GI 8 lecture

Question 1

Describe the chronica abd pain with IBS

Answer 1

1) Cramping sensation with variable intensity & periodic exacerbations
2) Mild-to-severe
3) Relieved with defecation
4) Abdominal bloating with increased flatulence and/or belching

Question 2

Describe the altered bowel habits with IBS

Answer 2

1) Diarrhea
2) Constipation
3) Alternating diarrhea and constipation
4) Normal BMs alternating with diarrhea and/or constipation

Question 3

Describe the features of IBS

Answer 3

1) Many patients relate a life-long history of altered bowel habits
2) Associated conditions: fibromyalgia, PTSD, GAD, chronic fatigue syndrome
3) Fear of serious disease
4) Exacerbation of diarrhea may coincide with menstrual cycle
5) Bleeding, fever, weight loss, nocturnal awakening with diarrhea are NOT part of IBS (alarm features)

Question 4

Define the following subtypes of IBS:
1) IBS with predominant constipation (IBS-C)
2) IBS with predominant diarrhea (IBS-D)

Answer 4

1) Patient reports that abnormal bowel movements are usually constipation (type 1 and 2 0n the BSFS)
2) Patient reports that abnormal bowel movements are usually diarrhea (type 6 and 7 in the BSFS)

Question 5

Define the following subtypes of IBS:
1) IBS with mixed bowel habits (IBS-M)
2) IBS unclassified (IBS-U)

Answer 5

1) Patient reports that abnormal bowel movements are usually both constipation and diarrhea (more than one-fourth of all the abnormal bowel movements were constipation and more than one-fourth were diarrhea)
2) Patients who meet diagnostic criteria for IBS but cannot be accurately categorized into one of the other three subtypes

Question 6

The _____________________________ should be used to record stool consistency with IBS

Answer 6

Bristol stool form scale (BSFS)

Question 7

IBS:
1) What should Hx include?
2) What abt PE?

Answer 7

1) History: IBS features, BSFS, organic disease, med exposures, recent gastroenteritis, FHx (CRC, IBD, Celiac)
2) Usually normal, possible tender abdomen; include DRE for constipation

Question 8

What labs should be done to exclude alternative Dx for IBS?

Answer 8

1) All IBS: CBC
2) IBS-D: fecal calprotectin or lactoferrin, stool test for giardia, Celiac serologies, CRP (if calprotectin or lactoferrin not available)
3) Colonoscopy: age-appropriate CRC screening in all pts

Question 9

List the DDXs for IBS

Answer 9

IBS-D: Celiac disease, microscopic colitis, SIBO, IBD
IBS-C: dyssynergic defecation, slow colonic transit

Question 10

Describe management for IBS

Answer 10

1) Clinician-patient relationship key to successful management
2) Direct therapy to the initial predominant symptom
3) Allow adequate time for visits
4) Schedule regular return visits
5) Provide patient with information, educational material
6) Be an empathic listener
7) Reassure patient this is a benign disorder
8) Refer for therapy when necessary

Question 11

List 2 main causes of mesenteric ischemia and their etiologies

Answer 11

1) Occlusive: primary thrombosis or embolism
2) Low flow states: severe heart failure, sepsis, or hypotension

Question 12

Describe mesenteric ischemia

Answer 12

1) Inadequate blood supply to the mesentery
2) Results from reduction in intestinal blood flow (arterial occlusion, venous occlusion, or arterial vasospasm)
3) Involves small intestine or colon (colonic ischemia)
4) Acute or chronic
5) Intestinal mucosa most sensitive to ischemia (under perfusion causes sloughing)

Question 13

Mesenteric ischemia: Describe the parts of the intestinal vascular supply

Answer 13

1) Celiac artery (stomach & duodenum)
2) Superior mesenteric artery (SMA)(distal duodenum to mid-transverse colon)
3) Inferior mesenteric artery (IMA)(transverse colon to rectum)
4) Collateral pathways formed by natural anastomoses

Question 14

Acute mesenteric ischemia: What are the main 2 types and how common are they? Where does each originate?

Answer 14

1) SMA embolism (50%): usually originates from the left atrium, left ventricle, cardiac valves, or proximal aorta. hypercoagulable states, inflammatory disorders, cirrhosis & portal hypertension
2) SMA thrombosis (15-20%): strangulating obstructions (adhesions, hernias, volvulus, metastatic malignancy, intussusceptions) and vasculitis (systemic lupus erythematosus, polyarteritis nodosa)

Question 15

Acute mesenteric ischemia: List the 2 classifications and a variant

Answer 15

1) Low cardiac output & use of vasopressors (Non-Occlusive Mesenteric Ischemia (20-30%)
-Ischemic colitis (a variant; usually involves IMA)
2) Venous thrombosis (SMV, IMV, splenic vein, & portal vein)(5%)

Question 16

Describe the prognosis of acute mesenteric ischemia

Answer 16

Survival: depends on early diagnosis & treatment
1) 70-90% mortality if delayed diagnosis & gangrene
2) Up to 90% survivability if no peritonitis
3) Mortality rate > 50%

Question 17

Colorectal obstruction:
1) How common is it?
2) What are 2 origins?
3) What is the most common benign cause?

