Download Small bowel obstruction &post operative ileus

Small bowel obstruction
&post operative ileus
Definition:
mechanical or functional obstruction of the
intestines, preventing the normal transit of
the products of digestion.
It is a medical emergency. Although many
cases are not treated surgically, it is a
surgical problem.
Frequency:
Approximately 20% of patients admitted to
the hospital with an acute abdomen have
an intestinal obstruction
(most common surgical disorder of small
bowel)).
partial or complete, simple (ie, nonstrangulated) or strangulated.
Strangulated obstructions (40%) are surgical emergencies which
needsproper Dx and Rx..
If not diagnosed and properly treated, vascular compromise leads to
bowel ischemia and further morbidity and mortality.
Simple obstruction occludes the lumen only.(usually at one point).
Strangulated obstruction impairs the blood supply and also leads to
necrosis of the intestinal wall.
Closed loop obstruction the lumen is occluded in at least 2
places(eg, in volvolus), is commonly ass. With strangulation
Mortality/Morbidity
Mortality and morbidity are dependent on the etiology, the early
recognition and correct diagnosis of obstruction.
If untreated, strangulated obstructions cause death in 100% of
patients.
If surgery is performed within 36 hours, the mortality rate decreases
to 8%.
The mortality rate is 25% if the surgery is postponed beyond 36
hours in these patients.
Aetiology:
can be classified into 3 main groups
'extraluminal' extrinsic (eg, adhesions, hernias, volvulus)
intramural lesions in the bowel wall (eg, Crohn disease ,
tuberculosis, primary and secondary neoplasia, potassium
strictures, radiation strictures, complications of surgical
anastomosis)
Intraluminal (eg, foreign bodies, bezoars, food bolus)
most common cause Adhesions (60%) related to
previous surgery (within 4 weeks or decades later) or
peritonitis.
Adhesive bands occur between loops of bowel and the
operative site causing acute angulation and kinking,
The incidence parallels increasing number
laparotomies developing countries.
The second most common is an incarcerated hernia.
A loop may enter any form of hernia and become
obstructed narrow neck of a hernia, which
compromises the caliber of the bowel .
1-external hernia (femoral, indirect inguinal, umbilical,
incisional, epigastric, spigelian hernia)
2-internal hernia is clinically indistinguishable from
obstruction resulting from postoperative adhesions.
Neoplasms 20 % ( intrinsic 3%
extrinsic 17% )
Intrinsic neoplasms can either
progressively occlude the lumen(small-bowel lymphoma and
adenocarcinoma Lipomas, leiomyomas, and carcinoid tumors )
or
,more commonly, serve as leading point in intussusception
(Any polypoid mucosal or submucosal lesion ).
Extrinsic neoplasms: Secondary tumors ( gastric and colonic
carcinomas, ovarian cancers, and malignant melanomas) may
occasionally compromise the lumen of the small-bowel.
inflammatory bowel disease (5%) often causes
obstruction when the lumen is narrowed by
inflammation or fibrosis of the wall.
volvulus (3%) results from malrotation of bowel loop
around its mesenteric beds typically produces a
closed loop of bowel with a pinched base, leading to
intestinal obstruction with strangulation
Small-bowel tuberculosis is not uncommon in
certain parts of the world
miscellaneous causes (2%).
Intussusception: invagination of one loop of
intestine to another is rarely encountered in adults
(need leading point polyp or other intrluminal lesion.
(colickly pain, blood per rectum, palpaple mass
(intussuscepted segment).
Swallowed Forign bodies Bezoars
A food bolus may occur, with indigestible vegetable material
impacted in the terminal ileum. Patients with a food bolus will
usually have undergone gastric outlet surgery.
Gallstones may occur with a cholecystenteric fistula.
Strictures may occur following ulceration induced by
potassium tablets, nonsteroidal anti-inflammatory agents, and
therapeutic irradiation for bladder or cervical cancer.
An intramural hematoma may occur in cases of trauma or
spontaneously in patients receiving higher doses of
anticoagulant agents than are necessary.
Pathophysiology:
Obstruction of the small bowel leads to proximal dilatation of
the intestine due to accumulation of GI secretions and
swallowed air.
Swallowed air major source of gaseous distension (early)
nitrogen is not well absorbed by the mucosa.
Bacterial fermentation (later )other gases are produced
partial pressure of nitrogen in the lumen are lowered; gradient
of diffusion of nitrogen from blood to lumen.
Large quantities of fluid from the extracellular space are lost
into the gut ; and from the serosa into the peritoneal cavity.
fluid fills the the lumen proximal to the obstruction;
net secretion is enhanced
mediators substances (endotoxin, prostaglandins) released
from the luminal baceria are responsible.
