Intestinal obstruction and perforation

Question 1

How can intestinal obstruction be broadly classified?

Compare these

Answer 1

Mechanical: physical obstruction (increased peristalsis)

Non-mechanical: reduced or absent peristaltic

Question 2

List 4 causes of mechanical intestinal obstruction

Answer 2

1. Adhesions (small bowel)
2. Hernias (small bowel)
3. Malignancy (large bowel)
4. Volvulus (large bowel)]

+ diverticular disease, strictures (2^o Crohn’s), Intussusception

Question 3

List 3 causes of Non-mechanical intestinal obstruction

Answer 3

1. Paralytic ileus
2. Colonic Pseudo-obstruction (Ogilvie’s syndrome)
3. Neuromuscular

Question 4

Pathophysiology of obstruction?

Answer 4

Question 5

How does intestinal obstruction present?

Answer 5

1. Green bilious vomiting
2. Diffuse abdominal pain and distention
3. Absolute constipation and lack of flatulence
4. Abnormal bowel sounds

Question 6

What is bilious vomiting?

Answer 6

Containing bright green bile

Question 7

Describe the bowel sounds heard in mechanical obstruction

Answer 7

Can be high pitched and “tinkling” early in the obstruction and absent later

Question 8

Initial imaging for suspected bowel obstruction

What will this show?

Answer 8

Abdominal X-ray showing distended loops of bowel

Question 9

What are the normal diameters of the small bowel, colon and caecum?

Answer 9

• 3 cm small bowel
• 6 cm colon
• 9 cm caecum

Question 10

How do we differentiate between a small vs large bowel obstruction on X-ray

Answer 10

Small bowel obstruction:

• Dilated bowel (>3cm)
• Central abdominal location
• Valvulae conniventes (lines completely cross width of the bowel)

Large bowel obstruction:

• Dilated bowel (> 6cm, or > 9 cm at caecum)
• Peripheral location
• Haustral lines (lines do not completely cross bowel width)

Question 11

Gold standard imaging to confirm bowel obstruction?

Answer 11

A contrast abdominal CT scan

To confirm diagnosis and establish the site and cause

Question 12

Initial management of intestinal obstruction?

Answer 12

ABCDE approach and “drip and suck”

1. Nil by mouth
2. IV fluids
3. NG tube with free drainage

Question 13

What blood findings must we look out for in bowel obstruction?

What do these indicate

Answer 13

1. Electrolyte imbalances (U&Es)
2. Metabolic alkalosis due to vomiting stomach acid (VBG)
3. Bowel ischaemia (↑lactate)

Question 14

What is the definitive management of bowel obstructions?

Answer 14

Surgery (either laparoscopy or laparotomy) to correct the underlying cause

Question 15

List 4 complications of bowel obstruction?

Answer 15

1. Hypovolaemic shock
2. Bowel ischaemia
3. Bowel perforation
4. Sepsis

Question 16

How does bowel obstruction lead to shock?

Answer 16

Due to fluid stuck in the bowel rather than the intravascular space (third-spacing)

Leads to Hypovolaemic shock

Question 17

List 4 causes of Closed-Loop Obstruction

Answer 17

1. Adhesions that compress two areas of bowel
2. Hernias
3. Volvulus
4. Single point of obstruction in the large bowel, with a competent ileocaecal valve

Question 18

What is meant by a Closed-Loop Obstruction?

Answer 18

Where there are two points of obstruction along the bowel; meaning the middle section is sandwiched between

Question 19

What is the risk of an untreated close-loop obstruction?

Answer 19

Will inevitably expand, leading to ischaemia and perforation

Requires emergency surgery

Question 20

What are Bowel adhesions?

Answer 20

Scar tissue that bind the abdo contents together → causes kinking/squeezing of the bowel, leading to obstruction

Question 21

Are adhesions more common in the small or large bowel?

Answer 21

small

Question 22

List 4 causes of bowel adhesions

Answer 22

1. Abdominal or pelvic surgery
2. Peritonitis
3. Abdominal or pelvic infections (eg. PID)
4. Endometriosis

Question 23

What is a volvulus?

