SMALL BOWEL Flashcards
approach to Crohn’s disease related obstruction of the first two portions of the duodenum is
bypass is for involved duodenal tissues that are too unyielding.
The traditionally bypass with a gastrojejunostomy.
Stricturoplasty has been studied as an alternative to gastrojejunostomy with vagotomy and has been found to be an acceptable alternative to short segment duodenal Crohn’s disease with similar symptom relief and reoperation rates but fewer complications than bypass operations.
bile acids are absorbed into
The proximal intestine absorbs most of the dietary fat
unconjugated bile acids are absorbed into the jejunum by passive diffusion,
CONJUGATED bile acids that form micelles are absorbed in the ILEUM by active transport and are reabsorbed from the distal ileum.
The histologic type of small-intestinal malignancy that has increased the most in the last two decades is:
CARCINOID!
Historically, adenocarcinoma accounts for 30% to 50% of small-bowel tumors, making it the most common primary malignant tumor.
Acute pseudo-obstruction Distention that is cause of alarm
Often in chronic cases, distention in excess of 15 cm can be observed without evidence of colonic perforation or wall ischemia.
Normal midgut rotation of the intestine - what direction and what artery - what is potential zone of dead bowel
The axis of the midgut is the superior mesenteric artery (SMA), and rotates 180 - 270 degrees counterclockwise.
ischemia of the entire bowel supplied by the SMA from the proximal jejunum to the ascending and transverse colon.
antiinflammatories for Crohn’s
Adding mesalamine reduces the need for and duration of corticosteroid therapy once the disease is in remission.
Sulfasalazine ONLY effective for the treatment of Crohn’s colitis and ileocolitis, but NOT for the treatment of disease limited to the small intestine.
Like mesalamine, sulfasalazine contains a 5-ASA moiety; proximal absorption of this molecule is prevented by its attachment to sulfapyradine. Long-term use of sulfasalazine is limited, however, by the toxicity caused by the sulfapyradine molecule.
Gastrinoma
is the second most common islet cell tumor and is the most common symptomatic, malignant, endocrine tumor of the pancreas. Approximately half of gastrinomas arise in the duodenum. The hallmark of ZE syndrome is a virulent ulcer diathesis, massive gastric hypersecretion, and an islet tumor of the pancreas. In 75% of patients with ZE syndrome, the gastrinoma is sporadic; the remaining 25% of patients have an associated multiple endocrine neoplasia type 1 syndrome. The main symptoms are those of peptic acid hypersecretion, with abdominal pain as a chief complaint in approximately 75% of patients. Nearly two thirds of the patients have diarrhea, and 10% to 20% of the patients present with diarrhea alone. Most patients have peptic ulcers, with duodenal ulcers being the most common but jejunal ulceration may also be found. Current clinical clues to the diagnosis of patients with ZE syndrome include the presence of a virulent peptic ulcer or gastroesophageal reflux disease diathesis; absence of Helicobacter pylori or failure of the peptic ulcer to heal after either anti-H. pylori therapy or H2 receptor blockade; secretory diarrhea that persists; or signs and symptoms of the multiple endocrine neoplasia type 1 syndrome.
Carcinoid tumors occur where
in portions of the body that have developed from the embryonic foregut, midgut, and hindgut. Carcinoids of the bronchopulmonary tree and pancreas constitute the foregut component. The midgut and hindgut components are seen from the stomach to the rectum. The incidence of carcinoid tumors within the organs comprising the bronchopulmonary tree and the gastrointestinal tract varies widely. Almost half of these are seen in the appendix. Rectal carcinoids constitute 15% of the total. Carcinoids of the ileum and of the lungs and bronchi each comprise about 10%. No other site in the gastrointestinal tract, including the stomach, has an incidence of more than 5% of the total. Gastric carcinoids account for 2% to 3%.
Acute pseudo-obstruction initial management includes
If distention is painless and the patient has no signs of toxicity or bowel ischemia, expectant management can be successful in approximately 50% of cases.
If distention worsens so that the cecal diameter increases beyond 10 to 12 cm or if it persists for more than 48 hours, colonoscopy is recommended.
Endoscopic decompression is successful in 60% to 90% of cases, but colonic distention can recur in as many as 40% of cases.
