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
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
4. Introduction and Definitions
Accounts for 5% of all acute surgical admissions
Patients are often extremely ill requiring prompt
assessment, resuscitation and intensive
Obstruction A mechanical blockage arising from a
structural abnormality that presents a
physical barrier to the progression of gut
Ileus is a paralytic or functional variety of
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 )
2L enter the large intestine and 200 ml excreted in the
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
Normal intestinal mucosa has a significant immune role
Distension results from gas and/ or fluid and can exert
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
6. Patho-physiology II
Obstruction results in:
1. Initial overcoming of the obstruction by increased
2. Increased intraluminal pressure by fluid and gas
4. sequestration of fluid into the lumen from the surrounding
5. Lymphatic and venous congestion resulting in oedematous
6. Factors 3,4,5 result in hypovolaemia and electrolyte
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
7. Causes- Small Bowel
Luminal Mural Extraluminal
8. Small Bowel Adhesions
• Accounts for 60-70% of All SBO
• Results from peritoneal injury, platelet activation and fibrin
• Associated with starch covered gloves, intraperitoneal sepsis,
haemorrhage and wash with irritant solutions iodine and other
• 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%
• Accounts for 20% of SBO
• Commonest 1. Femoral hernia
2. ID inguinal
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:
• Strangulation is noted by:
» Persistent pain
» Constitutional symptoms
11. Large Bowel Obstruction
1. Carcinoma: The commonest cause, 18% of colonic ca. present
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
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
13. Radiological Evaluation
Always request: Supine, Erect and CXR
• Colonic and 1-2 small bowel
• 1-2 small bowel
Check gasses in 4 areas:
3. Free gas under diaphragm
Look for calcification
Look for soft tissue masses, psoas shadow
Look for fecal pattern
14. The Difference between small
and large bowel obstruction
Large bowel Small Bowel
•Peripheral ( diameter 8 cm max)
•Presence of haustration
•Central ( diameter 5 cm max)
•Ileum: may appear tubeless
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
• It can define
– the level of obstruction
– The degree of obstruction
– The cause: volvulus,
hernia, luminal and mural
– 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
• As: follow through, enema
• Limited use in the acute
• Gastrografin is used in
acute abdomen but is
• Useful in recurrent and
• May able to define the level
and mural causes.
• Can be used to distinguish
adynamic and mechanical
Barium should not be used in
a patient with peritonitis
17. How to initially investigate
• 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
• 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
• ECG and other investigations for co-morbid factors
19. Clinical Findings
• Persistent pain may be a sign of strangulation
• Relative and absolute constipation
The Universal Features
Colicky abdominal pain, vomiting, constipation (absolute), abdominal
Complete HX ( PMH, PSH, ROS, Medication, FH, SH)
•Pain is rapid
•Vomiting copious and
contains bile jejunal
is limited or localized
Distal small bowel
•Pain: central and
•Vomitus is feculunt
•Distension is severe
•May continue to pass
flatus and feacus
•? Preexisting change
in bowel habit
•Colicky in the lower
•Vomiting is late
•Cecum ? distended
20. Clinical Findings
P, BP, RR, T, Sat
vomitus if possible
•Full lung and heart
distension and it’s
If deemed necessary.
21. Initial Management in the ER
• 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+
• Draw blood for lab investigations
• Inform a senior member in the team.
• 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
• 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
• 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,
• Diagnosis is unclear in a virgin abdomen
The cause has been diagnosed and the patient is stabalised
• Associated with the following conditions:
• Postoperative and bowel resection
• Intraperitoneal infection or inflammation
• Extra-abdominal: Chest infection, Myocardia infarction
• Endocrine: hypothyroidism, diabetes
• Spinal and pelvic fractures
• Retro-peritoneal haematoma
• Metabolic abnormalities:
• Bed ridden
• Drug induced: morphine, tricyclic antidepressants
25. Is this an ileus or
• Is there an under lying cause?
• Is the abdomen distended but tenderness is not marked.
• Is the bowel sounds diffusely hypoactive.
• 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