Surgery

Question 1

3 subtypes of bowel obstruction

Answer 1

• Simple (1 obstruction + no vasc compromise, partial or complete)
• Closed Loop (obs at 2 points, gross distension -> perforation)
• Strangulated (compromised blood supply)

Question 2

Causes Closed Loop Bowel Obstruction

Answer 2

Left colorectal cancer with competent ileocaecal valve

Volvulus

Question 3

Commonest Causes of SBO in Adults

Answer 3

Adhesions (60%) 
Hernia
CD
Malignancy
Appendicitis

Question 4

Causes SBO in Children

Answer 4

Appendicitis
Intusussception
Intestinal atresia
Volvulus

Question 5

Causes LBO

Answer 5

Colorectal Neoplasia (60%)
Diverticular stricture (20%)
Volvulus (5%) - Sigmoid in 80%

Question 6

Other causes of BO (Mechanical and Non-mechanical

Answer 6

Non mechanical = paralytic Ileus (SB)

Mechanical
- Intraluminal - impacted matter, gallstones

• Intramural - stricture (IBD, surgery), neoplasia
• Extramural - hernia, adhesions

Question 7

4 Symptoms of Bowel Obstruction

Answer 7

PAIN - central/colicky

DISTENSION

VOMITING

ABSOLUTE CONSTIPATION

Question 8

Signs of BO

Answer 8

Tachycardia (hypovolaemia, strangulation)
Dehydrated/hypovolaemic
Fever (inflammation/strangulation)
Surgucal scars
Hernias
Mass (neoplastic/inflammatory)
Bowel sounds (inc in mechanical obs, dec in ileus)

Question 9

PR findings in BO

Answer 9

empty rectum
rectal mass
hard impacted stool
blood from higher pathology

Question 10

Ix for BO

Answer 10

Bloods

• FBC - raised WCC
• U+E - dehydration, electrolyte
• amylase - high in strangulated/ perforated
• VBG - high lactate in strangulation
• G+S, clotting - if having surgery

Imaging

• AXR + erect film for fluid levels
• CT - show transition point

Gastrograffin studies

Colonoscopy

Question 11

AXR in SBO findings 
Diameter 
Location
Markings 
LB Gas
No loops
Fluid levels

Answer 11

Diameter >3cm
Location = central
Markings = valvulae coniventes (completely across)
LB Gas - absent 
No loops - many
Fluid levels - many, short

Question 12

AXR in LBO findings 
Diameter 
Location
Markings 
LB Gas
No loops
Fluid levels

Answer 12

Diameter >6 (>9 if caecum)
Location = peripheral
Markings = HAUSTRA (partially across)
LB Gas = present, not in rectum
No loops = few
Fluid levels = few, long

Question 13

Medical Mx BO

Answer 13

DRIP AND SUCK

NBM, IV fluids (dehydrated), NGT (aspiration), Catheterise (UO)

Question 14

Risk factors

Pathophysiology
…of Sigmoid Volvulus (LBO)

Answer 14

2* constipation
Neuropsych: MS, PD, psych
M>F, elderly

Sigmoid = S-shaped colon above rectum. Twisting sigmoid -> volvulus

Can lead to ischaemic bowel, necrosis, perforation

Question 15

Sign Sigmoid Volvulus on AXR

Answer 15

coffe bean/inverted U

Question 16

Mx Sigmoid Volvulus (LBO)

Answer 16

• sigmoidoscopy + flatus tube
• may need sigmoid colectomy (if bowel necrosis/failed decompression)
• if recurrent, elective sigmoidoscopy