Which electrolyte does colon secrete?
K- potassium via Na/K ATPase
What is vascular supply of ascending colon?
SMA (ascending colon and proximal 2/3 of transverse) via the ileocolic, right colic and middle colic arteries
Which portions of colon are supplied by the IMA? what are the branches?
distal 1/3 of transverse colon, descending colon, sigmoid colon, and upper portion of rectum via the left colic, sigmoid branches, and superior rectal artery.
Path of the Artery of Drummond
aka marginal artery, travels along colon margin, connecting SMA to IMA as a collateral
What is the arc of riolan?
meandering mesenteric artery- short direct connection bt proximal SMA and proximal IMA; becomes enlarged w SMA or IMA stenosis
What is the source of the superior rectal artery?
IMA
What is the source of the middle rectal artery?
internal iliac artery (Lateral stalks during LAR/APR contain the middle rectal arteries)
What is the source of the inferior rectal artery?
internal pudendal (off the iliac artery)
What are the hemorrhoidal arteries?
The rectal arteries
AKA the hypogastric arteries?
Internal iliac arteries
What is Griffith’s point? Why is this significant?
splenic flexure- watershed area at SMA-IMA junction
What is Sudeck’s point? Why is this significant?
superior rectal and middle rectal artery junction; watershed area
Which is more sensitive to ischemia- colon or small bowel? Why?
Colon is more sensitive due to poor collaterals
Into which vessel does the IMV drain?
drains to the splenic vein; splenic vein joins the SMV to create the portal vein behind neck of pancreas
Into which vessel do the superior rectal veins drain?
into IMV (then to portal vein)
Into which vessel do the middle rectal veins drain?
dual drainage system into IMV and internal iliac veins
Into which vessel do the inferior rectal veins drain?
into internal iliac veins and then IVC- which is how rectal tumors can cause isolated lung mets
What is the lymph node drainage of the rectum?
Superior and middle rectum drain to IMA nodes
Lower rectum drains to IMA and internal iliac nodes
What is the innervation of the external anal sphincter?
inferior rectal (anal) branch of the internal pudendal nerve (sympathetic)
From which muscle does the external anal sphincter arise?
Continuation of the puborectalis muscle which is part of the levator ani muscle group
What is the innervation of the internal anal sphincter?
pelvic splanchnic nerves S2-S4, parasympathetic
From which muscle does the internal anal sphincter arise?
continuation of the muscularis propria (smooth muscle, circular layer)
What marks the junction between rectum and anal canal?
Levator ani
What is the main nutrient of colonocytes?
short chain fatty acids (e.g. butyrate)
What is Denonvillier’s fascia?
Fascia on anterior aspect of rectum: recto-prostatic fascia in men; recto-vaginal fascia in women
What is Waldeyer’s fascia?
Fascia on posterior aspect of rectum: recto-sacral fascia/pre-sacral fascia; separates the rectum from the presacral venous plexus and the pelvic nerves
What is disuse proctitis?
Diversion proctitis- occurs with Hartman’s pouch
S/S: grey mucous drainage (sloughed dead mucosa), urgency to defecate
What is the treatment for disuse proctitis?
short chain fatty acid enemas
What is the most common long term complication from pouch formation? What is the diagnosis and treatment?
Infectious pouchitis- can be acute or chronic
Sx: purulent drainage, diarrhea, hematochezia, fever, low abd pain, malaise
Dx: colonoscopy- friable, inflamed pouch; biopsy to rule out Crohn’s disease
Tx: Cipro and flagyl
At what age do you start screening for colon cancer?
50 for normal risk; 40 for intermediate risk or 10yrs younger than family member at diagnosis
What are the screening options for colon cancer?
- Colonoscopy every 10yrs
- high sensitivity fecal occult blood testing every 3yrs with flex sig every 5yrs
- high sensitivity fecal occult blood testing every year
- double contrast barium enema or CT colonography every 5 yrs
What can cause false positive stool guaiac test?
beef, vitamin C, iron, cimetidine
What are the risk factors for sigmoid volvulus?
debilitated, pysch hx, elderly, nursing home residents, laxative abuse, high fiber diets
What is the initial treatment for sigmoid volvulus?
