Intestinal Obstruction

Intestinal Obstruction

1. INTESTINAL OBSTRUCTION Dr. Raju Khatiwada Resident General surgery KISTMCTH

2. CONTENTS I ntroduction C lassification Pathophysiology Mechanical obstruction types Diagnostic evaluation Treatment

3. INTRODUCTION Bowel obstruction occurs when the normal flow of intraluminal contents is interrupted . The small bowel is involved in approximately 80 percent of cases of mechanical intestinal obstruction 1

4. CLASSIFICATION Intestinal obstruction may be classified into two types: Dynamic: in which peristalsis is working against a mechanical obstruction. It may occur in an acute or a chronic form Adynamic: in which there is no mechanical obstruction; peristalsis is absent or inadequate (e.g. paralytic ileus or pseudo-obstruction ).

5. CLASSIFICATION C linically classified into: Small bowel obstruction Large bowel obstruction According to the presentation Incomplete/partial/ subacute complete

6. CAUSES OF INTESTINAL OBSTRUCTION Bailey and love textbook of surgery, 27th edition

7. SMALL BOWEL OBSTRUCTION Acute mechanical small bowel obstruction is a common surgical emergency. It accounts for 2 to 4 percent of emergency department visits, approximately 15 percent of hospital admissions, and 20 percent of emergency surgical operations for abdominal pain 2

8. CAUSES OF MECHANICAL SMALL BOWEL OBSTRUCTION

9. Lesions Extrinsic to the Intestinal Wall: Lesion intrinsic to the intestinal wall: Intraluminal., obtrurator obstruction Adhesion Hernia: external/internal hernia Neoplastic Intraabdominal abscess Congenital: malrotation, duplications, cysts Inflammatory: crohn’s disease, tuberculosis, diverticulitis Neoplastic: primary/ metastatic Traumatic: hematoma, ischemic stricture Miscellaneous: intussusception, endometriosis Gallstone Enterolith Bezoar Foreign body

10. LARGE BOWEL OBSTRUCTION Defined as bowel obstruction distal to the ileocecal valve, can occur as a result of a variety of etiologies. Broadly, it is classified into mechanical (dynamic) obstruction and functional (adynamic or pseudoobstruction). Mechanical obstruction can be further characterized into endoluminal, mural, and extraluminal causes The most common etiology of mechanical obstruction in the United States is colorectal cancer (CRC), whereas colonic volvulus is more common in Russia, Eastern Europe, Africa, the Middle East, and India

11. CAUSES OF MECHANICAL LARGE BOWEL OBSTRUCTION

12. INTRALUMINAL MURAL EXTRALUMINAL FUNCTIONAL Intrinsic mass-neoplasm Foreign body Bezoar Fecal impaction Diverticular stricture Crohn disease stricture Ischemic stricture Radiation stricture Infectious (i.e., lymphogranuloma venereum , tuberculosis, schistosomiasis ) Hirschsprung disease Sigmoid volvulus Cecal volvulus Hernia (inguinal, ventral, internal) Metastatic/ intraabdominal tumor Abdominal abscess Retroperitoneal fibrosis Adhesions (rare in large bowel) Colonic pseudo-obstruction (Ogilvie) Toxic megacolon Paralytic ileus

13. PATHOPHYSIOLOGY Dilatation proximal to obstruction. Hyper-peristalsis F laccidity and paralysis. The distension proximal to an obstruction is caused by gas and fluids.

14. MECHANICAL OBSTRUCTION SIMPLE: When bowel loop is occluded at one level. CLOSED-LOOP STRANGULATION

15. CLOSED-LOOP OBSTRUCTION This occurs when the bowel is obstructed at both the proximal and distal points. A classic form of closed-loop obstruction is seen in the presence of a malignant stricture of the colon with a competent ileocaecal valve (present in up to one-third of individuals).

16. STRANGULATION This is the end result op close-loop obstruction when major artery supply is occluded, causing gangrene over the obstructed area. The morbidity and mortality associated with strangulation are largely dependent on the duration of the ischaemia and its extent .

