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Y4: Colorectal surgery > Bowel obstruction > Flashcards

Bowel obstruction Flashcards

1
Q

Describe bowel obstruction?

A
  • Mechanical impedance to the normal propulsive action through the intestine
  • Once occluded, dilatation of the proximal bowel occurs
  • This leads to secretion of large volumes of electrolyte-rich fluid into the bowel
    • Can be mistaken for diarrhoea
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2
Q

What is a closed loop obstruction?

A
  • If there is a second obstruction proximally
    • eg volvulus or obstruction with a competent ileocaecal valve
  • Surgical emergency as the bowel will continue to distend until the bowel wall becomes ischaemic and perforates
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3
Q

What is functional obstruction / paralytic ileus?

A
  • When the bowel is not mechanically blocked but does not work properly
    • eg inflammation, electrolyte derangement, recent surgery
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4
Q

What are the most common causes of obstruction in the small bowel?

A
  1. Adhesions
  2. Obstructed hernia
  3. Malignancy
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5
Q

What are the most common causes of obstruction in the large bowel?

A
  1. Colonic adenocarcinoma
  2. Diverticular disease
  3. Volvulus
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6
Q

How can causes of bowel obstruction be otherwise divided?

A
  • Intraluminal
    • Faecal concretion
  • Intramural
    • Colonic adenocarcinoma, crohns, diverticular strictures, volvulus
  • Extramural
    • Massive hernia, compression by tumour mass
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7
Q

Which cause of bowel obstruction are most commoon in children?

What cause of bowel obstruction is most common in people with crohns disease?

A

Intussusception

Inflammatory strictures

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8
Q

What are the cardinal clinical features of a bowel obstruction?

A
  • Abdominal pain
    • colicky or cramping, secondary to peristalsis, worse with movement
  • Vomiting
    • (less common with large bowel obstruction)
  • Constipation
  • Abdominal distension
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9
Q

Name some findings from examination that may be present in someone with bowel obstruction?

A
  • Focal tenderness on palpation
    • Guarding and rebound tenderness
  • Tympanic sound of percussion
  • Tinkling sounds on auscultation
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10
Q

Name some differentials for bowel obstruction?

A
  • Paralytic ileus
  • Toxic megacolon
  • Constipation
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11
Q

Describe the investigations which should be performed for suspected bowel obstruction?

A
  • FBC, CRP, U&Es, LFTs, Group and Save (G&S)
  • Venous blood gas (high lactate may indicate ischaemia)
  • CT with contrast of abdomen and pelvis
  • Abdominal x-ray (AXR)
  • Contrast fluoroscopy (in small bowel obstruction caused by adhesions from pervious surgery)
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12
Q

Why is CT imaging more useful than AXRs?

A
  • More sensitive for bowel obstruction
  • Can differentiate between mechnical and pseudo-obstruction
  • Can demonstrate site and cause of obstruction
  • May demonstrate the presence of metastases if caused by a malignancy
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13
Q

What are the AXR findings with someone who has a small bowel obstruction?

A
  • Dilated bowel >3cm
  • Central location
  • Valvulae conniventes visible
    • (lines completely crossing the bowel)
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14
Q

What are the AXR findings with someone who has a large bowel obstruction?

A
  • Dilated bowel (>6cm, or >9cm if at the caecum)
  • Peripheral location
  • Haustral lines visible
    • (lines not completely crossing the bowel)
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15
Q

Describe the management of bowel obstruction?

A
  • Urgent fluid resuscitation
  • Make patient nil by mouth
  • Insert NG tube to decompress the bowel
  • Analgesia + antiemetics
  • SURGERY may be required
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16
Q

How should patients with an adhesional small bowel obstruction from a previous surgery be managed?

A
  • Treated conservatively in the first instance
    • Unless evidence of strangulation or ischaemia
  • Obstruction in a patient who has not had previously surgery rarely settles without surgery
17
Q

What should be done if a patient’s bowel obstruction does not resolve within 24 hours?

A
  • A water soluble contrast study
    • If contrast does not reach colon by 6 hours then it is unlikely to resolve without surgery
18
Q

When is surgical intervention indicate in bowel obstruction?

A
  • Suspicion of ischaemia or closed loop obstruction
  • Small bowel obstruction in a patient with a virgin abdomen
  • Cause that requires surgical correction
    • (strangulated hernia or obstructing tumour)
  • Patients fail to improve with conservative measures within >48 hours
19
Q

Name some complications of bowel obstruction?

A
  • Bowel ischaemia
  • Bowel perforation, leading to faecal peritonitis
  • Dehydration and renal impairment
20
Q

Describe the digestive system components which receive blood from the Coeliac trunk? (T12)

A
  • Coeliac trunk -> hepatic artery
  • Hepatic artery -> gastroduodenal artery
  • Gastroduodenal artery
    • Blood to pylorus of the stomach and duodenum
21
Q

Describe the components of the digestive system which are supplied by the SMA? (L1)

A
  • Inferior pancreaticoduodenal artery supplies pancreas and distal duodenum
  • Jejunal and ileal arteries supply their namesakes
  • Ileocolic artery supplies terminal ileum, caecum and appendix
  • Right colic artery supplies the ascending colon
  • Middle colic artery supplies transverse colon
22
Q

Describe the compoennts of the digestive system which are supplied by the ingerior mesenteric artery? (L3)

A
  • Left colic artery supplies descending colon
  • Sigmoid artery supplies the sigmoid colon
  • Superior rectal artery supplies rectum to level of internal anal sphincter
23
Q

What is pictured here?

A
  • CT
  • Large bowel obstruction
    • Secondary to splenic flexure carcinoma
24
Q

What is pictured here?

A
  • AXR
  • Large bowel obstruction
25
Q

What is pictured here?

A
  • AXR
  • Small bowel obstruction
26
Q

Describe a major differential diagnosis for bowel obstruction?

A
  • Pseudo-obstruction
    • Exact mechanism unclear
    • Autonomic imbalance from decreased parasympathetic tone or excessive sympathetic output
27
Q

Management of pseudo-obstruction?

A
  • Stimulant enemas
  • Colonoscopic deflation
28
Q

Read the presentation of someone with large bowel obstruction

A
29
Q

How can you differentiate between pseudo-obstruction and obstruction?

A
  • Pseudo-obstruction has impressive abdominal distension with very little abdominal tenderness
  • Contrast enema can exclude mechanical causes almost always
30
Q

Differentials for small bowel obstruction?

A
  • Ileus
    • Less crampy abdominal pain
    • CT shows passage of contrast throughout small bowel and into retum
  • Large bowel obstruction
    • Very distended abdomen
    • X-ray shows dilated colon
31
Q

Read the presentations of small bowel obstruction

A
32
Q
A

Y4: Colorectal surgery (8 decks)

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