120 



LIGATION OF ARTERIES. 



wound, where it can be brought directly against a bone (mediate 

 compression). This plan rarely stops bleeding completely, however, 

 and at the end of the operation one is obliged to resort to some 

 other method. In dealing with hollow wounds long strips cl anti- 

 septic gauze, tarlatan, or muslin may be packed into the cavity under 

 pressure, and the lips of the wound provisionally united by a few 

 sutures. This usually checks bleeding from small vessels. 



Ligation is effected with threads of silk or catgut : chromic gut 

 is the best. When an artery crosses the field of operation, and must 

 be divided, it is isolated, ligatured in two places, and the section 

 made between the two ligatures. If a vessel, whether artery 

 or vein, is accidentally divided, the ends 

 are grasped with forceps and strongly 

 ligatured as high up as possible, using a 

 surgical knot. In the case of an artery, the 

 object is to divide the inner and middle coats, 

 which retract, and become incurved towards the 

 axis of the vessel, whilst the external stretches 

 slightly, and its surfaces are brought into 

 close apposition. When using catgut the 

 ends of the knot may be cut short, but in 

 the case of silk usually only one is cut short, the 

 other being brought outside the wound unless 

 asepsis be assured. It is withdrawn a day or 

 two later, when the vessel has been cut through. 

 Walls' or Greig-Smith's forceps, with large jaws 

 of conical or cylindro-conical section, are very 

 convenient when ligating vessels. The ligature, 

 on being tightened, slips over the nose of the 

 forceps, and surrounds the vessel. Immediate 

 ligation is always to be preferred. Where it is 

 impracticable, as when the ends of the vessels 

 have retracted deeply within the tissues and cannot be discovered, 

 or when the tissues are very friable and break away as grasped, 

 mediate ligation, or ligation in the continuity of the vessel, may be 

 performed. 



The instruments required are a scalpel, two retractors, dissecting 

 forceps, a director, ligatures, and aneurysm needle (Figs. 159 and 160), 

 i.e. a curved needle with fixed handle. The method is as follows : — • 

 The skin is incised directly over the artery, the lips of the wound 

 are drawn apart with retractors, and dissection cautiously continued 

 until the artery appears. A fold of the artery sheath is then lifted 



Figs. 159, 160.— 

 Aneurysm needles, 