17. SPECIAL TYPES OF MECHANICAL INTESTINAL OBSTRUCTION Internal hernia Obstruction from enteric fistula Bolus obstruction: Gallstone, food, trychobezoars, stercoliths and worms

18. Obstruction by adhesions and bands ADHESION: The lifetime risk of requiring an admission to hospital for adhesional small bowel obstruction subsequent to abdominal surgery is around 4% and the risk of requiring a laparotomy around 2 % Adhesions start to form within hours of abdominal surgery. Currently, no single agent or combination of agents has been convincingly shown to be effective Adhesions are a frequent cause of closed-loop obstruction Adhesive small bowel obstruction occurs in the absence of prior abdominal surgery in 3 to 9 percent of patients 3

19. The common causes of intra-abdominal adhesions. Acute inflammation: Sites of anastomoses, reperitonealisation of raw areas , trauma, ischaemia Foreign material: Talc , starch, gauze, silk Infection: Peritonitis, tuberculosis Chronic inflammatory conditions: Crohn’s disease Radiation enteritis

20. Prevention of adhesions Factors that may limit adhesion formation include: Good surgical technique Washing of the peritoneal cavity with saline to remove clots Minimising contact with gauze Covering anastomosis and raw peritoneal surface

21. Obstruction by Bands Bands Usually only one band is culpable. This may be: congenital , e.g. obliterated vitellointestinal duct; a string band following previous bacterial peritonitis; a portion of greater omentum, usually adherent to the parietes

22. Diagnosis The diagnostic evaluation should focus on the following goals: distinguish mechanical obstruction from ileus, determine the etiology of the obstruction, discriminate partial from complete obstruction, and discriminate simple from strangulating obstruction.

23. CLINICAL FEATURES OF INTESTINAL OBSTRUCTION The diagnosis of dynamic intestinal obstruction is based on the classic quartet of: Pain Distension vomiting and absolute constipation

24. Clinical features Small bowel obstruction Large bowel obstruction Pain Colicky/cramping Periumbilical with paroxysms of pain occurring every four or five minutes Colicky/cramping Infraumbilical with paroxysms of pain occurring every 20 to 30 minutes Nausea/Vomiting Proximal small bowel obstruction (duodenum, proximal jejunum) can cause severe nausea and vomiting Initially clear, becomes discolored and finally feculent (dark and foul smelling) Delayed or absent

25. Clinical features Small bowel obstruction Large bowel obstruction Distension In the small bowel the degree of distension is dependent on the site of the obstruction and is greater the more distal the lesion. Distension is a later feature in colonic obstruction and may be minimal or absent in the presence of mesenteric vascular occlusion Obstipation May be classified as absolute (i.e. neither faeces nor flatus is passed) or relative (where only flatus is passed). Same as SBO The administration of enemas should be avoided in cases of suspected obstruction. Dehydration More common

26. Physical examinations findings A hallmark of small bowel obstruction is dehydration, which manifests as tachycardia, orthostatic hypotension, reduced urine output, and, if severe, dry mucus membranes . A bdominal distension is the most frequent physical finding on clinical examination, occurring in 56 to 65 percent of patients 4

27. Abdominal tenderness Localised tenderness indicates impending or established ischaemia. The development of peritonism or peritonitis indicates overt infarction and/or perforation. In cases of large bowel obstruction , it is important to elicit these findings in the right iliac fossa as the caecum is most vulnerable to ischaemia.

28. Bowel sounds Hyperactive bowel sounds with audible rushes associated with vigorous peristalsis (borborygmi). Late in the obstructive course, minimal or no bowel sounds are noted. Normal bowel sounds are of negative predictive value Digital rectal examination: S hould be performed to identify fecal impaction or rectal mass as the source of obstruction. Gross or occult blood may be related to intestinal tumor, ischemia, inflammatory mucosal injury, or intussusception.

29. Clinical features In addition to the features above, it should be noted that: The presence of shock suggests underlying ischaemia, especially if the shock is resistant to simple fluid resuscitation . In impending or established strangulation, pain is never completely absent Generalised tenderness and the presence of rigidity indicate the need for early laparotomy

30. INVESTIGATIONS Laboratory tests are usually not helpful in the actual diagnosis of patients with small bowel obstruction but are extremely important in assessing the degree of dehydration Elevated lactic acid levels suggest intestinal ischemia or necrosis .

31. IMAGING The diagnosis of small bowel obstruction is usually confirmed with radiographic examination. The abdominal series consists of Abdominal X-ray in supine and upright position Chest X-ray in upright position

32. X-ray findings X-ray findings in small bowel obstruction are triad of dilated small bowel loops (>3 cm in diameter), air-fluid levels seen on upright films, and a paucity of air in the colon. The sensitivity of abdominal radiographs in the detection of small bowel obstruction ranges from 70% to 80%. Specificity is low.

33. X-ray Other findings in x-ray are: Step ladder pattern valvulae conniventes String of pearl sign Stretch/slit sign Absence of rectal gas Air fluid levels longer than 2.5 cm ( Upright or Left Lateral Decubitus)

34. X-ray findings in Large bowel obstruction Dilated colon ( Dilatation of the caecum >9cm, and >6cm for the rest of the colon is considered abnormal ) Colon cut-off sign No free gas Coffee-bean sign- volvulus Thumb print sign- intussusception

35. CT scan findings CT is 80% to 90% sensitive and 70% to 90% specific in the detection of small bowel obstruction. CT findings in small bowel obstruction are: discrete transition zone with dilation of bowel proximally decompression of bowel distally, intraluminal contrast that does not pass beyond the transition zone, and a colon containing little gas or fluid dilated bowel loop of more than 2.5 cm is very concerning for high-grade small bowel obstruction .