Decompressive colonoscopy followed by sigmoid colectomy during that admission– do NOT attempt colonoscopy if gangrenous bowel is seen on colonoscopy, pt has peritoneal signs or perforation
What is the treatment if decompressive colonoscopy fails to detorse a sigmoid volvulus?
go to OR for sigmoid colectomy
What is the treatment for cecal volvulus?
right hemicolectomy with primary anastomosis (only 20% detorse with colonoscopy)
What is seen on pathology of ulcerative colitis?
Spares the anus but involves the rectum, contiguous (no skip lesions), mucosal inflammation, crypt abscesses, Bimodal age of onset (20’s and 60’s)
What is seen on barium enema of a pt with ulcerative colitis?
“lead pipe” colon- loss of haustra, narrow caliber, short colon, loss of redundancy
What medications are for chronic management of UC?
sulfasalazine (5-ASA) and loperamide; azathioprine, cylcosporine, infliximab
What common med can worsen symptoms and cause flares in UC?
NSAIDs
What is the treatment for acute flare of UC?
steroids (hydrocortisone 100mg q8)
add cipro and flagyl if concern for toxic megacolon
What is toxic megacolon?
bloody stools, fever, tachycardia, hypotension, leukocytosis, abd distention, abd pain and tenderness
What is the initial treatment for toxic megacolon?
NGT, fluids, steroids, bowel rest, abx
What percentage of toxic megacolon will resolve with medical management?
50%– other 50% will require surgery
What are the surgical indications for toxic colitis/megacolon?
Absolute: pneumoperitoneum, diffuse peritonitis, major hemorrhage, uncontrolled sepsis, colonic distention >10-12cm w worsening pain and localized peritonitis
Relative: controlled sepsis, worsening colitis/failure to improve after 72 hrs, clinic deterioration, cont blood transfusions
What is the most common site of perforation in UC?
transverse colon
What is the most common site of perforation in Crohn’s?
distal ileum
What resection is performed in emergent UC cases?
total proctocolectomy with end ileostomy
What are the indications for elective/semi urgent surgery in UC?
significant hemorrhage, persistent obstruction/stricture, any dysplasia, cancer, failed medical tx resulting in 10-12 bloody BMs per day, failure to wean high dose steroids, failure to thrive, long standing disease
What is the most common reason for takedown of ileana anastomosis after colectomy in UC pts?
incontinence (i.e. pouch failure)
What is the cancer risk with UC?
1% per year starting 10yrs after initial diagnosis of pan-colitis; start colonoscopies 8-10yrs after diagnosis
Which pts are indicated for prophylactic colectomy after 20yrs of UC?
pts with primary sclerosing cholangitis, family hx of colon ca, young age at diagnosis, left sided colitis
What is the risk of finding cancer in specimen when total colectomy is performed for dysplasia in UC pt?
30% of UC pts w dysplasia will have cancer found on pathology.
What is the most common extra-intestinal indication for total colectomy?
failure to thrive in children
Which extra-intestinal manifestations of UC do NOT improve after colectomy?
primary sclerosing cholangitis, ankylosing spondylitis
Which extra-intestinal manifestations of UC actually DO improve after colectomy?
ocular problems, arthritis, anemia; 50% with pyoderma gangrenosum will improve
What blood test is associated with UC?
