Intestinal Obstruction

                                              INTESTINAL OBSTRUCTION                  

                Lecture 1
      د. كريم الأعرجي
                                                                                                                Patient’s Scenarios
 Case1: A 35-Year-old man presents to the emergency department with a colicy abdominal pain , recurrent vomiting , abdominal distension and absolute constipation with history of previous appendicectomy 5 years ago..O/E the  abdomen is distended with generalized tenderness and exaggerated bowel sounds . Abdominal x-rays ( erect &supine ) show multiple central air-fluid levels

 Case 2: A 60-Year-old man presents to the emergency department with  generalized abdominal distension , absolute constipation , colicy abdominal pain  and recurrent vomiting ,  .O/E the  abdomen is distended with generalized tenderness , and exaggerated bowel sounds . Abdominal x-rays ( erect &supine ) show peripheral multiple air-fluid levels . PR :Empty rectum with ballooning 

Case 3: A 45-Year-old lady presents to the emergency department with a colicy abdominal pain , recurrent vomiting , abdominal distension and absolute constipation .O/E there is tense , tender right groin mass below and lateral  to the pubic tubercle with negative cough impulse

  Case 4 : A 65-Year-old lady with history of atrial fibrillation presents to the emergency department with a colicy abdominal pain , recurrent vomiting , abdominal distension and bloody loose motion  .O/E the  abdomen is distended with generalized tenderness . Abdominal x-rays ( erect &supine ) show multiple central air-fluid levels . 

 Case 5 : A 45-Year-old man who failed to pass motion 72 hours after operation of bowel resection .The abdomen is distended with minimal tenderness and hypoactive bowel sounds .. Abdominal x-rays ( erect &supine ) show generalized gaseous distension

 . 
 Case 6 : A 35-Year-old man who gave a history of recurrent attacks of abdominal pain and vomiting during the last 2 years , presents  to the emergency department with  colicy abdominal pain  generalized abdominal distension , absolute constipation , and recurrent vomiting ,  .O/E the  abdomen is distended with generalized tenderness , and exaggerated bowel sounds . Abdominal x-rays ( erect &supine ) show multiple air-fluid levels

1. Objectives
   : At the end of these lectures ,the students will be able to understand and discuss intestinal obstruction in regards of the followings  
   Definition
2.  Types
   . Causes
    Pathophsiology
3. Risks &Complications (Strangulation 
4.  Clinical features
    Diagnosis &Other investigations
    Management
   Indications for surgery
    Adynamic intestinal obstruction
    
