Download - 33873_small Bowel Obstruction vs Ileus

8/11/2019 33873_small Bowel Obstruction vs Ileus

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Small bowel obstruction&post operative ileus

Dr.G.Devakannan M.S,M.Ch(uro)


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Obstruction of the intestine due to paralysisof the intestinal muscles

The paralysis does not need to becomplete to cause ileus ,but the intestinal

muscles be so inactive that it prevents thepassage of food and leads to functional

blockage of intestine.


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Definition: mechanical or functional obstruction of theintestines, preventing the normal transit ofthe products of digestion.It is a medical emergency . Although manycases are not treated surgically, it is asurgical problem.
http://en.wikipedia.org/wiki/Medical_emergencyhttp://en.wikipedia.org/wiki/Surgeryhttp://en.wikipedia.org/wiki/Surgeryhttp://en.wikipedia.org/wiki/Medical_emergency


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Frequency: Approximately 20% of patients admitted tothe hospital with an acute abdomen havean intestinal obstruction(most common surgical disorder of smallbowel)).


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partial or complete, simple (ie, nonstrangulated) or strangulated.

Strangulated obstructions (40%) are surgical emergencies whichneedsproper Dx and Rx..

If not diagnosed and properly treated, vascular compromise leads tobowel 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 tonecrosis of the intestinal wall.

Closed loop obstruction the lumen is occluded in at least 2places(eg, in volvolus), is commonly ass. With strangulation


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Mortality/Morbidity

Mortality and morbidity are dependent on the etiology, the earlyrecognition and correct diagnosis of obstruction.

If untreated, strangulated obstructions cause death in 100% ofpatients.

If surgery is performed within 36 hours, the mortality rate decreasesto 8%.

The mortality rate is 25% if the surgery is postponed beyond 36hours in these patients.


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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, potassiumstrictures, radiation strictures, complications of surgicalanastomosis)

Intraluminal (eg, foreign bodies, bezoars, food bolus)


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most common cause Adhesions (60%) related toprevious surgery (within 4 weeks or decades later) orperitonitis.

Adhesive bands occur between loops of bowel and theoperative 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, whichcompromises the caliber of the bowel .1-external hernia (femoral, indirect inguinal, umbilical,incisional, epigastric, spigelian hernia)2-internal hernia is clinically indistinguishable fromobstruction resulting from postoperative adhesions.


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Neoplasms 20 % ( intrinsic 3% extrinsic 17% )

Intrinsic neoplasms can eitherprogressively occlude the lumen(small-bowel lymphoma andadenocarcinoma 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 coloniccarcinomas, ovarian cancers, and malignant melanomas) mayoccasionally compromise the lumen of the small-bowel.


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inflammatory bowel disease (5%) often causesobstruction when the lumen is narrowed byinflammation or fibrosis of the wall.

volvulus (3%) results from malrotation of bowel looparound its mesenteric beds typically produces aclosed loop of bowel with a pinched base, leading tointestinal obstruction with strangulationSmall-bowel tuberculosis is not uncommon incertain parts of the worldmiscellaneous 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).


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Swallowed Forign bodies Bezoars

A food bolus may occur, with indigestible vegetable materialimpacted in the terminal ileum. Patients with a food bolus willusually have undergone gastric outlet surgery.

Gallstones may occur with a cholecystenteric fistula.

Strictures may occur following ulceration induced bypotassium tablets, nonsteroidal anti-inflammatory agents, andtherapeutic irradiation for bladder or cervical cancer.

An intramural hematoma may occur in cases of trauma or

spontaneously in patients receiving higher doses ofanticoagulant agents than are necessary.


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Pathophysiology:

Obstruction of the small bowel leads to proximal dilatation ofthe intestine due to accumulation of GI secretions andswallowed air.Swallowed air major source of gaseous distension (early)nitrogen is not well absorbed by the mucosa.Bacterial fermentation (later )other gases are producedpartial pressure of nitrogen in the lumen are lowered; gradientof diffusion of nitrogen from blood to lumen.Large quantities of fluid from the extracellular space are lostinto the gut ; and from the serosa into the peritoneal cavity.fluid fills the the lumen proximal to the obstruction;net secretion is enhancedmediators substances (endotoxin, prostaglandins) releasedfrom the luminal baceria are responsible.