HLA B27 (UC, sacroiliitis, ankylosing spondylitis)
What is the treatment for pyoderma gangrenosum?
steroids
MCC of colonic obstruction in infants
Hirschsprung’s disease
Epidemiology of Hirschsprung’s
more common in males 4:1
Most common sign of Hirschsprung’s
failure to pass meconium in first 24hrs; other s/s distention, constipation, vomiting, colitis; explosive release of watery stool with anorectal exam
Abd XR in Hirschsprung’s
dilated proximal colon or small bowel with distal decompression (decompressed portion does NOT have ganglion cells)
Diagnosis of Hirschsprung’s:
rectal suction cup biopsy- absence of ganglion cells in Auerbach’s myenteric plexus
Pathogenesis of Hirschsprung’s
failure of neural crest ganglion cells to progress in caudal direction; causes a functional colonic obstruction
Extent of colon involved in Hirschsprung’s
75% just have rectal involvement, 5% the rectum and entire colon is affected
Treatment for Hirschsprung’s
Resect rectum and colon until proximal to where ganglion cells appear (send margins to path intra op to confirm presence of ganglion cells)
Order of procedures in Hirschsprungs
Initially bring up colostomy
eventually connect good residual colon to anus - Soave or Duhamel pull through procedures
S/S of Hirschsprung’s colitis
tenderness, foul smelling diarrhea, sepsis, lethargy
MCC of death in Hirschsprung’s
hirschsprung’s colitis
Tx for Hirschsprung’s colitis
rectal irrigation to try and empty colon, may need emergency colectomy
Pathophys of imperforate anus
rectum fails to descend through the external sphincter complex; rectum ends as blind pouch usually with fistulous track to the GU system (males: urethra, bladder, scrotum; females: vagina)
Syndromes associated w imperforate anus
VACTERL (60% have anomaly, MC anomaly is urinary tract)
Location of anomalous anus
males: high lesion >50%; females: low lesions 90%
High lesion imperforate anus
rectum ends above levator ani muscle
Which gene mutation has been found in Hirschsprung’s?
RET protooncogene
Dx of imperforate anus
physical exam will show defects from no anus to perineal fistulas; plain xr/obsructive series; contrast study
What is a low lesion imperforate anus?
rectum ends below levator ani muscles
How is a low lesion discovered in imperforate anus?
meconium is seen on perineal skin/along median raphe, scrotum, or in lower vagina
How is a high lesion imperforate anus defect discovered?
males: meconium in urine; MC is fistula from rectum to prostatic urethra;
Females: meconium is seen in upper vagina- may have cloacal deformity
What is the procedure to correct imperforate anus?
colostomy
delayed anal reconstruction with posterior sagittal anoplasty to place rectum in external anal sphincter complex
closure of colostomy
How to prevent problems with long term constipation in pts after correction of imperforate anus?
need post-op dilation to avoid stricture
Most likely location of colon perforation with obstruction?
cecum
Most common cause of colon obstruction
- cancer 60%
2. diverticulitis 20%
pneumotosis intestinalis
air in bowel wall, asstd with ischemia and dissection of gas into bowel wall; NOT always an indication for resection
air in portal system
indicates significant infection or necrosis of the large or small bowel; often an indication for resection if due to bowel ischemia
Pseudo-ostruction of the colon
Ogilvie’s syndrome
Risk factors for Ogilvie’s
opiate use, bedridden, elderly, recent surgery, infection, trauma
Treatment for Ogilvie’s
IVF’s, replace electrolytes, dc narcotics, NGT, bowel rest, consider rectal tube, decompressive colonoscopy
If colonoscopy fails, proceed with cecostomy or resection if perforation or non viable bowel; neostigmine
Side effect of neostigmine
(MOA- acetylcholinesterase inhibitor)
Bradycardia– have atropine available
Organism in amebic colitis
entamoeba histolytica, primary infection occurs in colon, secondary infection occurs in liver
Transmission of entamoeba histolytica
oral-fecal: from contaminated food/water with feces that contain cysts
Risk factors for amebic colitis
travel to Mexico, EtOH
Diagnosis and treatment of amebic colitis
endoscopy–> ulceration, trophozoites; stool O&P; Tx w flagyl, diiodohydroxyquin
most common location of actinomyces
mouth (poor dentition), lung, and cecum (can be confused with cancer)
Path shows yellow-white sulfur granules
Treatment of actinomyces
penicillin or tetracycline, drainage of any abscesses
How long can stool guaiac stay positive after bleed?
