iliac artery if possible should not be divided, but may bleed smartly and require a ligature.
The peritoneum must then be very cautiously raised from the tumour, and supported, along with the intestines, by copper spatulæ. The surgeon will rarely succeed in obtaining anything like a satisfactory view of the vessel, but can expose it for the ligature by the aid of his finger-nail. An ordinary aneurism-needle will generally suffice for the conveyance of the ligature.
The difficulties may occasionally be much increased by special circumstances, such as great stoutness of the patient, and consequent thickness of the abdominal wall; or large size of the aneurism, which may cause alterations in the relation of parts and adhesion of the peritoneum. The ureter generally gives no trouble, as in pressing back the peritoneum it is adherent to it, and is removed along with it towards the middle line.