Bowel Obstruction

Question 1

Define bowel obstruction.

Answer 1

Partial or complete blockage of the bowel that results in failure of the intestinal contents to pass

Question 2

What are the three different groupings of classification of bowel obstruction?

Answer 2

Small bowel vs large bowel
Complete vs partial (complete no gas or faeces)
Acute vs chronic

Question 3

What classification of bowel obsruction is always an acute situation?

Answer 3

Complete obstruction

Question 4

What are the three main causes of bowel obstruction?

Answer 4

Adhesions
Hernias
Malignancy.

Question 5

What are all potential causes of bowel obstruction?

Answer 5

Three main: adhesions, hernias, malignancy
Other causes:
Volvulus
Stricture - 2 to Crohns or diverticular disease

Question 6

What background questions are important to ask a patient to help determine the cause of a bowel obstruction?

Answer 6

Hernias
Change in bowel habit, weight loss, PR bleeding
Previous abdominal surgery may have resulted in adhesions.

Question 7

What are the three different classifications of bowel obstructions based on the location relative to the bowel wall?

Answer 7

Intraluminal - in the lumen - ingestion of a foreign body
Intramural - in the wall - cancers,
Extramural - outside the wall - hernias, cancer, adhesions

Question 8

What is the difference between a dynamic (mechanical) and adynamic bowel obstruction?

Answer 8

Dynamic - physical blockage aka foreign body
Adynamic - failure of peristalsis, muscular or neurogenic.

Question 9

What is the difference between a simple and a strangulated bowel obstruction?

Answer 9

Simple - blood flow is not compromised manage conservativly
Strangulated - blood flow is compromised is a surgical emergency

Question 10

What are some common causes of obstructed bowel by age group?

Answer 10

Neonates - atresia, meconium, hirschsprung,
Infants - introsusception, pyloric stenosis, meckles diverticulum,
YA - adhesions, strangulated hernia
Adult - hernia, adhesion, inflammation, carcinoma
Elderly - CA, inflammation, sigmoid volvulus, impacted faeces.

Question 11

What is a volvulus?

Answer 11

When the intestines twist around itself and its supplying mesentery - results in cut of blood supply to this section of bowel.

Question 12

What is intussusception?

Answer 12

When the bowel folds into the section next to it, telescopes - cause of bowel obstruction.

Question 13

What are the key signs and symptoms of a bowel obstruction?

Answer 13

Nausea and vomiting (green bilious vomiting)
Absolute constipation (no stool or wind)
Abdominal pain - generalised
Abdominal distention
‘Tinkling’ bowel sounds
Dehydrated - colon responsible for reabsorbing fluid/water

Question 14

What are the cardinal symptoms of bowel obstruction?

Answer 14

Colicky abdominal pain
Vomiting
Distention
Obstipation/constipation

Question 15

How do the symptoms differ between a high/low small bowel obstruction and a large bowel obstruction?

Answer 15

High - early vomiting
Low SI - distention and vomiting
Large - constipation, vomiting is later to develop

Question 16

What investigation are important for suspected bowel obstruction?

Answer 16

Bloods - lactate (bowel ischemia), U&Es (electrolyte imbalances e.g hypokalemia), venous blood gas (metabolic alkalosis from vomiting)
Bedside - PR exam for impacted foecal matter, VBG for metabolic acidosis (ischemia, severe hypovolemia anaerobic metabolism) or metabolic alkalosis (excess vomiting - loss of hydrogen)
Imaging - CT abdomen (confirm location, perforation is present) , AXR (confirm presence of), Erect CXR (look for perforation)

Question 17

What is a radiological sign of perforated bowel obstruction?

Answer 17

Pneumoperitoneum - air under the diaphragm

Question 18

What is the initial non surgical management in all patients with a bowel obstruction?

Answer 18

NBM
“Suck and Drip” - NG tube - Ryle’s tube - to decompress the stomach/bowel, IV fluids rehydrate and address electrolyte abnormalities
Analgesia.

Question 19

What are the surgical management options for a bowel obstruction?

