Sabiston Small Bowel Flashcards
Anatomy , Lengths
duodenal length 20 cm
jejunal length at 100 to 110 cm
ileal length at 150 to 160 cm.
Anatomy , Jejunum Vs Ileum
jejunum :
larger circumference, thicker
can be identified during surgery by examining mesenteric vessels, only one or two arcades send out long, straight vasa recta to the mesenteric border
Ileum : blood supply to the ileum may have four or five separate arcades with shorter vasa recta
Mucosa of Small bowel
characterized by transverse folds (plicae circulares), which are prominent in the distal duodenum and jejunum
Blood Supply to Duodenum
Superior mesenteric artery > distal duodenum.
The celiac artery > proximal duodenum
Blood Supply to Small Bowel
-superior mesenteric artery (except for the proximal duodenum )
-SMA > courses anterior to the uncinate process of the pancreas and the third portion of the duodenum, it divides to supply the pancreas, distal duodenum, entire small intestine, and ascending and transverse colons.
-abundant collateral blood supply provided by vascular arcades coursing in the mesentery
Innervation
parasympathetic and sympathetic divisions of the autonomic nervous system
The parasympathetic fibers > the vagus nerve, traverse the celiac ganglion and influence secretion, motility, and probably all phases of bowel activity.
The sympathetic fibers > splanchnic nerves > located in a plexus around the base of the superior mesenteric artery
Location of myenteric (Auerbach) plexus and (Meissner plexus)
myenteric (Auerbach) plexus > muscularis propria (between the muscles)
(Meissner plexus) > networks of lymphatics, arterioles, and venules > in Submucosa
lamina propria Location and Role
between the epithelial cells and muscularis mucosae
Contains > plasma cells, lymphocytes, mast cells, eosinophils, macrophages, fibroblasts, smooth muscle cells, and noncellular connective tissue
protective role > rich supply of immune cells
Main functions of the crypt epithelium and Villous Epithelium
crypt epithelium > cell renewal, exocrine, endocrine, water, and ion secretion
villous epithelium > digestion and absorption.
What are the Four main cell types are contained in the mucosal layer
(i) absorptive enterocytes
(ii) goblet cells, which secrete mucus
(iii) Paneth cells, which secrete lysozyme, (TNF), and cryptdins, which are homologues of leukocyte defensin peptides related to the host mucosal defense system
(iv) enteroendocrine cells,produce the gastrointestinal hormone
What is the Main Cell in the Mucosa
Absorptive enterocytes
Function of The brush border of the small intestine
contains the enzymes
lactase, maltase, sucrase-isomaltase, and trehalase
split the disaccharides into their monosaccharides
Transport of the released hexoses (glucose, galactose, and fructose) is by
active transport.
The major routes:
sodium-glucose transporter 1 (SGLT-1), glucose transporter 5 (GLUT-5), and glucose transporter 2 (GLUT-2).
Protein Digestion
Pancreatic trypsinogen is secreted in the intestine by the pancreas in an inactive form > activated by the enzyme enterokinase, a brush border enzyme in the duodenum to an activated form of trypsin.
Bile Acid
-unconjugated bile acids absorbed into the jejunum by passive diffusion
-conjugated bile acids that form micelles are absorbed in the ileum by active transport
-then reabsorbed from the distal ileum and pass through the portal venous system to the liver for secretion as bile.
Vitamins Absorbtion
Calcium > duodenum and jejunum by active transport
facilitated by an acid environment and is enhanced by vitamin D and parathyroid hormone
Iron > as a heme or nonheme component > duodenum by an active process.
total absorption of iron is dependent on body stores of iron and the rate of erythropoiesis
Potassium, magnesium, phosphate, and other ions actively absorbed throughout the mucosa
Vitamin B1 > jejunum by an active process similar to the sodium-coupled transport system for vitamin C.
Vitamin B2 > the upper intestine by facilitated transport.
vitamin B12 > terminal ileum.
derived from cobalamin, freed in the duodenum by pancreatic proteases, binds to intrinsic factor
Vitamin B6 > simple diffusion into the proximal intestine
Motility
Sympathetic activity inhibits motor function
parasympathetic activity stimulates it.
motilin, its peak plasma level during phase III (intense bursts of myoelectrical activities resulting in regular, high-amplitude contractions) of migrating myoelectric complexes
The gut-associated lymphoid tissue is localized in four areas
-Peyer patches > activate and prime B and T cells
-lamina propria lymphoid cells
-Paneth cells
-intraepithelial lymphocytes > unique subtype of T cells.
major protective immune mechanisms for the intestinal tract is
the synthesis and secretion of IgA.
produced by plasma cells in the lamina propria
Which Primary colonic cancers Present Like SBO
Tumors arising from the cecum and ascending colon
MC Cause of SBO
Adhesions 60%
Malignant 20%
Hernia 10%
Crohns 5%
Early in the course of an obstruction
intestinal motility and contractile activity increase > diarrhea
Later in the course of obstruction
intestine becomes fatigued and dilates > water and electrolytes accumulate intraluminally and in the bowel wall itself > massive third-space fluid loss > dehydration and hypovolemia
proximal obstruction vs Distal obstruction
Proximal > dehydration, hypochloremia, hypokalemia, and metabolic alkalosis
Distal > large quantities of intestinal fluid into the bowel; however, abnormalities in serum electrolyte levels are usually less dramatic.