NO Rectal tubes - ineffective in managing distention of the proximal colon; however, such tubes can be useful after colonoscopy.
associations abnormalities with malrotaiton
Congenital diaphragmatic hernia (CDH)
predilection for malrotation which is found in up to 20% of patients with CDH.
Radiologic findings are classically described for malrotation
plain abdominal film with gastric and proximal duodenal distension.
Upper gastrointestinal studies are typically diagnostic,
however contrast enemas are helpful in the evaluation of neonatal obstruction - Cecal malposition is diagnostic when noted in a contrast enema, usually in the left of the abdomen or at the midline.
Crohn disease risk of small bowel cancer
as much as 100-fold in the more distal small bowel in regions of dysplasia
Like adenoma, sporadic adenocarcinoma has a predilection for what part of small bowel
duodenum
Approximately 80% of tumors are located in the duodenum or proximal jejunum.
A highly-selective vagotomy is recommended for Crohn’s disease patients when
after patients were found to be prone to ulcerations at the gastrojejunal stoma.
Crohn fistulas to the bladder what is the treatment
resection of small bowel portion of fistula
because chronic urinary tract infection on renal function
With ileovesical fistulas, the connection to the bladder is most commonly located at the dome and débridement and primary closure can be affected without endangering the trigone.
GISTs typically have one of three predominant histologic types:
spindle cell (70%),
epithelioid type (20%),
mixed histology.
GISTs become resistant to imatinib, and the median time to resistance and progression is
less than 2 years!!
Therefore, imatinib should never be used as primary therapy for a resectable lesion.
Reports vary, but the percentage of patients who need reoperation to manage recurrent disease is approximately
1.5% to 2% per year if the disease was present in a single intestinal segment
or
4% per year if it was present in multiple intestinal segments.
In closed-loop obstruction, the earliest symptom is
pain
( CAREFUL not abdominal “tenderness”)
abdominal PAIN is caused by traction on the mesentery and distention within the closed loop.
Peritonitis and abdominal tenderness appear only when the loop of intestine becomes necrotic.
Small intestine adenocarcinomas
30% of small tumors - CAREFUL alternative source lists adenocarcinomas most common small bowel tumor
MOST common duodenum.
(80% of SI adenocarcinomas arise in the duodenum or proximal jejunum)
frequently cause obstruction with associated anorexia.
Non-Hodgkin’s lymphoma (NHL) of GI tract - were present in the small intestine
25-35% of NHL will be found in the small intestine,
MOST common ILEUM ( alternate source list jejunum is equal frequency ileum)
most common site of carcinomas to present and small bowel
MOST common distal ileum.
most common extranodal site for non-Hodgkin’s lymphoma to present
The stomach harbors the MOST lymphomas,
small bowel SECOND most
colon third
A 60-year-old man has weight loss and abdominal pain. Assessment including esophagogastroduodenoscopy and abdominal computed tomographic (CT) scan demonstrates an adenocarcinoma of the third portion of the duodenum with enlarged porta hepatis and celiac lymph nodes but no evidence of non-nodal metastases. The most appropriate management for this patient would be:
For lesions amenable to segmental resection, segmental duodenal resection with regional lymphadenopathy is the procedure of choice. Pancreaticoduodenectomy is reserved for those patients with lesions in the first and second portion of the duodenum.
survival outlook for patients with these lesions may be relatively favorable, at least as compared to periampullary tumors.
Interestingly, conventional staging methods, based on local and regional nodal status, have not indicated a consistent survival pattern occurring with stage of disease.
This may reflect the limited experience with this rare malignancy and the small number of operations performed.
cause the release of secretin.
Fats, in whatever form,
and
acidification of the duodenal lumen
Malignant carcinoid syndrome
serotonin release
cardiac lesions particularly right heart valvular disease,
asthma
hepatomegaly
to develop carcinoid syndrome, a patient must
tumo does not primarily drain into the portal circulation for (bronchus, retroperitoneum)
or
hepatic metastases that overwhelm the capacity of the monoamine oxidase to breakdown serotonin.
In the gastrointestinal tract, more than 90% of carcinoids are found in three sites
—appendix (~45%), ileum (~30%), and rectum (~15%).
