1. Intestinal Obstruction: Pathophysiological Basis of Clinical Features. Dr Imran Javed. MBBS, FCPS Surgery. Associate Professor Surgery. Fiji National University.

2. Definitions Intestinal Obstruction: A mechanical blockage arising from a structural abnormality that presents a physical barrier to the progression of gut contents. Partial or complete Simple or strangulated Ileus: is a paralytic or functional variety of obstruction. 3. Patient Presentation A 50 year old gentleman presents with abdominal pain, distension and absolute constipation with repeated episodes of vomiting. His vital sign were stable, abdomen distended with diffuse tenderness but minimal peritonism. Bowel Sounds are hyperactive. 4. Common Questions Is this bowel obstruction or ileus? Is this a small or large bowel obstruction? Is this proximal or distal obstruction? What is the cause of this obstruction? Is this a complex or simple obstruction? How should I start investigating my patient? What is the role of other supportive investigations? What is my immediate/ intermediate treatment plan? What are the indications for surgery? 5. Intestinal Physiology 8L of isotonic fluid received by the small intestines (saliva, stomach, duodenum, pancreas and hepatobiliary ) 6L re-absorbed 2L enter the large intestine and 200 ml excreted in the faeces Air in the bowel results from swallowed air ( O2 & N2) and bacterial fermentation in the colon ( H2, Methane & CO2), 600 ml of flatus is released Enteric bacteria consist of coliforms, anaerobes and strep.faecalis. Normal intestinal mucosa has a significant immune role 6. Pathological events Distension results from gas and/ or fluid and can exert hydrostatic pressure.(Laplace Law) In case of Bowel Obstruction, Bacterial overgrowth can be rapid If mucosal barrier is breached it may result in translocation of bacteria and toxins resulting in bactaeremia, septaecemia and toxaemia. 7. Pathological Basis of clinical events. Initial overcoming of the obstruction(CONSTIPATION) by increased peristalsis(COLICKY ABDOMINAL PAIN) (ABDOMINAL DISTENTION) & (VOMITING)Increased intraluminal pressure by fluid and gas, sequestration of fluid into the lumen from the surrounding circulation Lymphatic and venous congestion resulting in edematous tissues (TISSUE EDEMA). Vomiting result in hypovolemia and electrolyte imbalance (ILEUS). Further: anoxia, mucosal necrosis and perforation and peritonitis.(COMPLICATIONS) Bacterial over growth with translocation of bacteria and its toxins causing bacteremia and septicemia.(SYSTEMIC SIGNS) 8. Principles of Management SUCK & DRIP. Decompress with Naso-gatric Tube or Flatus Tube. Replace lost fluid in vomiting or 3rd space. Correct electrolyte abnormalities (Hypcholremic, Hyopnatremic, Hypokalemic, metabolic Alkalosis) Recognize strangulation (Hernia) and perforation (Peritonitis) Systemic antibiotics (Broad Spectrum). 9. Causes of Small Bowel Obstruction. Luminal Causes: Foreign Body Bezoars Gall stone Food Particles Ascaris lumbricoides 10. Causes of Small Bowel Obstruction Mural Causes: Neoplasms( lipoma, polyps, leiomyoma, hematoma, lymphoma, carcinoid, carcinoma, secondary Tumors) Crohns Disease. Intestinal Tuberculosis. Stricture Intussusception Congenital (Atresia) 11. Causes of Small Bowel Obstruction Extra-mural: Postoperative adhesions. Congenital adhesions & Bands. Hernia (External & Internals, Incisional) Volvulus (Around base of Mesentery) 12. Small Bowel Adhesions Accounts for 60-70% of All Small Bowel Obstructions. Results from peritoneal injury, platelet activation and fibrin formation. Associated with starch covered gloves, intraperitoneal sepsis, haemorrhage and wash with irritant solutions iodine and other foreign bodies. As early as 4 weeks post laparotomy. The majority of patients present between 1-5 years Colorectal Surgery 25% Gynaecological 20% Appendectomy 14% 70% of patients had a single band Patients with complex bands are more likely to be readmitted Readmission in surgically treated patients is 35% 13. Hernias Accounts for 20% of SBO Commonest 1. Femoral hernia 2. ID inguinal 3. Umbilical 4. Others: incisional and internal H. The site of obstruction is the neck of hernia The compromised viscus is with in the sac. Ischemia occurs initially by venous occlusion, followed by edema and arterial compromise. Attempt to distinguish the difference between: Incarceration, Sliding, Obstruction. Strangulation is noted by: Persistent pain, Discoloration, Tenderness, Constitutional symptoms 14. Other Common causes of Small Bowel Obstructions. Intussusception: part of the intestine has invaginated into another section of intestine. Gall stone Ileus: caused by an impaction of a gallstone within the lumen of the small intestine. Which enters the gut lumen via cholecysto-enteric fistula. Crohns Disease:is a type of inflammatory bowel disease (IBD) 15. Large Bowel Obstruction Distinguishing ileus from mechanical obstruction is challenging According to Laplace's law: maximum pressure is at the its maximum diameter. Cecum is at the greatest risk of perforation Perforation results in the release of formed feaces with heavy bacterial contamination 16. Causes of Large Bowel Obstructions. 