Sepsis in SBO
-the jejunum and proximal ileum Normally have only 103 to 105 (CFU/mL) of bacteria.
-With obstruction (most commonly Escherichia coli, Streptococcus faecalis, and Klebsiella spp.) > reaching concentrations of 109 to 1010 CFU/mL.
increase in the number of indigenous bacteria translocating to mesenteric lymph nodes and even systemic organs
> amplifies the local inflammatory response leading to intestinal leakage and subsequent increase in systemic inflammation.
higher obstruction vs Distal
Higher > Nausea and vomiting , hyperactive bowel sounds
distally > less emesis;
initial and most prominent symptom is cramping abdominal pain, minimal or no bowel sounds are noted
As the obstruction becomes more complete with bacterial overgrowth, the vomitus becomes more feculent, indicating a late and established intestinal obstruction.
Plain abdominal film signs of SBO
Supine :
-Dilated gas or fluid filled small bowel >3 cm
-Dilated stomach
-Small bowel dilated out of proportion to colon
-Stretch sign
-Absence of rectal gas
-Gasless abdomen
-Pseudotumor sign
Plain abdominal film signs of SBO
Upright or Left Lateral Decubitus :
-Multiple air fluid levels
-Air fluid levels longer than 2.5 cm
-Air fluid levels in same loop of small bowel of unequal lengths
-String of beads sign
why put NGT in SBO
-empties the stomach
-reducing the hazard of pulmonary aspiration of vomitus
-minimizing further intestinal distention from swallowed air
Radiation enteropathy causing SBO Tx
can be treated nonoperatively with tube decompression and the potential addition of corticosteroids, particularly during the acute setting.
In the chronic setting, laparotomy will be required with possible resection of the irradiated bowel or bypass of the affected area.
If intestinal viability is questionable
the bowel segment should be completely released and placed in a warm, saline-moistened sponge for 15 to 20 minutes and then reexamined.
If normal color has returned and peristalsis is evident, it is safe to retain the bowel
Another options : Doppler probe, administration of fluorescein and Intraoperative near-infrared angiography or second-look laparotomy 18 to 24 hours after the initial procedure.
consideration of laparoscopic management in SBO
-mild abdominal distention
-proximal or partial obstruction;
-anticipated single-band obstruction
-and those with low risk of strangulation or perforation
laparoscopic found to be of greatest benefit in
-patients with fewer than three previous operations
-were seen early after the onset of symptoms
-and were thought to have adhesive bands as the cause.
the most effective means of limiting the number of adhesions
is a good surgical technique :
-gentle handling of the bowel to reduce serosal trauma
-avoidance of unnecessary dissection
-exclusion of foreign material from the peritoneal cavity
-the use of absorbable suture material when possible,
-avoidance of excessive gauze sponge use,
-the removal of starch from gloves
-adequate irrigation and removal of infectious and ischemic debris
-preservation and use of the omentum around the site of surgery or in the denuded pelvis
Causes of ileus.
- After laparotomy
- Metabolic and electrolyte derangements (e.g., hypokalemia, hyponatremia, hypomagnesemia, uremia, diabetic coma)
- Drugs (e.g., opiates, psychotropic agents, anticholinergic agents)
- Intraabdominal inflammation
- Retroperitoneal hemorrhage or inflammation
- Intestinal ischemia
- Systemic sepsis
Ileus vs SBO
-Plain abdominal radiographs may reveal distended small bowel as well as large bowel loops.
-In cases that are difficult to differentiate from obstruction, barium studies may be beneficial
Etiology of Crohns
-infectious : Mycobacterium paratuberculosis and enteroadherent E. coli.
-immunologic : Humoral and cell-mediated immune reactions , cytokines, such as interleukin (IL)-1, IL-2, IL-8, and TNF-α
genetic : NOD2, MHC, and MST1 3p21
Environmental factors : smoking
the single strongest risk factor for development of Crohns disease
-is having a first-degree relative with Crohn disease
-The most important gene in Crohn disease development is NOD2
The NOD2 gene is associated with a decreased expression of
antimicrobial peptides by Paneth cells.
Which Gene is a predictor of ileal disease, ileal stenosis, fistula, and Crohn-related surgery.
NOD2
Which gene can distinguish Crohn disease from ulcerative colitis
CARD15 > strongly associated with Crohn disease
CARD15, leads to impaired activation of
the transcription factor nuclear factor kappa B (NF-κB)
tumor suppressor gene play a role in the pathogenesis of Crohn disease and development of Crohn disease–related cancers
The FHIT gene located on 3p14.2
Environmental factors that increase the risk of Crohn disease
medications (oral contraceptives, aspirin, [NSAIDs]), decreased dietary fiber, and increase fat intake.
dysbiosis in which organisms increase the risk
decrease in intraluminal Bacteroides and Firmicutes
increase in Gammaproteobacteria and Actinobacteria
Ileal involvement has been shown with mutations of
IL10, CRP, NOD2, ZNF365, and STAT3
ileocolonic involvement has been shown with mutations
ATG16L1, TCF4, and TCF7L2
colonic involvement has been associated with mutations
HLA, TLR4, TLR1, TLR2, and TLR6.