Answer 23

Torsion of the colon around it’s mesenteric axis resulting in compromised blood flow and closed loop obstruction

Affected bowel can become ischaemic rapidly leading to bowel necrosis and perforation

Question 24

List 4 risk factors for a volvulus

Answer 24

1. Parkinson’s
2. Elderly
3. Chronic constipation
4. High fibre diet
5. Pregnancy
6. Adhesions

Question 25

List 2 locations where a volvulus tend to occur Highlight the most common

Answer 25

1. **Sigmoid** colon 2. Caecum

Question 26

Initial investigation for a suspected volvulus? Classic finding?

Answer 26

Coffee bean sign - indicative of sigmoid volvulus

Question 27

Investigation of choice to confirm diagnosis of sigmoid volvulus?

Answer 27

Contrast CT

Question 28

Initial management of a sigmoid volvulus?

Answer 28

‘Nil by mouth’ and ‘Drip and suck’

Question 29

Conservative management of a sigmoid volvulus?

Answer 29

endoscopic decompression (only if there is NO peritonitis)

Question 30

Surgical management of a volvulus?

Answer 30

1. Laparotomy 2. Hartmann’s procedure (sigmoid volvulus) 3. Ileocaecal resection or right hemicolectomy (caecal volvulus)

Question 31

What is paralytic ileus?

Answer 31

Condition affecting the small bowel, where normal peristalsis temporarily stops

Question 32

List 4 common causes of Ileus

Answer 32

1. Injury to the bowel 2. Handling of the bowel during surgery 3. Inflammation or infection 4. Electrolyte imbalance (e.g., hypokalaemia or hyponatraemia)

Question 33

How may the presentation of Ileus (non-mechanical) differ from mechanical obstruction?

Answer 33

Presentation is the SAME except there are **absent bowel sounds** (as opposed to the “tinkling” bowel sounds)

Question 34

Management of Ileus

Answer 34

1. Nil by mouth 2. NG tube if vomiting 3. IV fluids 4. Mobilisation - helps stimulate peristalsis 5. Total parenteral nutrition

Question 35

Compare structures involved in an upper vs lower GI perforation

Answer 35

UGI perforations UGI: eosophagus - small bowel (jejunum, ileum) LGI: caecum - rectum)

Question 36

How does GI perforation typically present?

Answer 36

1. Sharp, rapid onset abdominal pain 2. Systemically unwell 3. Pain worse with breathing and moving 4. Malaise, vomiting, and lethargy

Question 37

What is the importance of diagnosis in GI perforation

Answer 37

Delay in resuscitation and management → septic shock, multi organ dysfunction, and death Immediate ddx in anyone presenting with acute abdominal pain

Question 38

List 4 causes of Upper GI perforation

Answer 38

1. PUD 2. Small bowel tumours 3. Endoscopy 4. Foreign body

Question 39

How does a perforation in the thoracic region present?

Answer 39

1. Pain in chest, neck or radiating to the back 2. Worse on inspiration 3. Vomiting 4. Respiratory symptoms.

Question 40

List 4 causes of Lower GI perforation

Answer 40

1. Crohn's disease 2. Colon cancer 3. Colonoscopy 4. Diverticular disease

Question 41

What classification system is used to assess severity of acute diverticulitis?

Answer 41

Hinchey * I para-colonic abscess * II pelvic abscess * III purulent peritonitis * IV faecal peritonitis

Question 42

What may be seen on chest X-ray of bowel perforation?

Answer 42

Air under the diaphragm in pneumoperitoneum

Question 43

What 2 signs may be seen on an abdominal X-ray of bowel perforation?

Answer 43

1. Rigler’s sign (both sides of bowel visible \*image) or 2. Psoas sign (loss of sharp delineation of the psoas muscle border)

Question 44

Gold standard imaging to confirm bowel perforation?

Answer 44

A contrast abdominal CT scan To confirm diagnosis and establish the site and cause

Question 45

Management of GI perforation?

Answer 45

1. ABCDE 2. Broad spectrum antibiotics 3. Nil by mouth, NG tube, IV fluid resuscitation 4. Analgesia 5. Surgery