1. Carcinoma: The commonest cause, 18% of colonic carcinomas present with obstruction 2. Benign stricture: Due to Diverticular disease, Ischemia, Inflammatory bowel disease. 3. Volvulus: A. Sigmoid Volvulus: Results from long redundant, faecaly loaded colon with a narrow pedicle B. Caecal Volvulus 4. Hernia. 5.Congenital:Hirschusbrung, anal stenosis and agenesis 17. Diagnosis of Intestinal Obstruction Clinical Features: Colicky Abdominal Pain, Absolute Constipation, Vomiting & Abdominal Distension. Radiology: Plain X-ray Films (Erect & Supine). Contrast studies (Single & Double) Diagnostic as well as therapeutic. Ultrasound Scan & Doppler Studies. CT Scan (Plain & Contrast). MRI. 18. Other Investigations Hematological: CBC, ESR, Electrolytes, Urea & Creatinine Levels, LFTs, RFTs, Blood Glucose level, Serum Amylase level, cultures etc. Pathological: Urine Analysis & Cultures, FNAC or Biopsy for enlarged Lymph Nodes. Laparoscopic: Diagnostic as well as therapeutic. 19. Comparative Features in History Colonic Pre-existing change in bowel habit Colicky in the lower abdomen Vomiting is late Distension prominent Cecum ? distended Distal small bowel Pain: central and colicky Vomitus is feculent Distension is severe Visible peristalsis May continue to pass flatus and feaces before absolute constipation High Pain is rapid Vomiting copious and contains bile jejunal content Abdominal distension is limited or localized Rapid dehydration 20. Examination Findings Abdominal Abdominal distension and its pattern Hernial orifices Visible peristalsis Cecal distension Tenderness, guarding and rebound Organomegaly Bowel sounds High pitched Absent Rectal examination General Examination Vital signs: P, BP, RR, T, Sat dehydration Anaemia, jaundice, LN Assessment of vomitus if possible Full lung and heart examination Systemic examination If deemed necessary. CNS Vascular Gynaecological muscuoloskeltal 21. Radiological Evaluation Views: Supine, Erect and CXR Gas pattern: Gastric, Colonic and 1-2 small bowel Fluid Levels: Gastric, 1-2 small bowel Check gasses in 4 areas: Caecal, Hepatobiliary, Free gas under diaphragm, Rectum Look for soft tissue masses, psoas shadow Look for fecal pattern 22. The Difference between small and large bowel obstructionCentral ( diameter 5 cm max) Vulvulae coniventae Ileum: may appear tubeless Peripheral ( diameter 8 cm max) Presence of haustration 23. US Scan & Doppler Studies Free fluid, Abdominal Masses, Intestinal mucosal folds, Intestinal pattern of peristalsis, Doppler of mesenteric vasculature, Solid organs evaluation. 24. Role of CT in Diagnosis Used with iv contrast, oral and rectal contrast (triple contrast). Able to demonstrate abnormality in the bowel wall, mesentery, mesenteric vessels and peritoneum. Ensure: patient vitally stable with no renal failure and no previous allergy to iodine. 25. Findings on CT Scan Abdomen It can define the level of obstruction The degree of obstruction The cause: volvulus, hernia, luminal and mural causes The degree of ischemia Free fluid and gas 26. How It looks like. 27. Barium & Gastrografin studies Barium should not be used in a patient with suspected peritonitis. As: follow through, enema: Limited use in the acute setting Gastrografin is used in acute abdomen but is diluted Useful in recurrent and chronic obstruction May able to define the level and mural causes. Can be used to distinguish adynamic and mechanical obstruction 28. Abdominal Contrast Study 29. Indications for Surgery Immediate intervention: Evidence of strangulation (hernia.etc) Signs of peritonitis resulting from perforation or ischemia In the next 24-48 hours: Clear indication of no resolution of obstruction ( Clinical, radiological). Diagnosis is unclear in a virgin abdomen Intermediate stage: The cause has been diagnosed and the patient is stabilized 30. Causes of Intestinal Ileus Postoperative and bowel resection Intraperitoneal infection or inflammation Ischemia Extra-abdominal: Chest infection, Myocardia infarction Endocrine: hypothyroidism, diabetes Spinal and pelvic fractures Retro-peritoneal haematoma Metabolic abnormalities: Hypokalaemia Hyponatremia Uraemia Hypomagnesemia Bed ridden Drug induced: morphine, tricyclic antidepressants 31. Is this an ileus or obstruction Clinical features: Is there an under lying cause? Is the abdomen distended but tenderness is not marked. Is the bowel sounds diffusely hypoactive. Radiological features: Is the bowel diffusely distended Is there gas in the rectum Are further investigations (CT or Gastrografin studies) helpful in showing an obstruction. Does the patient improve on conservative measures 32. Abdominal Plain X-Ray in Ileus 33. Initial Management in the ER Resuscitate: Air way (O2 60-100%) Insert 2 lines if necessary IVF : Crytloids at least 120 ml/h. (determined by estimated fluid loss and cardiac function). Add K+ at 1mmmol/kg Draw blood for lab investigations NPO. Decompress with Naso-gastric tube and secure in position Insert a urinary catheter (hourly urinary measurements) and start a fluid input / output chart Intravenous antibiotics (no clear evidence) If concerns exist about fluid overloading a central line should be inserted Follow-up lab results and correction of electrolyte imbalance 34. Surgical Options Exploratory Laparotomy. 35. Keep the dam flowing !!!!!!!!!