Reflexely induced vomiting accentuates the fluid andelectrolytes deficit.Hypovolemia leads to multi-organ system failure and is thecause of death with non-strangulating obstruction.


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In strangulated obstruction (eg, incarcerated hernia, volvolus)complete obstruction of the intestinal lumen as well asocclusion of the vascular supply( early venous drainage, thenarterial supply).gangrenous bowel develops and might bleedsinto the the lumen and into the peritoneal cavity and eventuallyit perforates.

The luminal content of strangulated intestine (toxic mixture ofbacteria,bacterial products,necrotic tissue and blood)Some of this fluid enter the circulation by way of lymphaticsorby absorption from the peritoneal cavity, septic shock is theresult.

Note: Bacterial translocation from lumen to mesenteric L.N. andthe bloodstream even in simple obstruction.


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In general, the higher the level of obstruction, the less thedistention 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 takestime to fill). Colicky pain is most marked in patients with a distalobstruction.

Hypotension and tachycardia suggest fluid depletiontenderness and leukocytosis suggest strangulation.

In the early stages, bowel sounds are usually high-pitched, andthey occur in frequent runs as the bowel contracts in anattempt to overcome the obstruction.

A silent, tender abdomen suggests perforation or peritonitis,and it is a late sign


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Historypartial or complete VS simple or strangulated.

Abdominal pain (characteristic with most patients)Pain, often described as crampy and intermittent, is more prevalent insimple obstruction.

Often, the presentation the approximate location and nature of theobstruction. Usually, pain that occurs for a shorter duration of time and iscolicky and accompanied by bilious vomiting may be more proximal. Painlasting as many as several days, which is progressive in nature and withabdominal distention, may be typical of a more distal obstruction.Changes in the character of the pain may indicate the development of amore serious complication (ie, constant pain of strangulated or ischemicbowel).

NauseaVomiting, which is associated more with proximal obstructionsIn distal obstruction, (vomiting late,feaculent)Diarrhea (an early finding)Constipation (a late finding) as evidenced by the absence of flatus orbowel movements

Fever and tachycardia - Occur late and may be associated withstrangulationVirgin abdomen Previous abdominal or pelvic surgery, previousradiation therapy, or both (may be part of patient's medical history)History of malignancy (particularly ovarian and colonic)


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Examination:Vital signs: normal (early)

Tachycardia, hypotension (late)Temperature: normal (simple)elevated (strangulation)

Abdominal Ex: distension (more in distal).Mild tendernessVisible peristalsis

Bowel sounds: hyperactive (early)hypoactive (late)

Silent (peritonitis)Ex of hernias (incarcerated)


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In strangulation: shockfeverCramping abd pain become

severe continuos painAbd. Tenderness and rigiditySilent abdIncarcerated hernia,

abd. Mass(intussusceptum)

Gross or occult bloodLeukocytosis.acidosis

note: no historical , physical or lab worksentirely excludes the possibility ofstrangulation in complete SBO.


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investigation:

Essential laboratory tests

Serum chemistries: Results are usually normal or mildly elevated.BUN level: If the BUN level is increased, this may indicatedecreased volume state (eg, dehydration).

Creatinine level: Creatinine level elevations may indicatedehydration.

CBC: WBC count may be elevated with a left shift in simple orstrangulated obstructions.Increased hematocrit is an indicator of volume state (ie,dehydration).

Lactate dehydrogenase testsBlood gases analysisUrinalysis

Type and crossmatch: The patient may require surgicalintervention.


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Imaging studies:

Plain radiography:

Obtain plain radiographs first for patients in whom SBO issuspected.

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 gasIntramural 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 theIleus, a gas in the biliary tree as a result of thecholecystoduodenal fistula.


20/63Ladder-like pattern


21/63Multiple air fluid leves


22/63Dilated S.B.


23/63S.B.O. + P.U.H.(incarcerated)


24/63Strangulated L.I.H.


25/63Midgut volvolus


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Distended jej. Loobs,multiple air

fluidl evels,G.S.(arrow)


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Cecal volvolus


28/63Crohn dis,long stricture(ileum)


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Conventional barium follow-through examination and enteroclysisis valuable in detecting the presence of obstruction and indifferentiating partial from complete blockages.useful when plain radiographic findings are normal in thepresence of clinical signs of SBO or if plain radiographicfindings are nonspecific.A delay in transit time on a conventional follow-throughexamination of greater than 12 hours is suggestive of anorganic obstruction.

