Intestinal obstruction By: Dr. Wasfi M Salayta

Definition Any condition interferes with normal propulsion and passage of intestinal contents. Can involve the small bowel, colon or both small and colon as in generalized ileus.

Classification Cause of obstruction : mechanical or functional ( Ileus ). Duration of obstruction: acute or chronic. Extent of obstruction : partial or complete Type of obstruction : simple or complex (closed loop and strangulation) .

Mechanical obstruction There is physical blockage of intestinal lumen which due to: Intramural : congenital-tumor-hematoma-inflammatory Extramural : adhesion-volvulus-hernia –abscess-hematoma Lumen obstruction: stone-meconium-foreign body- impaction (stool-worm-barium) This mechanical obstruction can be partial ( lumen narrowed but allow transit some content) or complete ( lumen totally obstruction) this classify to simple obstruction (no vascular impairment) closed loop ( both ends are obstructed e.g volvulus) strangulation obstruction

Functional obstruction These obstructions secondary to factors cause either paralysis or dysmotility of intestinal peristalsis. Postoperative ileus is the most common form of functional bowel obstruction. Postoperative ileus present to some extent after most intra-abdominal operation Postoperative ileus correlates with degree of surgical trauma and type of operation ,so patients operated on for radiation enteropathy-chronic obstruction or sever peritonitis has more prolong P.O.I Different anatomic segments of GIT also recover at different rates after manipulation and trauma : Small bowel within hours after operation. Stomach may take 24-48 hr . Colon 3-5 days post op.

Occurs within the first 6 weeks post operation This should be differentiated from early postoperative mechanical bowel obstruction: Occurs within the first 6 weeks post operation Acute adhesions are responsible cause > 90% other causes are: Internal herniation intra-abdominal abscess intramural hematoma anastomatic edema and leak Difficult to differentiate by clinical presentation and X-ray so contrast study and CT scan helpful to differentiated between them

Epidemiology 1% of all hospitalization 3% of emergency surgical admissions More frequent in female patients because of gynecological-obstetric and pelvic surgical operations are important etiologies for post operative adhesions Adhesion is the most common cause of intestinal obstruction 80% of bowel obstruction due to small bowel obstruction and the most common causes are adhesion—hernia---neoplasm while 20% due to colon obstruction and the most common cause is CR-cancer 60-70% while 30% are diverticular disease and volvulus Mortality rate range between 3% for simple bowel obstruction to 30% when there is strangulation or perforation Recurrent rate vary according to method of treatment if conservative 12% while the operation treatment recurrent rate 8-32%

Path physiology Patho-physiology of bowel obstruction incompletely understood Bowel distension-decreased absorption-intralumial hypersecrtion and alteration in motility are found but yet the mechanisms are responsible not clear. In opposite to old explaination that pathophysiology of obstruction decreases in blood flow responsible for these changes , recently these changes in part related to increase in blood flow in association with intramural inflammatory reaction ( strong evidence suggests this inflammatory reaction plays key role).   Recent data show mucosal production of reactive oxygen metabolites which modulate not gut motility but also permeability may be one important mediator of some changes seen in simple bowel obstruction.

Etiology Mechanical bowel obstruction: Small bowel obstruction: Adhesion 60% Hernia 20% Neoplasm 5% Volvulus 5%. Others: IBD-GALL STONE-FOREIGN BODY-INTUSSUSCEPTION. Large bowel obstruction : Cancer 60%. Diverticular disease 15%. Volvulus 15%. Others: hernia –fecal impaction-inflammatory.

Etiology Functional bowel obstruction: three types Vascular occlusion ileus. Spastic ileus. ( intestine remain contracted and no propulsive) causes are: Uremia. Porphyria. Heavy metal poison. Adynamic or inhibition ileus : Post operation mostly after abdominal surgery Metabolic causes: DKA- hyponateremia-hypokalemia – hypomagnesaemia. Drugs: morphine –TCA-antacid-anticonvulsant. Intra-abdominal inflammation—sepsis—occult wound infection. Pneumonia—renal stone—retroperitoneal hematoma---fracture spine and ribs

Diagnosis History and physical examination: Four cardinal symptoms (pain-vomiting-distension and obstipation). Proximal obstruction earlier symptoms with prominent vomiting and less distension. While vomiting uncommon in colon obstruction till late stage Location and characteristic of pain differentiate between mechanical obstruction and ileus which sever –cramp and localized in mid of abdomen in mechanical while diffuse and mild in ileus. Examination : Vital signs.( PR-Temp-BP) Hydration status. Abdominal and rectal examinations

Diagnosis Laboratory : CBC: increase PCV (dehydration ) and increase in WBC. KFT: increase in BUN and creatinine . Lactate concentration-amylase-lactic dehydrogenase useful but not sensitive in evaluations of bowel obstruction especially to rule out necrosis Serum concentration of phosphate--intestinal fatty acid binding protein and isoforms of creatine phosphokinase (isoform B): identify presence of intestinal cell necrosis but the specificity and sensitivity still note accurate. ABG: metabolic and respiratory acidosis.

Diagnosis Radiological : Upright CXR with supine and upright abdominal radiographs:initial imaging study. CXR : Detect extra-abdominal condition present with bowel obstruction e.g. pneumonia. Presence of pneumoperitoneum indicates perforated viscus. Abdominal X-RAY Small bowel considered dilated when diameter more than 3 cm while proximal colon 9 cm and the sigmoid 5 cm. Dilated small bowel tend to be in the central portion of abdomen recognized by presence plicae circularis. Dilated colon tend to be in the periphery of abdomen and recognized by haustral marking. Can be diagnostic in 50-80% of patients The cause of bowel obstruction can often determined Presence of pneumobilia suggest G.S ileus. Sigmoid and cecal volvulus produce pathognomnic images.

Diagnosis Contrast studies: Computed tomography: Indications are controversial. Identify site and often the cause of obstruction. Differentiate between colonic and distal small bowel obstruction Differentiate between ileus-partial and complete obstruction. Computed tomography: Recently become valuable in B.O especially when plain films failed in diagnosis or suspect strangulation. Sensitivity 93% and specificity 100% Accuracy 94% in diagnosis of BO

Treatment Resuscitation. Conservative treatment Previous surgery. Incomplete obstruction. Advanced malignancy. Uncertain diagnosis. Indications for surgery Generalized or localized peritonitis. Perforation. Irreducible hernia. Palpable mass. Virgin abdomen. Closed loop Failure to improve.

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