Intestinal obstruction Flashcards
(13 cards)
Define intestinal obstruction
Normal flow on normal flow of intestinal contents is interrupted. It can be classified pathologically into mechanical
obstruction (dynamic) or function obstruction (adynamic)
Mechanical : there is obstruction
Functional : there is no obstruction
mechanical (peristalsis working against a mechanical obstruction)
functional (absence of peristalsis without obstruction)
Small bowel obstruction is more common than large bowel. What is the common causes of SBO ?
Adhesion , hernia , strictures and cancers
How bowel obstruction manifestated ?
simple obstruction > bowel ischemia > gangrenous bowel > perforation
Bowel ischemia is resulted from compromised arterial supply .
4 cardinal symptoms of IO (AbCDV)
Abdominal pain
Constipation
Distension (Abdominal)
Vomiting
Pathophysiology of abdominal pain
- Visceral pain secondary to distention – colicky in nature
- Centred on the umbilicus (small bowel) or lower abdomen (large bowel)
- Progression to more focal, constant pain → need to rule out complications (i.e. perforation / peritonitis)
In term of vomiting , what is the different between small bowel and large bowel?
▪ Proximal Small Bowel Obstruction: greenish blue, bile stained (obstruction distal to ampulla of vater)
▪ Distal Small Bowel Obstruction: brown and increasingly foul smelling (feculent = thick brown foul)
▪ Large Bowel: uncommon to have vomiting esp. if competent ileocecal valve, usually late symptom
Proximal : distal to ampulla -> bile is released into duodenum
Distal : foul smell and brown color arise due to the stagnation and decomposition of intestinal contents in the affected portion of the bowel
Ileocecal valve : the valve that separate the small and large intestine
Abdominal distension :
does it prominent in large bowel or distal small bowel obstruction ? and why
Prominent in large bowel ,
because :
i)large bowel contents are typically solid , consisting of feces which can cause noticeable distension
ii) large intestine has a wider diameter than the small intestine ,when obstruction occur here , enlargement is more noticeable
Differential diagnosis of IO
-mechanical causes
Mechanical causes :
-gallstones
-parasites
-foreign body
-stricture (abnormal narrowing of a tubular structure within the body)
-intraperitoneal bands and adhesions
-hernia
-volvulus (twisted intestine)
hernia cause IO when there is strangulation
Differential diagnosis of IO
-functional causes
Paralytic ileus
-Hypo-mobility w/o obstruction leading to accumulation of gas & fluids with associated distention,
vomiting, absence of bowel sounds and obstipation
Pseudoobstruction
-Recurrent obstruction (usually colon) that occurs in the absence of a mechanical cause or acute intraabdominal disease
-eg : toxic megacolon
How to differentiate SB and LB in abdominal X ray
Small intestine
: centrally located
:circular or transverse folds of mucosa ( valvulae conniventes)
Large intestine
:peripherally located
:haustration (d/t contraction of colon muscles)
Investigation - Biochemical
Biochemical (FAULBIA)
- FBC: leukocytosis with left shift may indicate complications
- U/E/Cr: any dehydration/electrolyte imbalances due to (or acute renal failure from dehydration)
- ABG: acidosis from bowel ischemia or alkalosis due to vomiting (more for pyloric stenosis in children)
- Lactate (trend): surrogate measurement for anaerobic respiration, important if suspecting of ischemic bowel
- Inflammatory markers – CRP, procalcitonin
- Blood cultures (if fever, tachycardia, hypotension)
- Amylase – ? acute pancreatitis (AXR may just show small bowel dilatation)
Imaging Investigation
i)erect CXR
-to look for free air under diaphragm , any aspiration pneumonia
ii) abdominal CXR
- In general ≥ 5 fluid levels are diagnostic of intestinal obstruction
-Assess for complications: Rigler’s Sign / double-wall sign → pneumoperitoneum. Thumb-print sign / pneumatosis
intestinalis → ischemic bowel
iii)CT abdomen and pelvis
-▪ Able to identify transition point, severity of obstruction, any fecalization in small bowel proximal to transition, closed-loop
obstruction
▪ Able to identify complications – pneumoperitoneum, ischemic bowel (no bowel wall enhancement), necrotic bowel
(pneumatosis intestinalis)
▪ Target sign – intussusception
▪ Whirl sign – rotation of SB mesentery in volvulus
▪ Air in distal bowel with no transition point – paralytic ileus
Management
i)ABC - give supplemental oxygen oxygenation may be affected due to splinting of the diaphragm
ii)Keep NBM - because bowel rest can help the recovery of the patient
iii)NG tube insertion - large bore to prevent small diameter tube blocked
iv)IV fluid rehydration
