This document provides an overview of small intestinal obstruction. It begins by defining small intestinal obstruction as a blockage of the small intestine. It then discusses the epidemiology, pathophysiology, signs and symptoms, causes, complications, diagnosis and treatment of small intestinal obstruction. The main points are that adhesion and hernia are the most common causes, and treatment involves correcting fluid and electrolyte imbalances, nasogastric decompression, antibiotics and potentially surgery for cases of strangulation or complete blockage. The document provides details on evaluating and managing both mechanical and paralytic forms of small intestinal obstruction.

1. INTESTINAL
OBSTRUCTION OF SMALL
INTESTINE
BY
DR.AKINBI OLUBAYODE.O

2.  Introduction
 Definition
 Epidemiology
 Pathophysiology
 Signs and Symptoms
 Etiology
 Complications
 Diagnosis
 Treatment

3. The small intestine or small bowel is the part of the
gastrointestinal tract between the stomach and the
large intestine, and is where much of the digestion
and absorption of food takes place. The small
intestine has three distinct regions – the
duodenum, jejunum, and ileum. The primary
function of the small intestine is the absorption of
nutrients and minerals from food.

4. Small Intestinal obstruction occurs when there is a
blockage of the small intestine i.e. a blockage in the
duodenum, jejunum or ileum.
When an obstruction occurs, ingested food, liquids
and digestive secretions accumulate above the
blockage, the bowel section involved in the
blockage becomes distended and the segment can
collapse. The normal functions of the bowel wall
are compromised and the distended section gets
progressively worse. The blockage may be partial
or complete.

6.  20% of patients admitted for acute abdomen
have an intestinal obstruction. Small bowel
obstruction is responsible for 80% of these
cases.
 Adhesion and hernia are the most common
causes of small bowel obstruction.

7.  Small-bowel obstruction (SBO) leads to
proximal dilatation of the intestine due to
accumulation of GI secretions and swallowed
air. This bowel dilatation stimulates cell
secretory activity, resulting in more fluid
accumulation.
 This leads to increased peristalsis above and
below the obstruction, with frequent loose
stools and flatus early in its course.

8.  Vomiting occurs if the level of obstruction is
proximal. Increasing small-bowel distention
leads to increased intraluminal pressures.
 This can cause compression of mucosal
lymphatics, leading to bowel wall
lymphedema. With even higher intraluminal
hydrostatic pressures, increased hydrostatic
pressure in the capillary beds results in
massive third spacing of fluid, electrolytes, and
proteins into the intestinal lumen.
 The fluid loss and dehydration that ensue may
be severe and contribute to increased
morbidity and mortality.

9.  Strangulated SBOs are most commonly
associated with adhesions and occur when a
loop of distended bowel twists on its
mesenteric pedicle.
 The arterial occlusion leads to bowel ischemia
and necrosis. If left untreated, this progresses
to perforation, peritonitis, and death.
 Bacteria in the gut proliferate proximal to the
obstruction. Microvascular changes in the
bowel wall allow translocation to the
mesenteric lymph nodes.
 This is associated with an increase in the
incidence of bacteremia due to Escherichia coli,
but the clinical significance is unclear.

10. Intestinal obstructions are either the result of
something blocking part of the intestine and its
associated with abdominal pain (mechanical) or
due to paralysis of intestinal musculature, there is
absence of pain(paralytic ileus).
Mechanical obstruction of Small intestine:
 Intestinal adhesions — bands of fibrous tissue
in the abdominal cavity that can form after
abdominal or pelvic surgery
 Hernias — portions of intestine that protrude
into another part of your body

11.  Tumors in the small intestine
 Inflammatory bowel diseases, such as Crohn's
disease
 Twisting of the intestine (volvulus)
 Telescoping of the intestine (intussusception)

12. Etiology
Paralytic ileus
Paralytic ileus can cause signs and symptoms of
intestinal obstruction, but doesn't involve a
physical blockage. In paralytic ileus, muscle or
nerve problems disrupt the normal coordinated
muscle contractions of the intestines, slowing or
stopping the movement of food and fluid through
the digestive system.

