THE ABDOMINAL CAVITY 343 



not always sufficient to re-establish the circulation, if the inferior 

 mesenteric artery is ligatured beyond the origin of the lowest 

 sigmoid branch. In abdomino-perineal or abdomino- sacral 

 removal of the rectum, the inferior mesenteric requires to be 

 ligated. If the ligature is applied below the origin of the lowest 

 sigmoid artery, the vitality of the lower part of the pelvic colon 

 is seriously imperilled. It is necessary, therefore, to apply the 

 ligature on the proximal side of the lowest sigmoid branch. 

 The anastomosis between the sigmoids is sufficient to ensure 

 the passage of blood through the lowest sigmoid back into the 

 inferior mesenteric, and thus the blood-stream reaches the pelvic 

 colon along the normal channel. 



Colotomy. The pelvic colon is usually selected as the site 

 for an inguinal colotomy on account of its wide range of 

 movement. A loop of the gut with its mesentery is brought 

 out of the abdomen through the left rectus and its sheath, or 

 through a gridiron incision which is made at a slightly lower 

 level than the appendicular incision (p. 248) on the opposite 

 side. A glass rod or rubber tube is passed through the mesentery 

 to support the bowel by resting on the skin surface on each side 

 of the wound, and the serous and muscular coats of the colon 

 are stitched to the parietal peritoneum. 



Owing to the circular course followed by the blood-vessels 

 in the wall of the gut, the colotomy opening is made transversely. 

 If complete division of the bowel and its mesentery is carried 

 out, only one or two small vessels in the edge of the pelvic 

 meso-colon require to be tied. This part of the operation is 

 quite painless and may be carried out without any anaesthetic. 



Many surgeons prefer to make the opening near the com- 

 mencement of the pelvic colon, because when a more distal 

 portion is used there is subsequently a distinct tendency to 

 prolapse of the mucous membrane. On the other hand, when 

 the opening is made in the lower part of the pelvic colon, the 

 proximal loop of the pelvic colon acts as a reservoir. 



In some cases the pelvic colon and meso-colon are so short 

 that it is impossible to bring the bowel out at the abdominal 

 wound. It is then necessary either to mobilise the iliac colon 

 by dividing the peritoneum freely along the left paracolic gutter, 

 or to utilise the transverse colon or the caecum. 



The Excision of a part of the pelvic colon presents little 

 difficulty when the gut possesses a long mesentery, and axial 

 anastomosis may be carried out. When the pelvic meso-colon 



'2'2 c 



