Small Bowel 2 Flashcards
What is the most common malignant neoplasm of small bowel?
CARCINOID
What are the top 4 malignant neoplasms of small bowel?
- CARCINOId
- Adenocarcinoma
- Lymphoma
- GISTs
Most common symptoms of malignant small bowel neoplasms?
pain + weight loss
These small bowel neoplasms arise from the enterochromaffin cells (Kulchitsky cells) in the crypts of Lieberkuhn;
carcinoids
Carcinoid of small bowel arise form what cells?
enterochromaffin cells (Kulchitsky cells) in the crypts of Lieberkuhn
The GI tract is the most common site for carcinoid tumors, the small intestine is the 2nd most common site, what’s first?
APPY
In the small intestine, carcinoids almost always occur where?
within last 2 feet of ileum
What do carcinoids secrete?
serotonin + substance P
What symptoms characterize carcinoid syndrome?
cutaneous flushing
bronchospasm
diarrhea
vasomotor collapse
What are the top 3 locations we see carcinoids in the GI tract?
appendix–> 45% (only 3% will mets)
ileum–> 28% (35% will metastasize)
rectum –> 16%
Small bowel carcinoids tend be multi-centric, in what % of pts?
20-30%
What % of pts with carcinoids develop carcinoid syndrome?
10%
What do we need to develop carcinoid syndrome?
you need hepatic mets or extra-abdominal disease due to first pass metabolism of vasoactive peptides
Common signs and symptoms of carcinoid syndrome?
flushing diarrhea hepatomegaly cardiac lesions (right heart valve dx) asthma
What causes diarrhea in carcinoid syndrome?
increased serotonin levels circulating
How do we diagnose carcinoid syndrome??
carcinoids make serotonin–> metabolized by liver/lung into 5-HIAA
- measure urine levels of 5-HIAA over 24 hrs
- *measure plasma levels of chromogranin A (seen in 80% of pts with carcinoid tumors)
Surgical management of carcinoids of small bowel?
tumors < 1 cm, without LN involvement–> segmental intestinal resection
tumors > 1 cm, LN involved, multiple tumors–> wide excision of bowel + mesentery
lesion of terminal ileum–> R-Hemi
small duodenal tumors–> local excision
more extensive duodenal tumors–> pancreaticoduodenectomy
Connection between carcinoid tumors and anesthesia?
anesthesia can precipitate a carcinoid crisis;
hypotension, bronchospasm, flushing
How do we treat carcinoid crisis precipitated by anesthesia?
IV bolus of 50-100 micro-grams of octreotide
What is the role of surgery in pts with carcinoid tumors an widespread metastatic disease?
surgical debulking still done to provide relief of sxs
Medication used to tx symptoms of carcinoid syndrome?
somatostatin analogues like ocreotide
Why is there limited success with chemotherapy for carcinoids?
they’re slow growing
Role of chemo for carcinoids?
limited to pts non-responsive to anything else
pts who have a high proliferation rate
5 yr survival rates in pts with carcinoids?
resection of carcinoid tumor localized to primary site–> 100%
pts with regional disease–> 65%
pts with distant mets–> 25-35%
Peak incidence of adenocarcinoma of small bowel?
7th decade
Where do we find most adenocarcinomas?
duodenum + prox. jejunum
Treatment for duodenal adenocarcinoma?
pancreaticoduodenectomy unless found in 3rd or 4th part of duodenum
jejunal + ileal adeno–> segmental resection + mesentery
Where do we find small bowel lymphomas?
ileum–> greatest concentration of gut-associated lymphoid tissue
What is neoadjuvant therapy for malignant GIST?
imatinib
What is imatinib?
tyrosine kinase inhibitor that blocks c-kot in malignant GISTs, inhibits BCR-ABL
What is the most common acquired diverticulum of small bowel and what is the most common congenital diverticulum of small bowel?
acquired–> duodenal diverticulum
congenital–> Meckel’s
These represents 2nd most common cause of diverticula after colon:
duodenal diverticula
commonly seen peri-ampullary around D2
Tx for duodenal diverticula?
most are asymptomatic, when found should be left alone
symptomatic diverticula–> diverticulectomy with Kocher maneuver
Most commonly encountered congenital anomaly of the small intestine occurring in 2% of the population:
Meckel’s diverticulum
Is Meckel’s diverticulum a true diverticulum?
YES
What is a Meckel’s diverticulum?
failure or incomplete closure of the omphalomesenteric/vitelline duct
Where do we commonly see a Meckel’s diverticulum?