Answer 17

1) 25% of all intestinal obstructions
2) Functional or mechanical (partial or complete)
3) Volvulus (5-15%)
-Sigmoid volvulus most common cause of large bowel obstruction

Question 18

List some other causes of colorectal obstruction

Answer 18

Post-op adhesions, strictures due to diverticular disease, hernia with colonic incarceration

Question 19

Colorectal obstruction:
1) 70% occurs where?
2) What labs are needed?

Answer 19

1) At or distal to transverse colon
2) Assess for hypovolemia, metabolic abnormalities
Cancer markers

Question 20

Describe the Sx of acute (complete or near-complete) colorectal obstruction

Answer 20

1) Bloating, abdominal pain, obstipation
2) +/- nausea, +/- vomiting
3) Infra-umbilical, cramping pain
4) Paroxysms of pain q20-30 minutes

Question 21

List the risk factors for colorectal obstruction

Answer 21

1) Malignancy (colorectal, pancreatic & ovarian cancer; lymphoma)
2) Postoperative adhesive bowel disease
3) Stricture due to prior colorectal resection
4) Stricture due to repeated inflammation (diverticulitis)
5) Hernia with colonic incarceration
6) Volvulus (due to anatomic or physiologic abnormalities)

Question 22

Describe the initial management of colorectal obstruction

Answer 22

1) Supportive care, decompression of sigmoid volvulus
2) Surgical management: Urgent for acute complete or near complete (benign or malignant etiology)

Question 23

________________ & ___________ are the most useful & practical studies for colorectal obstruction

Answer 23

Plain films & CT

Question 24

Describe the workup of colorectal obstruction

Answer 24

1) CBC with diff, CMP, lipase, UA
2) Acute abdominal series
3) If no clear cause, consider CT
4) NPO
5) Pain Control
6) Medical or Surgical Management

Question 25

Describe colorectal polyps

Answer 25

1) Discrete mass lesions that protrude into the intestinal lumen 2) Most commonly sporadic 3) May be due to familial polyposis syndrome 4) 70% removed during colonoscopy are adenomatous (precancerous) 5) Usually asymptomatic 6) May ulcerate & bleed 7) May cause intestinal obstruction (large polyps)

Question 26

Toxic megacolon: 1) Define it and its main etiologies 2) What are some other etiologies?

Answer 26

1) Total or segmental non-obstructive colonic dilatation occurring in context of systemic toxicity -Potentially lethal complication of IBD (most common UC) or infectious colitis 2) C. diff infection, infectious colitis (Salmonella, Shigella, Campylobacter), amoebic colitis, CMV colitis (in HIV/AIDS)

Question 27

What are some precipitating risk factors for toxic megacolon?

Answer 27

Hypokalemia, antimotility agents (loperamide), opiates, anticholinergics, antidepressants

Question 28

What are the symptoms of toxic megacolon?

Answer 28

1) Signs & symptoms of acute colitis (resistant to therapy) usually present for 1 week prior to dilatation 2) Severe bloody diarrhea most common presenting symptom 3) Diarrhea may improve prior to onset of megacolon 4) Malaise, abdominal pain, distention

Question 29

What may you find in the Hx of a patient with toxic megacolon?

Answer 29

1) Prior IBD attacks (especially UC) 2) Extraintestinal manifestations of IBD 3) Recent travel 4) Antibiotic or chemotherapy use 5) Use of antimotility agents 6) HIV/AIDS status

Question 30

List the diagnostic criteria for toxic megacolon

Answer 30

Radiographic evidence of colonic distention 1) **PLUS at least 3:** fever (>38C, >100.4F), HR >120 BPM, neutrophilic leukocytosis (>10,500/microL), anemia 2) **PLUS at least 1:** dehydration, AMS, electrolyte disturbances, hypotension

Question 31

Describe the diagnostic eval of toxic megacolon

Answer 31

1) CT abd/pelvis with PO & IV contrast (rectal contrast CT), then serial plain films 2) Baseline plain abdominal films upon admission 3) Labs: CBC/diff, BMP or CMP, CRP or ESR, stool studies (culture, micro, C. diff) 4) Limited endoscopy for selected patients

Question 32

What is the pathogenesis of toxic megacolon?

Answer 32

Severe inflammation of smooth muscle layer --> paralysis of colonic smooth muscle --> dilatation

Question 33

What are the signs of toxic megacolon on PE?

Answer 33

-Toxic-appearing patient with altered sensorium -Tachycardia -Fever -Postural hypotension -Lower abdominal distention & tenderness + peritoneal signs *Large doses of steroids, analgesics, & AMS may mask S/Sx

Question 34

Toxic megacolon: How do you Dx?

Answer 34

Based on clinical signs of systemic toxicity with radiographic evidence of colonic dilatation (> 6 cm) (use diagnostic criteria)

Question 35

List some DDxs for toxic megacolon

Answer 35

Congenital megacolon (Hirschsprung’s disease), acquired megacolon (due to chronic constipation), colonic pseudo-obstruction (Ogilvie syndrome), diffuse gastrointestinal dysmotility, acute colonic obstruction, volvulus, pelvic tumors, & intraluminal obstructive tumors.