Intestine 7 and 8 ppt.pdf

Diverticular disease Bowel Obstruction Intestine 7&8 Dr Thiri Tin 15 August 2022 DIVERTICULAR DISEASE Diverticular disease Acquired pseudo- diverticular outpouchings of the colon mucosa and submucosa 90% occur in the si...

Diverticular disease Bowel Obstruction Intestine 7&8 Dr Thiri Tin 15 August 2022 DIVERTICULAR DISEASE Diverticular disease Acquired pseudo- diverticular outpouchings of the colon mucosa and submucosa 90% occur in the sigmoid colon, but the whole colon may be affected. True diverticula, such as Meckel diverticulum involve all three layers of the colonic wall. Multiple - diverticulosis Diverticular disease Risk factors Rare in persons younger than age 30 Common in those older than age 60 Disease is much less common in Japan as well as developing countries (?dietary differences). Pathogenesis Colonic diverticula result from: unique structure of the colonic muscularis propria There are focal discontinuities in the inner circular muscle layer at sites where nerves and arterial vasa recta penetrate External longitudinal layer of the muscularis propria is arranged in three bands - taeniae coli. elevated intraluminal pressure Sigmoid colon » elevated by exaggerated peristaltic contraction, » enhanced by low-fiber diets » Reduced stool bulk. Leads to mucosal herniation through the anatomic weak points in the muscularis propria. Morphology Macroscopically Small, flask-like outpouchings 0.5 to 1 cm in diameter Regular distribution alongside the taeniae coli Most common in the sigmoid colon May be missed on casual inspection compressible easily emptied of fecal contents often surrounded by the fat-containing epiploic appendices Morphology Microscopy Thin wall flattened or atrophic mucosa compressed submucosa attenuated or totally absent muscularis propria Hypertrophy »circular layer of the muscularis propria in the affected bowel segment is common. Complications Obstruction Inflammation, producing diverticulitis and peridiverticulitis Increased pressure within an obstructed diverticulum can lead to perforation Complications of complications With or without perforation segmental diverticular disease-associated colitis fibrotic thickening in and around the colonic wall stricture formation. Perforation pericolonic abscesses sinus tracts peritonitis. Clinical features Most are asymptomatic May present with Intermittent cramping continuous lower abdominal discomfort constipation abdominal distention sensation of not being able to completely empty the rectum alternating constipation and diarrhea that can mimic IBS Minimal chronic or intermittent blood loss, massive hemorrhage BOWEL OBSTRUCTION Bowel obstruction May occur at any level The small intestine is most often involved (narrow lumen) Aetiology 80% of mechanical obstruction -: Hernias, intestinal adhesions, intussusception, and volvulus. 10% to 15%-: Tumors, infarction, and strictures, for example, Crohn disease. Bowel obstruction Clinical features Abdominal pain and distention Vomiting Constipation. Course of disease Surgical intervention is usually required in cases where the obstruction has a mechanical basis or is associated with bowel infarction. Hernia Weakness or defect in the abdominal wall may lead to protrusion of a serosa-lined pouch of peritoneum Hernia sac Acquired hernias Anteriorly Inguinal and femoral canals Umbilicus Sites of surgical scars – Incisional hernia Common, occurring in up to 5% of the population Most frequent cause of intestinal obstruction worldwide. Inguinal hernia Inguinal hernias Indirect inguinal hernia vs Direct hernia Hesselbach’s triangle. Boundaries of Hesselbach’s triangle: laterally: inferior epigastric artery inferiorly: inguinal ligament medially: lateral border of rectus abdominis. Cough reflex Distinction between inguinal and femoral hernias relationship of hernia to the pubic tubercle inguinal hernias lie above and medially. femoral hernias lie below and laterally. Femoral hernias are more common in females. Complications Irreducible  Hernia contents cannot be manipulated back into abdominal cavity Incarcerated  herniated tissue becomes permanently trapped in the hernia sack Obstruction  the lumen of hollow viscera is blocked (normal blood supply) Strangulated  cut-off of arterial and venous blood supply, leading to ischaemic infarction Complications Pathogenesis of strangulated hernia: Pressure at the neck of the pouch impairing venous drainage of the entrapped viscus resultant stasis and oedema increase the bulk of the herniated loop permanent entrapment (incarceration) and, arterial and venous compromise (strangulation), and infarction may occur. Other late complications: Perforation, fistula formation, rupture of hernia (within sac or to overlying skin) Complications Adhesions Cause Fibrous adhesions are most often acquired, but can be congenital in rare cases. Surgical procedures, infection, or other causes of peritoneal inflammation, such as endometriosis. Pathology Fibrous bridges create closed loops through which other viscera may slide and become entrapped, resulting in internal herniation. Complications Obstruction Strangulation Infarction Volvulus Twisting of a loop of bowel about its mesenteric point of attachment BOTH luminal and vascular compromise Thus - obstruction AND infarction Occurs most often in large redundant loops of sigmoid colon, followed by the cecum, small bowel, stomach, or, rarely, transverse colon.  Sigmoid volvulus Non-specific Ahaustral large, dilated loop of the colon Air-fluid levels. Specific coffee bean sign Frimann-Dahl sign liver overlap sign northern exposure sign  Intussusception Pathogenesis Occurs when a segment of the intestine, constricted by a wave of peristalsis, telescopes into the immediately distal segment. Once trapped, the invaginated segment is propelled by peristalsis and pulls the mesentery along. May progress to intestinal obstruction, compression of mesenteric vessels, and infarction. Causes Idiopathic - usually no underlying anatomic defect Cases have been associated with viral infection and rotavirus vaccines Due to reactive hyperplasia of Peyer patches and other mucosa-associated lymphoid tissue acting as the leading edge of the intussusception. Intraluminal mass or tumour that serves as the initiating point of traction. Diagnosis Contrast/air enemas can be used both diagnostically and therapeutically for idiopathic intussusception Surgical intervention is necessary when a mass is present. Thank you. Best of luck!