What characteristic can distinguish it from ulcerative colitis
rectal sparing
Gross pathologic features at exploration
1- thickened gray-pink or dull purple-red loops of bowel
2- areas of thick gray-white exudate or fibrosis of the serosa.
3- skip areas
4- extensive fat wrapping caused by the circumferential growth of the mesenteric fat around the bowel wall, (creeping fat)
5- bowel wall thickened, firm, rubbery, and almost incompressible
6- uninvolved proximal bowel may be dilated secondary to obstruction
7- Involved segments adherent to adjacent intestinal loops or other viscera, with internal fistulas
8- The mesentery of the involved segment is thickened, with enlarged lymph nodes
9- On opening of the bowel, the earliest gross pathologic lesion is a superficial aphthous ulcer noted in the mucosa.
on opening the bowel, the earliest gross pathologic lesion is
superficial aphthous ulcer noted in the mucosa.
With disease progression, the ulceration becomes results in transmural inflammation
characteristics of The ulcers
linear
may join to produce transverse sinuses with islands of normal mucosa in between
thus giving the characteristic ‘‘cobblestone appearance’’
Characteristic histologic lesions of Crohn disease are
noncaseating granulomas with Langerhans giant cells.
Granulomas appear later in the course and are found in the wall of the bowel or in regional lymph nodes
massive gastrointestinal bleeding in CD can occasionally occur, particularly in
duodenal Crohn disease > chronic ulcer formation
long-standing Crohn disease can develop
Dysplasia
Adenocarcinoma
MC in the Ileum
Extraintestinal cancer with CD
squamous cell carcinoma of the vulva and anal canal
Hodgkin and non-Hodgkin lymphomas
especially those treated with immunomodulators
Serologic markers useful in the diagnosis of Crohn disease.
-Perinuclear antineutrophil cytoplasmic antibody
(target proteins bactericidal/permeability increasing protein [BPI], lactoferrin, cathepsin G and elastase)
-Anti–Saccharomyces cerevisiae antibody (ASCA)
useful in differentiating Crohn disease from ulcerative colitis
-outer membrane porin of flagellin (anti-CBir1),
-outer membrane porin of E. coli (OmpC-IgG)
> predict development of IBD even in Low risk patients
inflammatory markers specific to the intestine
- Stool lactoferrin, an iron-binding protein in the secretory granules of neutrophils
- fecal calprotectin, a protein with antimicrobial properties released by squamous cells in response to inflammation,
- both calprotectin and lactoferrin levels correlate with CT enterography (CTE)
-Helpful screening tools for detecting early small bowel Crohn disease
Montreal classification of Crohn disease
see
MRE may be superior to CTE in detecting
intestinal strictures and ileal wall enhancement
the gold standard for the diagnosis of Crohn disease.
Ileocolonoscopy with biopsies of the terminal ileum
Endoscopic advances that allow better evaluation of the small intestine include
-single-balloon enteroscopy
-double-balloon enteroscopy
-spiral enteroscopy
the most well-established technique is double-balloon enteroscopy, which allows increased enteral intubation (240–360 cm)
push enteroscopy (90–150 cm)
ileocolonoscopy (50–80 cm)
Best Modality for identification of intestinal ulceration.
capsule endoscopy has been found to be superior to any other modality in the identification of intestinal ulceration.
criterion for an abnormal finding is the presence of three or more ulcers in the absence of NSAID use.
Aminosalicylates
-Sulfasalazine (azulfidine) is an aminosalicylate with 5-aminosalicylic acid
-use in maintenance therapy has fallen out of favor
-Mesalamine, a slow release of 5-aminosalicylic acid
-If remission is achieved with induction,continued for maintenance
-SE: interstitial nephritis (1%)
Corticosteroids
-Budesonide, high first-pass hepatic metabolism, allows targeted delivery to the intestine mitigating the systemic effects of steroid therapy.
-The preferred primary treatment for patients with mild to moderately active Crohn disease with localized ileal disease
-9 mg/day
-prednisone, in moderate to severe CD.
-not ideal for maintenance therapy (50% become “steroid dependent,”)
-Parenteral corticosteroids indicated for severe disease once the presence of an abscess has been excluded
-40–60 mg daily
How to taper Steroids ?
tapered by 5 to 10 mg/ week until 20 mg
and then by 2.5 to 5 mg weekly until cessation
What Should you do when starting steroids ?
-Dual-energy x-ray absorptiometry scan
-calcium and vitamin D supplementation
-consideration of bisphosphonate therapy
Antibiotics
-metronidazole
-ciprofloxacin
-rifaximin
-clofazimine
-ethambutol
-isoniazid,
-rifabutin
-used in septic complications and beneficial in perianal disease.
Immunosuppressive agents
-AZT and 6-MP are effective for maintaining steroid-induced remission
-weekly IV MTX is effective for both induction and maintenance therapy.
SE: pancreatitis, hepatitis, fever, and rash.
chronic liver disease, bone marrow suppression, and the potential for malignant transformation.