Reflexely induced vomiting accentuates the fluid and
electrolytes deficit.
Hypovolemia leads to multi-organ system failure and is the
cause of death with non-strangulating obstruction.
In strangulated obstruction (eg, incarcerated hernia, volvolus)
complete obstruction of the intestinal lumen as well as
occlusion of the vascular supply( early venous drainage, then
arterial supply).gangrenous bowel develops and might bleeds
into the the lumen and into the peritoneal cavity and eventually
it perforates.
The luminal content of strangulated intestine (toxic mixture of
bacteria,bacterial products,necrotic tissue and blood)
Some of this fluid enter the circulation by way of lymphatics
orby absorption from the peritoneal cavity, septic shock is the
result.
Note: Bacterial translocation from lumen to mesenteric L.N. and
the bloodstream even in simple obstruction.
In general, the higher the level of obstruction, the less the
distention and the more rapid the onset of vomiting.
Conversely, in patients with a distal small-bowel obstruction,
central abdominal distention may be marked and vomiting
(feaculent) is, usually, a late feature (because the bowel takes
time to fill). Colicky pain is most marked in patients with a distal
obstruction.
Hypotension and tachycardia suggest fluid depletion
tenderness and leukocytosis suggest strangulation.
In the early stages, bowel sounds are usually high-pitched, and
they occur in frequent runs as the bowel contracts in an
attempt to overcome the obstruction.
A silent, tender abdomen suggests perforation or peritonitis,
and it is a late sign
History
partial or complete VS simple or strangulated.
 Abdominal pain (characteristic with most patients)
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Pain, often described as crampy and intermittent, is more prevalent in
simple obstruction.
Often, the presentation the approximate location and nature of the
obstruction. Usually, pain that occurs for a shorter duration of time and is
colicky and accompanied by bilious vomiting may be more proximal. Pain
lasting as many as several days, which is progressive in nature and with
abdominal distention, may be typical of a more distal obstruction.
Changes in the character of the pain may indicate the development of a
more serious complication (ie, constant pain of strangulated or ischemic
bowel).
Nausea
Vomiting, which is associated more with proximal obstructions
In distal obstruction, (vomiting late,feaculent)
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
Virgin abdomen Previous abdominal or pelvic surgery, previous
radiation therapy, or both (may be part of patient's medical history)
History of malignancy (particularly ovarian and colonic)
Examination:
Vital signs: normal (early)
Tachycardia, hypotension (late)
Temperature: normal (simple)
elevated (strangulation)
Abdominal Ex: distension (more in distal).
Mild tenderness
Visible peristalsis
Bowel sounds: hyperactive (early)
hypoactive (late)
Silent (peritonitis)
Ex of hernias (incarcerated)
In strangulation: shock
fever
Cramping abd pain become
severe continuos pain
Abd. Tenderness and rigidity
Silent abd
Incarcerated hernia,
abd. Mass
(intussusceptum)
Gross or occult blood
Leukocytosis.
acidosis
note: no historical , physical or lab works
entirely excludes the possibility of
strangulation in complete SBO.
investigation:
Essential laboratory tests
Serum chemistries: Results are usually normal or mildly elevated.
BUN level: If the BUN level is increased, this may indicate
decreased volume state (eg, dehydration).
Creatinine level: Creatinine level elevations may indicate
dehydration.
CBC: WBC count may be elevated with a left shift in simple or
strangulated obstructions.
Increased hematocrit is an indicator of volume state (ie,
dehydration).
Lactate dehydrogenase tests
Blood gases analysis
Urinalysis
Type and crossmatch: The patient may require surgical
intervention.
Imaging studies:
Plain radiography:
Obtain plain radiographs first for patients in whom SBO is
suspected.
At least 2, supine or flat and upright, are required
Ladder-like pattern Dilated small-bowel loops with air fluid levels
(>6)
Absent or minimal colonic gas
Intramural gas secondary to ischemia. This is a poor
prognostic sign.
Gallstone ileus presence of a calcified intraluminal stone
(often in the terminal ileum)
radiologic signs of a small-bowel obstruction above the
Ileus, a gas in the biliary tree as a result of the
cholecystoduodenal fistula.
Ladder-like pattern
Multiple air fluid leves
Dilated S.B.
S.B.O. + P.U.H.(incarcerated)
Strangulated L.I.H.
