Intestinal Obstruction, Appendicitis

Question 1

Who is most affected by meconium ileus? How can it progress?

Answer 1

Children/newborns with cystic fibrosis

In later life –> meconium ileus equivalent (MIE) syndrome. This is an important cause of small intestine obstruction unique to CF.

Question 2

Describe the pathophysiology of meconium ileus as a cause of intestinal obstruction.

Answer 2

Viscid consistency of meconium in CF causes meconium ileus at birth

Material is so viscid that it cannot be moved –> obstruction

Later in life -> MIE syndrome (causes small bowel obstruction)

Question 3

What does meconium ileus look like on imaging with contrast dye?

Answer 3

Last part of SI shows dried out “pebbles” of meconium (stool surrounded by contrast dye)

Question 4

How does colonic adenocarcinoma cause intestinal obstruction.

Answer 4

Collonic adenocarcinomas forms in an annular ring like fashion in bowel wall –> constriction and ultimately obstruction in stomach or large bowel

Question 5

What is caecal volvulus? Name 3 common symptoms.

Answer 5

A twisting of the bowel

Abdominal pain, distension and absolute constipation.

Question 6

Who is most affected by caecal volvulus? Where does it usually occur in the bowel?

Answer 6

• Volvulus is most common in adults, where it occurs with equal frequency in small intestine (around a twisted mesentery) and colon (in either sigmoid or cecum which are more mobile).
• In very young children, volvulus almost always happens in the small intestine.

Question 7

What is the pathophysiology of caecal volvulus?

Answer 7

• Twisted bowel results in ischaemia and accumulation of gas and fluid in the bowel obstucted
• Ultimately causing necrosis/gangrene
• Patients require surgical intervention

Question 8

Name a luminal, wall and exrinsic cause of bowel obstruction.

Answer 8

• Lumen - meconium ileus
• Wall - colonic adenocarcinoma
• Extrinsic - caecal volvulus

Question 9

Describe a typical presentation of intestinal obstrction.

Answer 9

Cardinal symptoms - pain, vomiting, distentsion, absolute constipation.

True colic - intermittent severe central pain (small bowel every 2-20min, large bowel every 30mins)

Question 10

True or false?

“Caecal vulvulus occurs when the mesentery twists around the caecum”

Answer 10

False

Caecal volvulus occurs when the caecum attached to the large mesentery twists. This causes the bowel to twist around the mesentery which causes obstruction.

Question 11

What causes appendicits?

Answer 11

• Obstruction of lumen by a faecolith (very hard piece of faeces) leads inference with the blood supply which decreases walls resistance to infection.
• Appendix constricts to try and drive faecolith out of appendix which leads to an increased pressure in the bowel wall.
• Blood flow is disturbed which leads to ischaemic changes; therefore the bowel wall is more prone to bacterial invasion.
• Inflammation of the wall is caused by bacterial invasion.

Question 12

Which gut organisms cause a secondary bacterial infection in appendicitis?

Answer 12

E. Coli

Streptococci

Question 13

What happens in acute appendicitis? How does it progress?

Answer 13

• Earliest lesion causes a superficial ulceration of the mucosa (if extensive then necrosis)
• Interference with circulation causes necrosis and perforation with spread to peritoneal cavity
• If infection is walled off then you have a localised abscess(localised area of tissue necrosis) which can progress to generalised peritonitis
• Ulceration stops at mucosal surface

Question 14

What will be raised in FBC of appendicitis? What will be found in the surrounding exudate?

Answer 14

WBC

Neurophils in exudate

Question 15

Describe the clinical presentation of appendicitis.

Answer 15

• Begins with generalised central abdominal pain (referred pain)
• Pain shifts to right iliac fossa over a few hours to a few days, and is more severe
• Patients commonly experience loss of appetite and vomiting
• Some patients develop generalised peritonitis: generalised abdominal pain, nausea and vomiting, sweating, rigors

Question 16

True or false?

“Ischaemic changes in appendicitis are caused by increased pressure in the bowel wall”

Answer 16

True

Appendicitis is due to obstruction by faecolith. This causes the appendix to constrict to try and drive faecolith out of the appendix, which in turn increases the pressure in the bowel wall. This leads to disturbance in blood flow and ischaemic changes. Thus the bowel wall is prone to ischaemic changes.