Bowel Obstruction vs Ileus

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    Small bowel obstruction

    &post operative ileus

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    Frequency:

    Approximately 20% of patients admitted to

    the hospital with an acute abdomen have

    an intestinal obstruction

    (most common surgical disorder of small

    bowel)).

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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 numberlaparotomies developing countries.

    The second most common is an incarcerated hernia.A loop may enter any form of hernia and becomeobstructed 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 either

    progressively 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 strangulation

    Small-bowel tuberculosis is not uncommon incertain 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).

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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 enhanced

    mediators 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 as

    occlusion 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 of

    bacteria,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. and

    the 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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    History

    partial or complete VS simple or strangulated.

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

    simple 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).

    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 orbowel movements

    Fever and tachycardia - Occur late and may be associated withstrangulation

    Virgin 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 tenderness

    Visible peristalsis

    Bowel sounds: hyperactive (early)

    hypoactive (late)Silent (peritonitis)

    Ex of hernias (incarcerated)

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    In strangulation: shock

    fever

    Cramping abd pain become

    severe continuos painAbd. Tenderness and rigidity

    Silent abd

    Incarcerated hernia,

    abd. Mass(intussusceptum)

    Gross or occult blood

    Leukocytosis.

    acidosis

    note: no historical , physical or lab worksentirely excludes the possibility of

    strangulation 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 analysis

    Urinalysis

    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