1. Small Bowel Obstruction
Professor. Abdulaziz AL Saigh
(FRCS, FACS)

2. Intestinal obstruction
Definition
Etiology
Pathogenesis
Diagnosis
Treatment of intestinal obstruction

3. definition
When gastrointestinal luminal content is pathologically prevented from passing distally

4. Epidemiology Most frequent surgical disorder of the small intestine
Etiologies according to their relationship to intestinal wall:
1. Intraluminal (e.g., foreign bodies, gallstones, or meconium)
2. Intramural (e.g., tumors, Crohn's disease–associated inflammatory strictures)
3. Extrinsic (e.g., adhesions, hernias, or carcinomatosis)
Stricture: an abnormal narrowing of a bodily passage (as from inflammation, cancer, or the formation of scar tissue) <esophageal stricture>; also : the narrowed part
Carcinomatosis: a condition in which multiple carcinomas develop simultaneously usually after dissemination from a primary source
Simultaneous: happening or done at the same time as sth else
Meconium : a dark greenish mass of desquamated cells, mucus, and bile that accumulates in the bowel of a fetus and is typically discharged shortly after birth

5. Etiology

6. Causes of intestinal obstruction
Dynamic
Intraluminal
Fecal impaction
Foreign body
Bezoars
Gall stones
Intramural
Stricture
malignancy
Extramural
Adhesions & bands
Hernias (internal – external)
Volvulous
Intussception
Adynamic
Paralytic ilus
Mesenteric vascular occlusion
Pseudo obstruction

7. Causes according to age
Neonates: congenital atresia, volvulus neonatorum, anorectal malformation, mechonium ileus and hirshsprung’s disease
Infant: ileocecal intussusception, hirschsprung’s disease and strangulated hernia
Adult: adhesions, strangulated hernia
Elderly: colon carcinoma, adhesion and strangulated hernia.

9. Pathogenesis Simple obstruction:
When the bowel occluded at a single point along the intestinal tract.
Closed loop obstruction:
When segment of bowel is closed in two points along its proximal & distal end & trap the mesentery.
Strangulation:
When blood supply to a closed loop segment of bowel becomes compromised leading to ischemia, necrosis and perforation.

10. Pathophysiology
In the onset, gas and fluid accumulate within the intestinal lumen proximal to the site of obstruction
Intestinal activity increases Colicky pain & Diahrrea
Where does the gas & fluid come from?
Bowel distends and intraluminal and intramural pressures rise
Impair of intestinal microvascular perfusion Ischemia
Necrosis
strangulated bowel obstruction

11. Continues partial small bowel obstruction
only a portion of the intestinal lumen is occluded
pathophysiologic events occur more slowly & strangulation is less likely
closed loop obstruction
accumulating gas and fluid cannot escape
Leading to a rapid rise in luminal pressure, and a rapid progression to strangulation

12. Closed Loop Obstruction
Closed loop obstruction is a specific type of obstruction in which two points along the course of a bowel are obstructed at a single location thus forming a closed loop. Usually this is due to adhesions, a twist of the mesentery or internal herniation. In the large bowel it is known as a volvulus. In the small bowel it is simply known as small bowel closed loop obstruction. Especially in the small bowel the risk of strangulation and bowel infarction is high with a mortality rate of 10-35%.

13. Diagnosis Focus on the following goals:
(a) distinguish mechanical obstruction from ileus
(b) determine the etiology of the obstruction
(c) discriminate partial from complete obstruction
(d) discriminate simple from strangulating obstruction
Ileus (paralytic ileus, adynamic ileus) is temporary absence of the normal contractile movements of the intestinal wall.
Abdominal surgery and drugs that interfere with the intestine's movements are a common cause.
Bloating, vomiting, constipation, cramps, and loss of appetite occur.
The diagnosis is made by x-ray.
People are given nothing to eat or drink, and a thin suction tube is passed through the nose into the stomach.

14. Clinical picture Cardinal symptoms
Pain, distension, vomiting, absolute constipation
The nature of the presentation will be influenced by the site
In 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
In low small intestinal obstruction, pain is predominant with central distension. Vomiting is delayed. Multiple central fluid levels are seen in radiography
In large bowel obstruction, distention is early and pronounced. Pain is mild and vomiting and dehydration are late. The proximal colon and caecum are distended on abdominal radiography

15. Clinical picture
The nature of the presentation will also be influenced by whether the obstruction is: Acute , Chronic, Acute on chronic, Sub acute.
Acute obstruction usually occurs in small bowel obstruction, with sudden onset of sever colicky central abdominal pain, distension and early vomiting and constipation.
Chronic obstruction is usually seen in large bowel obstruction, with lower abdominal colic and absolute constipation followed by distension.
Acute on chronic obstruction there is short history of distension and vomiting against a background of pain and constipation.
Sub acute obstruction implies an incomplete obstruction.
Presentation will be further influenced by whether the obstruction is
Simple: in which the blood supply is intact
Strangulating, strangulated.

