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Year 3 > Intestinal obstruction & ileus (GI) > Flashcards

Intestinal obstruction & ileus (GI) Flashcards

1
Q

Define bowel obstruction.

A

Interruption of normal passage of bowel contents through the bowel, either due to a functional or mechanical obstruction

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2
Q

Define functional bowel obstruction (paralytic ileus).

A

Temporary disturbance of peristalsis - common complication after bowel surgery

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3
Q

Define mechanical bowel obstruction.

A

Due to a structural barrier e.g. tumour or adhesions

Can be classified as SBO (80%) or LBO (20%)

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4
Q

What are some causes of a small bowel obstruction? (6)

A
  • adhesions (from previous abdominal surgery) - most common
  • incarcerated hernias (e.g. inguinal)
  • gallstones (gallstone ileus)
  • Crohn’s disease (inflammatory phlegmon causes obstruction)
  • intestinal malignancy
  • appendicitis
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5
Q

What are some causes of a large bowel obstruction? (3)

A
  • malignant tumours e.g. colorectal carcinoma
  • diverticular disease (strictures)
  • sigmoid/caecal volvulus (360 degree twist –> closed loop obstruction –> ischaemia and necrosis)
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6
Q

How can bowel obstruction be classified (based on bowel wall)? (3)

A
  • intraluminal - faecal impaction, gallstone ileus, ingested foreign body
  • mural - Crohn’s disease, tumours, diverticulitis, inflammatory strictures, intussusception, lymphoma, Meckel’s diverticulum
  • extramural - strangulated hernia, volvulus, adhesions, peritoneal metastasis
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7
Q

What type of bowel obstruction is common after surgery?

A

Functional bowel obstruction (paralytic ileus) - temporary disturbance of peristalsis

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8
Q

What causes colicky abdominal pain and vomiting in bowel obstruction?

A

Resulting proximal dilatation of intestine + peristalsis

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9
Q

What causes constipation (and diarrhoea) in bowel obstruction?

A

Distal interruption of faecal flow –> constipation, hyperperistalsis distal to obstruction –> diarrhoea

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10
Q

What are both small and large bowel obstructions?

A

Medical emergencies

LBO = surgical emergency

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11
Q

What should we consider in all patients who present with large bowel obstruction?

A

Malignancy

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12
Q

What are the cardinal clinical features of mechanical bowel obstruction? (5)

A
  • colicky abdominal pain
  • vomiting
  • constipation (may be absolute - failure to pass flatus or stool)
  • abdominal distension - worse in LBO vs SBO
  • decreased bowel sounds (may be tympanic/high-pitched)
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13
Q

What signs are specific to small bowel obstruction? (2)

A
  • early onset bilious vomiting
  • tinkling bowel sounds (more common in early bowel obstruction)
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14
Q

What signs are specific to large bowel obstruction? (3)

A
  • late onset vomiting - may progress to faecal vomiting
  • absolute constipation (and earlier) - not passing wind/faeces
  • very distended abdomen
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15
Q

What may there be a history of in large bowel obstruction?

A

Possible malignant symptoms like change in bowel habit, weight loss, rectal bleeding

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16
Q

What signs of peritonitis might there be in bowel obstruction? (6)

A
  • localised or generalised guarding
  • fever
  • leukocytosis
  • tachycardia
  • metabolic acidosis
  • continuous pain
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17
Q

When would symptoms from adhesions vs post-operative ileus present?

A
  • adhesions - no symptoms until months/years after surgery
  • post-operative ileus - may occur sooner
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18
Q

What is the main clinical difference between paralytic ileus and mechanical bowel obstruction?

A
  • paralytic ileus (post-operative ileus) - complete absence of bowel sounds
  • mechanical bowel obstruction - tinkling bowel sounds
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19
Q

What might DRE show in bowel obstruction?

A

Hard faeces on DRE - faecal impaction or empty rectum in proximal bowel obstruction

20
Q

What are some risk factors for bowel obstruction? (5+3+2)

A
  • adhesions
  • incarcerated hernia
  • gallstone ileus
  • Crohn’s disease (also increased CRC risk)
  • appendicitis
  • malignancy - colorectal cancer
  • diverticular disease
  • volvulus
  • malrotation (–> midgut volvulus –> necrosis and death)
  • intussusception - ‘pinched off’ intestine
21
Q

What is the gold standard diagnostic investigation for bowel obstruction?