13. Paralytic ileus can affect any part of the intestine.
Causes can include:
 Abdominal surgery
 Pelvic surgery
 Infection
 Certain medications, including antidepressants
and pain medications that affect muscles and
nerves
 Muscle and nerve disorders, such as
Parkinson's disease

14.  Crampy abdominal pain that comes and goes
 Nausea
 Vomiting - Associated more with proximal
obstructions
 Diarrhea - An early finding
 Constipation - A late finding, as evidenced by
the absence of flatus or bowel movements
 Fever and tachycardia - Occur late and may be
associated with strangulation
 Severe bloating
 Decreased appetite

15. Untreated, intestinal obstruction can cause serious,
life-threatening complications, including:
 Tissue death: Intestinal obstruction can cut off
the blood supply to part of your intestine. Lack
of blood causes the intestinal wall to die. Tissue
death can result in a tear (perforation) in the
intestinal wall, which can lead to infection.
 Infection: Peritonitis is the medical term for
infection in the abdominal cavity. It's a life-
threatening condition that requires immediate
medical and often surgical attention.

16.  Dehydration
 Electrolyte and Metabolic imbalance
a) Hypokalemia
b) Hypernatremia
c) Alkalosis and Acidosis
 Septicaemia
 Respiratory failure, respiratory acidosis from
distension of the abdomen
 Shock
a) Hypovolemic: loss of ECF and or sequestration
of blood
b) Endotoxic

17. The following are adjunctive lab tests used in the
evaluation of SBO:
 Serum chemistries
 Blood urea nitrogen (BUN) level
 Creatinine
 Complete blood count (CBC)
 Lactate dehydrogenase tests
 Urinalysis
 Type and crossmatch

18.  Abdominal CT scan
 Abdominal x-ray
 Barium enema
 Abdominal Ultrasound

19. Although urgent relief of the obstruction is the ultimate
aim, the general condition of the patient must first be
improved by correcting fluid and electrolyte deficiencies
and starting antimicrobial treatment.
1. GENERAL MEASURES
a) Correction of fluid, electrolyte and metabolic
imbalance: fluid and electrolyte deficiencies must be
corrected by the administration of Ringers lactate or
dextrose/saline and dextrose water. Potassium chloride
is added when urine output is greater than 30ml/h.
Pulse and blood pressure are checked quarter-hourly
and urine output hourly.

20. b) Antiemetic's: Used in treatment of nausea and
vomiting e.g Promethazine (Phenergan, Phenadoz,
Promethegan), Ondansetron (Zofran, Zuplenz)
c).Nasogastric decompression: Gastric aspirant
must be done to remove swallowed air and
intestinal contents which regurgitate into the
stomach. It also prevents aspiration into the
trachea and bronchi during induction of
anaesthesia.
d). Sedation: morphine 10-15mg or pethidine
100mg should be given to relieve pain.
e). Antibiotics to combat infection: Growth and
spread of bacteria should be prevented with broad
spectrum antibiotics such as gentamicin with
clindamycin or cefuroxime and metronidazole.

21. Nonoperative treatment for several types of SBO are as
follows:
 Malignant tumor - Obstruction by tumor is usually
caused by metastasis; initial treatment should be
nonoperative (surgical resection is recommended
when feasible)
 Inflammatory bowel disease - To reduce the
inflammatory process, treatment generally is
nonoperative in combination with high-dose
steroids; consider parenteral treatment for
prolonged periods of bowel rest, and undertake
surgical treatment, bowel resection, and/or
stricturoplasty if nonoperative treatment fails.

22.  Intra-abdominal abscess - CT scan ̶ guided
drainage is usually sufficient to relieve
obstruction
 Radiation enteritis - If obstruction follows
radiation therapy acutely, nonoperative
treatment accompanied by steroids is usually
sufficient; if the obstruction is a chronic sequela
of radiation therapy, surgical treatment is
indicated
 Incarcerated hernia - Initially use manual
reduction and observation; advise elective
hernia repair as soon as possible after reduction

23.  Acute postoperative obstruction - This is difficult
to diagnose, because symptoms often are
attributed to incisional pain and postoperative
ileus; treatment should be nonoperative
 Adhesions - Decreasing intraoperative trauma to
the peritoneal surfaces can prevent adhesion
formation
Surgical care
 A strangulated obstruction is a surgical
emergency. In patients with a complete small-
bowel obstruction (SBO), the risk of strangulation
is high and early surgical intervention is
warranted. Laparoscopy has been shown to be safe
and effective in selected cases of SBO

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