can be positive up to 3 weeks after a bleed
Hematochezia
lower GI bleed; maroon colored stools
Hematemesis
bleeding anywhere from pharynx to ligament of Trietz (UGI bleed); melena and hematochezia can occur with UGI bleed
Melena
passage of black tarry stools; requires only 50cc of blood
Azotemia after GI bleeds
increased BUN after GI bleed- caused by production of urea from bacterial action on intraluminal blood
Rate of bleed to be picked up on arteriography
> 0.5cc/min
Rate of bleed to be picked up by tagged RBC scan
> 0.1cc/min; most sensitive test but hard to localize the exact area
What is a double balloon endoscopy and when is it used?
AKA push endoscopy- upper endoscopy using a rigid over tube to prevent coiling in the stomach in order to get down into small bowel
What protocol should be followed in severe GI bleed?
Follow trauma protocol: massive transfusion and permissive hypotension (SBP >70) until bleeding is found and treated, avoid excessive crystalloids
Diagnosis of GI bleed
- NG lavage to rule out UGI source- be sure to see bile!
- proctoscopy to rule out hemorrhoids
- vasopressin to slow bleeding if hypotensive
- Colonoscopy to be diagnostic and therapeutic. tattoo the bleeding area
Diagnostic studies guidelines for mild LGIB
colonoscopy
Guidelines for moderate LGIB (BP>90)
colonoscopy
Guidelines for massive LGIB (SBP <90 despite blood transfusion)
colonoscopy
Guidelines for massive LGIB with persistent shock, unstable pt, SBP 60’s
Angiography to embolize or to localize which side of colon then to OR for segmental resection; may need blind total abd colectomy if massive bleeding and clinical condition does not allow attempt at localization or if bleeding is not localized on angio (life saving maneuver)
What must be done prior to total abd colectomy for GI bleed?
RULE OUT upper GI bleed and hemorrhoids as source of bleed
If colonoscopy does not localize bleed, what steps are next?
angiography –> tagged RBC scan –> video capsule study –> Meckel scan –> Push endoscopy
MCC of small bowel bleeding
- Angiodysplasia 2. tumor 3. Meckel’s 4. Crohn’s
MCC of painless lower GI bleed in kids and teens
Meckel’s diverticulum
pathophys of diverticula
straining causes increased intraluminal pressure, herniation of mucosa through the colon wall at sites where arteries enter the muscle; circular muscle thickens adjacent to the diverticulum leading to luminal narrowing
What percentage of the population has diverticulosis?
35%; 90% occur in sigmoid colon
Where do most diverticular bleeds occur?
right side
MCC Of lower GI bleed
diverticular bleed
Most common location in colon for angiodysplasia bleeds
right side of colon, small bowel
Which bleeds are more severe- diverticular or AVMs?
Diverticular
Which bleeds are more likely to recur- diverticular or AVMs?
AVMs
MCC of obscure GI bleeds
AVMs
What are the signs of angiodysplasia on angiography?
slow emptying, tufts
What associated pathology do pts with AVMs have?
aortic stenosis- AVMs improve after valve replacement
Also high incidence with LVADs
Which medications can be used to help control bleeding in AVMs?
aminocaproic acid, octreotide
What are common causes of ischemic colitis?
low flow states- recent MI/CHF, sepsis, medical ICU pt, cardiac surgery, severe dehydration, massive diarrhea, hypoxia (COPD, ARDS) ligation of IMA during surgery such as AAA repair
Which areas of the colon are most vulnerable to low flow states?
