Intestinal Obstruction Ahmed Badrek-AmoudiFRCS
The common Scenario 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. The plain abdominal xray was taken on admission.
What are your objectives? You should be able to address the following 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? • What are the medico-legal and ethical issues that I should address?
Introduction and Definitions • Accounts for 5% of all acute surgical admissions • Patients are often extremely ill requiring prompt assessment, resuscitation and intensive monitoring • Obstruction A mechanical blockage arising from a structural abnormality that presents a physical barrier to the progression of gut contents. • Ileus is a paralytic or functional variety of obstruction Obstruction is: Partial or complete Simple or strangulated
Patho-physiology I • 8L of isotonic fluid received by the small intestines (saliva, stomach, duodenum, pancreas and hepatobiliary ) • 7L 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 • Distension results from gas and/ or fluid and can exert hydrostatic pressure. • In case of BO 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.
Patho-physiology II Obstruction results in: • Initial overcoming of the obstruction by increased paristalsis • Increased intraluminal pressure by fluid and gas • Vomiting • sequestration of fluid into the lumen from the surrounding circulation • Lymphatic and venous congestion resulting in oedematous tissues • Factors 3,4,5 result in hypovolaemia and electrolyte imbalance • Further: localised anoxia, mucosal depletion necrosis and perforation and peritonitis. • Bacterial over growth with translocation of bacteria and it’s toxins causing bacteraemia and septicaemia. • Decompress with NGT • Replace lost fluid • Correct electrolyte abnormalities • Recognise strangulation and perforation • Systemic antibiotics.
Small Bowel Adhesions • Accounts for 60-70% of All SBO • 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%
Hernia • 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. • Ischaemia occurs initially by venous occlusion, followed by oedema and arterialc ompromise. • Attempt to distinguish the difference between: • Incaceration • Sliding • Obstruction • Strangulation is noted by: • Persistent pain • Discolouration • Tenderness • Constitutional symptoms
Other causes Intussusception Gall stone Ileus IBD
Large Bowel Obstruction Aetiology: 1. Carcinoma: The commonest cause, 18% of colonic ca. present with obstruction 2. Benign stricture: Due to Diverticular disease, Ischemia, Inflammatory bowel disease. 3. Volvulus: 1. Sigmoid Volvulus: Results from long redundant, faecaly loaded colon with a narrow pedicle 2. Caecal Volvulus 4. Hernia. 5. Congenital : Hirschusbrung, anal stenosis and agenesis
Sigmoid Volvulus Colonic Obstruction
Radiological Evaluation Normal Scout Always request: 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 calcification Look for soft tissue masses, psoas shadow Look for fecal pattern
Role of CT • Used with iv contrast, oral and rectal contrast (triple contrast). • Able to demonstrate abnormality in the bowel wall, mesentery, mesenteric vessels and peritoneum. • It can define • the level of obstruction • The degree of obstruction • The cause: volvulus, hernia, luminal and mural causes • The degree of ischaemia • Free fluid and gas • Ensure: patient vitally stable with no renal failure and no previous alergy to iodine
Role of barium gastrografin studies Barium should not be used in a patient with 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
How to initially investigate your patient • Lab: • CBC (leukocytosis, anaemia, hematocrit, platelets) • Clotting profile • Arterial blood gasses • U& Crt, Na, K, Amylase, LFT and glucose, LDH • Group and save (x-match if needed) • Optional (ESR, CRP, Hepatitis profile • Radilogical: • Plain xrays • USS ( free fluid, masses, mucosal folds, pattern of paristalsis, Doppler of mesenteric vasulature, solid organs) • Other advanced studies (CT, MRI, Contrast studies……senior decision) • ECG and other investigations for co-morbid factors
Clinical Findings1. History • Persistent pain may be a sign of strangulation • Relative and absolute constipation
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 • Inform a senior member in the team. • 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 • The patient should be nursed in intermediate care • Rectal tubes should only be used in Sigmoid volvulus.
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 stabalised
Ileus • Associated with the following conditions: • 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
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 investigasions (CT or Gastrografin studies) helpful in showing an obstruction. Does the patient improve on conservative measures