Midgut volvolus
Distended jej. Loobs,multiple air
fluidl evels,G.S.(arrow)
Cecal volvolus
Crohn dis,long stricture(ileum)
Conventional barium follow-through examination and enteroclysis
is valuable in detecting the presence of obstruction and in
differentiating partial from complete blockages.
useful when plain radiographic findings are normal in the
presence of clinical signs of SBO or if plain radiographic
findings are nonspecific.
A delay in transit time on a conventional follow-through
examination of greater than 12 hours is suggestive of an
organic obstruction.
Barium enema study
ileocecal intussusception or other causes of ileocecal
obstruction
useful if a distal colonic obstruction cannot be excluded by
using plain abdominal radiograph findings
In children with intussusception, barium enema studies are not
only diagnostic but possibly therapeutic as well.
dilated loops, stretching of the mucosal folds
a narrowed segment ending in a beak
. Multiple strictures and polypoid filling
defectsvproximal small bowel deposits of non-
ileocecal intussusception (carcinoid
tumor of the terminal ileum)
double-contrast barium enema
multiple fluid levels in the centrally
Stricture,shouldering of the terminal
ileum caused by adenocarcinoma
Computed Tomography
CT scans clearly demonstrate abnormalities of the bowel
wall, the mesentery, the mesenteric vessels, and the
peritoneum.
useful in making an early diagnosis of strangulated obstruction
particularly when clinical and radiographic findings are
inconclusive.
proved useful etiologies of SBO extrinsic causes such as
adhesions and hernia from intrinsic causes such as neoplasms or
Crohn
disease. It also differentiates the above from intraluminal
causes such as bezoars.
about 90% sensitive and specific in detecting SBO.
is the study of choice if the patient has fever, tachycardia,
localized abdominal pain, and/or leukocytosis.
It is capable of revealing abscess, inflammatory process,
extraluminal pathology resulting in obstruction, and mesenteric
Ischemia.
enables the clinician to distinguish between ileus and
mechanical small bowel in postoperative
patients.
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does not require oral contrast for the diagnosis of SBO because
the retained intraluminal fluid serves as a natural contrast agent.
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Obstruction is present if the small-bowel loop is greater than 2.5
cm in diameter dilated proximal to a distinct transition zone of
collapsed bowel less than 1 cm in diameter.
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A smooth beak indicates simple obstruction without vascular
compromise; a serrated beak may indicate strangulation.
Bowel wall thickening indicates early strangulation.
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Portal venous gas indicates early strangulation.
Pneumatosis indicates early strangulation.
useful in identifying abscesses, hernias, and tumors.
may be less useful in the evaluation of small bowel ischemia
associated with obstruction
extrinsic mass compressing a loop
of small bowel (desmoid t.)
incarcerated umbilical hernia
dilated S.B. +A.F.L.
nonstrangulated small-bowel loop
+L ing. H.
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Ultrasonography
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Ultrasonography is less costly and less invasive than CT scanning.
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It may reliably exclude SBO in as many as 89% of patients.
Management:
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Continued NG suction: This provides symptomatic relief,
decreases the need for intraoperative decompression, and
benefits all patients. No clinical advantage to using a long tube
(nasointestinal) instead of a short tube (NG) is observed.
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Nonoperative treatment: A nonoperative trial of as many as 3
days is warranted for partial or simple obstruction. Provide
adequate fluid resuscitation and NG suctioning Monitor urine
output (foley cath) . Resolution of obstruction occurs in
virtually all patients with these lesions within 72 hours.
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administration of analgesia and antiemetic
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Antibiotics are used to cover gram-negative and anaerobic
organisms.
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Surgical treatment: A strangulated obstruction is a surgical
emergency. In patients with a complete SBO, the risk of
strangulation is high and early surgical intervention is
warranted. Patients with simple complete obstructions in whom
nonoperative trials fail also need surgical treatment but
experience no apparent disadvantage to delayed surgery.
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Adhesions: Decreasing intraoperative trauma to the peritoneal
surfaces can prevent adhesion formation.
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Malignant tumor: Obstruction by tumor is usually caused by
metastasis. Initial treatment should be nonoperative; surgical
resection is recommended when feasible.
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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. Undertake surgical treatment,
bowel resection, and/or stricturoplasty if nonoperative
treatment fails.
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Intra-abdominal abscess: CT-guided drainage is usually
sufficient to relieve obstruction.
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Radiation enteritis: If obstruction follows radiation therapy
acutely, nonoperative treatment accompanied by steroids is
usually sufficient. If obstruction is a chronic sequela of
radiation therapy, surgical treatment is indicated.
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Acute postoperative obstruction: This is difficult to diagnose
because symptoms often are attributed to incisional pain and
postoperative ileus. Treatment should be nonoperative.