Griffith’s Point (splenic flexure)
Sudeck’s point (rectum)
Which areas are spared in ischemic colitis?
middle and lower rectum spared bc blood supply from middle rectal (off internal iliac) and inferior rectal (off internal pudendal)
Ischemic colitis on CT
(thumbprint sign) thick edematous mucosa, thick colon wall, fat stranding
Best test for diagnosis of ischemic colitis and what will it show?
colonoscopy- thick cyanotic, edematous mucosa covered in exudates
Best tx for ischemic colitis
antibiotic and fluid resuscitation; if gangrenous, hemorrhage, or perforation then no colonoscopy, go straight to OR
If necrotic bowel seen on colonoscopy–> OR
Whats the risk of cancer in hyperplastic polyps?
none
Risk of cancer in tubular adenomas
<5%
risk of cancer in tubovillous adenoma
20% contain cancer
Which polyp type is most likely to be symptomatic and contain cancer
villous adenoma, <2cm, these are also usually sessile too; 40% contain cancer
MC location of polyps
left side
What do you do if entire polyp can’t be removed endoscopically?
need segmental resection
What is carcinoma in situ?
high grade dysplasia with basement membrane intact
When is polypectomy adequate?
- if margins are clear (2mm)
- is well differentiated
- no neuro/vascular/lymphatic invasion
Pathology shows T1 lesion after transanal excision of rectal villous adenoma. Transanal excision is adequate if:
- margins are clear (2mm)
- is well differentiated
- no neuro/vascular/lymphatic invasion
If pathology shows T2 lesion after transanal excision of rectal polyp, what does pt need?
APR or LAR; can do pre-op chemo-XRT if T3 or T4
Most common location of colon cancer
sigmoid colon
Main gene mutations in colon cancer:
tumor suppressors: APC, p53, DCC, proto-oncogene: k-ras
What bacteria is associated with colon cancer?
step gallolyticus (strep bovis biotype I) and clostridium septicum
what can cause false positive fecal occult blood test
beef, Vit C, iron, antacids, cimetidine
Most important prognostic indicator
node status
path of colon mets to liver and lung
portal vein –> liver mets
iliac vein –> lung mets
5 year survival of pts with colon ca w liver mets
35%
5 year survival of pts with colon ca w lung mets
25%
how does rectal cancer spread to spine
spreads directly to spine via Batson’s plexus
What are adequate margins for colon cancer? rectal cancer?
colon cancer margins: 4-5cm
rectal cancer margins: >2cm
low rectal cancer T1 margins: >2mm
What does rectal pain indicate?
that rectal cancer is growing into sphincters or pelvic floor; patient needs APR
MC location of colon perforation
cecum- Law of LaPlace (tension = pressure x diameter)
Best method for detecting intrahepatic metastases
intra operative US- has resolution of 3-5mm
which arteries are ligated in right hemicolectomy
ileocolic and right colic arteries
which arteries are ligated in left hemicolectomy
left colic artery
which arteries are ligated in extended right hemicolectomy
ielocolic, right colic, and middle colic arteries
which arteries are ligated in extended left hemicolectomy
middle and left colic artery
which arteries are ligated in transverse colectomy
middle colic artery
whats resected in LAR?
sigmoid colon and rectum
which arteries are ligated in LAR?
sigmoid and rectal arteries
why do you need a 2cm margin on rectal cancer?
need 2cm above anal canal to be resected with the end to end stapler as the donut– send donut to path!!
LAR easier in men or women?
generally easier in women bc wider pelvis
What is the benefit of diverting loop ileostomy when doing LAR?
decreases complications of a leak should one occur
what are the complications of injured pudendal nerves?
risk of incontinence and ejaculatory failure– watch when taking down lateral stalks
T for colorectal cancer
Tis: in mucosa/carcinoma in situ T1: submucosa T2: muscularis propria T3: invades subserosa T4: through serosa into free peritoneal cavity (perforates into visceral peritoneum or invades adjacent tissues/organs)
N for colorectal cancer
N0: nodes negative
N1: 1-3 nodes positive
N2: >=4 nodes positive
Stage 0 for colorectal cancer
Tis, N0 M0
Stage 1 for colorectal cancer
T1-2, N0 M0
Stage 2 for colorectal cancer
2a: T3 N0 M0
2b: T4 N0 M0
Stage 3 for colorectal cancer
3a: T1-2, N1, M0
3b: T3-4, N1 M0
3c: Any T, N2, M0
Stage 4 colorectal cancer
any T, any N, M1
What are criteria for trans anal excision of low rectal lesions
T1 < 4cm < 1/3 of circumference negative margins of at least 2mm well differentiated no neuro/vasc/lymph invasion
Which colon cancers get chemo?
