1、AnatomyThe jejunal mucosa is relatively thick with prominent plicae circulares;the mesenteric vessels form only one or two arcades with long vasa recta.The ileum is smaller in circumference and has thinner walls;the mesenteric vessels form multiple vascular arcades with short vasa recta.Blood supply
2、 to the jejunoileum and distal duodenum is entirely from the superior mesenteric artery,which courses anterior to the third portion of the duodenum.The celiac artery supplies the proximal duodenum.Physiology Motility:Peristalsis consists of intestinal contractions passing aborally at a rate of 1 to
3、2 cm/seccontractions initiated by the migrating myoelectric complex(MMC)under the control of both neural and humoral pathways ENDOCRINE FUNCTIONObstruction Etiology:Common causes of small bowel obstruction in industrialized countries:Clinical Manifestations and Diagnosis Cardinal symptoms:colicky ab
4、dominal pain nausea vomiting abdominal distention failure to pass flatus and fecesPhysical Exam distended abdomen peristaltic waves minimal or no bowel sounds Mild abdominal tenderness with/without a palpable mass Exam to rule out incarcerated hernias Rectal examRadiologic and Laboratory Examination
5、s Plain abdominal radiographs:accuracy60%-dilated loops of small intestine without evidence of colonic distention -multiple air-fluid levels,often in a stepwise pattern -demonstrate the cause of the obstruction CT:for more complex casesPlain abdominal film shows complete bowel obstruction caused by
6、a large radiopaque gallstone(arrow)obstructing the distal ileum.CT scan of the abdomen of a patient with a mechanical bowel obstruction secondary to an abscess in the right lower quadrant(arrow).Multiple dilated and fluid-filledloops of small bowel are noted.Simple Vs Strangulating Obstruction“Class
7、ic”signs of strangulation:-tachycardia-fever-Leukocytosis-a constant,noncramping abdominal painDifferentiation of partial from complete SBO Partial SBO:pass flatus or liquid stools Complete SBO:obstipation Differentiation of Proximal /distal SBO pain:epigastric/periumbilical area vomiting:prominent/
8、later onset distention:no/predominateTreatment Medical and surgical management The overlapping sequence:investigation resuscitation operation The timing of operation depends on three factors:-duration -opportunity of vital organ function -risk of strangulationMedical Management Nasointestinal /nasog
9、astric intubation Intravenous fluids/blood plasma administration Broad-spectrum antibiotics administrationSurgical principles The nature of problem determines approach to management of SBO.The criteria of determining bowel viability:color,motility,arterial pulsation If questionable,released and placed,re-examined