What regulates Immunosupressive Therapy ?
thiopurine methyltransferase (TPMT), which is the primary enzyme that metabolizes AZT and 6-MP
decreased TPMT activity > increased risk of fatal bone marrow suppression
Any test can be done before starting immunosupressive therapy ?
TPMT genotype testing > determine genetic predisposition to adverse outcomes
MTX side effects
hepatotoxicity
myelosuppression
not used in pregnant women.
Other agents help in fistula?
FK-506 inhibits the production of IL-2 by helper T cells
effective for fistula improvement, but not fistula remission
patients with severe disease who do not respond to IV steroids, what to give ?
cyclosporine and FK-506.
Anti-TNF therapy
-Infliximab for moderate to severe Crohn disease
-For induction and maintenance agent
-can results in perineal fistula closure
Which agent is ideal in pregnant and nursing women
certolizumab (humanized antibody fragment)
does not cross the placenta and is not excreted in breast milk
Anti TNF Concern
-increased risk for TB reactivation
-invasive fungal and opportunistic infections,
-demyelinating CNS lesions
-activation of latent multiple sclerosis
-exacerbation of congestive heart failure
-concerns for increased risk of melanoma
Patients who develop a flare while on anti-TNF agents
measurement of serum drug concentrations and antidrug antibodies
increase dosage (if low drug concentration and low antibodies)
switch to another anti-TNF agent (high antidrug antibodies)
switch to another drug class (normal drug concentration).
Novel therapies
-used if the patient has failed or is unable to tolerate anti-TNF therapy
-Natalizumab
-vedolizumab
-Ustekinumab
What extraintestinal complications of Crohn disease Does not Subside after resection
ankylosing spondylitis and hepatic complications.
Do Fistulizing disease requires operative intervention
rarely requires operative intervention unless the fistula involves the bladder, vagina or skin
New Technique minimize anastomotic restenosis in Crohn disease
antimesenteric functional end-to-end hand-sewn anastomosis (known as Kono-S anastomosis)
Why anastomotic recurrence happens in CD
fecal stasis and subsequent bacterial overgrowth
At exploration, the appendix is found to be normal, but the terminal ileum is edematous and beefy red with a thickened mesentery and enlarged lymph nodes
this patient has acute ileitis, Due to early CD or Bacteriologic > Campylobacter and Yersinia
Intestinal resection should not be performed
In the absence of acute inflammatory involvement of the appendix or the cecum, appendectomy should be performed.
In patients for whom it is difficult to determine whether the site of obstruction is caused by an acute exacerbation or a chronically strictured segment
stool lactoferrin and calprotectin levels may help identify acute inflammation
There are two types of bypass operations: exclusion bypass and simple (continuity) bypass
-proximal transected end of the ileum is anastomosed to the transverse colon in an end-to-side fashion with or without construction of a mucous fistula using the distal transected end of the ileum (exclusion bypass)
-or an ileotransverse colonic anastomosis is made in a side-to-side fashion (continuity bypass).
Indications for Bypass
-severe gastroduodenal CD not amenable to strictureplasty
-older poor-risk patients
-patients who have had several prior resections and cannot afford to lose any more bowel
-those in whom resection would necessitate entering an abscess or endangering a normal structure.
Sx for Fistula
-fistula between two or more adjacent loops of diseased bowel > segments should be excised
-fistula involves an adjacent normal organ (bladder or colon) > only the segment of the diseased small bowel and fistulous tract should be resected, and the defect in the normal organ should simply be closed
-ileosigmoid fistulas do not necessarily require resection of the sigmoid because the disease is usually confined to the small bowel.
-However, if the segment of sigmoid is also found to have Crohn disease, it should be resected along with the segment of diseased small bowel.
Abscess Tx
abscess < 3 cm and have not been on biologics or have an associated fistula can be treated with antibiotics alone.
Abscesses that do not meet these criteria should undergo percutaneous drainage
Patient with generalized peritonitis
safer option > create an ostomy until the intraabdominal sepsis is controlled Then return for restoration of intestinal continuity after a period of 4 to 6 weeks
The most common urologic complication in CD
-ureteral obstruction, secondary to ileocolic disease with retroperitoneal inflammatory compression
after abdominoperineal resection in patients with Crohn disease
Wound filled with well-vascularized pedicles of muscle (e.g., gracilis, semimembranosus, rectus abdominis) or omentum or by using an inferior gluteal myocutaneous graft.
Tx for perianal
-nonoperative unless an abscess or complex fistula develops
-Nonsuppurative, chronic fistulization or perianal fissuring treated with antibiotics, immunosuppressive agents (e.g., AZT or 6-MP), and infliximab
Several uncontrolled studies have shown some benefit with cyclosporine or FK-506 treatment.
Fistula Tx
fistulotomy > superficial, low trans-sphincteric, and low intersphincteric fistulas
High transsphincteric, supra-sphincteric, and extrasphincteric fistulas > noncutting seton
Fissure Tx in CD
usually lateral, relatively painless, large, and indolent and often respond to conservative management
Duodenal disease in CD
Gastrojejunostomy to bypass the disease rather than duodenal resection is the procedure of choice
the leading cause of disease-related deaths in patients with Crohn disease
Gastrointestinal cancer
Typhoid Enteritis
-contaminated water supplies and inadequate waste disposal.
