a o og ogy o n es na
s ruc on
Major Causes of Intestinal Obstruction Mechanical Obstruction Hernias (internal, external) Intestinal adhesions Intussusception Volvulus
Other Less Frequent Conditions Tumours Inflammatory strictures Obstructive gallstones, fecaliths Congenital strictures, atresia Congenital bands Meconium in cystic fibrosis Imperforate anus
Intestinal Obstruction Single Obstruction Mechanical obstruction Without occlusion of blood supply
Strangulation Interfere mesenteric blood supply (most serious complication) Blood supply compromised
Disruption of tips of intestinal villi
Obstruction of venous outflow
Venous thrombosis Etiology of Intestinal Obstruction Luminal Atresia Malrotation Inflammatory bowel disease Intussusception Medication (KCl, NSAIDs) Gall stone ileus Foreign bodies Meckels diverticulum Hypertrophic pyloric stenosis Strictures Neoplasms Constipation Enteroliths Bezoars Intestinal Obstruction Herniation
Blood extravasate into bowel wall, mesentery
Extraluminal Adhesions Hernias Volvulus Carcinomatosis Pancreatitis Retroperitoneal haematoma Abscess, sepsis Enteric neuropathy Aganglionosis Hirschprung disease
Luminal bacteria invades submucosa
Intestinal wall
Peritoneal cavity
Endotoxin
Macrophage
IL1
Shock
Adhesions
Inguinal Direct, Indirect Reducible swelling, irreducible swelling Strangulated (blood supply)(gangrene) Femoral Female Umbilical Birth weight infants Internal Mesenteric Diaphragmatic Epigastric (extraperitoneal) Cardinal Signs (Intestinal Obstruction) Pain Abdominal Intermittent, severe, colicky Poorly localised around umbilicus Distention Accumulation of gas, liquid Upper small bowel stomach distended, vomiting Lower small bowel central abdomen distended Vomiting High Small Bowel Obstruction Lower Small Bowel Obstruction Vomiting early, frequent, copious, Vomiting delayed, less frequent colicky, colicky, minimal distention (large absorptive surface above obstruction, obstruction, fluid slowly collects) Dehydration Semidigested food Faeculent vomiting Mucoid gastric juice (bacterial growth) Yellowish bile Large Bowel Obstruction Vomit delayed 2-3 days Becomes faeculent soon (faecal) Signs of dehydration uncommon Absolute Constipation No faeces, No flatus 1 or 2 evacuation may occur after obstruction (contents distal to obstruction) After that, absolute constipation
Intussusceptions
Intussusceptions Children Common 80% Ileo-ileal Peyer patches
Adult Tumours Benign Malignant Infraction y y
Volvulus
Twisting of bowel upon itself Location Small intestine (most common) nd Sigmoid colon (2 common) rd Caecum (3 common) Segments with long mesenteric attachment y y y
Distention Occur proximal to site of obstruction Normal peristalsis, evacuation continues distally Later, empty intestine becomes immobile Composition Gaseous swall owed air 68% Diffusion from blood 22% Bacterial, digesti on product 10% Amount of air from all sources/ day 7-10L Expelled in flatus 0.5L Amount of fluid ingested + secretions 8-10L/D Intestinal secretions alone 7.5-8L/D Absorption of fluid Occur in distal jejunum, distal jejunum, ileum In high small bowel obstruction Mucosal surface area distal to obstruction not available for reabsorption Fluid continues to accumulate proximally (distention, vomited) Multiple fluid levels Pockets of gas trapped above pools of liquid (in loops of bowel) Multiple fluid levels erect X-ray of abdomen
Circulatory Changes in Intestinal Obstruction Simple Obstruction Intraluminal pressure in bowel lumen
Closed Loop Obstruction Intraluminal pressure
Affect blood flow, Intramural circulation
All circulatory changes in simple obstruction (accelerated)
Loop
Venous return is impeded Mucosa congested
Capillary rupture Haemorrhage
Example Stenosing carcinoma of distal colon Pressure (in closed loop)
All layers of intestine involved
Mucosal anoxia
Necrosis, perforation (antimesenteric border) Hasten the process Thrombosis of intramural, mesenteric veins Intraluminal Fluid Accumulation (due to) Osmolality (from enzymatic breakdown of intestinal contents) Alteration Alteration in blood supply Digestive secretions Inability to absorb H2O, electrolytes at normal rate Prostaglandins ( fluid secretion) Failure of flui d, electrolyte absorption Progressive contraction of extracellular fluid, vomiting Fluid depletion, visceral vascular volume Hypovolaemic shock y y y
Pseudo-Obstruction Adynamic ileus Paralytic ileus (functional) Abdominal operation Trauma Peritonitis Ischaemia Spinal cord injury Systemic infection Secondary pseudo-obstruction Affect smooth muscle scleroderma Affecting neural Hirschprung disease, Chagas disease, Amyloidosis Endocrine DM, hypothyroidism Pharmacological agents Irradiation, jejuno-ileal bypass, infarct y y y y y y y
y y y y y
Ileus Cessation of normal intestinal motility Causes Post-operative Post-operative ileus (POI) Sympathetic nervous sytem (mediate POI) Component Threshold Threshold Spinal reflex Prevertebral gangionectomy (abolished by splanchnectomy) Large Bowel Obstruction Obstruction often gradual > 40 y/o Pain minimal, absent (unless there is peritonitis) peritonitis) Progressive constipation LOA, LOW Nausea, vomiting Most common causes Volvulus Acute diverticulitis Colorectal carcinomas Examination Abdomen distended Abdomen non-tended (unless peritonitis supervenes) y y y
Strangulation Major arterial supply occluded
Ulceration, Ulceration, Gangrene
Perforate caecum (pressure is highest)
Dusky
Black (gangrene)
