Small Bowel Obstruction (SBO)

Last updated 20.09.12

 

Definition

-  Bowel obstrction occurring in the small intestine

 

Features

-  20% of acute Sx admission in US

-  100% death rate in untreated strangulated hernias

-  8% mortality if Sx within 36hrs, 25% > 36hrs

-  Partial vs Complete

-  Simple vs Strangulated

-  Extrinsic compression more common than intrinsic blockage

-  SBO --> stomach dilation, distal bowel decompression

-  Bowel dilation --> ischaemia --> necrosis, strangulation, sepsis

 

Associated S/S

-  Initial diarrhoea (freq & loose) & flatus

-  Dehydration: 3rd space losses, may be severe

-  Constipation: nil stool

-  +/- obstipation: takes 12-24hrs for colon to empty

-  Nausea & vomiting

-  Bilious: proximal obstruction

-  Faecalent: distal obstruction

-  --> Metabolic alkalosis

-  Colicky periumbilical abdo pain

-  Pain progressive over several hours: distal

-  Change in pain may indicate strangulation

-  Paroxysms every 4-5min

-  Abdo distention

-  > if distal

-  Early = hyperactive bowel sounds

-  Later = hypoactive bowel sounds

-  Tympany

-  Hernias

-  Fever, tachycardia: strangulation

-  Perforation

-  Peritonitis

 

Causes

-  Paediatric Bowel Obstruction

-  Adhesions 60%: previous Sx

-  May occur any time

-  Appendicectomy

-  Colorectal & upper GIT Sx

-  Gynae Sx

-  Hernias 2nd most common

-  Crohns disease adhesions or strictures (5%)

-  Neoplasia 3rd most common (20%)

-  Rule out if no surgical Hx

-  Sup Mesenteric A. Syndrome

-  Ischaemic strictures

-  Foreign bodies: gall stone ileus..

 

DDx

-  Paralytic ileus

-  Pseudoobstruction

 

Ix

-  PR Exam

-  Gross or occult blood: strangulation, Ca

-  Masses: obturator hernia

-  U&E

-  Elevated Cr, Urea: dehydration

-  FBE

-  WBC: elevated

-  LDH: strangulation

-  Urinalysis

-  Group & Hold: Sx Mx likely

-  AXR: supine & upright

-  75% sens, 53% spec

-  Air fluid levels

-  Dilated loops

-  Minimal or absent colonic gas

-   If air in rectum & S/S >12hrs SBO unlikely

-  Pneumoperitoneum

-  CXR: perforation: pneumoperitoneum

-  CT - Abdo wo contrast: strangulation, Dx cause

-  90% sens & spec

-  Presence, level, cause & severity of SBO

-  Gastrograffin F/T or Enteroclysis

-  Demonstrates failure to passs contrast: obstruction

-  May assist in clearing obstruction

 

Mx

-  NBM & IV Fluids: NS or Hartmans

-  NGT

-  Bowel decompression

-  Esp if ongoing vomiting

-  Analgesia

-  Antiemetics

-  +/-Abx

-  Surgery

-  Laparoscopy, laparotomy

-  +/- adhesionlysis

-  As per cause

 

 

 

References