Abdominal Pain and Bowel
Obstruction
Mike Goodwin
CRASH Course
October, 2010
Abdominal Pain - Approach
History
 Physical
 Labs
 Imaging
 Provisional Dx

History
PQRST AAA etx
 But don’t forget
 PSx
 Bowel/Gyne/Urol ROS

Physical Exam
Complete
 General appearance/vitals/H+N/Chest
 Abdo:
 Rigidity
 Rebound
 Guarding
 IPPA
 DRE / Pelvic / Groin / Flank-CVA

Labs

Everyone:
 CBC, lytes BUN Cr
 LFT, Bili, Amylase/Lipase, lactate
 Urinalysis
 Urine Preg
Imaging
AXR
 3-views
 Free air
 Distended bowel/air-fluid
 Calcifications (panc or kidney/ureter)
 US
 If GS disease suspected
 Lower abdo pain in female

Imaging

CT Abdo
 Test of choice for most patients
 Protocols to minimize contrast
nephropathy
Bowel Obstruction: Overview
History
 Etiology
 Pathophysiology
 Clinical presentation
 Imaging
 Management
 Special considerations

Causes of Small Bowel Obstruction
in Adults

Lesions Extrinsic to the Intestinal
Wall

Lesions Intrinsic to the Intestinal
Wall

Intraluminal/Obturator Obstruction
Lesions Extrinsic to the Intestinal
Wall




Adhesions (usually postoperative)
Neoplastic
 Carcinomatosis
 Extraintestinal neoplasms
Hernia
 External (e.g., inguinal, femoral, umbilical,
or ventral hernias)
 Internal (e.g., congenital defects such as
paraduodenal, foramen of Winslow, and
diaphragmatic hernias or postoperative
secondary to mesenteric defects
Intra-abdominal abscess
Lesions Intrinsic to the Intestinal
Wall



Congenital
 Malrotation
 Duplications/cysts
Inflammatory
 Crohn’s disease
 Infections
 Tuberculosis
 Actinomycosis
 Diverticulitis
Neoplastic
 Primary neoplasms
 Metastatic neoplasms

Traumatic
 Hematoma
Ischemic stricture
Miscellaneous
 Intussusception
 Endometriosis
 Radiation
enteropathy/stricture


Intraluminal/Obturator Obstruction

Gallstone

Enterolith

Bezoar
Common causes of small bowel
obstruction in industrialized countries.
Pathophysiology

Early: Increased motility & contractility
• Bowel dilation, fluid/lytes accumulate in lumen
and bowel wall
• Third spacing, intravascular volume depletion
Bowel obstruction
Increased intraluminal pressure
Decreased mucosal blood flow
Progressive Ischemia
Perforation & Peritonitis
Clinical Diagnosis

History
 Colicky abdominal pain
 Nausea / vomiting
 Abdominal distension
 Failure to pass flatus / feces
Physical Examination



Vitals: Tachycardia, hypotension
Abdomen:
 Distension
 Surgical scars
 Bowel sounds, increased or decreased
 Localized tenderness / rebound / guarding
suggests strangulation
 Hernia exam (ventral, groin, etc)
Rectal exam:
 Rectal masses
 Blood – suggesting ischemia, malignancy
Radiology

Plain Abdo X-Rays
 Confirm Diagnosis
 Localize obstruction to small bowel or
colon
 Evidence of complete or incomplete
Plain X-ray Features





Dilated Small Bowel (>3 cm)
Multiple air-fluid levels
Colonic gas pattern
 Normal / Dilated (Ileus or partial
obstruction)
 Absence of gas c/w complete obstruction
*Thickened bowel wall
*Pneumatosis intestinalis
*Suggests ischemia/strangulation
Plain X-rays





Lappas et al 2001
Review of 12 AXR findings with SBO
Findings:
Combination of
 Air-fluid levels of different heights in the
same bowel loop
 Mean air-fluid level diameter of 2.5 cm or
greater
Most predictive of a high-grade partial or
complete SBO
AXR Disadvantages
20-30% false negative rate
 Does not localize site of obstruction
 Does not establish etiology of
obstruction

