Intestinal Obstruction

Intestinal Obstruction:

Introduction:

Intestinal obstruction is defined as a blockade of the flow of intestinal content, which results in not only anatomic, functional changes but also systemically physiologic disorders.

The leading cause is postoperative adhesions (60%), followed by malignancy, Crohn disease, and hernias.

Etiology And Classification:

(A).According to its basic causes: mechanical, dynamic obstruction,and obsturction of vascular supply origin
1). Mechanical obstruction
 -from lesions within the wall of the intestine(intrinsic)
- from extra-intestinal lesions ( extrinsic)
 -from obstructing intra-luminal substances.
 -congenital, inflammatory, neoplastic, or   traumatic origin.
  -Adhesions of postoperative, congenital origin,   Henias,
 -Intra-luminal foreign bodies

2). Dynamic obstruction
   Nerval reflex or toxin stimulation, acute diffuse peritonitis, abdominal operation, retroperitoneal hematoma and infection.
  Spastic obstruction in intestinal functional disorder or toxication.
3). Obstruction of blood supply origin
  thrombosis or embolism, then intestinal paralysis.

(B).According to whether the vascular supply to intestinal wall is compromised, simple and strangulation obstruction.
  Simple obstruction,
    without threat to the viability of the intestinal wall.
  Strangulation obstruction,
   the vascular supply  is compromised.

(C).According to obstruction level or site:
   Proximal, distal intestinal, or large bowel obstruction, or high  and low obstruction
(D.)According to the extent of obstruction
      Incomplete and complete obstruction,
5.According to mode of onset and progression of obstruction.
     Acute and chronic obstruction

Pathophysiology:

Motility of small intestine

The intestine contracts vigorously.The patient complains bitterly of crampy abdominal pain.
 Finally the intestine dilated.

Absorption and secretion

-water and electrolytes accumulate.
  -a decrease in absorption,
  -an increase in intestinal secretion.

Infection and toxemia
-The bacteria proliferate, produce  toxin.
-Vascular supply or viability compromised,

  -results in severe peritonitis and toxemia

Shock
 - Severe dehydration,
 - decrease of blood volume
  -electrolytic disturbance,
 - acid-base imbalance,
 -bacterial infection and toxemia

Clinical Manifestations:

-Nausea and vomiting
 - Colicky abdominal pain
 - constipation
 - Abdominal distention.
 -Their onset varies not only with the duration of established obstruction but also with its anatomic site

(A.)Nausea and vomiting:
      may be the only symptoms.
1).The nature of the vomitus.
       undigested food particles.
       becomes bilious.
       feculent.
2).The onset and character of vomiting.
      Recurrent vomiting of bile-stained fluid
      Prolonged nausea precedes vomiting, feculent.
     Vomiting is a late finding if the ileocecal valve  prevents reflux.

(B.) Crampy (spastic) abdominal pain:

Þ      Pain, often described as crampy and intermittent, is more prevalent in simple obstruction, poorly localized, and lasting 1-3 minutes.

Þ      Often, the presentation may provide clues to the approximate location and nature of the obstruction. Pain lasting as many as several days, which is progressive in nature and with abdominal distention, may be typical of a more distal obstruction.

Þ      Severe ,continuous abdominal pain suggests intestinal ischemia or peritonitis.

(C.)Abdominal distention:
  Develop later in the course of the obstruction
  Associated with obstructed site or level.
1)not prominent in proximal intestinal obstruction,
2)prominent and diffuse in distal intestinal obstruction and paralytic obstruction.
3)colon is obstructed, abdominal distention is often round abdomen.
4)Abdominal distention of intestinal torsion, is asymmetrical.

(D.)Constipation and obstipation:
  -The onset of obstipation, a late development.
 - Still pass flatus:  
   the distal, unobstructed intestine empties.
   partial or incomplete obstruction

Physical Examination:

Inspection:
The degree of abdominal distention varies with both the duration and the location of the obstruction. Peristalsis is occasionally visible.

Palpation:
  -Localized tenderness or a tender, palpable mass
  -Signs of localized or generalized peritonitis

Auscultation:
  - Obstructed bowel sounds with the abdominal borborygmi of tinkles, splashes, and rushes that coincide with the abdominal colic.
 -With late obstruction , it loses its contractile activity, and rushes may be absent.
  -Borborygmus (Bowel sounds) may be absent in paralytic obstruction.

