Other intestinal disorders, diverticuli, hirsprung

Question 1

angiodysplasia

Answer 1

tortuous dilation of vessels causes hematochezia (blood passes through anus). often in cecum, terminal ileum, and ascending colon, esp in older pts.
(high stress in left colon = diverticula; on the right = angiodysplasia)

Question 2

ileus

Answer 2

intestinal hypomotility without obstruction. causes constipation and decreased flatus and a distended/typmanic abdomen with reduced bowel sounds. seen with abdominal surgery, opiates, hypokalemia, and sepsis

Question 3

meconium ileus

Answer 3

in CF, meconium plug obstrucst the intestine, preventing stool passage at birth

Question 4

necrotizing enterocolitis

Answer 4

necrosis of intestinal mucosa and possible perforation. colon is usually involved but it can involve the whole GI tract. among neonates, it is more common in preemies.

Question 5

Hirsprung disease: what is the problem, who gets it, what is involved

Answer 5

congenital megacolon caused by defective relaxation and peristalsis of rectum and distal sigmoid colon. associated with Down syndrome and RET mutations.

Question 6

What is the pathophysiology behind Hirsprung disease?

Answer 6

failure of the ganglion cells to descend. ganglion cells come from neural crest and descend to the wall of the bowel. remember, the myenteric plexus is important for good peristalsis and relaxation (Auerbach, in muscularis propria btw the two layers). the submucosal plexus (meissners) regulates blood flow and secretions. both are needed for proper function. in Hirsprung, in the rectum and distal sigmoid colon, you lack both of these plexus- no peristalsis, no relaxation of the rectum.

Question 7

clinical features of Hirsprung disease and dx and tx

Answer 7

bilious emesis, failure to pass meconium, empty vault on DRE, massive dilation of bowel proximal to obtruction with risk for rupture. must do rectal suction biopsy to look for ganglion cells (you need to collect the submucosa too).
treatment: resection of the involved bowel.

Question 8

What are colonic diverticula? What causes a colonic diverticulum? Where does it arise?

Answer 8

outpouchings of mucosa and subumucosa through the muscularis propria (false diverticulum). associated with wall stress related to constipation in older adults. arises where the vasa recta traverses the muscularis propria, which is a weak point in the colonic wall. sigmoid colon most common.

Question 9

What are complications of diverticula?

Answer 9

bright red rectal bleeding (hematochezia)- diverticulum is near the artery.
diverticulitis- left sided “appendicitis” from obstruction of diverticulitis. may perforate and cause peritonitis, abscess formation or bowel stenosis.
fistula (classically, colovesicular- connects to the bladder. air or stool passes through the urine).

Question 10

hereditary hemorrhagic telangiectasias

Answer 10

autosomal dominant disorder resulting in thin walled blood vessels, esp. in mouth and GI tract. rupture presents as bleeding.

Question 11

colonic polyps: what are the common types?

Answer 11

raised protusions of the colonic mucosa. most common types are hyperplastic and adenomatous.

Question 12

hyperplastic colonic polyp

Answer 12

d/t hyperplasia of glands. most common type of polyp. usually arises in the left colon and is benign without malignant potential. surface of the polyp has a sawtooth appearance.

Question 13

adenomatous polyp

Answer 13

neoplastic proliferation of glands; second most common polyp. benign, but PREMALIGNANT. may progress to CA via the adenoma-carcinoma sequence. the lining of the glands are darker than normal.

Question 14

adenoma carcinoma sequence

Answer 14

APC causes risk of polyp (must knock out both copies; located on chromosome 5), then KRAS causes development of polyp. To become cancer, you mus also have p53 mutation and increased cyclooxygenase. Therefore, ASA protects against adenoma-CA sequence.

Question 15

What are some risks for progression of an adenoma to cancer?

Answer 15

1. size > 2 cm
2. sessile growth: grows flat on the wall instead of on a stalk/peduncle
3. villous is worse than tubular adenoma.

Question 16

What is Gardner syndrome?

Answer 16

familial adenomatous polyposis with fibromatosis (non-neoplastic prolif of fibroblasts; is destructive; often retroperitoneal) and osteomas (usually arises in the skull)

Question 17

What is Turcot syndrome

Answer 17

FAP (familial adenomatous polyposis with CNS tumors like medulloblastoma and glial tumors

Question 18

juvenile polyp

Answer 18

sporatic hammartoma (tumor made of disorganized, normal tissue).  arises in kids under 5.  solitary rectal polyp that can prolapse and bleed.
large numbers of juvenile polyps increases risk for progression to carcinoma.

Question 19

Peutz-Jeghers syndrome

Answer 19

hamartomatous polyps throughout the GI tract. associated with mucocutaneous hyperpigmentation on the lips, oral mucosa, and genital skin. autosomal dominant. incr. risk of colorectal, breast, and gyn CA.