CT Scan
95% sensitive
 96% specific
 95% accurate in determining the
presence of complete or high-grade
SBO
 Shows site and cause of obstruction in
95% of instances
 Less accurate for partial SBO (50%
some studies)

CT for SBO
CT performed with IV and PO contrast
 High-grade SBO seen even with no
contrast
 Lesser grades of obstruction seen with
PO contrast
 IV contrast for assessment of bowel wall
for signs of edema or ischemia.

CT Findings in Patients with Small Intestinal
Obstruction
Type of Obstruction
Simple obstruction,
partial or complete
Findings
Proximal
bowel dilatation
Discrete transition zone
with collapsed distal small
bowel
No passage of oral
contrast beyond the
transition zone
Little gas or fluid in colon
CT Findings in Patients with Small Intestinal
Obstruction
Type of Obstruction
Findings
Closed-loop obstruction
Bowel
Wall Changes
Mesenteric
Changes
U-shaped,
distended,
fluid-filled bowel loop
Whirl sign
Beak sign
Radial
distribution dilated
bowel loops
Thickened mesenteric
vessels converging toward
point of obstruction
CT Findings in Patients with SBO
Type of Obstruction
Strangulated Obstruction
Bowel Wall Changes
Mesenteric
Other
Changes
Findings
Bowel
wall thickening
Target sign
Pneumatosis intestinalis
Dec. bowel wall
enhancement
Blurring of mesenteric
vessels
Obliteration of mesentery
and vessels
Engorgement of
mesenteric vasculature
Ascites
When to Order CT?
Clinical presentation or abdominal films
nondiagnostic
 Hx of abdominal malignancy
 Immediate postsurgical patients
 Patients who have no history of
abdominal surgery

Barium / Contrast Studies
History of recurring obstruction
 Low-grade mechanical obstruction
 Defines the obstructed segment and
degree of obstruction

Gastrograffin Swallow in
Adhesive SBO, Cochrane
Review, 2004


Diagnostic
 Gastrofraffin seen in the cecum on AXR
within 24 hours predicts resolution
 Sensitivity of 0.96, specificity of 0.96
Therapeutic
 Hospital length of stay 2-3 days shorter in
non-operative patients
 Studies prospective, non-blinded
Simple Versus Strangulating
Obstruction
Classic signs:
 Fever
 WBC inc
 Constant Abdo pain
 But no parameters reliably detect
strang.
 CT findings detect late ischemic
changes

Treatment – Nonoperative



Fluid resuscitation
 IV resuscitation with isotonic saline
 Electrolyte replacement
 Monitor urine output
Tube decompression
 Empties stomach
 Reduces aspiration risk
 No benefit to long intestinal tubes
In partial obstruction: 60-85% success rate
Treatment - Operative
 Complete
obstruction
 Generally mandates operation
 Some have argued for
nonoperative approach in
selected patients
 12-24hr delay of surgery is safe
 >24hr delay is unsafe
Operative Technique
Dependent on underlying problem
 Adhesive band: Lysis of adhesions
 Incarcerated hernia: manual reduction
and closure of defect
 *Presence of hernia with SBO
mandates OR
 Malignant tumors: Difficult challenge
 Diverting stoma
 Resection / anastamosis
 Enteroenterostomy

Intestinal Viability at Surgery
Release obstructed segment
 Place in warm sponge x 15-20 minutes
 If normal colour and peristalsis: return to
abd
 Doppler probe adds little to clinical
judgment (Bulkley, 1981)
 Fluorescein may be useful in difficult
cases
 “Second look” in 24 hrs if questionable
viability or if clinically deteriorates post-op

Laparoscopy in Acute SBO?