-primarily by Salmonella typhi
-penetrate the small bowel mucosa, > lymphatics
-Hyperplasia of the reticuloendothelial system, including lymph nodes, liver, and spleen
-Peyer patches > hyperplastic > ulcerate > hemorrhage or perforation.
-Diagnosis > organism from blood, bone marrow, and stool cultures
-Tx fluoroquinolones and third-generation cephalosporins.
-single perforation in the terminal ileum > simple closure
-Multiple perforations > resection with primary anastomosis
Protozoa Enteritis in AIDS
-Cryptosporidium, Isospora, and Microsporidium
-most frequent class of pathogens causing diarrhea in patients with AIDS
-Diagnosis > acid-fast staining of the stool or duodenal secretions
-Immunochromatography Stool
-Tx > prophylactic cotrimoxazole and a highly active antiretroviral therapy
Bacteria Enteritis in AIDS
- Salmonella, Shigella, and Campylobacter
-diagnosis of Shigella or Salmonella > stool cultures.
-Campylobacter > PCR techniques evaluating stool and serum
-Bacteremia and serious infections > IV imipenem or ciprofloxacin if the organisms are multiply resistant
the pregnant patient may be safely treated with erythromycin
Mycobacteria in Immunocopromised
-Mycobacterium tuberculosis or Mycobacterium avium complex (MAC)
-most frequent site of intestinal involvement of M. tuberculosis is the distal ileum and cecum
-bowel wall appears thickened, and an inflammatory mass often surrounds the ileocecal region
-Stricture and Fistula can Form
-caseating granulomas found most commonly in the lymph nodes
-Radiographic > thickened mucosa with distorted mucosal folds and ulcerations
-CT > thickening of the ileocecal valve and cecum.
-Tx for MAC > amikacin, ciprofloxacin, cycloserine, and ethionamide, Clarithromycin
Viruses
-CMV is the most common viral cause of diarrhea in immunocompromised
-Enteric CMV > mucosal ischemic ulcerations
-Diagnosis > viral inclusion > intranuclear inclusion > owl’s eye appearance
-Tx > ganciclovir
MC Locations for Small Bowel Tumors
-Adenocarcinoma is the most common malignant neoplasm (30% to 50%)
-Neuroendocrine tumors (NETs) (25% to 30%)
-Adenocarcinomas are more prevalent in the proximal small bowel
-Other malignant lesions are more common in the distal small bowel
MC benign Tumor, and MC one to produce Symptoms
-Adenomas are the most common benign tumors
-stromal tumors are the most common benign small bowel lesions that produce symptoms.
when a benign tumor is identified at operation, What would You Do ?
-resection is indicated because symptoms are likely to develop over time.
-At operation, a thorough search of the remainder of the small bowel is warranted because multiple tumors are not uncommon
Patients with GIST, nearly 20% of patients are found to have
metastatic disease, most commonly in the liver
How to Confirm Diagnosis of GIST
biopsy with immunohistochemical staining for
-KIT (95%)
-anoctamin-1 (98%)
stromal tumors express
-CD117
-the KIT proto-oncogene protein that is a transmembrane receptor for the stem cell growth factor
-and 70% to 90% express CD34, the human progenitor cell antigen.
-These tumors infrequently stain positive for
actin (20%–30%), S100 (2%–4%), and desmin (2%–4%)
How to measure or predict Mets or Recurrence
-Tumors larger than 5 cm, regardless of mitotic index, have higher rates of metastasis and recurrence
-those with a high mitotic index have a higher risk of metastasis and recurrence regardless of size.
Adenomas MC found in which part
20% duodenum
30% jejunum
50% ileum.
Which type of Adenoma is considered Premalignant
Both true and villous adenomas are thought to proceed along a similar adenoma-carcinoma sequence as colorectal adenomas
in FAP , you perform Screening , when to take Bx
biopsy of all suspicious, villous, or large (>3 cm) adenomas in addition to random duodenal biopsy specimens
When to Perform pancreaticoduodenectomy or pancreas-preserving duodenectomy in Fap adenomas
high-grade dysplasia
carcinoma in situ
or a Spigelman stage IV
Spigelman
see
Recommended surveillance in relation to the Spigelman classification.
see
Hamartomas in PJS MC location
are most commonly found in the jejunum and ileum
Patients with Small Bowel Hamartomas may also have ?
50% of patients may also have rectal and colonic lesions, and 25% of patients have gastric lesions
How To treat Surgically
-Resection > limited to the segment of bowel that is producing complications.
Because of the widespread nature of intestinal involvement, cure is not possible; therefore, extensive resection is not indicated.
MC Symptom in PJS is Abd pain Why ?
recurrent colicky abdominal pain, usually the result of intermittent intussusception
PJS Extracolonic cancers where ?
occurring in 50% to 90% of patients (small intestine, stomach, pancreas, ovary, lung, uterus, and breast).
Hemangiomas of Small Bowel
-submucosal proliferation of blood vessels.
-jejunum MC location
-can be part of Osler-Weber-Rendu disease.
-Turner syndrome > cavernous hemangiomas of the intestine.
-MC Symp intestinal bleeding.
-Angiography and Tc-99m RBC scanning > diagnostic studies.