While more carcinoid tumors occur in the appendix, the tendency of appendiceal carcinoids to metastasize is low (~3%)
most common site for carcinoid tumors that cause carcinoid syndrome
ileal carcinoids metastasize about 35%of the time, making it much more likely to have carcinoid syndrome of ileal origin from metastatic disease.
postoperative maintenance therapy is best approached with what maintenance therapies for Crohn’s
controlled-release 5-ASA and 6-mercaptopurine.
Maintenance with 5-ASA is associated with few side effects but requires up to 12 pills per day and is expensive.
biologics may have a role in recurrence prevention.
smoking fracture on Crohn’s disease
smoking can increase the risk of recurrence.
NSAIDs effects on Crohn’s disease
CAREFUL-sulfasalazine aspirin derivative intraluminally helps with Crohn’s
in contrast, oral NSAID’s may INCREASE Crohn’s recurrence
6-Mercaptopurine side effects
associated with risk of bone marrow suppression.
Patients taking 6-mercaptopurine maintenance need periodic blood cell counts. Emergent data suggest that
In the adult of the short bowel syndrome most common causes
mesenteric occlusion,
midgut volvulus,
traumatic disruption of the superior mesenteric vessels
. Multiple sequential resections, most commonly associated with recurrent Crohn disease, account for 25% of patients.
In neonates, the most common cause of short bowel syndrome is
bowel resection secondary to necrotizing enterocolitis.
The clinical hallmarks of the short bowel syndrome include
diarrhea, fluid and electrolyte deficiency, and malnutrition.
GALLSTONES due to the disruption of enterohepatic circulation
nephrolithiasis from hyperoxaluria.
which is better tolerated extensive resection of proximal or distal small bowel
PROXIMAL
if the distal two thirds of the ileum, including the
ileocecal valve, are resected, significant abnormalities of absorption of bile salts and vitamin B12 may occur, resulting in diarrhea and anemia. Proximal bowel resection is tolerated much better than is distal bowel resection because the ileum can adapt and increase its absorptive capacity more efficiently than can the jejunum.
carcinoids multicentricity
Unlike in the appendix, where multicentricity is rare, carcinoids of the small bowel are multiple 30% to 40% of the time. In addition, 30% to 50% of small-bowel carcinoids are associated with second primary malignant tumors, most frequently of the breast and colon. Gastrointestinal carcinoids can elicit a marked desmoplastic reaction. The mesentery of the small bowel becomes fibrotic and foreshortened; the result is kinking of the bowel or even intestinal ischemia as a result of sclerosis of the mesenteric blood vessels. This finding is readily identified on computed tomography scans and is sometimes associated with calcifications while the small bowel appears fixed and angulated.
Peritoneal adhesions account for what percentage of small bowel obstructions in the United States
more than 50% of cases of small-bowel obstruction in the United States.
Hernias of all types are second only to adhesions as the most frequent cause of obstruction!
Richter hernia.
only a portion of the bowel wall is incarcerated.
most frequently occurs in association with femoral or inguinal hernia.
Complete obstruction can occur if more than one half to two thirds of the bowel circumference is incarcerated.
Of adult cases of intussusception, what percentage are associated with pathologic processes.
90%
Tumors, benign and malignant, can act as a lead point against the intussusception in more than 65% of cases among adults.
Characteristics of Crohn disease seen with colonoscopy include
aphthoid ulcer,
discrete serpiginous ulcerations that usually track along the long axis of the bowel,
diseased mucosa separated by skip areas of normal mucosa,
rectal sparing,
strictures.
In healthy humans, total transit time from the duodenum to the terminal ileum is
2-4 hours
approximately 220 minutes (±53 minutes).
The composition of the meal affects the rate of occurrence and propagation of contractions during the postprandial period.
Frequency of contraction is greatest with meals containing glucose and least after meals high in fat. Therefore, transit is regulated to optimize absorption of nutrients.
enteroclysis
, which involves the oral insertion of a tube into the duodenum to instill air and barium directly into the small intestine and to follow the movement fluoroscopically, has been helpful in the assessment of obstruction.7 Enteroclysis has been advocated as the definitive study in patients for whom the diagnosis of low-grade, intermittent, small bowel obstruction is clinically uncertain.
