bowel obstruction Flashcards
(24 cards)
Differential diagnoses for a man who hasn’t opened bowels for 6 days and who has been vomiting
Bowel obstruction
Constipation
Paralytic ileus
Toxic megacolon
What is paralytic ileus
functional obstruction of bowel due to temporary paralysis which usually affects the whole bowel
-COmmon post op
What is toxic megacolon
Acute colonic distension
Due to acute colitis and system toxicity
Secondary to IBD or colonic infections such as C.Diff
What is bowel obstruction
Mechanical (physical) or functional (decreased bowel motility) blockage of the bowel, resulting in absolute constipation. There will be dilatation of proximal bowel with accumulation of fluid into the intestinal lumen
4 key symptoms of bowel obstruction
Nausea and vomiting
Colicky abdominal pain
Abdominal distension
Absolute constipation
How do the symptoms of small bowel obstruction present
Vomiting is early feature. Constipation is often late
How do symptoms of large bowel obstruction present
Vomiting is a late feature
Constipation and pain is early
Pain in supra-pubis
Signs of bowel obstruction (when examined)
Abdominal distension
Abdo tenderness (sharp and constant is a sign of ischaemia)
Central resonance to percussion
Tinkling bowel sounds when auscultating
Dehydration (vomiting and lack of fluid intake and third spacing)
What is ‘third spacing’ and why does ti cause dehydration
Bowel occlusion leads to gross dilatation of proximal limb. This leads to increased bowel peristalsis and increased secretions of electrolyte rich fluid into the bowel
-Can lead to hypokalaemia,
consequences of a strangulating obstruction
Blood supply compromised which leads to infarction and therefore perforation. BOwel contents released and can lead to peritonitis.
what are strangulating obstructions
Interruption of intestinal blood supply with simultaneous blockage of intestinal lumen
Signs of peritonitis
Colicky pain --> continuous Tachycardia Oyrexia Peritonism Decreased or absent bowel sounds Raised CRP AND WCC
What is a closed loop obstruction
Obstruction with two obstructed points.
\Bowel will become distended, stretching the bowel wall until it becomes ischaemic and perforates
What is the ileocaecal valve
Between small bowel and large bowel which stops the contents of large bowel back flowing
Complications concerning the ileocaecal valve
If large bowel becomes blocked and ileocaecal valve closes (competent), causes a closed loop obstruction
What is sigmoid volvulus
When bowel twists around itself which leads to a closed loop obstruction
mechanical bowel obstruction common causes
Adhesions Hernias Crohn's Malignancy Diverticular disease Volvulus
Exams and investigations for a suspected bowel obstruction
Bedside:
observations (dehydrated? shocked? infection or peritonitis)
-Abdo exam (distension, tenderness, rebound tenderness, central resonance, tinkling bowel sounds, dehydration, scars)
-Hernial orifices
-PR (obstructing mass)
Bloods:
- FBC (raised WBC= infection/inflammation due to perforation or impending perforation) Microcytic anaemia found in presence of underlying malignancy
- U&E (Hypokalaemia- colon secretes K+ and bicarbonate in exchange for na+ and h2- absorption. IF disrupted then hypokalaemia). Increased urea= severity of dehydration/renal failure
- CRP - infection/ perforation
- G&S and co-ag (pre surgery)
- VBG (metabolic derangement secondary to dehydration or excessive vomiting). High lactate- ischaemia
Basic imaging
-AXR
Erect CXR if perforation suspected
-CT
How to differentiate between small and large bowel in X-ray
Small- <3cm. HAs valvular conniventes. Lies in centre of abdo
Large- <6cm. Has haustra. Lies around edge of Abdo
What investigation should always be done in suspected bowel obstruction and why
CT- all obstruction is malignant until proven otherwise
Management of small bowel obstruction
Drip and such
Managemt. of large bowel obstruction
Surgery
What is a sign that ischaemia may be developing
Rebound tenderness
What is needed if a patient is vomiting during a small bowel obstruction
Patient requires a NG tube
