Intestinal ObstructionAhmed 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 questionsIs 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 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 obstruction Obstruction is:Partial or completeSimple or strangulated

Patho-physiology I8L of isotonic fluid received by the small intestines (saliva, stomach, duodenum, pancreas and hepatobiliary )7L absorbed2L enter the large intestine and 200 ml excreted in the faecesAir in the bowel results from swallowed air ( O2 & N2) and bacterial fermentation in the colon ( H2, Methane & CO2), 600 ml of flatus is releasedEnteric bacteria consist of coliforms, anaerobes and strep.faecalis.Normal intestinal mucosa has a significant immune roleDistension results from gas and/ or fluid and can exert hydrostatic pressure.In case of BO Bacterial overgrowth can be rapidIf mucosal barrier is breached it may result in translocation of bacteria and toxins resulting in bactaeremia, septaecemia and toxaemia.

Patho-physiology IIObstruction results in:Initial overcoming of the obstruction by increased paristalsisIncreased intraluminal pressure by fluid and gasVomiting sequestration of fluid into the lumen from the surrounding circulationLymphatic and venous congestion resulting in oedematous tissuesFactors 3,4,5 result in hypovolaemia and electrolyte imbalanceFurther: localised anoxia, mucosal depletion necrosis and perforation and peritonitis.Bacterial over growth with translocation of bacteria and its toxins causing bacteraemia and septicaemia.Decompress with NGTReplace lost fluidCorrect electrolyte abnormalitiesRecognise strangulation and perforationSystemic antibiotics.

Causes- Small Bowel

Small Bowel AdhesionsAccounts for 60-70% of All SBOResults 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 yearsColorectal Surgery 25%Gynaecological 20%Appendectomy 14%70% of patients had a single bandPatients with complex bands are more likely to be readmittedReadmission in surgically treated patients is 35%

HerniaAccounts for 20% of SBOCommonest 1. Femoral hernia 2. ID inguinal 3. Umbilical 4. Others: incisional and internal H.The site of obstruction is the neck of herniaThe 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:IncacerationSlidingObstructionStrangulation is noted by: Persistent painDiscolourationTendernessConstitutional symptoms

Other causesIBDGall stone IleusIntussusception

Large Bowel Obstruction

Aetiology: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

Sigmoid VolvulusColonic Obstruction

Radiological EvaluationNormal ScoutAlways request: Supine, Erect and CXRGas pattern:Gastric, Colonic and 1-2 small bowelFluid Levels:Gastric1-2 small bowelCheck gasses in 4 areas:CaecalHepatobiliaryFree gas under diaphragm RectumLook for calcificationLook for soft tissue masses, psoas shadowLook for fecal pattern

The Difference between small and large bowel obstruction

Role of CTUsed 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 obstructionThe degree of obstructionThe cause: volvulus, hernia, luminal and mural causesThe degree of ischaemiaFree fluid and gas

Ensure: patient vitally stable with no renal failure and no previous alergy to iodine

Role of barium gastrografin studies

As: follow through, enemaLimited use in the acute settingGastrografin is used in acute abdomen but is dilutedUseful in recurrent and chronic obstructionMay able to define the level and mural causes.Can be used to distinguish adynamic and mechanical obstructionBarium should not be used in a patient with peritonitis

How to initially investigate your patientLab:CBC (leukocytosis, anaemia, hematocrit, platelets)Clotting profileArterial blood gassesU& Crt, Na, K, Amylase, LFT and glucose, LDHGroup and save (x-match if needed) Optional (ESR, CRP, Hepatitis profileRadilogical:Plain xraysUSS ( free fluid, masses, mucosal folds, pattern of paristalsis, Doppler of mesenteric vasulature, solid organs)Other advanced studies (CT, MRI, Contrast studiessenior decision)ECG and other investigations for co-morbid factors

Understanding the clinical findings

Clinical Findings1. History

Persistent pain may be a sign of strangulationRelative and absolute constipation

Clinical Findings2. Examination

Initial Management in the ERResuscitate: Air way (O2 60-100%)Insert 2 lines if necessaryIVF : Crytloids at least 120 ml/h. (determined by estimated fluid loss and cardiac function). Add K+ at 1mmmol/kgDraw blood for lab investigationsInform a senior member in the team.NPO.Decompress with Naso-gastric tube and secure in positionInsert a urinary catheter (hourly urinary measurements) and start a fluid input / output chartIntravenous antibiotics (no clear evidence)If concerns exist about fluid overloading a central line should be insertedFollow-up lab results and correction of electrolyte imbalanceThe patient should be nursed in intermediate careRectal tubes should only be used in Sigmoid volvulus.

Indications for SurgeryImmediate intervention:Evidence of strangulation (hernia.etc)Signs of peritonitis resulting from perforation or ischemia

In the next 24-48 hoursClear indication of no resolution of obstruction ( Clinical, radiological).Diagnosis is unclear in a virgin abdomen

Intermediate stageThe cause has been diagnosed and the patient is stabalised

Legal issues and consent

IleusAssociated with the following conditions:Postoperative and bowel resectionIntraperitoneal infection or inflammationIschemiaExtra-abdominal: Chest infection, Myocardia infarctionEndocrine: hypothyroidism, diabetesSpinal and pelvic fracturesRetro-peritoneal haematomaMetabolic abnormalities:HypokalaemiaHyponatremiaUraemiaHypomagnesemiaBed riddenDrug induced: morphine, tricyclic antidepressants

Is this an ileus or obstructionClinical featuresIs 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 distendedIs there gas in the rectumAre further investigasions (CT or Gastrografin studies) helpful in showing an obstruction.

Does the patient improve on conservative measures

Example of ileus