SAB 2011
Enteroclysis can help detect a small-bowel lesion that could cause repeated hemorrhage (even after neg angio, tag rbc, upper endoscopy, and colooscopy!)
Intraoperative enteroscopy may be necessary if findings at enteroclysis are normal and should be more sensitive to detect mucosal lesions such as angiodysplasia of the small bowel.
GF / SCORE 2011
Non GI sites of carcinoids
10% of primary carcinoids occur in the bronchus or lung.
Other sites,
ovaries,
testicles,
pancreas,
kidney, are far less common.
Gastrointestinal carcinoids most commonly originate in the
distal small bowel, often in close proximity to the appendix.
Many textbooks quote the appendix as being the most common site for carcinoid, but the data to support this statement were from statistics obtained in the 1960s.
Whether or not the appendix versus terminal ileum is the most common site for carcinoid remains a controversial subject.
Recent Surveillance Epidemiology and End Results
most common sites are the
small intestine (44.7%), rectum (19.6%), appendix (16.7%), colon (10.6%), stomach (7.2%).
-GF 2011
What is the blood supply of the small bowel in a patient with a type 4 small bowel atresia (Christmas tree or apple peel deformity)?
The small bowel is provided by retrograde flow from the INFERIOR mesenteric artery (even though this is jejunum), through the right colic artery, into the ileocolic artery.
Because of this blood supply, the midgut is coiled around the ileocolic artery, giving it the appearance of a Christmas tree or apple peel.
prenatal vascular accident which occurs proximally in superior mesenteric artery.
Crohn disease extraintestinal manifestations
dermatologic,
ocular,
hepatobiliary,
joint disorders.
Dermatologic disorders that occur with Crohn disease include erythema nodosum and pyoderma gangrenosum.
Ocular manifestations of Crohn disease include uveitis and episcleritis.
Ankylosing spondylitis, sacral ileitis, and a seronegative peripheral polyarthropathy are associated with Crohn disease.
Patients with Crohn disease are at risk of primary sclerosing cholangitis, but this serious complication is less common with Crohn disease than with ulcerative colitis.
Crohn disease-associated peripheral arthritis, uveitis, episcleritis, erythema nodosum, and possibly pyoderma gangrenosum parallel the activity of intestinal disease and typically regress with successful medical management or complete surgical resection of the affected segments of bowel.
Ankylosing spondylitis and primary sclerosing cholangitis do not correlate with bowel disease activity, and thus the clinical course is not attenuated by surgical resection of intestinal Crohn disease.
Once in its ionized form, calcium is primarily absorbed in the
duodenum, although this process occurs throughout the length of the small intestine.
Internal fistula from Crohn’s disease procedure of choice - recurrence rate
limited resection or suture to achieve a tension-free closure of the uninvolved organ and resection of the involved organ
Because the disease does not usually extend into the uninvolved organ,
Resection of both segments is required only if both are involved with Crohn’s disease.
reoperation due to recurrent fistulization is uncommon.
clinical scenario most likely fits open-loop distal small-bowel obstruction.
intermittent to constant pain with low-volume feculent vomiting.
Distention is marked and progressive, and tenderness is diffuse.
The feculent vomiting suggests distal rather than proximal obstruction.
The lack of severe pain and signs of peritoneal irritation (CAREFUL - diffuse abdominal pain is not the same as severe or peritonitis!) - suggest that closed-loop obstruction is unlikely.
procedure of choice for duodenal adenocarcinoma
For lesions amenable to segmental resection, segmental duodenal resection with regional lymphadenopathy
Pancreaticoduodenectomy is reserved for those patients with lesions in the first and second portion of the duodenum.. (that can’t be reasonably resected with scope and watched….)
The small intestine reabsorbs
nearly 80% of the fluid that passes through it. This dynamic process is accomplished by a rapid bidirectional movement of fluid in the intestinal lumen.
A total of 6 to 11 L of water enters the duodenum every day; of this, approximately 1 to 1.5 L enters the colon.
Alterations in this fine balance caused by either impaired absorption or augmented secretion can result in overall net secretion of water and diarrhea.
