Small Intestine Flashcards
1
Q
Primitive gut appears at the
A
4th week
2
Q
Arises from junction of fore and midgut
Make up first 20cm
A
duodenum
3
Q
Develops from proximal limb of midgut
A
Jejunum and upper part of ileum
4
Q
Develops from caudal limb of midgut loop
A
Distal ileum
5
Q
Midgut rotates at week
A
11
6
Q
Midgut rotation
A
270 counterclockwise around SMA
7
Q
Failure of duodenal recanalization
A
Duodenal stenosis or atresia
8
Q
Layers of SI
A
Mucosa
Submucosa
Muscularis
Serosa
9
Q
Layer that contains Brunner’s glands
Vessels, lymphs, myenteric plexus meissner
A
Submucosa
10
Q
Produce alkaline secretion against gastric chyme
A
Brunner’s glands
11
Q
Strongest layer in SI
A
submucosa
include in anastomosis
12
Q
Remaining 5-6cm
A
Jejunum 40%
Ileum 60%
13
Q
Differentiated by greater circumference, longer vasa recta and few arcades, longer and greater plicae circulares
A
jejunum
14
Q
Villi on mucosal surface epithelium:
A
simple columnar with brush border
15
Q
Arise from pluripotent cells of crypts in Lieberkuhn
Migrate to top of villi
95% of epithelium
A
Enterocyte
16
Q
Base of crypts of Lieberkuhn
Phagocytosis, mucosal defense, regulation of flora, secretion of antimicrobial peptide
A
Paneth cell
17
Q
Above Peyer’s
Specialized for APC
A
Microfold M cell
18
Q
Specialized for mucous secretion
A
Goblet cell
19
Q
Specialized to produce and secrete hormones (secretin, motilin, somatostatin, cholecystokinin, peptide YY, GLP2, GIP
A
Enteroendocrine
20
Q
Arterial supply by SMA enters
A
Mesenteric side of jejunum and ileum
21
Q
First to become ischemic after impaired blood supply
A
Mesenteric side of jejunum and ileum bec of SMA entry
22
Q
Duodenum bs
A
Celiac artery
SMA
23
Q
Jejunum and ileum BS
A
SMA
24
Q
Venous drainage of SI
A
SMV
25
Parasympathetic innervation of SI
Vagus nerve
26
Sympathetic innervation of SI
Splanchnic nerve
27
Lymph drainage of SI
Regional mesenteric lymph node draining into cysterna chyli
28
Stimulates INTESTINAL epithelial proliferation
GLP2
29
Inhibits GI motility and GI secretion
somatostatin
30
Inhibits INTESTINAL ONLY motility and secretion
Peptide YY
31
Inhibits HCl secretion
GIP
32
Purpose of villi and microvilli
Inc surface area of SI making it principal site for digestion and absorption
33
Volume absorbed in SI each day
Transcellular Na creates osmotic gradient driving water absorption via tight junction and intercellular space
2/3 (6 out of 9) L
Na, Cl, K, Ca, Mg, iron and water jejunum
34
Glucose
| Galactose transport
SGLT1 (apical brushborder)
GLUT2 (bloodstream)
Secondary active transport (cotransporter)
35
Fructose transporters
GLUT5 (apical brushborder)
GLUT2 (bloodstream)
Facilitated diffusion
36
Carbohydrate digestion primary location
Duodenum
| Proximal jejunum
37
Carbohydrate absorbed forms
Monosaccharides
38
AA and Di and tripeptide transporters
Na/AA co transport
| Di and tri peptides/H co transport
39
Site of primary protein digestion
Proximal jejunum
40
Absorbed form of protein
AA
| Di and tripeptide
41
Lipid mode of transport
Monoglyceride and FFA via passive diffusion
42
Absorbed form of lipid
Monoglyceride/FFA
43
Primary location of lipid absorption
Duodenum
| Proximal jejunum
44
Bile salt primary site of absorption
Ileum
45
Vitamins ADEK and H20 soluble (B,C,folate) are absorbed in
Jejunum
46
B12 absorbed in
ileum
47
```
Key energy source for enterocyte
Dec uptake (stress) impairs defenses leading to
```
Glutamine
Bacterial translocation and sepsis
48
Also known as intestinal housekeeper
Key regulator hormone
MMC Migrating Myoelectric Complex
Motilin
49
Immune and barrier function of SI
Peyer’s patches
M cells for AP
B cells secreting IgA
50
Has more adaptive capacity
Ileum
51
Basal pacemaker rhythm of SI
interstitial cells of Cajal
52
Highly coordinated contraction moving contents through SI
| Peristaltic reflex
Propulsive (propagating)
53
Mixing of contents (chyme, digestive enzyme) exposes contents to absorptive surface