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Incarcerated hernia: Initially use manual reduction and
observation. Advise elective hernia repair as soon as possible
after reduction.
Indications for surgery
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Absolute
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Relative
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Generalised peritonitis
Localised peritonitis
Visceral perforation
Irreducible hernia
Palpable mass lesion
'Virgin' abdomen
Failure to improve
Trial of conservatism
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Incomplete obstruction
Previous surgery
Advanced malignancy
Diagnostic doubt - possible ileus
Complications
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Sepsis
Intra-abdominal abscess
Wound dehiscence
Aspiration
Short-bowel syndrome (as a result of multiple surgeries)
Death (secondary to delayed treatment)
Prognosis:
With proper diagnosis and treatment of the
obstruction, prognosis is good. Complete
obstructions treated successfully nonoperatively
have a higher incidence of recurrence than those
treated surgically.
Mortality and morbidity are dependent on the etiology,
the early recognition and correct diagnosis of
obstruction.
If untreated, strangulated obstructions cause death in
100% of patients.
If surgery is performed within 36 hours, the mortality rate
decreases to 8%.
The mortality rate is 25% if the surgery is postponed
beyond 36 hours in these patients.
Paralytic ileus
Background
After abdominal surgery, a normal physiological
ileus occurs.
spontaneously resolves within 2-3 days
the terms postoperative adynamic ileus or paralytic
ileus are defined as ileus of the gut persisting for
more than 3 days following surgery.
Ileus occurs from hypomotility of the gastrointestinal
tract in the absence of a mechanical bowel
obstruction.
This suggests that the muscle of the bowel wall is
transiently impaired and fails to transport intestinal
contents.
This lack of coordinated propulsive action leads to
the accumulation of both gas and fluids within the
bowel.
the postoperative state is the most common scenario for ileus
development.
Frequently, ileus occurs after intraperitoneal operations, but it
may also occur after retroperitoneal and extra-abdominal
surgery.
The longest duration of ileus is noted to occur after colonic
surgery.
The stomach regains activity in 1-2 days, and the colon regains
activity in 3-5 days.and the small bowe within 24-48 hours
Causes of adynamic ileus
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Sepsis
Drugs (eg, opioids, antacids, coumarin, amitriptyline,
chlorpromazine)
Metabolic (eg, low potassium, magnesium, or sodium levels;
anemia; hyposmolality)
Myocardial infarction
Pneumonia
Trauma (eg, fractured ribs, fractured spine)
Biliary and renal colic
Head injury and neurosurgical procedures
Intra-abdominal inflammation and peritonitis
Retroperitoneal hematomas
Clinical
History
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Patients with ileus typically present with vague, mild abdominal
pain and bloating.
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nausea, vomiting, and poor appetite.
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Abdominal cramping is usually not present.
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Patients may or may not continue to pass flatus and stool.
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Hx previous operation
Physical
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distended and tympanic abdomens, depending on the degree
of abdominal and bowel distension.
may be tender.
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A distinguishing feature is absent or hypoactive bowel sounds
unlike the high-pitched sound of obstruction.
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The silent abdomen of ileus reveals no discernible peristalsis
or succussion splash.
Pseudo-obstruction
Mechanical Obstruction
(Simple)
Sympt Mild abdominal
oms
pain, bloating,
nausea,
vomiting,
obstipation,
constipation,
Crampy abdominal pain,
constipation, obstipation,
nausea, vomiting, anorexia
Crampy abdominal pain,
constipation, obstipation,
nausea, vomiting, anorexia
Physic Silent abdomen,
al
distension,
Exami tympanic
nation
Findin
gs
Borborygmi, tympanic,
peristaltic waves,
hypoactive or hyperactive
bowel sounds, distension,
localized tenderness
Borborygmi, peristaltic
waves, high-pitched bowel
sounds, rushes, distension,
localized tenderness
Plain
Radio
graph
s
Isolated large bowel
dilatation, diaphragm
elevated
Bow-shaped loops in ladder
pattern, paucity of colonic
gas distal to lesion,
diaphragm mildly elevated,
air-fluid levels
Ileus
Large and small
bowel dilatation,
diaphragm
elevated
Workup
Laboratory Studies
Laboratory studies and blood work should focus on evaluations for
infectious, electrolytic, and metabolic derangements.
Imaging Studies
On plain abdominal radiographs, ileus appears as copious gas
dilatation of the small intestine and colon.
With enteroclysis, the contrast medium in patients with paralytic ileus
should reach the cecum within 4 hours; if it remains stationary for
longer than 4 hours, mechanical obstruction is suggested.