-If a hemangioma is localized preoperatively, resection of the involved intestinal segment is warranted.
-Intraoperative transillumination and palpation may help to identify a nonlocalized hemangioma.
In contrast to benign lesions, malignant neoplasms almost always
-produce symptoms
the most common > pain and weight loss.
-Obstruction usually the result of tumor infiltration and adhesions.
NENs Divided into Groups , Mention them
-divided > NETs and neuroendocrine carcinomas
-NETs > benign or malignant type
-subdivided : (grade 1, G1)
(grade 2, G2) and (grade 3, G3) tumors
based on > appearance, mitotic rates, behavior (invasion of other organs, angioinvasion), and Ki-67 proliferative index.
On the other hand, neuroendocrine carcinomas are all G3, poorly differentiated malignant tumors
NETs are also categorized based on the embryologic site of origin and secretory product
-foregut (respiratory tract, thymus)
>produce low levels of serotonin (5-hydroxytryptamine) but may secrete 5-hydroxytryptophan or adrenocorticotropic hormone
-midgut (jejunum, ileum and right colon, stomach, proximal duodenum)
>high serotonin production
-hindgut (distal colon, rectum)
> rarely produce serotonin but may produce other hormones, such as somatostatin and peptide YY.
In the small intestine, NETs almost always occur within
the last 2 feet of the ileum
the most prominent secreted humoral agents by Nets
serotonin and substance P
carcinoid syndrome, secondary to serotonin or tachykinin production, is characterized by
episodic attacks of cutaneous flushing
bronchospasm
diarrhea, and vasomotor collapse
is present mostly in those patients with hepatic metastases
Primary tumors that secrete directly into the venous system, bypassing the portal system
(e.g., ovary, lung), give rise to carcinoid syndrome without metastasis.
MC Location for NETs in GIT ?
small intestine (38%)
rectum (34%)
Colon (16%)
stomach (11%)
in Korea, the most common site for NETs is the rectum
The malignant potential for NETs (ability to metastasize) is related to
location, size, depth of invasion, and growth pattern
smaller than 1 cm> 2% associated with Mets
1 to 2 cm > 50%
larger than 2 cm > 80% to 90%
gross appearance of NETs
-Small, firm, submucosal nodules , yellow on the cut surface.
-subtle as a small whitish plaque seen on the antimesenteric border of the small intestine.
-associated with a larger mesenteric mass caused by nodal disease and desmoplastic invasion of the mesentery.
-tend to grow very slowly, but after invasion of the serosa, the intense desmoplastic reaction produces mesenteric fibrosis, intestinal kinking, and intermittent obstruction.
unusual observation in NETs
-coexistence of a second primary malignant neoplasm of a different histologic type.
-synchronous adenocarcinoma (most commonly in the large intestine) > occur in 10% to 20% of patients with NETs.
-Multiple endocrine neoplasia type 1 is associated with NETs in approximately 10% of cases
Secretory products of neuroendocrine tumors
see
Malignant carcinoid syndrome
vasomotor, cardiac, and gastrointestinal manifestations
cutaneous flushing (80%)
diarrhea (76%)
hepatomegaly (71%)
cardiac lesions, most commonly right-sided heart valvular disease (41%–70%)
and asthma (25%)
Cutaneous flushing in the carcinoid syndrome may be of four varieties:
- diffuse erythematous, > short-lived > face, neck, and upper chest;
- violaceous, > attacks may be longer > develop a permanent cyanotic flush, with watery eyes and injected conjunctivae
- prolonged flushes > up to 2 or 3 days > entire body and > profuse lacrimation, hypotension, and facial edema
- bright-red patchy flushing > gastric NETs.
The three most common cardiac lesions are
pulmonary stenosis (90%)
tricuspid insufficiency (47%)
tricuspid stenosis (42%)
Malabsorption and pellagra ?
> Niacin deficiency VitB3 (dementia, dermatitis, and diarrhea) are occasionally present and are thought to be caused by excessive diversion of dietary tryptophan.
Diagnose Carcinoid
A combination of serum CgA measurement with 24-hour urine 5-HIAA is an acceptable diagnostic combination with increased sensitivity.
CT Diagnose Carcinoid
CT> solid mass with spiculated borders and radiating surrounding strands that is associated with linear strands within the mesenteric fat and kinking of the bowel, a diagnosis of gastrointestinal NET can be made
Diagnosis for Carcinoid
-CT Scan
-MRI Liver ( For Mets )
-18F-fluorodeoxyglucose PET Scan
18FDG is taken up only in high-grade NETs (e.g., high Ki-67 expression) > most NETs have low Ki-67 expression
-18F-L-dihydroxyphenylalanine (18F-DOPA)
> improved the sensitivity of PET
-Scintigraphic localization
> Octreotide is a synthetic analogue of somatostatin, and indium (111In)-labeled pentetreotide specifically binds to somatostatin receptor subtypes 2 and 5.
-Somatostatin receptor imaging with gadolinium 68Ga–DOTATATE PET/CT
68Ga-DOTATATE PET/CT is a clinically useful imaging technique to
-localize primary tumors in patients with neuroendocrine metastases of unknown origin
-to define the existence and extent of metastatic disease.