Non propagating
Segmental
54
Pattern of contraction that occurs during fasting state
Conducts peristaltic contraction from distal stomach to ileum every 90-120 min
Controlled by enteric ns
Migrating myoelectric complex
55
Phase I MMC
Quiesence
56
Phase II
Irregular disorganized electrical and mechanical activity
57
Regular high altitude electric burst and contraction
Phase III
58
Enhances GI motility as agonist at motilin receptor
Erythromycin
59
Post op return of bowel function
SI 1 day
Stomach 2 days
Large intestine 3-5 days
60
70, F
s/p Sigmoid colectomy
12 yrs prior crescendo-decrescendo abdominal pain, vomiting and dec passage of flatus and stool
Mx of SBO?
Clinical exam
CT scan
Most likely by adhesion
NPO
IV fluids
NGT
61
Most common surgical disorder of SI
| Accompanied by inc secretion dec absorption
SBO
62
Complete obstruction where lumen is occluded proximally and distally
High risk of necrosis as inc intraluminal pressure may limit perfusion and result in ischemia
Closed loop obstruction
| volvulus
63
Most commonly caused by failure of peristalsis
| Affects all ages
Non mechanical obstruction
| paralytic ileus
64
Causes of mechanical obstruction
```
adhesion
neoplasm
hernia
Crohn’s
Congenital anomaly
Gallstone ileus
Cystic fibrosis
Diverticular disease
SMA
foreign body stricture
volvulus
```
65
Most common cause of pediatric SBO
hernia
66
Crampy intermittent pain
Nonfeculent emesis
Scaphoid abdomen
Proximal SBO
67
Pain with late and feculent emesis
Distal SBO
68
```
Abdominal sx
Cancer
Previous SBO
leukocytosis, hemoconcentration, hypochloremic hypokalemic metabolic alkalosis by emesis
lactic acidosis
```
SBO
69
SBO dx
Abdominal series (supine, upright)
airfluid level, gasless colon, dilated SI loops >3cm in ladder-like pattern
70
Higher sensitivity and specificity
CT scan
| 90% in series
71
Useful in identifying etiologic factors and strangulation
CT: wall edema, portal venous gas, pneumatosis intestinalis, poor enhancement of SI)
will not show adhesion
72
Most cases of partial SBO due to adhesions resolve in 48h
expectant management
73
SBO tx
Fluid resuscitation
Electrolyte correction
Antibiotics if ischemic
74
Partial SBO mx
IV
NPO
NGT
with serial abdominal exam and radiographs
avoid narcotics
75
Operative intervention in SBO warranted if
Persistence beyond 5-7 days
Progresses to complete
Clinical status deteriorates (peritonitis, hemodynamic instability, fever, leukocytosis)
76
Complete SBO mx
Early operative intervention to minimize mobidity and mortality
77
Viability of SI may be assessed by
color
peristalsis
marginal arterial pulses
via fluorescein or Doppler
78
SBO in Crohn’s tx
Nonoperatively with TPN
Treat Crohn’s if stable without peritonitis
SBO beyond 7 - 10 days, operative intervention
79
Virgin abdomen SBO tx
operative intervention
| rule out pathologic cause with follow up studies if resolves on its own
80
Intraabdominal cancer SBO
adhesion or obstruction, adhesiolysis or bypass
if carcinoma, nonoperative
81
Recent intraabdominal infection SBO tx
Pelvic or colorectal non operative 10-20 days
Risk of ischemia low but failure to improve with conservative course, operate
82
2nd-4th decade
Ashkenazi Jews
Environmental exposure in genetically predisposed
Abd pain, diarrhea, fever, weight loss
Anywhere in GI tract but most commonly:
Crohn’s disease
Distal ileum 75% with B12 deficiency
83
Crohn’s dx
CT scan
| Upper GI with small bowel follow-through or endoscopy
84
CT findings of Crohn’s
```
Transmural inflammation
Skip lesion
Granuloma
Fissure
Creeping mesenteric fat
```
85
Surgical indication for Crohn’s
```
Failure of medical management
Development of obstruction #1
Perforation
Perianal disease
Abscess
Fistula
Toxic megacolon
```
FATPOP
86
POD6 s/p ileal resection for Crohn’s
45, M
Low grade fever, vague abdominal pain, ileus
Wound is erythematous with feculent discharge
Appropriate work up?
