Page 148 - Medicine and Surgery

P1: KOA
BLUK007-04 BLUK007-Kendall May 25, 2005 7:57 Char Count= 0

144 Chapter 4: Gastrointestinal system

the small or large bowel, a malrotation or Hirschsprung hasmarkingsthatcrossthewholeboweldiameter(valvu-
disease.Childrendevelopintestinalobstructionfromex- lae conniventes) whereas large bowel markings (haus-
ternal hernia, intussusception or surgical adhesions. In tra) only partially extend across the diameter. Erect
adults external hernia, large bowel cancer, adhesions, di- abdominal X-ray may demonstrate fluid levels and any
verticular disease and Crohn’s disease may all cause ob- co-existent perforation.
struction.
Management
Pathophysiology Following resuscitation, prompt diagnosis and opera-
The bowel may obstruct from an intraluminal mass, tion are essential to avoid strangulation. Nil by mouth,

amural problem or extramural compression. These NG suction and i.v. fluids are used in non-surgical causes
result in a simple obstruction. The bowel above the or patients unable to tolerate procedures.
lesion becomes progressively distended resulting in Small bowel obstruction:
painfulstretching.Theremaybecompressionofblood Hernias are reduced and repaired, adhesions and
vessels and a consequent ischaemia. bands are divided.
In avolvulus, malrotation or hernia there may be Lesions within the bowel wall such as tumours require

strangulation. There is occlusion of the low-pressure resection with end-to-end anastomosis.
veins resulting in congestion and oedema. As the ex- Gallstones or food bolus causing intraluminal ob-
tracellular pressure rises arteries become obstructed struction are milked into the colon.
causing ischaemia and infarction. Strangulated bowel is resected and an end-to-end
anastomosis performed.
Clinical features Right colonic obstruction:
Patients present with pain, vomiting and a failure to pass Obstructive lesions of the right colon are managed by
faeces or flatus. The site of pain is dependent on the righthemicolectomy and end-to-end ileocolic anas-
embryological gut: tomosis.
Foregut (stomach to half way along the second part of Palliative side-to-side anastomosis between the ileum

duodenum). Pain is felt in the epigastrium. and transverse colon is performed in cases of inoper-
Midgut (until two thirds of way along the transverse able tumours.

colon). Pain is felt in the umbilical region. Left colonic obstruction:Surgery is often a two-stage
Hind gut (down to the dentate line of the rectum). procedure to reduce the risk of anastomotic leakage.

Pain is felt in the suprapubic region. Resection of bowel with both ends exteriorised or
Physicalexaminationrevealsabdominaldistension,pos- aHartman’s procedure (a defunctioning colostomy
sibly visible peristalsis. Auscultation reveals exaggerated with closure of the distal stump, which is returned to
bowel sounds and high pitched tinkling sounds when the abdominal cavity).
bowel becomes distended with fluid or gas. Restoration of continuity at elective surgery some
weeks later.
Complications
Obstruction may progress to perforation and peri-

tonitis. Paralytic ileus
Inavolvulus there are two points of obstruction. Sim-

Definition
ilarly in proximal colonic obstruction the ileocaecal
Acessation of the peristaltic movement of the gastroin-
valve forms a second point of obstruction. A closed
testinal tract causing a form of intestinal obstruction.
loop obstruction therefore results with rapid compro-
mise of blood supply and high risk of strangulation. Aetiology/pathophysiology
Causesofparalyticileusincludeabdominalsurgery,peri-
Investigations tonitis, pancreatitis, metabolic disturbance (including
Abdominal X-ray reveals the distension and allows as- hypokalaemia) or retroperitoneal bleeding. Inflamma-
sessment of the position within the bowel. Small bowel tion of the serosal surface of the small bowel causes