The benefits of 64Cu-DOTATATE imaging
-better true positive lesion detection
-longer shelf life and scanning window when compared with 68Ga-DOTATATE, making it an ideal diagnostic too
Tx of NETs
-tumors < 1 cm without regional LN Mets
> segmental resection
- > 1 cm, with multiple tumors, or with regional LN Mets, regardless of the size of the primary tumor, wide excision of bowel and mesentery is required.
-Lesions of the terminal ileum > right hemicolectomy.
-Small duodenal tumors > excised locally
-more extensive lesions may require pancreaticoduodenectomy
anesthesia may precipitate a carcinoid crisis , how to Tx
characterized by hypotension, bronchospasm, flushing, and tachyarrhythmias.
treated with IV octreotide bolus of 50 to 100 μg
> may be continued as an infusion at 50 μg/hr.
Mets to liver Tx
-Even with liver metastasectomy > high recurrence rate of 75%.
-In these cases, transarterial chemoembolization or radioembolization has been shown to provide liver-directed control of disease.
-resection of the primary tumor, with or without mesenteric resection, > improve survival and to slow progression of hepatic metastases in patients with unresectable disease
Medical therapy
-Somatostatin analogs (SSAs) are the standard of care
-octreotide (Sandostatin) and lanreotide
-relieve symptoms and delay cancer progression (antiproliferative effect)
-Octreotide LAR is recommended for Grade 1 and 2 NETs and not recommended in grade 3
For patients who have disease progression on SSA therapy
-Everolimus, a mammalian target of rapamycin (mTOR) inhibitor, initially developed as immunosuppressant therapy, is approved for the treatment of nonfunctional gastrointestinal NETs with unresectable, locally advanced or metastatic disease
somatostatin refractory diarrhea in the setting of carcinoid syndrome
the serotonin synthesis inhibitor, telotristat etiprate
Currently, the role of chemotherapy ?
streptozotocin, 5-fluorouracil (5-FU), and cyclophosphamide.
-to patients with G2 metastatic disease who are symptomatic, are unresponsive to other therapies, or have high tumor proliferation rates.
Resectable adenocarcinomas in the second portion of the duodenum are treated with
pancreaticoduodenectomy
regional lymphadenectomy of the periduodenal, peripancreatic, and hepatic lymph nodes as well as involved vascular structures is necessary.
For Adenocarcinoma patients with metastatic disease
FOLFOX
(oxaliplatin, 5-FU, and leucovorin)
FOLFIRI
(irinotecan, 5-FU, and leucovorin)
as first-line therapy significantly improves the performance status and progression-free survival
the main prognostic factor for adenocarcinoma
LN invasion
moreover, the number of lymph nodes assessed and the number of positive lymph nodes are of prognostic value
(Required > 10 LN)
Lymphoma
-in children younger than 10 years, they are the most common intestinal neoplasm.
-most commonly found in the ileum
-RF > celiac disease and immunodeficient states e.g AIDS
-Asymptomatic small bowel lymphomas > chemoresponsive and do not require surgery.
-B-cell lymphomas > chemosensitive than T-cell lymphomas and have high remission rates
-T-cell lymphomas > more resistant to therapy > progress to symptoms of obstruction or perforation if not resected.
-Regardless of cell type, resection is indicated at any onset of symptoms because progression to life-threatening hemorrhage or perforation portends a dismal prognosis
GISTs MC Found in ?
more common in the jejunum and ileum
GISTs mostly arise from
the muscularis propria
The most useful indicators of survival and the risk for metastasis include
the size of the tumor at presentation
mitotic index
evidence of tumor invasion into the lamina propria.
GIST Tx capsule rupture occurs, What to Do
-receive adjuvant therapy regardless of the extent of the tumor before surgery.
-It is advisable to perform an en bloc resection, to include adjacent organs, for prevention of tumor capsule rupture.
-A laparoscopic approach in patients with large tumors is strongly discouraged.
Radiologic criteria for unresectability for GISTS
-infiltration of the celiac trunk, superior mesenteric artery, or portal vein.
Small GISTs (<2 cm) found incidentally in surgical specimens, What to Do
do not require further treatment.
Algorithm for GIST Tx
see
effective treatment for advanced GISTs after failure of either imatinib or sunitinib
Regorafenib > second-generation tyrosine kinase inhibitor that targets c-kit, RET, BRAF, VEGFR, PDGFR, and fibroblast growth factor receptor.
-Sorafenib > VEGF, c-kit, PDGFR, and BRAF inhibitor and has been effective in imatinib- and sunitinib-resistant tumors
All intraluminal duodenal diverticula require treatment
True, because recurrence of symptoms is certain.
For Duodenum diverticula embedded deep within the head of the pancreas
duodenotomy is performed,
with invagination of the diverticulum into the lumen, which is then excised, and the wall is closed
Alternative methods for duodenal diverticula associated with the ampulla of Vater include an extended sphincteroplasty through the common wall of the ampulla in the diverticulum
perforated diverticulum
excised and the duodenum closed with a serosal patch from a jejunal loop.
If the surrounding inflammation is severe, > divert the enteric flow> gastrojejunostomy or duodenojejunostomy.