16. History
Pain: crampy paroxysms 4-5 minute interval, less in distal obstruction, centered on the umbilicus in small bowel obstruction or lower abdominal in large bowel obstruction.
Sever persistent pain indicates strangulation.
Usually doesn't occur in paralytic ileus.
Nausia and vomiting: more common with a higher obstruction and may be the only symptoms in gastric outlet obstruction.
As obstruction progress the character of the vomitus alters from digested food to faeculent material, as a result of the presence of enteric bacterial overgrowth.

17. History
In the small bowel the degree of distension is dependent on the site of the obstruction and is greater the more distal the lesion. Visible peristalsis may be present. Distension is delayed in colonic obstruction and may be minimal or absent in the presence of mesenteric vascular occlusion.
Constipation may be classified as absolute (neither faeces nor flatus passed) or relative (where only flatus passed). Absolute conistipation is a cardinal feature of complete intestinal obstruction. Some patients may pass flatus or faeces after the onset of obstruction as a result of evacuation of the distal bowel content. No constipation in: Richter’s hernia, gall stone obstruction, mesenteric vascular occlusion, pelvic abscess, partial obstruction (faecal impaction – colonic neoplasm) in which diarrhea may often occur

18. Clinical picture On Examination General examination
Tachycardia, hypotension, demonstrating the severe dehydration that is present.
Fever suggests the possibility of strangulation.

19. Clinical picture Local abdominal examination
Inspection: distended abdomen, the degree of distension some what dependant on the level of obstruction.
Previous surgical scars should be noted. Early in the course of bowel obstruction, peristaltic waves can be observed, particularly in thin patients
Palpation: Mild abdominal tenderness may be present with or without a palpable mass; however localized tenderness, rebound and guarding suggest peritonitis and strangulation.
Incarcerated hernias should be rolled out in the groin, the femoral triangle and the obturaror foramin.
Percussion:
Auscultation: hyper active bowel sounds with audible rushes associated with vigorous peristalsis (borborygmi). Late in the obstructive course, minimal or no bowel sounds are noted.
Rectal examination: to assess intraluminal masses and to examine the stools for occult blood, which may be indication of malignancy, intussusception or infarction.

20. Strangulation
Classic picture of strangulation include tachycardia, fever, leukocytosis and a constant non cramping abdominal pain. Tenderness with rigidity, shock with the cardinal signs of intestinal obstruction.
In cases of intestinal obstruction in which pain persists despite conservative management, even in absence of the above signs, strangulation should be considered.
When strangulation occurs in an external hernia, the lump is tense, tender and irreducible, there is no impulse on cough and it has recently increased in size.

21. Strangulation pathology
The venous return is compromised before the arterial supply. The resultant increase in capillary pressure leads to local mural distension with loss of intravascular fluid and red blood cells intramurally and extraluminally.
Once the arterial supply is impaired, haemorrhagic infarction occurs. As the viability of the bowel is compromised there is marked translocation and systemic exposure to anaerobic organisms with their toxins.
The morbidity of intra-peritonial strangulation is far greater than with an external hernia, which has a smaller absorptive surface.

22. Causes of strangulation
External: hernial orifices.. Adhesions and bands
Interrupted blood flow: volvulus, intussusceptions
Increased intraluminal pressure: closed loop obstruction
Primary: mesenteric infarction

23. Closed loop obstruction
This occurs when the bowel is obstructed at both the proximal and distal points.
It is present in many cases of intestinal strangulation. Unlike cases of non strangulating obstruction, there is no early distension of the proximal intestine. When gangrene of the strangulated segment is imminent, retrograde thrombosis of the mesenteric veins result in distension on both sides of the strangulated segment.
A classic form of closed loop obstruction is seen in the presence of a malignant stricture of the right colon with a competent ileocaecal valve. The inability of the distended colon to decompress itself into the small bowel results in an increase in luminal pressure, which is greatest at the caecum, with subsequent impairment of blood supply. Unrelieved, this results in necrosis and perforation