5. Definition :  Intestinal obstruction ( IO ) is defined as a failure of the forward transit of GIT contents . It is either mechanical(dynamic ) when there is mechanical blockage that prevents the forward progression of GIT contents or adynamic in which there is no mechanical obstruction but  peristalsis may be absent such as  paralytic ileus or there may be interference with blood supply  such as mesenteric vascular occlusion
   ? Types : Mechanical IO is classified according to the followings
6. Onset : Either acute, usually of small bowel  with a sudden onset of central abdominal pain  and severe symptoms  , chronic with a gradual onset , acute-on-chronic with a chronic symptoms then there is sudden obstruction and subacute which indicates an incomplete obstruction .
   . Anatomic level : High (Small bowel obstruction ) which is either high small bowel obstruction, vomiting occurs early and is profuse with rapid dehydration. Distension is minimal with little evidence of fluid levels on abdominal radiography or low small bowel obstruction, pain is predominant with central distension. Vomiting is delayed. Multiple central fluid levels are seen on radiography . Low ( Large bowel obstruction ) ,distension is early and prominent. Pain is mild and vomiting and dehydration are late. The  colon and caecum are distended on abdominal radiography .
   3. Nature (Stage ) : Simple or strangulated (gangrenous )  obstruction with interference with blood supply .
   ? Causes : Causes can be discussed according to 
   1. Incidence into
7. a) Postoperative adhesions and fibrous bands is the most common 
   b) Obtructed hernia :Inguinal , PUH , Incisional etc 
   c) Tumours
   d) Others
   . Anatomical :Obstruction of any tube may be due to
8. a) Intraluminal such as gall stone , faecal material
   b) Intramural such as tumour
   c) Extraluminal such as obstructed hernia , fibrous band 
10.  .Age
    a) Neonatal :Congenital stenosis
    b) Infant  :Hirschbrung’s disease
    c) Young adult & middle age :Obstructed hernia
    d) Elderly :Tumours of bowel 
11.  Pathophysiology :The pathophysiological consequences may occurs proximal , at or distal to obstruction and these effects are reflected on general condition of the patient .
       Proximal :At the beginning of obstruction , peristalsis increases trying to overcome obstruction which will lead to intestinal colic & due to antiperistalsis vomiting may occurs , proximal intestines dilate  , filled with fluids &gases .Gases consist of swallowed gas and from bacterial fermentation .Fluids consist of oral fluids and GIT fluids(Normally :About 8 liters from saliva , stomach , biliary , pancreas &small intestine , 4L above the ampulla of Vater &4L below the ampulla .The fluid is  absorbed by small intestine and 2 L enter the colon and only 200 ml are passed in the faeces  .In IO there is impairment of absorption of fluids by intestine so fluids will be sequestrated within lumen & tissues leading to dehydration .
    Rise of intraluminal pressure  will obstruct lymphatics , veins and arteries with swelling of the wall , ischaemia , strangulation , perforation , peritonitis , septicaemia with all its sequelae .
    Transudation and translocation of intraluminal bacteria to the peritoneal cavity or to the hernia sac forming very toxic fluids .r from pressure from within the lumen by faecal mass .
12. . At site of obstruction :There will be ischaemia at sites of pressure at the neck of hernia , bands etc.
    Distal to obstruction : The intestine empties its contents and gets collapsed . So the patient initially may have a normal bowel motion.
          Generally the patient will develop dehydration & electrolytes disturbance  , toxicity with its sequelae.  Dehydration is due to fluid loss through vomiting , fluids sequestration within the lumen and intestinal wall and peritoneum (Third space loss)
    Closed loop obstruction : This occurs when there is complete obstruction distally and valve –like action proximally allowing the bowel to fill but preventing reflux back leading to  rise of intraluminal pressure with subsequent impairment of blood supply.
    A classic form of closed-loop is seen in the presence of a malignant  tumours of the right colon with a competent ileocaecal valve with strangulations and perforation of the caecum due to its greatest diameter ( Laplace’s law ) .
    ? Complications
    1. Fluids& electrolyte disturbance due to vomiting , fluids loss within the  lumen and fluids sequestrations in the tissues .
    2. Toxaemia due to transudation of bacteria and its toxins to the peritoneal cavity and hernia sac or through ischaemic intestinal mucosa or GIT perforation with peritonitis .
    ? Clinical features : The cardinal clinical features of dynamic intestinal obstruction are Abdominal pain ,Vomiting , Abdominal distention & Absolute constipation for flatus &stools (Obstipation ) . These symptoms vary according to the level and nature of IO .
    1. Abdominal pain is usually colicy with pain-free interval  , more prominent in small than large intestine , periumbilical in small IO  , suprapubic in large bowel obstruction .In strangulated IO , it becomes persistent and localized to the site of gangrenous segment 
    2. Vomiting : Early it may be clear but it becomes faeculent ( not faecal ) in late obstruction due to bacterial decomposition of intestinal contents and altered blood transducing through ischaemic mucosa .( The only true  faecal vomiting is what it occurs in gastrocolic fistula as a complication of  stomal ulcer after gastrojejunostomy or gastric carcinoma ) .It occurs and  is more prominent in high level IO and late  in low ( Large bowel ) IO .
    3. Abdominal distention : It is mild in low IO due to a short segment and marked in low ( Large ) IO ad sigmoid volvulus .
    4.  Constipation : It is absolute for flatus and stool (Obstipation ) and prominent  in large bowel obstruction .In acute high IO , patient may pass motion for a while due to emptying of the distal segment of bowel or may be due to the followings :
    ? Obstruction associated with pelvic abscess 
    ? Partial obstruction (faecal impaction/colonic neoplasm)  
    ? Richter’s hernia;
    ? Gallstone ileus
    ? Mesenteric vascular occlusion;
                            
    ? .Physical examination 
    1. General : Dehydration     , Tachycardia , Hypotension , Fever .Strangulation is suggested if patient is toxic , persistent pain , fever , tachycardia and hypotension 
13.  Abdomen   
     Inspection: Distension with visible peristalsis.  Obstructed external abdominal hernia (Groin &Ventral hernia ) .   Presence of surgical postoperative scar which suggest adhesion or band
    Palpation : Generalized tenderness and mass .Localized tenderness may suggest strangulated intestinal segment .
    • Percussion : Tympanic
     Auscultation :At the beginning of IO the bowel sounds may be exaggerated especially during the colic but may be absent in established gangrene .
    • Rectal examination (PR ) : Usually the rectum is empty (Ballooning of the rectum ) or mass may be felt in pouch of Douglas.
    Clinical features of strangulation :The Dx. is entirely clinical and three is no absolute criteria for diagnosing strangulation and mechanical obstruction should be presumed to be strangulated until proved to be otherwise . The features which suggest strangulation are  Constant pain , abdominal tenderness with rigidity and shock

References   

 . Lecture Notes on General Surgery ; Harold Ellis , Sir Roy Calne , Christopher Watson ; Blackwell Publishing ; Tenth edition ; 2002

 .Bailey &Love s Short Practice Of Surgery ;Norman S. Williams ,Cristopher J.K.Bulstrode & P.Roman O Connell 25th edition ;2008 Edward Arnold Ltd.