Interruption of duodenal continuity proximal to the perforated diverticulum > pyloric closure with suture or a row of staples.
f the diverticulum is posterior and perforates into the substance of the pancreas,
operative repair may be difficult and dangerous.
Wide drainage with duodenal diversion may be all that is feasible
Surgical jejunostomy should also be considered for all patients with acute perforation to ensure nutrition
Jejunal and Ileal Diverticula causing malabsorption
secondary to the blind loop syndrome and bacterial overgrowth in the diverticulum can usually be given antibiotics.
Obstruction may be caused by enteroliths that form in a jejunal diverticulum , Tx ?
subsequently dislodged and obstruct the distal intestine.
treated by enterotomy and removal of the enterolith, or sometimes the enterolith can be milked distally into the cecum.
When the enterolith causes obstruction at the level of the diverticulum, bowel resection is necessary.
Why there is heterotopic tissues in meckels ?
Cells lining the vitelline duct are pluripotent;
incarceration of the diverticulum in an inguinal hernia
(Littre hernia)
When the appendix is found to be normal during exploration for suspected appendicitis
the distal ileum should be inspected for the presence of an inflamed Meckel diverticulum.
Neoplasms can also occur in a Meckel diverticulum
NET as the most common malignant neoplasm (77%).
Other histologic types include adenocarcinoma (11%), which generally originates from the gastric mucosa, GIST (10%), and lymphoma
how to increase the sensitivity of 99mTc-pertechnetate scan for Meckels
Cimetidine may be used to increase the sensitivity of scintigraphy by decreasing the peptic secretion, while not affecting radionuclide uptake
Incidental Meckels , What to do ?
It is generally recommended that asymptomatic diverticula found in children during laparotomy should be resected.
The treatment of Meckel diverticula encountered in the adult patient, however, remains controversial.
Meckel diverticulum becoming symptomatic in the adult > 2% or less
The factors associated with a higher risk of complications, and warranting consideration of resection
age younger than 50 years
male sex
diverticulum length >2 cm
ectopic tissue or palpable abnormalities.
Small Bowel Ulceration
-more commonly in the ileum, with single or multiple ulcerations noted
-Complications necessitating operative intervention include bleeding, perforation, and obstruction.
-NSAIDs are known to induce an enteropathy characterized by increased intestinal permeability leading to protein loss and hypoalbuminemia, malabsorption, and anemia.
-Treatment of complications from small bowel ulcerations is segmental resection and intestinal reanastomosis
Multiple factors prevent the spontaneous closure of fistulas
retained foreign body
radiation enteritis
inflammatory bowel disease or infection
epithelialization of the fistula tract
neoplasm
distal obstruction.
Factors predictive of nonoperative fistula closure
see
Blind loop syndrome in small bowel
> diarrhea, steatorrhea, megaloblastic anemia, weight loss, abdominal pain, and deficiencies of the fat-soluble vitamins as well as neurologic disorders.
> bacterial overgrowth in stagnant areas of the small bowel produced by stricture, stenosis, fistulas, or diverticula (e.g., jejunoileal or Meckel diverticulum)
Blind Loop
> vitamin B12 Deficiency > megaloblastic anemia.
confirmed by > cultures obtained through an intestinal tube or > 14C-xylose or 14C-cholylglycine breath tests.
> the Schilling test (57Co-labeled vitamin B12 absorption) > pattern of urinary excretion of vitamin B12 resembling that of pernicious anemia (a urinary loss of 0% to 6% of vitamin B12 compared with the normal of 7%–25%).
Tx > course of a broad-spectrum antibiotic (e.g., tetracycline) should return vitamin B12 absorption to normal.
Radiation Enteritis
morbidity risk increases with dosages exceeding 5000 cGy.
pharmacologic interventions to reduce the side effects of radiation enteritis
1- Angiotensin-converting enzyme inhibitors
2- statins
reduce acute gastrointestinal symptoms during radical pelvic radiotherapy.
3- Sucralfate, > stimulate epithelial healing and form a protective barrier , help in bleeding from radiation proctitis
4- Superoxide dismutase, a free radical scavenger,
5- glutathione, antioxidants (e.g., vitamin A, vitamin E, beta-carotene), histamine antagonists, and the combination of pentoxifylline and tocopherols
6- probiotics as having a radioprotective effect in the gut;
7- The most effective radioprotectant agent appears to be amifostine
Which part of Small bowel can increase absorptive capacity more efficiently
Proximal bowel resection is tolerated better than distal resection because the ileum can adapt more than the jejunum.
Pharmacological tx for Short Bowel
-teduglutide, a GLP-2 analogue > restoration of intestinal functional and structural integrity through significant intestinotrophic and proabsorptive effects.
-Somatropin, a recombinant human growth hormone that elicits anabolic and anticatabolic influence
direct effect or indirectly through IGF-I
superior mesenteric artery syndrome or Wilkie syndrome,
RF > supine immobilization, scoliosis, and placement of a body cast > cast syndrome.
after proctocolectomy and J-pouch anal anastomosis
Dx : barium upper gastrointestinal series or hypotonic duodenography
Tx : conservative, duodenojejunostomy, gastrojejunostomy to bypass the obstructing segment, or duodenal derotation (Strong procedure)
