4.Intestinal Obstruction- Causes

7/30/2019 4.Intestinal Obstruction- Causes

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INTESTINAL

OBSTRUCTIONSProfessor Panna Lal Saha

Professor of Surgery & Head

Department of Surgery

BGC Trust Medical College

Chittagong


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Intestinal Obstruction

Professor Panna Lal Saha

Professor of Surgery & Head

Department of SurgeryBGC Trust Medical College

Chittagong


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The common Scenario
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Definition

Intestinal obstructions are a

partial or complete blockage ofthe small or large intestine,

resulting in failure of thecontents of the intestine to pass

through the bowel normally.


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Introduction and Definitions

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


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Acute intestinal obstruction

This term is often used to describe intestinal obstruction of short

duration, in a patient who has not previously undergone any

abdominal surgery.

The importance of lack of previous abdominal surgery is that the

obstruction is much less likely to settle on non operative

management.

Sub-acute intestinal obstruction

This term is often used to describe intestinal obstruction of shortduration, in a patient who has previously undergone abdominal

surgery. The importance of previous surgery is that the obstruction is

most likely due to adhesions, is often incomplete and will often

settle without operative intervention.Chronic intestinal obstruction

This term is often used to describe intestinal obstruction of longer

duration and would typically be seen in a patient with large bowel

obstruction who has an incompetent ileo-caecal valve.


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Patho-physiology I

8L of isotonic fluid received bythe small intestines (saliva,

stomach, duodenum, pancreas

and hepatobiliary ) 7L absorbed

1L enter the large intestine and

200 ml excreted in the faeces


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Patho-physiology I

Air in the bowel results fromswallowed air ( O2 & N2) andbacterial fermentation in the colon

( H2, Methane & CO2), 600 ml of

flatus is released

Enteric bacteria consist ofcoliforms, anaerobes and strep.

faecalis. Normal intestinal mucosa has a

significant immune role


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Patho-physiology I

Distension results from gas and/ orfluid and can exert hydrostaticpressure.

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 inbactaeremia, septaecemia andtoxaemia.


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Patho-physiology II

Obstruction results in:1. Initial overcoming of the

obstruction by increasedperistalsis

2. Increased intra luminalpressure by fluid and gas

3. Vomiting

4. Sequestration of fluid intothe lumen from thesurrounding circulation


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Patho-physiology II

Obstruction results in:

5. Lymphatic and venous congestionresulting in oedematous tissues

6. Factors 3,4,5 result inhypovolaemia and electrolyteimbalance

7. Further: localised anoxia, mucosaldepletion necrosis and perforation

and peritonitis.8. Bacterial over growth withtranslocation of bacteria and itstoxins causing bacteraemia and

septicaemia.


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Causes- Small BowelExtraluminaluraluminalPostoperativeadhesionsCongenitaladhesionsHerniaVolvulus

Neoplasimslipomapolypsleiyomayomahematomalymphomacarcimoidcarinomasecondary Tumors

CrohnsTBStrictureIntussusceptionCongenital

F. BodyBezoarsGall stoneFood ParticlesA. lumbricoides


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Causes of strangulation


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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.


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ADHESIVE INTESTINAL

OBSTRUCTION


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ADHESIVE INTESTINAL

OBSTRUCTION


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ADHESIVE INTESTINAL

OBSTRUCTION


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Small Bowel Adhesions

As early as 4 weeks post laparotomy. Themajority of patients present between 1-5years

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%


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Hernia

Commonest1. Femoral hernia

2. 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.


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Hernia

Ischaemia occurs initially by venous occlusion,

followed by oedema and arterialc ompromise.

Strangulation is noted by: Persistent pain

Discolouration

Tenderness

Constitutional symptoms


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Other causes

IBDGall stone IleusIntussusception
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Large Bowel Obstruction

Distinguishing ileus from mechanicalobstruction is challenging

According to Leplacs 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


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Large Bowel Obstruction

1. Congenital : Hirschsprungs disease, analstenosis and agenesis

2. Hernia.

3. Volvulus:

A. Sigmoid Volvulus:

Results from long redundant,

faecaly loaded colon with a narrow pedicle.

B. Caecal Volvulus

4. Benign stricture: Due to Diverticular disease,

Ischemia, Inflammatory bowel disease.

5. Carcinoma: The commonest cause, 18% of

colonic ca. present with obstruction


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Sigmoid Volvulus Colonic Obstruction


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Radiological Evaluation

Normal ScoutAlways request: Supine,

Erect and CXR

Gas pattern: Gastric,

Colonic and 1-2 small

bowel

Fluid Levels: Gastric

1-2 small bowel
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Radiological Evaluation

Normal ScoutCheck gases 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
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The Difference between small

and large bowel obstruction

Small BowelLarge bowel

Central ( diameter 5 cm max)

Vulvulae coniventae

Ileum: may appear tubeless

Peripheral ( diameter 8 cm max)

Presence of haustration


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Role of barium gastrografin

studies

As: followthrough, enema

Limited use in theacute setting

Gastrografin isused in acuteabdomen but isdiluted

Barium should not be used ina patient with peritonitis


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Role of barium gastrografin

studies

Useful in recurrentand chronic

obstruction May able to define

the level and muralcauses.

Can be used todistinguishadynamic andmechanicalobstruction

Barium should not be used ina patient with peritonitis


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How to initially investigate

your patient Lab:

CBC (leukocytosis, anaemia, hematocrit, platelets)

U& Crt, Na, K, Amylase, LFT and glucose, LDH

Group and save (x-match if needed)

Optional Liver function test

Radilogical: Plain xrays

USS ( free fluid, masses, mucosal folds, pattern ofparistalsis, Doppler of mesenteric vasulature, solid

organs) Other advanced studies (CT, MRI, Contrast

studiessenior decision)

ECG and other investigations for co-morbidfactors


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Understanding the

clinical findings

Cli i l Fi di


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Clinical Findings

1. History

The Universal Features

Colicky abdominal pain,

vomiting,

constipation (absolute),

abdominal distension.

Cli i l Fi di


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Clinical Findings

1. History

Colonic

Preexisting

change in

bowel habitColicky in the

lower abdomin

Vomiting is late

Distensionprominent

Cecum ?

distended

Distal small

bowel

Pain: central and

colicky

Vomitus isfeculunt

Distension is

severe

Visible peristalsis

May continue to

pass flatus and

feacus before

absolute

constipation

High

Pain is rapid

Vomiting copious

and contains bilejejunal content

Abdominal

distension is

limited or localized

Rapid dehydration

Cli i l Fi di


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Clinical Findings

1. History

Persistent pain may be

a sign of strangulation

Relative and absoluteconstipation


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Initial Management in the ER

Resuscitate:

Air way (O2 60-100%)

Insert 2 lines if necessary

IVF : Crystalloids at least 120 ml/h.

(determined by estimated fluid loss andcardiac function). Add K+ at 1mmmol/kg


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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


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Intravenous antibiotics (no clear

evidence)

If concerns exist about fluid overloading

a central line should be inserted

Follow-up lab results and correction ofelectrolyte imbalance

The patient should be nursed in

intermediate care

Rectal tubes should only be used in

Sigmoid volvulus.


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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


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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


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Is this an ileus or

obstructionClinical 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) helpfulin showing an obstruction.

Does the patient improve on conservative measures


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Example of ileus
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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
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4.Intestinal Obstruction- Causes

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