24. Investigations Plain x- ray of abdomen: erect and supine
The obstructed small bowel is characterized by straight segments that are generally central and lie transversally. No gas is seen in the colon.
The jejunum is characterized by its valvulae conniventes, which giving a concertina or ladder effect.
Ileum: the distal ileum has been described as featureless.
Caecum: a distended caecum is shown by a rounded gas shadow in the right iliac fossa.
Large bowel, except the caecum is shows haustrel folds, which, unlike valvulae conniventes are spaced irregularly, do not cross the whole diameter of the bowel and do not have indentations placed opposite one another
Blood urea nitrogen and electrolytes
Blood picture
Ultrasonography
CT scan
Endoscopy

25. Radiographic Examination
Abdominal series in X-ray:
(1) Abdomen Supine,
(2) Abdomen Upright,
(3) Chest Upright.
most specific triad for small bowel obstruction:
dilated small bowel loops (>3 cm in diameter)
air-fluid levels
a paucity of air in the colon
Specificity of plain Radiography is low (ileus and colonic obstruction)
False-negative (proximal of small intestine OR filled with fluid but no gas)
Paucity : a small amount of sth; less than enough of sth

29. CT-Scan a 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
Closed-loop obstruction
U-shaped or C-shaped dilated bowel loop
mesenteric vessels converging toward a torsion point
Strangulation (thickening of the bowel wall, pneumatosis intestinalis)
Discrete : independent of other things of the same type SYN separate

30. Small bowel obstruction
Small bowel obstruction. A computed tomographic scan of a patient presenting with signs and symptoms of bowel obstruction. Image shows grossly dilated loops of small bowel, with decompressed terminal ileum (I) and ascending colon (C), suggesting a complete distal small bowel obstruction. At laparotomy, adhesive bands from a previous surgery were identified and divided.

31. Intestinal pneumatosis
Intestinal pneumatosis. This computed tomographic scan shows intestinal pneumatosis (arrow). The cause of this radiologic finding was intestinal ischemia. Patient was taken emergently to the operating room and underwent resection of an infarcted segment of small bowel.

32. The CT-presentation of a closed loop obstruction in the small bowel depends on two things:
length of the bowel segment that forms the closed loop
orientation of the loop in relation to the imaging plane
If we have a short closed loop oriented within the plane of imaging, we will see a U- or C-shaped loop of bowel.

33. Another important appearance of a closed loop obstruction is that of a radial array of dilated small bowel loops with the mesenteric vessels converging to a central point. This is almost always due to a small bowel volvulus.

34. If the closed loop is longer and is oriented perpendicular to the plane of section, we will see a clump of bowel loops as shown in the case on the left. Sometimes this is difficult to appreciate on just the axial images and coronal or sagittal reconstructions can be helpful. In this case there is also mesenteric edema and localised ascites in combination with dilated loops with wall thickening indicating strangulation and risk of infarction.

35. Treatment
The treatment is urgent relief of obstruction after preparation
Preoperative preparation (fluid and electrolyte replacement, antibiotics and tube decompression)
Operation: exploration
Immediate operation indicated in peritonitis, incarcerated hernia, suspected or confirmed strangulation, sigmoid volvoulus with systemic toxicity or peritoneal irritation, small bowel volvulus, colonic volvoulus above sigmoid.
Conservative (with exeption)
Indication : adhesive. Ileocaecal intussusception. Sigmoid volvoulus. Feacal impaction.
Reassess patient every 4 hours. Look for change in pain, abdominal findings, and volume and character of nasogastric aspirate. Repeat abdominal x- ray, and look for change in gas distribution, and free intraperitoneal air.
Classify patient’s condition as improved, unchanged or worse.
Decide whether operative treatment is necessary and if so, whether it should be done on urgent or elective basis.
Urgent operation: indications include: lack of response to 24 – 48 hrs. of nonoperative therapy (increasing abdominal pain, distension or tenderness; NG aspirate changing from nonfeculent to feculent.

36. Treatment Fluid resuscitation and antibiotics
Patients with intestinal obstruction are usually dehydrated and depleted of sodium, chloride, and potassium, requiring aggressive intravenous replacement with an isotonic saline solution such as lactated ringer’s
Urine output: should be monitored by the placement of foley’s catheter.
After the patient has formed adequate urine, potassium chloride should be added to the infusion if needed. Serial electrolyte measurements, as well as hematocrit and white blood cell count are performed to assess the adequacy of fluid repletion.
Central venous line: may be needed especially in elderly as the patient may require large amount of fluid
Broad spectrum antibiotics: are given prophylactically by some surgeons based on the reported findings of bacterial translocation, and as preoperative preparation.

