a presentation about intestinal obstruction for general surgery students

1. Intestinal Obstruction
Ahmed Badrek-Amoudi FRCS

2. 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.

3. What are your objectives?
You should be able to address the following questions
1. 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?

4. 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

5. 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.

6. Patho-physiology II
Obstruction 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.

7. Causes- Small Bowel
Extraluminal
Mural
Luminal
Postoperative
adhesions
Congenital
adhesions
Hernia
Volvulus
Neoplasims
lipoma
polyps
leiyomayoma
hematoma
lymphoma
carcimoid
carinoma
secondary Tumors
Crohns
TB
Stricture
Intussusception
Congenital
F. Body
Bezoars
Gall stone
Food Particles
A. lumbricoides

8. 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%

9. 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

10. Other causes
IBD
Gall stone Ileus
Intussusception

11. 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
•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 contamination

12. Sigmoid Volvulus Colonic Obstruction

13. 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

14. The Difference between small
and large bowel obstruction
Small Bowel
Large bowel
•Central ( diameter 5 cm max)
•Vulvulae coniventae
•Ileum: may appear tubeless
•Peripheral ( diameter 8 cm max)
•Presence of haustration

15. 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

16. Role of barium gastrografin
studies
• 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
Barium should not be used in
a patient with peritonitis

17. 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

18. Understanding the
clinical findings

19. Clinical Findings
1. History
• Persistent pain may be a sign of strangulation
• Relative and absolute constipation
The Universal Features
Colicky abdominal pain, vomiting, constipation (absolute), abdominal
distension.
Complete HX ( PMH, PSH, ROS, Medication, FH, SH)
Colonic
•? Preexisting change
in bowel habit
•Colicky in the lower
abdomin
•Vomiting is late
•Distension prominent
•Cecum ? distended
Distal small bowel
•Pain: central and
colicky
•Vomitus is feculunt
•Distension is severe
•Visible peristalsis
•May continue to pass
flatus and feacus
before absolute
constipation
High
•Pain is rapid
•Vomiting copious and
contains bile jejunal
content
•Abdominal distension
is limited or localized
•Rapid dehydration

20. Clinical Findings
2. Examination
Others
Systemic examination
If deemed necessary.
•CNS
•Vascular
•Gynaecological
•muscuoloskeltal
Abdominal
•Abdominal
distension and it’s
pattern
•Hernial orifices
•Visible peristalsis
•Cecal distension
•Tenderness,
guarding and
rebound
•Organomegaly
•Bowel sounds
–High pitched
–Absent
•Rectal examination
General
•Vital signs:
P, BP, RR, T, Sat
•dehydration
•Anaemia, jaundice,
LN
•Assessment of
vomitus if possible
•Full lung and heart
examination

21. 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.

22. 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

23. Legal issues and consent

24. 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

25. 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

26. Example of ileus