2ft proximal to ileocecal valve
Why is not uncommon to find different tissues within a Meckel’s?
the cells of the vitelline duct are pluripotent
can see gastric mucosa (50% of time)
can see pancreatic mucosa (5% of time)
Do we see Meckel’s in the mesenteric or anti-mesenteric border of the bowel?
ANTI-mesenteric border
Most common clinical presentation of a Meckel’s?
bleeding (seen in 25-50% of pts)
What causes the bleeding encountered in Meckels?
chronic acid producing gastric mucosa adjacent to ileum
Are Meckel’s malignant vs benign?
majority benign
How does a Meckel’s cause SB obstruction?
SB volvulizes around the fibrotic Meckel’s band attached to abdominal wall
What is a Littre’s hernia?
inguinal hernia containing Meckel’s diverticulum
How does a Meckel’s cause intussussception?
the diverticulum, if broad, can invaginate into the SB lumen and be carried forward by peristalsis
How do we try and treat intussussception caused by a Meckel’s?
usually barium enema
will ultimately need diverticular resection to prevent recurrence
This should be on the differential alongside appendicitis in someone with RLQ:
Meckel’s diverticulitis
if operating for suspected appendicitis and the appendix is normal, check the distal ileum for an inflamed Meckel’s
Best test for Meckel’s?
Pertechnetate scan –> which is taken up preferentially by gastric mucosa cells and ectopic gastric tissue in the diverticulum
What do you do for asymptomatic Meckel’s diverticula found in child vs adults?
children–> remove
adults–> controversial
What is pneumatosis intestinalis?
multiple gas-filled cysts found in the GI tract
cysts seen in subserosa, submucosa, rarely muscle
most common in jejunum
spontaneous rupture of cysts give rise to pneumoperitoneum
WHat causes pneumoperitoneum in pneumatosis intestinalis?
rupture of thin walled gas-filled cysts found in subserosa, submucosa of intestinal wall
peritonitis is unusual
** pneumatosis intestinalis represents one of few cases of sterile pneumoperitoneum
In pts with free abdominal air but no signs of peritonitis, we can consider this on differential;
pneumatosis intestinalsis
Most cases of pneumatosis intestinalis assc with what?
COPD
immunocompromised states
Pneumatosis intestinalis in neonates usually assc with what?
necrotizing enterocolitis
What is the tx for pneumatosis intestinalis?
no tx unless rare complications occur;
volvulus
tension pneumo
rectal bleeding
What is vascular compession of the duodenum called by the SMA?
SMA syndrome, AKA Wilkie’s syndrome
What is Wilkie’s syndrome?
compression of duodenum by SMA
What portion of duodenum compressed by SMA resulting in Wilkie’s syndrome?
D3
This medication has been shown to significantly decrease severity of nausea/vomiting in pts with malignant bowel obstruction?
ocreotide
The two most common types of ectopic tissue seen in a Meckel’s are?
gastric
pancreatic
Nodal and distant mets are common with carcinoids 1-2 cm in size, with nodal spread seen in what % and liver spread in what %?
nodal spread in 60-80%
liver mets 20%
Carcinoid syndrome results from what ?
circulating vasoactive products; serotonin, histamine, kallikrein, bradykinin, prostaglandins
normally these products deactivated by monoamine oxidase in liver
for carcinoid syndrome to occur these products must be released in the systemic circulation through primary bronchial carcinoid, retroperitoneal mets or another source that does not drain thru portal circulation or have haptic mets that overwhelm liver’s MAO
How do we treat liver mets in carcinoid syndrome?
usually removed, helps provide symptomatic relief in pts who don’t respond to the somatostatin analogues
SB adenocarcinoma is relatively rare, found mostly where?
duodenum + jejunum –>80%
***+ surgical margin assc. with poor prognosis
In pts with Peutz-Jeghers syndrome, 90% of pts have what small bowel lesions?
hamartomatous polyps, mostly in jejunum
69% of pts with Peutz-Jeghers syndrome, that have hamartomatous polyps in the small bowel, develop what?
intussussception
Complication rates of stricturoplasties vs segmental resections for strictures in Crohn’s?
stricturoplasties have higher complications rates; post-op bleeding from suture line
thus stricturoplasties for Crohn’s are used to preserved substantial bowel length, they’re not used to small strictures that can be segmentally resected due to higher risk of complications
Gold standard to diagnose intussussception, showing characteristic ‘bull’s eye sign”;
CT with IV/PO contrast
In adults that present with intussussception, the lead point is ususally?
a small bowel tumor 80% of the time
thus a segmental resection of affected area, don’t reduce the intussussception, lymphadenectomy, anastomosis
Why don’t we reduce intussussception in adults?
tumor cells can be shed or tumor can be disrupted given inflamed nature of the bowel
Most common xray findings in intussussception and most pathognomonic xray finding in intussussception:
most common–> non-specific air fluid levels, no gas in colon
pathognomonic–> sausage shaped soft tissue density, outlined by two strips of air
Best test to diagnose Crohn’s?
c-scope with bx
What are the two forms of pneumatosis intestinalis?
cystic—> seen in submucosa as cysts
linear–> seen in subserosa, muscualris as a thin linear gas pattern
Mortality rate from enterocutaneous fistulas?