Postoperative ileus after an open
cholecystectomy.
Management:
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Most cases of postoperative ileus resolve with watchful waiting
and supportive treatment. Patients should receive intravenous
hydration. For patients with vomiting and distension, use of a
nasogastric tube provides symptomatic relief; however, no
studies in the literature support the use of nasogastric tubes to
facilitate resolution of ileus. Long intestinal tubes have no
benefit over nasogastric tubes.
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For patients with protracted ileus, mechanical obstruction must
be excluded with contrast studies. Underlying sepsis and
electrolyte abnormalities, particularly hypokalemia,
hyponatremia, and hypomagnesemia, may worsen ileus. These
contributing conditions are easily diagnosed and corrected.
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Discontinue medications that produce ileus (eg, opiates). In
one study, the amount of morphine administered directly
correlated with the time of bowel sound occurrence and the
passage of flatus and stool.
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The use of postoperative narcotics can be diminished by
supplementation with nonsteroidal anti-inflammatory drugs
(NSAIDs).
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NSAIDS may improve ileus by improving local inflammation
and by decreasing the amount of narcotics used.
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No single objective variable accurately predicts the resolution
of ileus. A clinician must assess the overall status of the patient
and evaluate for adequate oral intake and good bowel function.
A patient's report of flatus, bowel sounds, or stool passage
may prove misleading; therefore, clinicians must not rely solely
on self-reporting.
Diet
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Generally, delay oral feeding until ileus resolves clinically.
However, the presence of ileus does not preclude enteral
feeding. Postpyloric feeding into the small bowel can be
cautiously performed. Start feeds at one-quarter or one-half
strength at a slow rate and gradually advance.
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One report showed that gum chewing as a form of sham
feeding enhanced early recovery from postoperative ileus after
laparoscopic colectomy.
Activity
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Conventional wisdom and wide practice foster the notion that
ambulation stimulates bowel function and improves
postoperative ileus, although this has not been shown in the
literature.
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In a nonrandomized study evaluating 34 patients, seromuscular
bipolar electrodes were placed in segments of the
gastrointestinal tract after laparotomy. Ten patients were
assigned to ambulate on postoperative day 1, and the other 24
were assigned to ambulate on postoperative day 4. No
significant difference between the 2 groups was displayed in
myoelectric recovery in the stomach, jejunum, or colon.
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Hence, postoperative ambulation remains beneficial in
preventing the formation of atelectasis, deep vein thrombosis,
and pneumonia but has no role in treating ileus.
Medication
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No randomized trials have assessed the benefits of
suppositories and enemas for the treatment of ileus.
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Use of prokinetic agents has had moderate success.
Rectal cisapride (Propulsid), a serotonin agonist, has
reportedly been successful in treating ileus, but the US Food
and Drug Administration (FDA) has withdrawn this agent
because of the possibility it causes cardiac dysrhythmias.
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Erythromycin, a motilin receptor agonist, has been used for
postoperative gastric paresis but has not been shown to be
beneficial for ileus.
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Metoclopramide (Reglan), a dopaminergic antagonist, has
antiemetic and prokinetic activities. Data have shown that the
drug may actually worsen ileus.
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Thoracic epidural administration has been shown to be beneficial.
Epidural blockade with local anesthetics improves postoperative
ileus by blockage of inhibitory reflexes and efferent sympathetics.
Studies have shown that combinations of thoracic epidurals
containing bupivacaine alone or in combination with opioids improve
postoperative ileus.
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Methylnaltrexone and ADL 8-2698 (alvimopan [Entereg]) are now
approved by the FDA in the United States.
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These agents inhibit peripheral mu-opioid receptors. Receptor
blockade abolishes the adverse gastrointestinal effects of opioids
without impairing the analgesic effects of such drugs.21
Methylnaltrexone is indicated for opioid-induced constipation in
patients with advanced illness receiving palliative care, when
response to laxatives has not been sufficient.
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In a study of 14 healthy volunteers evaluating the use of morphine
plus oral methylnaltrexone in increasing doses, methylnaltrexone
significantly reduced morphine-induced delay in oral-cecal transit.
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Alvimopan is indicated to help prevent postoperative ileus
following bowel resection.
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Both methylnaltrexone and alvimopan do not traverse the
blood-brain barrier, and the latter agent has the advantage of
being long acting.
Notes:
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First you have exclude mechanical obstruction in patients with
protracted ileus
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Administration of neostigmine, especially in patients with
cardiac problems, to treat ileus.
Thank you