GI - bowel obstruction

Question 1

what kinds of obstruction are there?

Answer 1

• mechanical blockage GI tract:
  ● “simple” - one obstructed bit no vascular compromise
  ● “strangulated” - vessel occlusion also occurs, pt iller than you would expect, more localised sharp pain + peritonism
  ● “closed-loop” - proximal and distal compression (incarcerated hernias and volvulus) ↑ risk perforation
• functional:
  ● “pseudo-“ - ↓ bowel motility in absence of mechanical obstruction
• pseudo-obstruction [large bowel] can be due to ↑ sympathetic tone - acute known as Ogilvie’s syndrome, decompressed with colonoscopy
• paralytic ileus [small bowel] is due to neurohormonal factors often following surgery/illness, and only needs conservative support

Question 2

causes of obstruction?

Answer 2

luminal:
● faeces
● GS ileus
● large polyp
● foreign body

intramural:
● ***tumour COMMON LARGE B.
● ***strictures - Crohn's/diverticulitis LARGE B.
● intussusception
● infarction

extramural:
● ***adhesions COMMON SMALL B.
● ***strangulated hernia COMMON SMALL B.
● ***volvulus LARGE B.
● compression

Question 3

Hx: patient presents firstly with colicky abdominal pain , then either V or distention, then constipation +/- obstipation (no flatus or faeces)?

Ex: tender abdo, with tympanic (not dull) percussion, tinkling bowel sound?

Answer 3

bowel obstruction
(small = 1st pain, 2nd V)
(large = 1st pain, 2nd distension/C)

Question 4

Ex: if silent bowel sounds?

Answer 4

ileus

Question 5

Ex: if tinkling bowel sounds?

Answer 5

bowel obstruction

Question 6

Ex: if scars/ hernia?

Answer 6

possible cause (adhesions)

Question 7

Ex: if fever or shock?

Answer 7

perforation

Question 8

what if patient has a competent ileocecal valve (20 percent of pop)?

Answer 8

can potentially be very ill, septic, dehydrated, and hemodynamically unstable

valve prevents a decompression of the large bowel into the small bowel and leads to a closed loop obstruction

↑ perforation risk

Question 9

is small or large bowel more likely to perforate?

Answer 9

large (usually at caecum)

Question 10

Ix bowel obstruction?

Answer 10

● bloods
- ↑ wbc, ↓ Hb
- ↓ K+ from V
- ↑ lactate (ischaemia in strangulation)
- LFTs/amylase/lipase (ΔΔ GB disease)
- coag, group + save if pre-op
● imaging
- **SUPINE AXR (erect shows fluid levels)
- **erect CXR ( ΔΔ air under diaphragm if perforation)
- **A-P CT (dilated bowel, and transition zone)
+/- barium enema (volvulus; bird’s beak sign)

Question 11

Ix: supine AXR finds dilated loops of bowel >6cm in daimeter, with incomplete markings across surface (haustra)?

Answer 11

large bowel obstruction

Question 12

Ix: supine AXR finds a coffee-bean V shape pointing from LIF up towards the RUQ?

Answer 12

sigmoid volvulus

Question 13

Ix: supine AXR finds the large bowel dilated up and out of the RIF, replaced there by small bowel?

Answer 13

ceacal volvulus

Question 14

in the lower colon, which bit connects to the small bowel, and which bit connects to the rectum?

Answer 14

caecum - small bowel (ileocecal)

sigmoid - rectum

Question 15

Ix: supine AXR finds dilated, central loops of bowel >4cm, with complete markings across surface like coins (valvulae conniventes)?

Answer 15

small bowel obstruction

Question 16

Ix: supine AXR shows a “double-wall” appearance to to bowel, and erect CXR shows pneumoperitoneum?

Answer 16

perforation (double wall = Rigler’s sign)

• bowel obstruction
• duodenal ulcer
• recent abdominal surgery

Question 17

if suspected CA or therapeutic relief of sigmoid volvulus?

Answer 17

endoscopy/sigmoidoscopy

Question 18

Tx bowel obstruction?

Answer 18

● supportive: “drip and suck”
- fluids, NG tube to empty stomach, fasting
- analgesia, Abx, thromboprophylaxis
- (ileus and small bowel obstruction conservatively at first)
● surgery:
- laparotomy (strangulation and large bowel- ASAP)
- adhesions should rarely need surgery

Question 19

Tx: when is surgery indicated ASAP?

Answer 19

● strangulation (emergency)
● generalised peritonitis
● perforation/imminent perforation (caecum >10cm)
● irreducible hernia
● caecal volvulus

Question 20

Tx: when is surgery indicated relatively quickly (<24 hrs but not ASAP0?

Answer 20

● failure to improve with drip and suck
● palpable mass
● virgin abdomen (no previous surgery)

Question 21

Tx: alternatives to surgery in bowel obstruction?

Answer 21

● sigmoid volvulus w/t peritonitis - rigid/flexible sigmoidoscopy (high recurrence - still needs endoscopy)
● expanding metal stents if unfit for surgery in CA

Question 22

cardinal Sx obstruction? (4)

Answer 22

1) V (N+anorexia)
2) Colic (early Sx)
3) C (distal)
4) abdominal distension (tinkling bowel sounds)

Question 23

main diff in Sx between large and small bowel obstruction?

Answer 23

small - early V, less distension, and pain higher up

large - pain more constant

Question 24

Sx of an ileus?

Answer 24

less pain, and no bowel sounds

Question 25

Sx of a strangulated obstruction?

Answer 25

● patient is iller than you would expect
● the pain is sharper. more constant and localised
●peritonism (fever, ↑ wbc)

Question 26

Ix: electrolyte imbalance to beware in obstruction?

Answer 26

↓ K+ from V

Question 27

Ix: risk of colonoscopy in bowel obstruction?

Answer 27

perforation!!

Question 28

causes of paralytic ileus?

Answer 28

abdo surgery
pancreatitis
spinal injury
↓ K+
↓ Na+
uraemia
peritoneal sepsis
TCAs

Question 29

Sx sigmoid volvulus?

Answer 29

often in elderly + C; rapid, severe, strangulated obstruction