CLINICAL FEATURES OF INTESTINAL OBSTRUCTION Dynami

CLINICAL FEATURES OF INTESTINAL OBSTRUCTION Dynamic obstruction

The diagnosis of dynamic intestinal obstruction is based on the classic quartet of pain, distension, vomiting and absolute constipation. Obstruction may be classified clinically into two types: /uni25CF small bowel obstruction – high or low; /uni25CF large bowel obstruction. The nature of the presentation will also be influenced by whether the obstruction is: /uni25CF complete; /uni25CF incomplete. A complete small bowel obstruction has all the cardinal features. In cases of complete large bowel obstruction there is often a surprising lack of preceding symptoms. Both small and large bowel obstruction can present with more chronic symptoms in which the symptoms and signs are intermittent or the obstruction is incomplete. Incomplete obstruction is also referred to as partial or subacute. Features of obstruction /uni25CF /uni25CF /uni25CF Summary box 78.7 Cardinal clinical features of acute obstruction /uni25CF /uni25CF /uni25CF /uni25CF Presentation will be further influenced by whether the obstruction is: /uni25CF simple – in which the blood supply is intact; /uni25CF strangulating/strangulated – in which there is interference to blood flow . The common causes of intestinal obstruction in wes tern countries and their relative frequencies are shown in Figure 78.1 . The underlying mechanisms are shown in Summary box 78.2 . The clinical features vary according to: /uni25CF the location of the obstruction; /uni25CF the duration of the obstruction; /uni25CF the underlying pathology; /uni25CF the presence or absence of intestinal ischaemia. Late manifestations of intestinal obstruction that may be encountered include dehydration, oliguria, hypovolaemic shock, pyrexia, septicaemia, respiratory embarrassment and peritonism. In all cases of suspected intestinal obstruction, the hernial orifices m ust be examined.

In high small bowel obstruction , vomiting occurs early, is profuse and causes rapid dehydration. Distension is minimal with little evidence of dilated small bowel loops on abdominal radiography In low small bowel obstruction , pain is predominant with central distension. Vomiting occurs later. Multiple dilated small bowel loops are seen on radiography In large bowel obstruction , distension is early and pronounced. Pain is less severe and vomiting and dehydration are later features. The colon proximal to the obstruction is distended on abdominal radiography. The small bowel will be dilated if the ileocaecal valve is incompetent ( Figure 78.3 Abdominal pain Distension Vomiting Absolute constipation