37. Treatment Tube decompression and follow up
Nasogastric suction empty the stomach, reducing the risk of pulmonary aspiration and reduce further intestinal distension
Simple intestinal obstruction can be treated conservatively with resuscitation and nasogastric tube suction, resolution of symptoms and discharge without surgery have been reported in 60% to 85% of patients with an adhesive simple intestinal obstruction.
Initial conservative treatment for simple intestinal obstruction with close observation in case of clinical deterioration of the patient or increasing distension on repeated radiographes require operative intervention.

39. Operative managment Incarcerated hernia: reduction and repair
Mid line exploration: (under general anesthesia)
Release of adhesions or fibrous band
Untwisting volvulus (viable bowel)
Resection anastomosis (gangrenous bowel, intestinal tumor or pathological stricture)
Reduction of Intussusception
Proximal ileostomy or colostomy.

40. Operative management Define the obstructed point operatively:
Follow the distended bowel distally till find the collapsed intestine and define the lesion.
Determine bowel viability:
By color, motility and arterial pulsations if viability is questionable the bowel segment released and covered by sponge soaked with normal saline for 15 to 20 min. then revaluate

41. Enterotomy and extraction of the stone.
Septic peritonitis
ileostomy
Intestinal anastomosis

42. Intussusception

43. Adynamic Paralytic ileus Mesenteric vascular occlusion
Pseudo intestinal obstruction

44. Paralytic ileus Causes of ileus Post laparotomy
Metabolic and electrolyte derangements: hypokalemia, hyponatremia, hypomagnesaemia, uremia, diabetic coma
Drugs: opiates, psychotropic agents, anti cholinergic agents
Intra abdominal inflammation & sepsis
Retroperitoneal hemorrhage or sepsis
Intestinal ischemia
Systemic sepsis

45. Paralytic ileus Treatment:
Abdominal distension without colicky pain, may be nausea and vomiting
Plain X ray: distended small and large bowel
Treatment:
Supportive with nasogastric suction and intravenous fluid
Correct the underlying condition, treatment of sepsis, correct metabolic or electrolyte abnormalities, stop drugs that produce ileus
Colonoscopy to decompress the colon.

46. Mesenteric ischemia Mesenteric vascular disease classified as:
Acute (with or without occlusion)
Venous
Chronic arterial
Sources of embolisation: left atrium in fibrillation, mural myocardial infarction, atheromatous plaque from an aortic aneurysm and mitral valve vegetation.
Primary arterial thrombosis: in atherosclerosis and thromboangitis obliterans.
Venous thrombosis: portal hypertension, portal pyaemia and sickle cell disease.

47. Mesenteric ischemia Pathology: Clinical picture: Investigation:
hemorrhagic infarction, the intestine and it’s mesentery become swollen and edematous, blood stained fluid exudes into the peritoneal cavity and bowel lumen.
Clinical picture:
Sudden onset of sever abdominal pain in patient with atrial fibrillation or atherosclerosis. The pain is central
Persistent vomiting, bleeding per rectum (altered blood)
Hypovolemic shock.
Investigation:
Profound neutrophil leucocytosis
Plain X ray thickened small intestine with no gas.
Angiography

48. Mesenteric ischemia Treatment: Full resuscitation Embolectomy
Revascularization in early embolic cases
Resection of all affected bowel, early post operative anti coagulation
In massive resection, patient may need intravenous alimentation or consider small bowel transplantation.

49. Pseudo obstruction Factors associated with pseudo obstruction
Idiopathic
Metabolic: diabetes, intermittent porphyria, acute hypokalaemia, uremia, myxodema
Sever trauma: especially to lumber spine and pelvis
Shock
Burns
Myocardial infarction
Stroke
Septicemia
Retroperitoneal irritation by: blood, urine, enzymes (pancreatitis), tumors.
Drugs: tricyclic antidepressants, phenothiazines, laxatives

50. Therapy marked depletion of intravascular volume decreased
oral intake, vomiting, and sequestration of fluid in bowel lumen and wall
IV fluid and bladder catheter(urine output)
Broad-spectrum antibiotics
NG tube (decreases nausea, distention, and the risk of vomiting & aspiration)
Integral : being an essential part of sth

52. Thank you