Small Bowel Obstruction
By:
Dr. Yasser El Basatiny
Prof. of Laparoscopic Surgery
Intestinal obstruction
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Definition
Etiology
Pathogenesis
Diagnosis
Treatment of intestinal obstruction
definition
• When gastrointestinal luminal content is
pathologically prevented from passing distally
Etiology
Causes of intestinal obstruction
Dynamic
Adynamic
• Intraluminal
Paralytic ilus
Mesenteric vascular occlusion
Pseudo obstruction
Fecal impaction
Foreign body
Bezoars
Gall stones
• Intramural
Stricture
malignancy
• Extramural
Adhesions & bands
Hernias (internal – external)
Volvulous
Intussception
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.
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.
Pathophysiology
• Early in the course of an obstruction, intestinal
motility and contractile activity increase in an effort
to propel luminal contents past the obstructing
point. Later in the course of obstruction, the
intestine becomes fatigued and dilates, with
contractions becoming less frequent and less
intense
• As the bowel dilates, water and electrolytes
accumulate both intraluminally and in the bowel
wall itself. This massive third space fluid loss
accounts for dehydration and hypovolemia.
pathophysiology
• The metabolic effects of fluid loss depend on the site
and duration of the obstruction. With a proximal
obstruction, dehydration may be accompanied by
hypochloremia, hypokalemia, and metabolic alkalosis
associated with increased vomiting. Distal obstruction of
the small bowel may result in large quantities of
intestinal fluid into the bowel; however, abnormalities in
serum electrolytes are usually less dramatic.
• Oliguria, azotemia, and hemoconcentration can
accompany the dehydration. Hypotension and shock can
ensue. Other consequences of bowel obstruction include
increased intra abdominal pressure, decreased venous
return, and elevation of the diaphragm, compromising
ventilation. These factors can serve to further potentiate
the effect of hypovolemia.
pathophysiology
• As the intraluminal pressure increases in the bowel, a
decrease in mucosal blood flow can occur. These alterations
are particularly noted in patients with a closed loop
obstruction in which greater intraluminal pressure are
attained.
• A closed loop obstruction, (produced commonly by a twist
of the bowel) can progress to arterial occlusion and
ischemia if left untreated and may potentially lead to bowel
perforation and peritonitis.
• Bacteria translocating to mesenteric lymph nodes and even
systemic organs. However, the overall importance of this
bacterial translocation on the clinical course has not been
entirely defined.
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
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.
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.
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
Clinical picture
• On Examination
• General examination
Tachycardia, hypotension, demonstrating the
severe dehydration that is present.
Fever suggests the possibility of strangulation.
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.
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.
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.
Causes of strangulation
• External: hernial orifices.. Adhesions and
bands
• Interrupted blood flow: volvulus,
intussusceptions
• Increased intraluminal pressure: closed loop
obstruction
• Primary: mesenteric infarction
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
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
Small bowel obstruction
Multiple dilated small bowel
loops are seen (white
arrowheads).
There is fecal material in the
right and left colon (arrows).
Air is seen in the rectum.
The surgical staples indicate
recent abdominal surgery
(black arrowheads).
Erect plain X-ray
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.
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.
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.
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.
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
Enterotomy and extraction of the stone.
Septic peritonitis
ileostomy
Intestinal anastomosis
Intussusception
Adynamic
• Paralytic ileus
• Mesenteric vascular occlusion
• Pseudo intestinal obstruction
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
Paralytic ileus
• 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.
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.
Mesenteric ischemia
Pathology:
• 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
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.
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
Thank you