Barium enema studyileocecal intussusception or other causes of ileocecalobstructionuseful if a distal colonic obstruction cannot be excluded byusing plain abdominal radiograph findingsIn children with intussusception, barium enema studies are notonly diagnostic but possibly therapeutic as well.


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dilated loops, stretching of the mucosal foldsa narrowed segment ending in a beak


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. Multiple strictures and polypoid filling

defectsvproximal small bowel deposits of non-


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ileocecal intussusception (carcinoid

tumor of the terminal ileum)


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double-contrast barium enema

multiple fluid levels in the centrally


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Stricture,shouldering of the terminalileum caused b adenocarcinoma


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Computed TomographyCT scans clearly demonstrate abnormalities of the bowelwall, the mesentery, the mesenteric vessels, and theperitoneum.

useful in making an early diagnosis of strangulated obstructionparticularly when clinical and radiographic findings are

inconclusive.

proved useful etiologies of SBO extrinsic causes such asadhesions and hernia from intrinsic causes such as neoplasms orCrohn disease. It also differentiates the above from intraluminalcauses 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 mesentericIschemia.enables the clinician to distinguish between ileus andmechanical small bowel in postoperative patients.


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does not require oral contrast for the diagnosis of SBO becausethe retained intraluminal fluid serves as a natural contrast agent.

Obstruction is present if the small-bowel loop is greater than 2.5cm in diameter dilated proximal to a distinct transition zone ofcollapsed bowel less than 1 cm in diameter.

A smooth beak indicates simple obstruction without vascularcompromise; a serrated beak may indicate strangulation.Bowel wall thickening indicates early strangulation.

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 ischemiaassociated with obstruction


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extrinsic mass compressing a loopof small bowel desmoid t.


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incarcerated umbilical herniadilated S.B. +A.F.L.


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nonstrangulated small-bowel loop+L in . H.


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Ultrasonography

Ultrasonography is less costly and less invasive than CT scanning.

It may reliably exclude SBO in as many as 89% of patients.


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Management:

Continued NG suction: This provides symptomatic relief,decreases the need for intraoperative decompression, andbenefits all patients. No clinical advantage to using a long tube(nasointestinal) instead of a short tube (NG) is observed.

Nonoperative treatment: A nonoperative trial of as many as 3days is warranted for partial or simple obstruction. Provideadequate fluid resuscitation and NG suctioning Monitor urineoutput (foley cath) . Resolution of obstruction occurs invirtually all patients with these lesions within 72 hours.

administration of analgesia and antiemetic

Antibiotics are used to cover gram-negative and anaerobicorganisms.


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Surgical treatment: A strangulated obstruction is a surgicalemergency. In patients with a complete SBO, the risk of

strangulation is high and early surgical intervention iswarranted. Patients with simple complete obstructions in whomnonoperative trials fail also need surgical treatment butexperience no apparent disadvantage to delayed surgery.

Adhesions: Decreasing intraoperative trauma to the peritoneal

surfaces can prevent adhesion formation.

Malignant tumor: Obstruction by tumor is usually caused bymetastasis. Initial treatment should be nonoperative; surgicalresection is recommended when feasible.

Inflammatory bowel disease: To reduce the inflammatoryprocess, treatment generally is nonoperative in combinationwith high-dose steroids. Consider parenteral treatment forprolonged periods of bowel rest. Undertake surgical treatment,bowel resection, and/or stricturoplasty if nonoperativetreatment fails.


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Intra-abdominal abscess: CT-guided drainage is usuallysufficient to relieve obstruction.

Radiation enteritis: If obstruction follows radiation therapyacutely, nonoperative treatment accompanied by steroids isusually sufficient. If obstruction is a chronic sequela ofradiation therapy, surgical treatment is indicated.

Acute postoperative obstruction: This is difficult to diagnosebecause symptoms often are attributed to incisional pain andpostoperative ileus. Treatment should be nonoperative.

Incarcerated hernia: Initially use manual reduction andobservation. Advise elective hernia repair as soon as possibleafter reduction.


