Rectal Bleeding

Question 1

What is melena? From where is it almost always from?

Answer 1

• melena is a black, tarry, very offensive smelling bowel motion
• it is due to the presence of digested RBCs, and is therefore nearly always from the upper 1/3 of the GIT (includes nose bleeds!)
• requires a slow bleed; rapid bleed will result in hematemesis

Question 2

What exactly gives melena its color, texture, and smell?

Answer 2

• the oxidation of the RBCs’ iron

Question 3

What else can cause very dark/black stool? How can we differentiate it from melena?

Answer 3

• iron tablets and bismuth chelate

- differentiate from melena because these motions smell normal

Question 4

What can cause a trivial amount of rectal bleeding (ie, some blood on toilet paper)? What about larger amounts of blood (ie, blood in the toilet bowl)?

Answer 4

• trivial: skin tear, hemorrhoids, anal fissure

- large amount: arterial bleeding, ischemic colitis, diverticular rupture

Question 5

Bleeding with perianal pain indicates what pathology? What about with severe abdominal pain? Mild abdominal pain?

Answer 5

• perianal pain: rectoanal fissure/ external hemorrhoids
• severe abdominal pain: ischemic colitis
• mild abdominal pain: enteritis

Question 6

Which type of hemorrhoids are painful? Why?

Answer 6

• external hemorrhoids (below the pectinate line) are painful because they receive somatic innervation
• internal hemorrhoids (above the pectinate line) receive visceral innervation and are therefore not painful

Question 7

What should be suspected in a patient with rectal bleeding on aspirin and NSAIDs? What about a patient with rectal bleeding and vomiting?

Answer 7

• aspirin and NSAIDs: peptic ulcer with bleeding

- vomiting: infection or Mallory-Weiss tear

Question 8

What serum tests can we run in order to help rule in/out an upper GI bleed? What other symptoms are associated with an upper GI bleed?

Answer 8

• serum urea levels can be elevated because digested blood is a source of urea
• other symptoms: melena, hematemesis, tachycardia, low BP

Question 9

Elevated urea levels also indicate an issue with renal clearance - how can we differentiate between an issue with the kidneys and an upper GI bleed?

Answer 9

• in an upper GI bleed, urea will be elevated but creatinine will be normal
• (in renal disease, both will be elevated)

Question 10

What is the most common upper GI cause of rectal bleeding? Most common cause of lower GI bleeding?

Answer 10

• upper: ulcers

- lower: ruptured diverticulosis

Question 11

What type of bleeding results from ruptured diverticula?

Answer 11

• massive, usually painless rectal bleeding
• fresh blood as well as clots will be in the toilet bowl
• (can lead to shock!)

Question 12

What is perianal hematoma? What does it result from?

Answer 12

• a painful lump with a dark blue/black appearance

- results from a burst perianal vein due to a heavy effort

Question 13

What is a hemorrhoid? What do we use to treat them?

Answer 13

• an enlargement of the vascular cushion (which contains A-V connections) in the proximal anal canal
• treat via sclerosant injection, rubber-band ligation, or hemorrhoidectomy

Question 14

Four Degrees of a Hemorrhoid

Answer 14

• 1st degree: bleeding w/ defecation, no prolapse
• 2nd degree: bleeding and prolapse w/ defecation; spontaneous reduction afterwards
• 3rd degree: bleeding and prolapse w/ defecation; prolapse must be manually reduced (pain)
• 4th degree: bleeding, permanent irreversible prolapse (very painful)

Question 15

How will patients with an anal fissure present? How do we treat anal fissures?

Answer 15

• intense and constant pain that worsens with defecation, resulting in an apprehension to go
• treat via botulinum toxin (chemical sphincterotomy) or a surgical sphincterotomy

Question 16

What is the most common source of lower GI bleeding?

Answer 16

• 95% of cases are due to bleeding in the colon

Question 17

What are the most common causes of lower GI bleeding in patients under 50? In patients over 50?

Answer 17

• under 50: infectious colitis, anorectal disease, IBD (especially ulcerative colitis)
• over 50: diverticulosis, angiodysplasia, malignancy, ischemic colitis

Question 18

What is the most common source of bleeding resulting in brown stools mixed with blood or with blood streaks? Resulting in large amounts of bright red blood? Resulting in maroon stools? Resulting in black stools?

Answer 18

• stools mixed with blood or w/ streaks: anorectal
• large bright red blood: colon
• maroon stools: right colon or small intestine
• black stools: upper GI