Small bowel obstruction

assalamualaykum,, it has been so long since i wrote the last topic,, now im back,, bringing you an interesting info about bowel obstruction. just so u know,, i got “thinking obstruction” while writing this topic.. this is actually my elective posting in the digestive surgery department project,, the digestive surgeon told me to make some kind of literature review. and so this is some part of it

so people  happy reading :D

Small Bowel Obstruction

Small bowel obstruction is obstruction to the downward flow of intestinal content. 1

A. Ethiology 2

The cause of small bowel obstruction can be categorized into :

  • Lesion extrinsic to the intestinal wall :
    • Adhesion (post operative)
    • Hernia : external (femoral, inguinal, umbilical, ventral); internal (congenital defect, foramen of Wislow, diagfragmatic hernia)
    • Neoplastic : carcinomatosis, extraintestinal neoplasm
    • Intra abdominal abcess
  • Lesion intrinsic to the intestinal wall :
    • Congenital : malrotation; duplication
    • Inflammatory : Chron disease, infection (tuberculosis, actinomycosis, diverticulitis)
    • Neoplastic : primary neoplasm, metastatic neoplasm
    • Traumatic : hematoma, ischemic stricture
    • Miscellaneous : intussuseption, endometriosis, radiation/ enteropathy stricture
  • Intraluminal / obturator obstruction :
    • Gallstone
    • Enterolith
    • Bezoar
    • Foreign body

Adhesion are responsible for more than 60% of  bowel obstruction. Adhesion is mainly caused by gynecologic procedure, appendectomy, and colorectal resection. This preponderance of lower abdominal obstruction is thought to be due to that bowel is more mobile at the pelvic space and more tethered in the upper abdomen.

Adhesion present the form of secondary wound healing. The mesothelial tissue response to injury is initiated locally and thence propagated and guided by cytokine signaling. Systemic and genetic element may also potentiate the cascade such as bacterial contamination.

There are vast array of cytokines implicated in the development of abdominal adhesion after laparotomy. Tumor necrosis factor is one of the important factor. TNF elucidation lower the using of monoclonal antibody after intestinal operation. Vascular endothelial grothw factor (VEGF) is another factors influencing the adhesion post operative. VEGF facilitate increased vascular permeability (essential for the early proinflamatory response to injury) as well as the subsequent deposition of the fibrin rich matrix necessary for subsequent cellular migration and proliferation. VEGF is induced by mast cell. Mast cell effects the threshold concentration of VEGF by exiting the egress of neutrophil and monocyte from the circulation to the peritoneum. 3

The study conducted by byrol et al shows that neutrophil is the main factor in forming adhesion.4 Byrol et al used 40 wistars and divide it into three group. The first group received saline, the second group received cyclophosphamide (which will induce neutropenia) and the third group received human GM CSF (granulocyte macrophage colony stimulating factor). To all of these group were doe mid line laparotomy. All animal from each group were done peritoneal lavage also. The neutrophil count, neutrophil phagocitosys and adherence index were determined in each group after 1 day laparotomy done. The result shows that in group II, the neutrophilic count were lower compared to the other group (p<0.05) and in histologic examination fewer bundles of collagen were seen. It is concluded that inhibition and activation of neutrophil affect the cascade of postoperative adhesion formation.

Malignant tumors account for 20% of the cases in small bowel obstruction. Most of these tumors are metastatic lesion from malignancy in ovarium, pancreas, gaster or colon which obstruct the small intestine due to peritoneal implants. Another peritoneal implants came from the hematogenic spread from distatnt sites such as breast, lung and melanoma. Large intra abdominal tumor also cause obstruction due to extrinsic compression of the lumen. Primary small bowel tumor it self can cause obstruction yet rare.

Hernias are the third to cause small bowel obstruction, and account 10% of all cases. Most common forms are ventral or inguinal hernias. Internal hernias usually related to prior abdominal surgery. The rest (ec femoral, obturator, lumbar, sciatic) be the least to cause hernia. 2

Crohn’s disease account for about 5% cases. Obstruction can result from acute inflammation and edema.

Intra abdominal abscess, as a consequences of ruptured appendix, diverticulum, or dehiscence of an intestinal anastomosis with other miscellaneous ( intussusceptions, polyp, gallstones, divertikulum, and foreign body) account for the rest 5% of small bowel obstruction.

B.  Pathophysiology 2,5

Early phase of obstruction : intestinal motility and contractility increase as an effort to propel the luminal content past the obstructing point. Increase in peristaltic occur above and below the point of obstruction. This mechanism answer the findings of diarrhea that may accompany partial or total obstruction in the early phase.

Later phase of obstruction : the intestine become fatigue and dilate, the contraction become less frequent and less intense. As the bowel dilates, water and electrolyte accumulate both intraluminal and in the wall of intestine. . This bowel dilatation stimulates cell secretory activity, resulting in more fluid accumulation. This will later cause dehydration and hypovolemia. If the obstruction is proximal part of the small bowel dehydration may be accompanied by hypochloremia, hypokalemia, and metabolic alkalosis associated with increased vomiting. Otherwise if the obstruction is in the distal part of the small bowel may result in large quantities of intestinal fluid into the bowel however the abnormalities in serum electrolyte is less dramatic.