Enterocutaneous fistula
NGT
NPO
initiate TPN
protect skin
Confirm with fistulogram and identify abscess with CT
Initiate 4-6w course conservative management
Drain abscess
Start antibiotics if septic
87
communication between two epithelial lined surface
Intestinal fistula
88
Low fistula
<200 ml
89
Moderate fistula
200-500 ml daily
90
High fistula
>500 ml daily output
91
Fistula in 5-6d post op
| Low grade fever, abdominal pain and ileus
Phase I
| Recognition, resuscitation, skin protection and drainage control
92
Does not improve spontaneous closure rate but may dec output
Somatostatin
93
After 7-10 days diagnostic options include CT scan to identify drainable abscess or fistulogram (anatomy)
Abscess should be drained
Phase II
| Investigation
94
If fistula fails to close spontaneously over 4-6w period
Operative repair necessary
30-50%
Phase III
| Conservative management and decision making
95
Extensive adhesiolysis or resection of involved area
G or J tube might be necessary for decompression or enteral feeding
Close fascia tension-free
Phase IV
| Operative repair
96
Enteric feeding should advance gradually to goal
Phase V
| Healing
97
95% of fistulas occur
after surgical procedure
98
Impede closure of fistulas
```
Foreign bodies
Radiation
Inflammatory bowel/infection
Epithelialization
Neoplasm
Distal obstruction
Sepsis
```
99
Factors with higher chance of spontaenous closure
favorable location
favorable initiating factor
absence of infection or malnutrition
healthy bowel, small nonepithelialized defect with tract >2cm in length
100
Mortality in fistula is due to
sepsis
101
Congenital true diverticula
Meckel
| Duodenal wind-sock diverticula
102
Present in adult as SBO
| Managed conservatively
Meckel’s
103
Outpouchings at site of vessels
| Involve mucosa, submucosa and from abnormality in motility
False diverticula
104
Most SI diverticula are
asymptomatic
105
Sx for diverticular complication
Diverticulectomy with patch or Roux-en-Y duodenojejunostomy if large
Duodenal diverticulization
Resection of affected segment with anastomosis
106
1% of retrograde ERCP
Asymptomatic to peritonitis with shock
Dx confirmed by CT revealing retroperitoneal or free intraperitoneal air
NPO, NGT, abdominal series and IV antibiotics if mild
Lap if unstable
Post ERCP duodenal perforation
107
Majority of SI diverticula are found in
jejunum
108
Comprise about 2% of GI malignancies
| 5th-6th decades
SI neoplasm
109
Benign SI tumors are commonly
adenoma on duodenum
| may be associated with FAP
110
Most common SI malignancy
Found on
Adenocarcinoma
duodenum: inc risk with Crohn’s, FAP, HNPCC
111
Less frequent than appendiceal lesion found within 2ft of ileocecal valve
Carcinoid
112
May be primary or disseminated disease
B cell are most common primary
Affects the:
Lymphoma
Ileum
113
Rf for lymphoma
Immunosupression (posttransplant lymphoprolif disorder, AIDS, celiac sprue, Crohn’s)
114
Less frequent than gastric lesion
GIST
115
```
Include melanoma
Lung
Renal cell
Pancreatic
Breast gastric
```
Metastases
116
Most common primary SI malignancy
Adenocarcinoma
Carcinoid
Lymphoma
Stromal tumor
ACLS
117
Anemia
| Guaiac + stool
Adenocarcinoma SI
118
Carcinoid patients have increased
5-HIAA or chromogranin A
119
SI carcinoma dx
EGD proximal lesion
Enteroclysis (diagnosis)
CT scan
120
80% of SI adenocarcinoma have
metastases at time of diagnosis
121
SI adenocarcinoma
No role for chemoradiation except lymphoma