A

CTAP with IV contrast - definitive Ix that helps establish cause, order ASAP

22
Q

When is CTAP with IV contrast contraindicated?

A

Contrast agents contraindicated in AKI

23
Q

What is the first-line investigation for bowel obstruction if patient is haemodynamically unstable?

A

Erect AXR

24
Q

What does imaging show in small bowel obstruction?

A

Central finding, distended bowel in middle of abdomen with valvulae conniventes going all the way across

25
Q

What does imaging show in large bowel obstruction?

A

Peripheral finding, distended bowel around outside of abdomen with haustra (do NOT go all the way across, only halfway)

26
Q

What would imaging show in sigmoid volvulus (LBO)?

A

Coffee bean sign

27
Q

What is the 3,6,9 rule in bowel obstruction?

A

Upper limits:

  • small bowel: 3cm
  • large bowel: 6cm
  • caecum: 9cm
28
Q

What do we monitor after surgery for post-operative paralytic ileus?

A

U&Es (deranged electrolytes can contribute to development of postoperative ileus so check K, Mg and PO4)

29
Q

What other scan can we do in bowel obstruction?

A

Erect CXR to look for perforation (pneumoperitoneum)

30
Q

What do we check in U&Es due to vomiting from bowel obstruction?

A

Hyponatraemia and hypokalaemic metabolic alkalosis

31
Q

What bloods do we do in bowel obstruction to check for bowel ischaemia? (3)

A
  • elevated lactate and metabolic acidosis
  • leukocytosis
  • amylase can be raised in SBO (not just pancreatitis)
32
Q

What are some differential diagnoses for bowel obstruction? (11)

A
  • SBO - colicky central pain, early onset bilious vomiting, late onset constipation
  • LBO - colicky/constant pain, late onset bilious/faecal vomiting, very distended abdomen, constipation –> absolute constipation
  • paralytic ileus - less cramping, often post-operative (/systemic infection/meds)
  • infectious gastroenteritis - D&V
  • intestinal pseudo-obstruction - chronic, constipation, neurological meds e.g. amitriptyline
  • acute colonic pseudo-obstruction - distension w/o tenderness
  • acute appendicitis - RLQ pain, N&V
  • acute pancreatitis - epigastric pain –> back, vomiting, amylase&lipase
  • toxic megacolon - initial colitis, sepsis, thumbprinting on AXR
  • pseudomembranous colitis - Abx/immunosuppressant, foul-smelling diarrhoea
  • endometriosis
33
Q

When is thumbprinting seen on AXR?

A

Toxic megacolon

34
Q

What do we do first when approaching bowel obstruction management?

A

ABCDE approach

35
Q

What is the initial management for bowel obstruction? (5)

A
  • NBM
  • IV fluid resuscitation
  • electrolyte replacement
  • NG tube - decompression of bowel, prevents aspiration of vomit
  • supportive care: analgesia (morphine) + anti-emetics
36
Q

How can we remember the first-line medical management of small bowel obstruction?

A

‘Drip and suck’ - IV fluids and gastric decompression (NG tube)

37
Q

What can we give for bowel obstruction patients not fit for surgery?

A

Gastrograffin

38
Q

What definitive treatment is there for bowel obstruction?

A

Surgery (laparotomy) if complicated bowel obstruction (i.e. strangulation or ischaemic bowel signs)

39
Q

What medication should we avoid in those with bowel obstruction?

A

Metoclopramide

40
Q

When is laparoscopic surgery contraindicated in bowel obstruction?

A

Acute intestinal obstruction with dilated bowel loops

41
Q

When is emergency surgery indicated in bowel obstruction?

A

Those with adhesional obstruction/signs of peritonitis, hernia strangulation, bowel ischaemia or perforation

Surgery type depends on cause

42
Q

How do we manage volvulus (bowel obstruction)?

A

Flexible sigmoidoscopy

43
Q

What can small bowel obstruction quickly lead to?

A

Peritonitis

44
Q

What are some complications of bowel obstruction? (7)

A
  • bowel ischaemia (–> necrosis)
  • bowel perforation (secondary to necrosis)
  • peritonitis
  • sepsis
  • intra-abdominal abscess
  • short bowel syndrome (need supplemental nutrition)
  • death
45
Q

Describe the prognosis of bowel obstruction.

A

High risk of recurrence, mortality rate high in complicated bowel obstruction

Year 3 (191 decks)

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