15-20%
Majority of enterocutaneous fistulas are caused by?
iatrogenic 85%
predisposing conditions; Crohn’s diverticulitis, malignancy, trauma (20%)
anastomotic leaks, bowel injury, erosion by suction catheters, lacs to bowel by mesh or retention sutures
Differences in proximal vs distal fistulas?
proximal fistulas–> higher output, more fluid & electrolyte loss
distal fistulas–> lower output, tend to close spontaneously
What is a high output fistula?
> 500 cc/day
What are some factors that prevent spontaneous fistula closure?
high output radiation enteritis cancer active IBD distal obstruction undrained abscess foreign body in fistula tract epithelialization of fistula tract fistula tract < 2.5 cm long
MC cause of death in pts with fistulas?
historically was malnutrition and dehydration
now it’s sepsis
How do we manage fistulas surgically?
source control, nutritional optimization
conservative course for 4-6 weeks, if it hasn’t closed, then surgery should be considered
ideally you want to wait 3-6 months
Role of ocretide in fistula management?
shown to reduce fistula outputs
not provided an improvement in fistula closure rates
Preferred operation for fistulas?
fistula tract excision
segmental resection of the involved segment of intestine
reanastomose
This is a rare condition manifested by diarrhea, stetatorrhea, megaloblastic anemia, weight loss, abd pain and malabsorption of fat soluble vitamins (ADEK):
blind loop syndrome
What causes blind loop syndrome?
bacterial overgrowth in a stagnant area of small bowel
usually due to stricture, stenosis, fistula, diverticula
What causes megaloblastic anemia in blind loop syndrome?
bacterial overgrowth due to stagnant area of bowel
these bacteria compete for B12
How do we treat megaloblastic anemia caused by bacterial overgrowth in blind loop syndrome?
course of broad spectrum abx, adding IF does not help
How can we confirm blind loop syndrome?
can get cultures from an intestinal tube
C-xylose breath test
Schilling test–> C-labeled Vit B12 is absorbed, and excretion in urine is noted (usually 0-6% in blind loop syndrome, normal is 7-25%)
Tx for blind loop syndrome?
IV B12
broad spectrum abx–> augmentin, kefflex + flagyl
For radiation enteritis, what’s the dose that can cause damage to the intestine?
dosages > 5000 cGy
Various drugs have been used to help with radiation enteritis, what’s the most promising?
amifostine
sulhydryl compound that is converted intra-cellularly to an active metabolite –> binds to free radicals and prevents cell damage
What is short bowel syndrome?
total SB length that is inadequate to support nutrition
Of cases of short bowel syndrome, 75% are due to massive intestinal resections from what?
mesenteric occlusion
volvulus
trauma to superior mesenteric vessels
MC cause of short bowel syndrome in neonates is?
necrotizing enterocolitis
Clinical hallmarks of short bowel syndrome?
diarrhea, malnutrition, fluid + electrolyte deficiency
Why do we see an increase in gallstones and kidney stones with short bowel syndrome?
decrease in enterohepatic circulation
hyperoxaluria causes kidney stones
What are some common causes of Wilkie’s syndrome?
vascular compression of duodenum usually due to weight loss, supine immobilization, scoliosis, body cast
Operative treatment for duodenal vascular compression by SMA?
duodeno-jejunostomy
Characterize fistulas and their outputs:
low output–> less than 200 cc/day
moderate–> 200-500
high output –> greater than 500 cc/day
IF a fistula remains open after 6-8 weeks, spontaneous closure is?
unlikely
In pts with carcinoid syndrome, they can become hypotensive unresponsive to fluids and pressors, what do we give?
ocreotide (somatostatin analogue)
Strongest risk factor for developing sxs with a Meckel’s?
ectopic gastric tissue
What are some risk factors assc with developing sxs due to a Meckels?
male sex
age less than 50
diverticulum > 2 cm
ectopic tissue
For a pt with an acute flare up for Crohn’s dx, initial management includes?
