Intestinal Obstruction Ahmed Badrek-Amoudi FRCS
The common ScenarioA 50 year old gentleman presentswith abdominal pain, distension andabsolute constipation. Withrepeated episodes of vomiting.His vital sign were stable, abdomendistended with diffuse tendernessbut minimal peritonism. BowelSounds are hyperactive.The plain abdominal xray was takenon admission.
What are your objectives?You should be able to address the following questions1. Is this bowel obstruction or ileus?2. Is this a small or large bowel obstruction?3. Is this proximal or distal obstruction?4. What is the cause of this obstruction?5. Is this a complex or simple obstruction?6. How should I start investigating my patient?7. What is the role of other supportive investigations?8. What is my immediate/ intermediate treatment plan?9. What are the indications for surgery?10. 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 promptassessment, resuscitation and intensive monitoringObstruction 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 obstructionObstruction 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 IIObstruction results in: 1. Initial overcoming of the obstruction by increased paristalsis 2. Increased intraluminal pressure by fluid and gas 3. Vomiting 4. sequestration of fluid into the lumen from the surrounding circulation 5. Lymphatic and venous congestion resulting in oedematous tissues 6. Factors 3,4,5 result in hypovolaemia and electrolyte imbalance 7. Further: localised anoxia, mucosal depletion necrosis and perforation and peritonitis. 8. 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
INTUSSUSCEPTIONInversion of the bowel upon itself secondary toa leading pointJuvenile Intussusception most often idiopathic Also secondary to Meckel"s diverticulumPresents 6 months to 2 years of age As early as 1 monthAcute painful episodes followed by periods oflethargyWhen incarcerated progress to continuouslethargyMay or may not have “currant-jelly” stool But often stool is heme positiveRule out with a left lateral Decubitus film
Large Bowel Obstruction •Distinguishing ileus from mechanical obstruction is challenging •According to Leplac’s law: maximum pressure is at the it’s maximum diameter. Cecum is at the greatest risk of perforation •Perforation results in the release of formed feaces with heavy bacterial contaminationAetiology:1. Carcinoma: The commonest cause, 18% of colonic ca. present with obstruction2. 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 Volvulus4. Hernia.5. Congenital : Hirschusbrung, anal stenosis and agenesis
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: 1. Caecal 2. Hepatobiliary 3. Free gas under diaphragm 4. Rectum Look for calcification Look for soft tissue masses, psoas shadow Look for fecal pattern
The Difference between small and large bowel obstruction Large bowel Small Bowel•Peripheral ( diameter 8 cm max) •Central ( diameter 5 cm max)•Presence of haustration •Vulvulae coniventae •Ileum: may appear tubeless
SymptomsThe four cardinal features of intestinal obstruction: -abdominal pain -vomiting -distension -constipationVary according to:-location of obstructionage of obstructionunderlying pathologyintestinal ischemia
SymptomsAbdominal pain colicky in nature, around the umbilicus in SBO while inthe lower abdomen in LBO if it becomes continuous, think about perforation orstrangulationVomiting -starts early in SBO and late in LBO -vomitus starts with clear color then becomes thick, brownand foul ( faeculent)-more with lower or complete obstruction -diarrhea may be present with partial obstructionDistension -more with lower obstruction
SymptomsConstipation -more with lower or complete obstruction -diarrhea may be present with partial obstruction-either absolute (no feces or flatus)<-cardinal in absoluteIOor relative (flatus passed)Distension -more with lower obstruction
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 gastrografinstudies 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 investigateyour 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 The Universal Features Colicky abdominal pain, vomiting, constipation (absolute), abdominal distension. Complete HX ( PMH, PSH, ROS, Medication, FH, SH) High Distal small bowel Colonic •Pain is rapid •Pain: central and •? Preexisting change colicky in bowel habit •Vomiting copious and •Vomitus is feculunt •Colicky in the lower contains bile jejunal •Distension is severe abdomin content •Vomiting is late •Visible peristalsis •May continue to pass •Distension prominent •Abdominal distension is limited or localized flatus and feacus •Cecum ? distended before absolute constipation •Rapid dehydration• Persistent pain may be a sign of strangulation• Relative and absolute constipation
Clinical Findings2. Examination General Abdominal Others•Vital signs: •Abdominal Systemic examination P, BP, RR, T, Sat distension and it’s If deemed necessary. pattern •CNS•dehydration •Hernial orifices •Vascular•Anaemia, jaundice, •Visible peristalsis •GynaecologicalLN •Cecal distension •muscuoloskeltal•Assessment of •Tenderness,vomitus if possible guarding and•Full lung and heart reboundexamination •Organomegaly •Bowel sounds –High pitched –Absent •Rectal examination
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 SurgeryImmediate intervention:• Evidence of strangulation (hernia….etc)• Signs of peritonitis resulting from perforation or ischemiaIn the next 24-48 hours• Clear indication of no resolution of obstruction ( Clinical, radiological).• Diagnosis is unclear in a virgin abdomenIntermediate stageThe 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 orobstructionClinical 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