36. CT in closed-loop obstruction Closed-loop obstruction is suggested by the presence of a U-shaped or C-shaped dilated bowel loop associated with a radial distribution of mesenteric vessels converging toward a torsion point . A limitation of CT scanning is its low sensitivity (<50%) in the detection of low-grade or partial small bowel obstruction.

37. CT scan in Strangulation Key points in the diagnosis of strangulation in CT scan: Reduced bowel wall enhancement on CT increases the probability of strangulation 11-fold . Absence of mesenteric fluid on CT decreases the probability of strangulation 6-fold. The clinical reliability of other CT signs is doubtful for predicting strangulation.

38. Other imaging modalities Barium radiography Small bowel follow through Enteroclysis MRI USG water-soluble contrast agent (WSCA) in adhesive small bowel obstruction (SBO )

39. USG Dilated small bowel loops greater than 2.5 cm in diameter is suggestive of small bowel obstruction. Ultrasound has 90% sensitivity and 96% specificity in diagnosing small bowel obstruction  Look for large bowel obstruction is as good as CT. However, CT scan is better at finding the cause of the obstruction  Khurana B, Ledbetter S, McTavish J, Wiesner W, Ros PR. Bowel obstruction revealed by multidetector CT. AJR Am J Roentgenol . 2002 May;178(5):1139-44. doi : 10.2214/ajr.178.5.1781139. PMID : 11959718.

40. Fourteen prospective studies were included. The appearance of contrast in the colon within 4-24 h after administration had a sensitivity of 96 per cent and specificity of 98 per cent in predicting resolution of SBO. If contrast does not reach the colon, surgery is required in about 90% of patients. WSCA administration was effective in reducing the need for surgery (OR 0.62; P = 0.007) and shortening hospital stay (WMD -1.87 days; P < 0.001) compared with conventional treatment.

41. TREATMENT Fluid and electrolyte replacement (resuscitation) Gastrointestinal drainage via a nasogastric tube Antibiotics Contrast challenge Surgical treatment is necessary for most cases of intestinal obstruction but should be delayed until resuscitation is complete , provided there is no sign of strangulation or evidence of closed-loop obstruction

42. Operative management Indications for early surgical intervention Obstructed external hernia Clinical features suspicious of intestinal strangulation Obstruction in a ‘virgin’ abdomen

43. Operative management Principles of surgical intervention for obstruction Management of: The segment at the site of obstruction The distended proximal bowel The underlying cause of obstruction

44. Operative management The operative procedure performed for small bowel obstruction according to the etiology of the obstruction. For example, adhesions are lysed, tumors are resected, and hernias are reduced and repaired. Regardless of the etiology, the affected intestine should be examined, and nonviable bowel should be resected.

45. OUTCOMES The perioperative mortality rate associated with surgery for nonstrangulating small bowel obstruction is less than 5 % Many patients who are treated conservatively for adhesive small bowel obstruction do not require future readmissions; less than 20 % patients who had undergone surgical intervention for adhesive small bowel obstruction, the risk of recurrent obstruction are 5.5% at 1 year, 11.3% at 3 years, and 13.5% at 5 years.

46. REFERENCES Drożdż W, Budzyński P. Change in mechanical bowel obstruction demographic and etiological patterns during the past century: observations from one health care institution. Arch Surg. 2012 Feb;147(2):175-80. doi : 10.1001/archsurg.2011.970. PMID : 22351915 . Cappell MS, Batke M. Mechanical obstruction of the small bowel and colon. Med Clin North Am. 2008 May;92(3):575-97, viii. doi : 10.1016/j.mcna.2008.01.003. PMID : 18387377 . Beardsley C, Furtado R, et al. Small bowel obstruction in the virgin abdomen: the need for a mandatory laparotomy explored. Am J Surg. 2014 Aug;208(2):243-8. doi : 10.1016/j.amjsurg.2013.09.034. Epub 2014 Jan 23. PMID : 24565365 . Markogiannakis H, Messaris E, et al,Acute mechanical bowel obstruction: clinical presentation, etiology, management and outcome. World J Gastroenterol . 2007 Jan 21;13(3):432-7. doi : 10.3748/wjg.v13.i3.432. PMID : 17230614; PMCID : PMC4065900.

47. REFERENCES Bailey and love textbook of surgery, 27th edition Sabiston’s textbook of surgery-21 st Edition Schwartz textbook of surgery, 11th edition. Uptodate

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