122
AD
associated with hamartoma of small and large bowel
mucocutaneous hyperpigmentation
Also assoc with increased risk of malignancies (gastric, esophageal, pancreatic, breast, endometrial, testicular, lung)
Peutz-Jeghers
123
Surveillance for Peutz-Jeghers
EGD and colonoscopy every other year beginning in adolescence as well as UTS, mammography, breast, gyne and testicular exam
124
Peutz Jeghers sx
Hemorrhage
Obstruction
Adenomatous lesion
125
Any age group
Extensive resection
Pediatric: nec enterocolitis, midgut volvulus, intestinal atresia, gastroschisis
Adult: Crohn’s, mesenteric ischemia, trauma, malignancy, radiation enteritis
Short bowel syndrome
126
Clinical syndrome of SBS occur with
<200cm of jejunoileal length
= 30% normal jejunoileal length for age
127
SBS dx
Hx of extensive resection or abdominal catastrophe
| Albumin, LFT, electrolyte, Hct, vitamin levels, fecal fat (Sudan stain), gastrin
128
SBS mx
```
Fluid and electrolyte
Nutritional support with TPN
H2 blocker or PPI
Anti diarrheal agents (diphenoxylate, loperamide)
Antibiotics
Enteral introduction
```
129
SBS sx
Nontransplant procedure to inc bowel length, absorptive capacity, transit time
130
Prolonged TPN may lead to
Liver failure
| Cholangitis
131
Placed through rectal muscle away from belt line in area easily visualized and assessed by patient
Intestinal ostomy
132
```
For protection of anastomosis
Temporary
Diarrhea, skin irritation
Dehydration, electrolyte imbalance
Necrosis, obstruction, stenosis, retraction, prolapse, parastomal hernia
```
Loop ileostomy
| Divided loop ileostomy
133
Decompression of distal (neoplasm) diversion after distal resection
Permanent or temporary
Diarrhea, dehydration, electrolyte imbalance, necrosis, obstruction, stenosis, retraction, prolapse, parastomal hernia
Brooke end ileostomy
134
Decompression of distal (neoplasm) diversion after distal resection
Permanent or temporary
Valve dislodgement
Incompetence, pouchitis, diarrhea, dehydration electrolyte imbalance, necrosis, retraction, parastomal hernia, prolapse
Kock continent ileostomy
135
Decompression of distal protection of low anastomosis
Treatment of perforation
Diversion after resection
Permanent or temporary
Necrosis, parastomal hernia, prolapse, obstruction
Colostomy (end, double barrel or loop, mucuous fistula)
136
Most likely malignancy of duodenum
Adenocarcinoma
137
Most likely malignancy of ileum
Carcinoid
138
Peutz Jeghers is associated with the mutation of
STK11 ch19
139
Determines mortality in eterocutaneous fistula
Site of origin
Output
Complication
15-20%
140
Most common cause of SI hemorrhage in
adult
children
AVM
Meckel’s
141
55, M
Cholecystectomy with incidental Meckel
Indication for resection
Resection not indicated for asymptomatic adult
Perform diverticulectomy for complication:
bleeding, diverticulitis, obstruction
142
Factors that influence adaption after SBS
Luminal nutrient
Hormones
Growth factors
Enteral feeding
143
Exploration for AA reveal normal appendix, thickened and erythematous terminal ileum and creeping fat
Dx?
Mx?
Crohn’s
If appendiceal stump not involved, perform appendectomy but do not resect ileum
144
Most common indication for surgery in Crohn’s
Obstruction
145
After extensive SI ileocecal valve resection for AMI with necrosis, patient develops diarrhea and malnutrition
What is initial medical management?
SBS
Fluid resusc
TPN
H2 blocker or PPI
Antidiarrheal agents