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Indications for surgery

AbsoluteGeneralised peritonitisLocalised peritonitisVisceral perforationIrreducible hernia

RelativePalpable mass lesion'Virgin' abdomenFailure to improve

Trial of conservatismIncomplete obstructionPrevious surgeryAdvanced malignancyDiagnostic doubt - possible ileus


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Complications

SepsisIntra-abdominal abscessWound dehiscenceAspirationShort-bowel syndrome (as a result of multiple surgeries)

Death (secondary to delayed treatment)

Prognosis:


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g

With proper diagnosis and treatment of theobstruction, prognosis is good. Completeobstructions treated successfully nonoperativelyhave a higher incidence of recurrence than thosetreated surgically.Mortality and morbidity are dependent on the etiology,

the early recognition and correct diagnosis ofobstruction.

If untreated, strangulated obstructions cause death in100% of patients.

If surgery is performed within 36 hours, the mortality ratedecreases to 8%.

The mortality rate is 25% if the surgery is postponedbeyond 36 hours in these patients.

Paralytic ileus


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Paralytic ileus

Background

After abdominal surgery, a normal physiologicalileus occurs.spontaneously resolves within 2-3 daysthe terms postoperative adynamic ileus or paralytic

ileus are defined as ileus of the gut persisting formore than 3 days following surgery.Ileus occurs from hypomotility of the gastrointestinaltract in the absence of a mechanical bowelobstruction.

This suggests that the muscle of the bowel wall istransiently impaired and fails to transport intestinalcontents.This lack of coordinated propulsive action leads tothe accumulation of both gas and fluids within the

bowel.


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the postoperative state is the most common scenario for ileusdevelopment.

Frequently, ileus occurs after intraperitoneal operations, but it

may also occur after retroperitoneal and extra-abdominalsurgery.

The longest duration of ileus is noted to occur after colonic

surgery. The stomach regains activity in 1-2 days, and the colon regainsactivity in 3-5 days.and the small bowe within 24-48 hours


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Causes of adynamic ileus

SepsisDrugs (eg, opioids, antacids, coumarin, amitriptyline,chlorpromazine)Metabolic (eg, low potassium, magnesium, or sodium levels;anemia; hyposmolality)Myocardial infarction

PneumoniaTrauma (eg, fractured ribs, fractured spine)Biliary and renal colicHead injury and neurosurgical proceduresIntra-abdominal inflammation and peritonitisRetroperitoneal hematomas


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Clinical

History

Patients with ileus typically present with vague, mild abdominalpain and bloating.

nausea, vomiting, and poor appetite.

Abdominal cramping is usually not present.

Patients may or may not continue to pass flatus and stool.

Hx previous operation


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Physical

distended and tympanic abdomens, depending on the degreeof abdominal and bowel distension.

may be tender.

A distinguishing feature is absent or hypoactive bowel soundsunlike the high-pitched sound of obstruction.

The silent abdomen of ileus reveals no discernible peristalsisor succussion splash.


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Mechanical Obstruction(Simple) Pseudo-obstruction Ileus

Crampy abdominal pain,constipation, obstipation,nausea, vomiting, anorexia

Crampy abdominal pain,constipation, obstipation,nausea, vomiting, anorexia

Mild abdominalpain, bloating,nausea,vomiting,obstipation,constipation,

Symptoms

Borborygmi, peristaltic

waves, high-pitched bowelsounds, rushes, distension,localized tenderness

Borborygmi, tympanic,

peristaltic waves,hypoactive or hyperactivebowel sounds, distension,localized tenderness

Silent abdomen,

distension,tympanic

Physic

alExaminationFindings

Bow-shaped loops in ladderpattern, paucity of colonicgas distal to lesion,diaphragm mildly elevated,air-fluid levels

Isolated large boweldilatation, diaphragmelevated

Large and smallbowel dilatation,diaphragmelevated

PlainRadiographs


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Workup

Laboratory Studies

Laboratory studies and blood work should focus on evaluations forinfectious, electrolytic, and metabolic derangements.

Imaging Studies

On plain abdominal radiographs, ileus appears as copious gasdilatation of the small intestine and colon.

With enteroclysis, the contrast medium in patients with paralytic ileusshould reach the cecum within 4 hours; if it remains stationary forlonger than 4 hours, mechanical obstruction is suggested.