Criteria:
Mild distension
 Proximal obstruction
 Partial obstruction
 Anticipated single-band obstruction
 No matted adhesions /
carcinomatosis

Special Considerations:
Recurrent Adhesions
Multiple agents have been tried, none
successful
 Hyaluronate-based membrane shown to
reduce severity of adhesion formation
(Becker, 1996; Vrigland, 2002)
 No studies yet to show reduction in
obstruction

Special Considerations:
Recurrent Adhesions
So far, best evidence to prevent
adhesions is good surgical technique:
 Gentle handling of bowel
 Avoid unnecessary dissection
 Exclusion of foreign material from
peritoneum
 Adequate irrigation / removal of debris
 Place omentum around site of surgery

Special Considerations: Acute
Post-op Obstruction




Obstructive symptoms after an initial return of
bowel function and resumption of oral intake
Technical complication versus adhesions
CT scan useful to evaluate for complications:
 Anastamotic leak
 Narrow anastomosis
 Internal hernia
 Obstruction at stoma
Early reoperation may be indicated
Acute Adhesive Postoperative
Obstruction
Difficult to distinguish from ileus
 Incidence 0.7%
 Highest incidence on small intestine
(3% – 10%)
 Present as early as POD 4
 Usually partial SBO
 CT preferred modality

Acute Postoperative
Obstruction (Adhesive)
80% spontaneous resolution of
symptoms
 4% of patients required more than 2
weeks of treatment
 SBO after laparoscopy: suspect hernia
at trocar site

Surgery for Malignant Bowel
Obstruction in Advanced
Gynaecological and Gastrointestinal
Cancer






Cochrane Review:2004
Role of surgery controversial
No firm conclusions from many retrospective
case series
Control of symptoms varies from 42% to over
80
Rates of re-obstruction, from 10-50%, though
time to re-obstruction was often not included
Continues to be a challenging problem
Steroids in Advanced Gyne/GI
Cancer With SBO





Cochrane Review of prospective data (89
patients)
Trend, not statistically significant, for
resolution of bowel obstruction using
corticosteroids
No statistically significant difference in
mortality
NNT 6
Morbidity associated with steroids appears
low
Summary
Guidelines for Operative and
Nonoperative Therapy
Emergent Operation
Incarcerated, strangulated hernia
 Peritonitis
 Pneumatosis
 Pneumoperitoneum
 Suspected / proven strangulation
 Closed-loop obstruction
 Complete bowel obstruction

Urgent Operation
Progressive bowel obstruction after
conservative measures started
 Failure to improve with conservative
therapy in 24-48 hours
 Early post-op technical complications
(not adhesions)

Operation Usually Delayed
Safely
Postoperative adhesions
 Immediate post-op obstruction
(adhesive)
 Acute exacerbation of Crohn’s dx,
diverticulitis, radiation enteritis
 Chronic, recurrent partial obstruction

Large Bowel Obstruction
Cancer
 Cancer
 Cancer (>90%)
 Other things
 Sigmoid Volvulus (5%)
 Diverticular Disease (3%)

Large Bowel Obstruction
Approach
 Contrast Enema
 CT Abdo
 Treat underlying cause

Acute Pseudo-Obstruction


Common ward consult
Predisposing
Conditions:






Surgery
Trauma
Infection
Cardiac (CHF/MI)
Neurological (PD, SCI,
MS, AD
Metabolic (↓K/Na)
Ogilvie’s Syndrome
Meds Assoc w/Ogilvie’s
 Narcotics
 Anticholinergic
 TCA
 Chlorpromazine
 Levodop
 Ca++ blockers
 Clonidine
Ogilvie’s Initial Tx:
 Correct fluid and lyte
 NPO/NG
 Rectal tube
 Limit offending
medications

>80% success
Ogilvie’s Treatment
Neostigmine
 2 mg IV
 Atropine at bedside
 Monitored bed
 Patient supine, on
bedpan 
 90% success rate
Colonoscopy
 If neostigmine fails
 Decompression
Surgery
 Last resort; rarely
needed
 If ischemia/perforation