2DefinitionAny 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.
3ClassificationCause of obstruction : mechanical or functional ( Ileus ).Duration of obstruction: acute or chronic.Extent of obstruction : partial or completeType of obstruction : simple or complex (closed loop and strangulation) .
4Mechanical obstruction There is physical blockage of intestinal lumen which due to:Intramural : congenital-tumor-hematoma-inflammatoryExtramural : adhesion-volvulus-hernia –abscess-hematomaLumen 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 tosimple obstruction (no vascular impairment)closed loop ( both ends are obstructed e.g volvulus)strangulation obstruction
5Functional 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 operationPostoperative 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.IDifferent anatomic segments of GIT also recover at different rates after manipulation and trauma :Small bowel within hours after operation.Stomach may take hr .Colon 3-5 days post op.
6Occurs within the first 6 weeks post operation This should be differentiated from early postoperative mechanical bowel obstruction:Occurs within the first 6 weeks post operationAcute adhesions are responsible cause > 90%other causes are:Internal herniationintra-abdominal abscessintramural hematomaanastomatic edema and leakDifficult to differentiate by clinical presentation and X-ray so contrast study and CT scan helpful to differentiated between them
7Epidemiology 1% of all hospitalization 3% of emergency surgical admissionsMore frequent in female patients because of gynecological-obstetric and pelvic surgical operations are important etiologies for post operative adhesionsAdhesion is the most common cause of intestinal obstruction80% 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 volvulusMortality rate range between 3% for simple bowel obstruction to 30% when there is strangulation or perforationRecurrent rate vary according to method of treatment if conservative 12% while the operation treatment recurrent rate 8-32%
8Path physiologyPatho-physiology of bowel obstruction incompletely understoodBowel 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.
10Etiology 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 surgeryMetabolic 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
11Diagnosis 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 stageLocation 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
12Diagnosis 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 necrosisSerum 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.
13Diagnosis 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-RAYSmall 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 patientsThe cause of bowel obstruction can often determinedPresence of pneumobilia suggest G.S ileus.Sigmoid and cecal volvulus produce pathognomnic images.
14Diagnosis Contrast studies: Computed tomography: Indications are controversial.Identify site and often the cause of obstruction.Differentiate between colonic and distal small bowel obstructionDifferentiate 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
15Treatment Resuscitation. Conservative treatment Previous surgery.Incomplete obstruction.Advanced malignancy.Uncertain diagnosis.Indications for surgeryGeneralized or localized peritonitis.Perforation.Irreducible hernia.Palpable mass.Virgin abdomen.Closed loopFailure to improve.