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Postoperative ileus after an opencholec stectom

Management:


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Management:

Most cases of postoperative ileus resolve with watchful waitingand supportive treatment. Patients should receive intravenoushydration. For patients with vomiting and distension, use of anasogastric tube provides symptomatic relief; however, nostudies in the literature support the use of nasogastric tubes tofacilitate resolution of ileus. Long intestinal tubes have nobenefit over nasogastric tubes.

For patients with protracted ileus, mechanical obstruction mustbe excluded with contrast studies. Underlying sepsis andelectrolyte abnormalities, particularly hypokalemia,hyponatremia, and hypomagnesemia, may worsen ileus. Thesecontributing conditions are easily diagnosed and corrected.

Discontinue medications that produce ileus (eg, opiates). Inone study, the amount of morphine administered directlycorrelated with the time of bowel sound occurrence and thepassage of flatus and stool.


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The use of postoperative narcotics can be diminished bysupplementation with nonsteroidal anti-inflammatory drugs

(NSAIDs).

NSAIDS may improve ileus by improving local inflammationand by decreasing the amount of narcotics used.

No single objective variable accurately predicts the resolutionof ileus. A clinician must assess the overall status of thepatient and evaluate for adequate oral intake and good bowelfunction. A patient's report of flatus, bowel sounds, or stoolpassage may prove misleading; therefore, clinicians must notrely solely on self-reporting.


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Diet

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 becautiously performed. Start feeds at one-quarter or one-halfstrength at a slow rate and gradually advance.

One report showed that gum chewing as a form of shamfeeding enhanced early recovery from postoperative ileus afterlaparoscopic colectomy.

Activity


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Activity

Conventional wisdom and wide practice foster the notion thatambulation stimulates bowel function and improvespostoperative ileus, although this has not been shown in theliterature.

In a nonrandomized study evaluating 34 patients, seromuscularbipolar electrodes were placed in segments of thegastrointestinal tract after laparotomy. Ten patients wereassigned to ambulate on postoperative day 1, and the other 24were assigned to ambulate on postoperative day 4. Nosignificant difference between the 2 groups was displayed inmyoelectric recovery in the stomach, jejunum, or colon.

Hence, postoperative ambulation remains beneficial inpreventing 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 ofsuppositories and enemas for the treatment of ileus.

Use of prokinetic agents has had moderate success.Rectal cisapride (Propulsid), a serotonin agonist, hasreportedly been successful in treating ileus, but the US Foodand Drug Administration (FDA) has withdrawn this agentbecause of the possibility it causes cardiac dysrhythmias.

Erythromycin, a motilin receptor agonist, has been used forpostoperative gastric paresis but has not been shown to bebeneficial for ileus.

Metoclopramide (Reglan), a dopaminergic antagonist, hasantiemetic and prokinetic activities. Data have shown that thedrug may actually worsen ileus.


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Thoracic epidural administration has been shown to be beneficial.Epidural blockade with local anesthetics improves postoperativeileus by blockage of inhibitory reflexes and efferent sympathetics.Studies have shown that combinations of thoracic epidurals

containing bupivacaine alone or in combination with opioids improvepostoperative ileus.

Methylnaltrexone and ADL 8-2698 (alvimopan [Entereg]) are nowapproved by the FDA in the United States.

These agents inhibit peripheral mu-opioid receptors. Receptorblockade abolishes the adverse gastrointestinal effects of opioidswithout impairing the analgesic effects of such drugs.21Methylnaltrexone is indicated for opioid-induced constipation inpatients with advanced illness receiving palliative care, whenresponse to laxatives has not been sufficient.

In a study of 14 healthy volunteers evaluating the use of morphineplus oral methylnaltrexone in increasing doses, methylnaltrexonesignificantly reduced morphine-induced delay in oral-cecal transit.


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Alvimopan is indicated to help prevent postoperative ileusfollowing bowel resection.

Both methylnaltrexone and alvimopan do not traverse theblood-brain barrier, and the latter agent has the advantage ofbeing long acting.


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Notes:

First you have exclude mechanical obstruction in patients withprotracted ileus

Administration of neostigmine, especially in patients withcardiac problems, to treat ileus.


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Thank you