Non-neoplastic Diseases Of The Large And Small Bowel

Question 1

Intestinal obstruction

Answer 1

Can occur anywhere but the small instinct is most common (since it has a small narrow lumen)

80% of obstructions = hernias/intestinal adhesions/intussusception/volvulus

Clinical manifestations:

• ab pain
• distention
• vomiting
• constipation

Question 2

Hernia sac

Answer 2

most frequent cause of intestinal obstruction worldwide and the 3rd most common cause of obstruction in the US

Any weakness or defect in the abdominal wall may permit protrusion of a serosa-lined pouch of peritoneum

Acquired hernia = typically occurs anteriorly via inguinal and femoral canals or umbillicus

Question 3

Adhesions

Answer 3

most common cause of intestinal obstruction in the US

Surgical procedures/infection/inflammation can cause adhesions between bowel segments and abdominal wall

Question 4

Volvulus

Answer 4

Twisting of a loop of bowel about its mesenteric point of attachment
-includes the lumen and vascular components

Presents with both obstruction and infarction
- occurs most commonly at sigmoid colon and rectum

Question 5

Intussusception

Answer 5

Occurs when a segment of the intestine is constricted by a wave of peristalsis
- causes that segment to “telescope” into the immediate distal segment, and then stays there by subsequent peristalsis

• Most common in children <2yrs (most common cause of intestinal obstruction in children)*
• Needs to be corrected or it can lead to infarction
• causes: viral infections (rotavirus), idiopathic , tumors, etc.

Question 6

Ischemic bowel disease

Answer 6

Caused by acute/chronic hypoperfusion or trans mural infractions
- common causes = severe atherosclerosis, aortic aneurysm, Hypercoagulable states, oral contraceptives, CMV virus, Angiodysplasia, etc.

Severity is determined by

1) timeframe of developed
2) vessels affected
3) watershed areas

Morphology shows

• segmental and patchy ischemia
• hemorrhagic and ulcerated mucosa

Question 7

Watershed zones in the bowel

Answer 7

watershed zones = intestinal segments that share arterial supply from the distal components of two separate arteries.
(Very prone to ischemia)

Zones include:

• splenic flexure
• sigmoid colon
• rectum

Question 8

Ischemic bowel disease clincial features

Answer 8

usually in older adults with cardiac disease

Symptoms:

• acute severe ab pain and tenderness
• (+/-) nausea/vomiting
• bloody diarrhea
• melanotic stool
• diminished bowel sounds

Mortality rates = 50% if the bowel mucosa breaks and sepsis occurs

Question 9

Angiodysplasia

Answer 9

Shows malformed submucosal and mucosal blood vessels for various reasons

• usually occurs in the cecum or descending/sigmoid colon
• usually presents within 60’s

**accounts for 20% of major lower intestinal bleeding

Question 10

Hemorrhoids

Answer 10

Dilated anal and perianal collateral vessels due to elevated venous pressure

• anastomosis between petal and caval system (in this case superior rectal veins and medicine/inferior rectal veins)
• affect 5% of the population

Common predisposing factors:

• constipation
• pregnancy
• portal HTN
• chronic venous stasis

Question 11

Internal vs external hemorrhoids

Answer 11

Internal = result of dilation of the superior hemorrhoidal plexus

External = result of dilation of the inferior hemorrhoid alone plexus

Both are at risk for rupture and rectal bleeding

Question 12

Sigmoid diverticulitis

*diverticulosis and diverticulitis *

Answer 12

Outpouching of colonic mucosa and Submucosa
- develop under conditions of elevated intraluminal pressure in the sigmoid colon

Are rare in younger patients but roughly 50% incidence in >60yrs
- more common in western world due to low fiber diets with high refined carbs

Diverticulosis = noninflammed diverticuli throughout colon

Diverticulitis = inflamed diverticuli usually due to obstruction

Question 13

Clinical features of sigmoid diverticulitis

Answer 13

usually asymptomatic

Symptoms:

• intermittent cramping
• continuous lower abdominal discomfort
• constipation
• diarrhea

Treatment = antibiotic use usually only. Sometimes requires surgical intervention

Question 14

Similarities between Ulcerative colits and Crohn’s disease

Answer 14

Both usually present in adolescence or in young adults

Both are more common in whites and eastern Ashkenazi Jewish populations

Both have ARG16L1 and IRGM genes mutated

Question 15

Inflammatory bowel disease pathogenesis

Answer 15

Is believed to be caused by alterations in host interactions with intestinal microbiota, intestinal epithelial dysfunction, aberrant mucosal immune responses and altered composition of gut microbiome
- some combination of excessive immune activation and defective immune regulation is responsible for IBD

could also be caused by transepithelial influx of luminal bacteria components which activates innate and adaptive immune responses

Question 16

What is the earliest lesion seen in Crohn’s disease

Answer 16

Aphthous ulcer

- promotes the cobblestone appearance

Question 17

Crohn’s disease specifics

Answer 17

Crohn disease
- concordance rates for twins =50%
(more genetic factor)
- NOD2 gene is a factor
- TH1/17 mediated
- most common in terminal ileum, ileocecal valve and cecum
- 40% = small intestine only
- 30% = both small intestine and colon
- 30% = only colon
- “skip lesions” are present on imaging with cobblestone appearance
- forms strictures over time due to transmural edema and inflammation
- mucosa appears distorted with damaged crypts on histology
- often show non-caseating granulomas
- cigarette smoking makes it worse

• *clinical symptoms:**
• diarrhea/fever and right lower ab pain (can mimic appendicitis)
• may or may not show bloody diarrhea
• symptoms often come and go

***often shows iron-deficency anemia/Vit B12/hypoalbuminema

Question 18

Extraintestinal manifestations of Crohn’s and UC

Answer 18

Uveitis

Sacroilitis

Ankylosis spondylitis

Erythema nodosum and clubbing of fingers

*both increased risk of developing colon adenocarcinoma

**UC is more likely to show percholangitis

Question 19

Ulcerative colitis specifics

Answer 19

Ulcerative colitis:

• concordance rates for twins = 16%
• TH2/IL-13 mediated
• ALWAYS involves the rectum
• skip lesions are NOT PRESENT
• can affect whole colon (“pancolitis”)
• strictures are NOT PRESENT
• leads to mucosal atrophy but not total loss
• ALWAYS produces bloody mucus diarrhea and lower ab pain
• smoking actually helps slow symptoms

Question 20

Colitis-associated neoplasia

Answer 20

Dysplasia that occurs due to the presence of UC and Crohn’s disease

Risk increases beginning about 8-10 years after disease initiation

Patients with pancolitis are at greater risk

Patients with more inflammatory cells are at greater risk

**because of this patients with IBD are enrolled in surveillance programs for neoplasia 8 years after diagnosis

Question 21

Acute appendicitis

Answer 21

Most common in adolescents and
Young adults
- lifetime risk is 7%
- males slightly more affected than females

Pathogenesis:

• either increased intraluminal pressure or obstruction of the appendix (most common is obstruction)
• rupturing and subsequent peritonitis or gangrenous appendicitis is the result of untreated acute appendicitis

Clinical features:

• extreme periumbilical pain localized to the right lower quadrant
• nausea/vomiting
• low grade fever
• mild elevated WBCs