As intraluminal substance accumulate intraluminal pressure also increase thus resulting in the decrease of mucosal blood flow which will cause ischemia and if leave untreated will cause intestinal perforation and peritonitis.

C. Diagnosis :

C.1 History

The cardinal symptoms of intestinal obstruction include colicky pain, nausea, vomitus, abdominal distention and failure to flatus or defecation. Typical crampy abdominal pain that has 4-5minute intervals is less frequent in distal obstruction. Nausea and vomit are more common in proximal obstruction. In distal obstruction associated with cramping abdominal pain. Diarrhea is the complain caused by increase intestinal movement at the early phase of obstruction, later patient will have constipation. 2,5

C.2 Physical examination

Tachycardia and hypotension may be due to dehydration. Fever suggest the probability of strangulation. In abdominal palpation, we would find distended abdomen and the amount of distention depends on the location of obstruction. On aouscultation, we would find audible rushes associated with the increase of peristaltic movement (borborigmy sound). Later phase of obstruction, the bowel sound may be diminished or no bowel sound are heard. Localized tenderness, rebound, and guarding may be the signs of strangulation. 2,5

A comprehensive examination should be done to rule out hernia from the cause of obstruction. Digital rectal examination should be performed to asses intraluminal masses and to examine the stool from occult blood which may be an indication of malignancy intussuseption and infarction. 5

C.3 Radiologic examination1,2 :

Goals: distinguishing between mechanical obstruction or ileus, determining the etiology of obstruction, discriminating partial from complete obstruction and strangulated or non strangulated obstruction.

Abdominal series X ray which consist of supine and upright position has high sensitivity to be the screening examination of small bowel obstruction. The findings of small bowel obstruction are dilatation of small bowel loops (>3cm), air fluid level as seen on upright film, paucity of air in the colon.

Computed tomography is 80-90% sensitive and 70-90% specific to detect small bowel obstruction. The findings of small bowel obstruction are dilatation of proximal small bowel, decompression of distal bowel and intraluminal contrass will not fill the obstruction defect.

Enteroclysis is a method of  inserting a tube orally until it reach duodenum to instill air and barium to the small intestine. then it is followed flouroscopicaly. Enteroclysis has been advocated to be the definitive study in patient with suspect of low grade intermittent small bowel obstruction. Barium study also precisely demonstrate the level of obstruction.

D. Treatment 2

1. Fluid resuscitation

Patient with obstruction are usually come with variable degree of dehydration with depleted electrolyte . An isotonic solution like Ringer Lactate is best to give according to the degree of dehydration. Also urine output should be monitored with folley catheter. Additional potassium chloride in the infusion may be needed it depends on the electrolyte measurement.

2. Antibiotics

Broad spectrum antibiotics are given prophylactically based on reported findings that there is bacterial translocation in mechanical obstruction.

3. Decompression

Inserting of nasogastric tube act as decompression to emptying the stomach, reducing the risk of aspiration and decrease abdominal distention.

4. Operative management

Patient with obstructive adhesive band may be treated with lysis of adhesion. The operation must be so gentle handling to reduce serosal trauma and avoid the unnecessary dissection. If the obstruction is caused by incarterated hernia then reducing the herniated segment and closuring the defect is best to do.

By pass surgery may be done in patient with patient with tumor in small intestine. it is sometimes difficult to evaluate bowel viability. To resolve this problem, put the bowel into normal saline in about 20 minutes then reassess the bowel.  If the normal color is returned and peristaltic is evident it is save to retain the bowel. Radiation entheropathy,which caused by radiation therapy in malignancies, may also caused bowel obstruction. Radiation entheropathy is usually threated by conservative way, tube insertion and corticosteroid administration.

E. Ileus 2

Ileus is defined as intestinal distension and the slowing or absence in luminal content passage without any proven of mechanical obstruction.

Ileus post operative is also treated conservational. Tube insertion to decrease the abdominal distension and electrolyte correction. Pharmacologic use such as drugs inhibiting the sympathetic system or stimulate parasympathetic system have not been proven to be effective.


  1. Minocha, Anil. Small Bowel Obstruction. In : Handbook of Digestive Disease. Slack Incorported; Ney Jersey; p259-63. 2004
  2. Evers, B Mark. Small Intestine. in : Sabiston Textbook of Surgery The biological basis of modern surgical practice 18th edition. Saunders: Philadelphia; p1289-1297.
  3. Cahill, Ronald A. Redmont, H Paul. Cytokine Orchestration in Post Operative Peritoneal Obstruction Adhesion. In : J Gastroenterology 2008.14(31);p 4861-66
  4. Vural, Birol et al. The Role of Neutrophil in Formation of Peritoneal Adhesion. In : Human Reproduction 1999 14(1):p45-54
  5. Nobie, Brian A et al. Small bowel Obstruction. In Medscape Reference. Taken from :
  6. Hopkins, Christy. Large Bowel Obstruction. In Medscape reference. Taken from:
  7. Bullard, Kelly M et al. colon rectum and anus. In : Schwatrz’s Principle of Surgery 8th Edition. Mc Graw Hill:p1084-86. 2005
  8. Cagir, Burt et al. Intestinal Pseudo obstruction Surgery. In: Medscape reference. Taken from :
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