oral steroids–> then taper
infliximab usually reserved for pts who have not responded to other therapies
This is a potent vasodilator that does not increase intestinal O2 uptake:
papaverine
What is MALT?
mucosal associated lymphoid tissue–> seen in stomach, asscs with h.pylori –> once h pylori treated, MATL regresses
when found in small bowel and isolated, resection takes care of it, nothing else to do
ALmost 80% of these small bowel tumors arise in duodenum and proximal jejunum and may assc. ulcers;
adenocarcinomas
frequently cause obstruction
Most appropriate antibiotics for small bowel intestinal overgrowth?
rifaximin (inhibits DNA dependent RNA polymerase)
usually for 14 days
Why do we need screening in pts with FAP if they’ve had a total procto-colectomy with ileo-anal anastomosis?
polyps typically seen throughout colon and rectum
but also seen in stomach, duodenum thus screening w/anoscopy and EGD recommended post-op regularly
Fistulization between gallbladder and duodenum?
produces gallstone ileus
What’s Bouveret’s syndrome?
GOO caused by gallstone in duodenum
Extrinsic compression of CBD by gallstone?
Mirizzi syndrome
Treatment for high risk GISTs?
prolonged adjuvant therapy usually with imatinib if ckit positive for 3 yrs or more
In pts with blind loop syndrome this test can aid in the diagnosis;
d-xylose test (carb breath test)
bacteria in blind loop break down carbs to hydrogen and methane which is detected in the breath
Bile salts and vit B12 are absorbed where?
terminal ileum
if terminal ileum resected, bile salts are not re-absorbed, introduced to colon, interfere with colonic absorption of fluids and electrolytes
pts experience diarrhea
Tx–> oral cholestyramine
What medications are known to be protective against radiation enteritis?
ACEi
statins
This syndrome characterized by severe post-prandial epigastric abdominal pain and nonbilious emesis, usually in pts w/gastric bypass surgery;
afferent loop syndrome
This medication indicated in pts with short bowel syndrome who can’t be weaned off TPN;
teduglutide
glucagon-like-peptide 2 analog
(ocreotide usually used short-term in pts with short gut syndrome)
Blind loop syndrome is most commonly associated with what procedure?
antecolic biliroth II with a long >30 cm afferent limb
(retrocolic loop gastroenterostomy is preferred)
Tx–> convert to a biliroth I or a Roux-en-Y
The vitelline duct connects the yolk sac to the midgut of the embryo, and self-involutes during 9th week of development, failure to involute leads to a?
Meckel’s
Crohn’s disease can have a 10-12 fold increased risk of what small bowel cancer?
adenocarcinoma
usually in the terminal ileum
Duodenal Crohn’s dx is unusual, tx of choice for Crohn’s involving the 1st and 2nd portions of the duodenum include?
gastrojejujonostomy and vagotomy (vagotomy done to prevent marginal ulcers)
duodenojejunostomy indicated for refractory strictures of 3rd/4th part of duodenum
***pancreaticoduodenectomy is not performed for duodenal Crohn’s
Most common complication following reversal of a loop ileostomy?
SBO - 7%
followed by SSI
Lymphomas of small bowel tend to be found where?
ileum
tend to be large when found
perforation occurs in 25% of pts
Different types of small bowel stricturoplasties:
single short segment 5-7 stricture; H-Mickulicz
medium segment 10-15 cm; Finney
>15 cm segment; Michelassi
large bowel does not respond well to stricturoplasties,
in large bowel strictures need resection, 7% chance of having cancer
Small bowel lymphomas are more commonly of B cell or T cell origin?
B cell
What part of small bowel do most small bowel lymphomas originate?
ileum—> has Peyer’s patches
Pts with a hx of this disease are more likely to develop T-cell lymphoma of small bowel;
celiac dx
Who is at higher risk of developing T cell lymphoma of small bowel?
pts w/celiac dx
immunocompromised pts
Most common small bowel location for lymphoma?
ileum
In what part of small intestine is most protein absorption taking place?
jejunum
How is protein digested?
begins in stomach, gastric acid denatures protein
small intestine, protein comes in contact with pancreatic proteases
trypsinogen gets activated by brush border enterokinase in duodenum
activated trypsin activates other enzymes
Approx. 80-90% of protein digestion and absorption occurs in the?
jejunum
A Heineke-Mickulicz stricturoplasty is indicated for strictures what size?
5-7 cm long
How to perform a Heineke-Mickulicz stricturoplasty?
make a longitudinal incision across the stricture
place two stay sutures on either end
close in a tranverse fashion with simple interrupted silk sutures
FInney stricturoplasties are best suited for what length strictures?
10-15 cm long