Percussion:
  - If the segment of intestine is strangulated, shifting dullness may be evident.
Rectal digital examination:
 - Low rectal carcinoma and intussuscepted segment are palpable sometimes
Laboratory tests:
  - Serve only to define the fluid and electrolyte status

Radiological Examination:

Abdominal roentgenograms:

-Plain radiographs usually confirm the clinical suspicion and define more accurately the site of obstruction. The accuracy of diagnosis of the small intestinal obstruction on plain abdominal radiographs is estimated to be approximately 60%.

-Supine and erect abdominal roentgenograms:
  When small bowel is obstructed,
      -dilated loops of small intestine
       -multiple air-fluid level
  When large bowel is obstructed,
       -the image of dilated colon and haustra of colon

CT Scan:

-CT scanning is useful in making an early diagnosis of strangulated obstruction. It also has proved useful in distinguishing the etiologies of intestinal obstruction.

 -CT scanning is about 90% sensitive and specific in diagnosing intestinal obstruction.

 -CT scanning is useful in identifying abscesses, hernias, and tumors.

Ultrasonography:

ß   Ultrasonography is less costly and less invasive than CT scanning.

Þ   It may reliably exclude intestinal obstruction in as many as 89% of patients.

Þ   Specificity is reportedly 100%.

Radiologic Examinations : summary

Plain abdominal radiographs are usually diagnostic of bowel obstruction in more than 60% of the cases, but further evaluation (possibly by CT or Ultrasonography) may be necessary in 20% to 30% of cases. CT examination is particularly useful in patients with a history of abdominal malignancy, in postsurgical patients, and in patients who have no history of abdominal surgery and present with symptoms of bowel obstruction.

Diagnosis:

must make clear the following questions:

1. Does intestinal obstruction exist?

2. Is intestinal obstruction mechanical or dynamic?

3. Is intestinal obstruction simple or strangulation    obstruction?

4. Is intestinal obstruction high or low site?

5. Is intestinal obstruction complete or incomplete?

6. Which causes lead to intestinal obstruction ?

1.Whether intestinal obstruction exists:
  Through symptoms and signs, the diagnosis can be made without difficulty.
  Abdominal roentgenograms is much helpful in diagnosis.

2.Whether the obstruction is mechanical or dynamic:
  mechanical obstruction, typical symptoms and signs.
  paralytic obstruction, episodic and cramping abdominal pain is absent, distention is prominent

3.Whether the obstruction is simple or strangulation obstruction:

Strangulation obstruction is associated with an increased morbidity  and mortality risk, and therefore recognition of early strangulation is important in differentiating from simple intestinal obstruction.

Strangulation obstruction, which usually involves a closed-loop obstruction in which the vascular supply to a segment of intestine is compromised, can lead to intestinal infarction.

Indications for strangulation:
1).Abrupt onset with continuous acute abdominal pain,
2).Shock
3).Manifestation of peritonitis: leukocytosis, hyperthermia.
4).Asymmetrical distention, local bulge, or mass with tenderness.
5).Hemic (hematic) vomitus, drainage
6).Conservative treatment in vain and no improvement in symptoms and signs.
7).Isolated, bulged, and distended intestinal loop on roentgenograms.

4.Whether the obstruction is high or low :
    Vomiting, in proximal intestinal obstruction.
   Distention in low obstruction, feculent vomitus
   Abdominal roentgenograms is helpful.
5.Whether the obstruction is complete or incomplete:
  frequency of vomiting, extent of distention, and roentgenograms.

6.Which causes leads to obstruction:
  According to the age, history, symptoms and signs, roentgenograms.
-Postoperative adhesions, postinflammatory origin
-Henias
-Congenital malformations
-Intestinal intussusception
-Obstruction of parasite origin
-Carcinomas and dry feces.

Treatment and Management:

The principle:
-correction of systemic disturbance 
-reduction of obstruction

1).Gastrointestinal decompression

2).Correction of water-electrolytic
     disturbance, acid-base imbalance

3).Prevention (Prophylaxis) and
    treatment of infection and toxemia

Treatment of obstruction:

1.Operative treatment
  strangulation obstruction or obstruction of neoplastic and congenital origin
The surgical procedures includes:
1)Lysis of adhesion, reduction of intussusception, torsion.
2)Enterectomy and anastomosis.
3)Bypass procedure for nonresectable lesions.
4)Enterostomy and exteriorization of intestine.
Treatment of obstructing carcinoma colon

2.Non-operative treatment:

simple, adhesive obstruction (incomplete ), paralytic obstruction, obstruction of parasite origin, and in the early stage of intestinal intussusception.
   close observation is very important.
  exacerbated, transferred to surgical intervention