Answer 19

1. Do-nothing - uncomplicated obstruction, stable patient, secondary to adhesion
2. Adhesiolysis - laparoscopic surgery to cut adhesion
3. Hernia repair
4. Colonic stenting - 2 to cancer, performed via colonoscopy
5. Bowel resection

Question 20

What is the difference between a low and high anterior resection of the bowel?

Answer 20

High - upper rectum (1/3) and sigmoid/lower left colon
Low - lower rectum and sigmoid colon

Question 21

what is the surgical procedure where the sigmoid colon is removed called?

Answer 21

Sigmoid colectomy

Question 22

What are the different types of hemicolectomy?

Answer 22

Left hemi - distal transverse and descending
Right hemi - - caecum, ascending and up to mid transverse
Extended right hemi -same as above but up to transverse colon at the splenic flexure

Question 23

What is a total abdominal colectomy?

Answer 23

Remove entire large colon

Question 24

What is a subtotal colectomy?

Answer 24

Removes all of large intestins except the sigmoid colon

Question 25

What is a total proctocolectomy?

Answer 25

Surgical removal of the colon and the rectum

Question 26

What is an abdominal-perineal resection?

Answer 26

Surgical procedures to remove the anus, rectum and sigmoid colon.

Question 27

What is a Hartmans procedure?

Answer 27

Type of colectomy - removes part of the sigmoid colon, remaining rectum is sealied, creating Hartmans pouch, remains colon is redirect to a colostomy Majority of large bowel obstructions occur in the sigmoid colon.

Question 28

In the case of bowel obstruction what are the indications for emergency surgery?

Answer 28

Clinically unstable patients with a life-threatening condition. Includes evidence of confirmed or pending - perforation, ischaemia, necrosis.

Question 29

What is the most common cause of small bowel obstruction?

Answer 29

Adhesions (90%) - most likley in patients with a history of previous abdominal surgery. Hernias also common

Question 30

How does the management plan for bowel obstruction tend to change based on the cause of the obstruction?

Answer 30

If adhesive SBO's -try conservative - most resolve on own, surgery would inc risk of further adhesions Non-adhesive - tend to require surgery.

Question 31

What is more common small or large bowel obstruction?

Answer 31

Small bowel

Question 32

What are the features of a small bowel obstruction on an x-ray?

Answer 32

Central positions of gas-filled and distended loops of bowel Valvulae conniventes - white lines passing full width of bowel - muscoal foldings.

Question 33

What are the main causes of large bowel (colorectal) obstruction?

Answer 33

Colon cancer - 60% - is the presenting complaint in 30% of colon cancer diagnosis Volvulus Severely impacted constipation.

Question 34

What is the surgical management required for large bowel (colorectal) obstruction?

Answer 34

75% of cases require surgical intervention Colorectal resections are common.

Question 35

What are the features shown on the x-ray? What diagnosis do they suggest?

Answer 35

Suggest a large bowel obstruction Dilated transverse and sigmoid colon Abrupt cut-off at point of obstruction Haustra - pouches formed by mucosa, do not extend full width of the bowel.

Question 36

What are some potential complications of a bowel obstruction and its management?

Answer 36

Surgical treatment - increase risk of adhesion and repeat obstruction, short bowel syndrome Perforated bowel - peritonitis Aspiration - pneumonia Strangulated bowel and ischemia/necrosis - sepsis

Question 37

What is meant by a closed loop obstruction?

Answer 37

When the section of the bowel is obstructed at both sides, so content can not drain proximally or distally Can be caused be two adhesion, hernias (with a loop of bowel out), large bowel obstruction + a competent ileocaecal valve. Is an emergency, more likely to continue to expand leading to ischemia and necrosis.

Question 38

What is the epidemiology of bowel obstruction?

Answer 38

80% small bowel obstructions SI obstruction - Found in around 10% of over 65yrs presenting to A&E with abdominal pain 6% mortality rate, increasing to over 10% when surgery is required.

Question 39

What are some common causes of gastrointestinal perforation?

Answer 39

Appendicitis Crohns disease Peptic ulcers Bowel obstruction Diverticulitis