Stage 3 and 4
Which rectal cancers get chemo?
Stage 2 and 3 get prep chemo-XRT, then adjuvant chemo
What is the chemo protocol in colorectal cancer?
FOLFOX, 6 cycles (5-FU, leucovorin, oxaliplatin)
What are the side effects of 5-FU
myelosuppression
What are the side effects of oxaliplatin?
nephrotoxicity, neurotoxicity, ototoxicity
Which chemo drugs are added for pts with metastatic colorectal cancer?
can add bevacizumab (avastin) or cetuximab (erbitux)
What is the MOA of bevacizumab?
monoclonal antibody to VEGF-A
What is the MOA of cetuximab?
monoclonal antibody to EGF receptor
What is the MOA of fluorouracil?
5-FU- thymidylate synthase inhibitor to block synthesis of pyrimidine thymidine needed to DNA replication
What is the MOA of leucovorin?
aka folinic acid- assists with selective reactivation of dihydrofolate reductase in normal cells in presence of methotrexate type chemos
What is the MOA of oxaliplatin?
inhibition of DNA replication and transcription
5-year survival for colorectal cancer
Stage 1: 95%
Stage 2: 80%
Stage 3: 65%
Stage 4: 10%
What is the survival benefit of chemo in colorectal cancer?
improves 5 year survival for stage 3 colorectal cancer
What is the main reason for surveillance colonoscopy after colorectal ca treatment?
to check for another primary (metachronous) cancer (5%!!)
Rate of recurrence of colorectal cancer?
20%- usually within first year
poor prognostic indicators for colon ca w liver mets
disease free interval <12 months > 3 tumors CEA >200mcg/L size >5cm positive nodes synchronous primary and liver met
5 year survival after resection of liver mets
35%
what is the treatment for acute radiation proctitis?
butyrate enemas
Pathophys behind late radiation proctitis
obliterative arteritis of submucosal vessels
Genetics of familial adenomatous polyposis
FAP, autosomal dominant, chromosome 5, mutation in APC tumor suppressor gene
Lifetime risk of CA with FAP
100% lifetime risk by age 50; rarely before age 20
Tx for FAP
total colectomy by age 20
Other common site of CA in FAP (not colon)
duodenal periampullary polyps and adenocarcinoma–> get EGD every 1-2 yrs; intra-abdominal desmoid tumors
What is the surgical procedure for FAP?
total proctocolectomy, rectal mucosectomy, ileo-anal pouch; total proctocolectomy with end ileostomy also an option
Surveillance for FAP post-colectomy
lifetime proctoscopy surveillance of residual rectal area and EGD every 1-2 yrs
MCC of death with FAP
peri-ampullarf CA of the duodenum– need whipple
Genetics of Gardner’s Syndrome
FAP variant; APG gene
Gardner’s syndrome
colon ca, osteomas, desmoid tumors
recurrence rate of desmoid tumors
70%, benign but locally invasive
Turcot’s syndrome
FAP variant- colon Ca and brain tumors
Genetic mutation in Lynch syndrome
HNPCC, defect in DNA mismatch repair genes, autosomal dominant
Lynch 1
just colon ca risk
Lynch 2
colon ca plus increased risk of ovarian, endometrial, bladder, and stomach ca
Amsterdam criteria
“3,2,1”
- at least 3 family members, one is a first degree relative of the other 2
- over 2 generations
- 1 relative with cancer before age 50
- FAP has been excluded
Familial Juvenile polyposis
hamartomatous polyps occur in upper GI tract and colon before age 20.
Risk of cancer and adenomatous change in familial juvenile polyposis
20%
Surveillance for familial juvenile polyposis
upper and lower endoscopy every year
Indication for colectomy in familial juvenile polyposis
adenomatous change in polyps
lap vs open colon surgery
less blood loss, longer operative time, shorter hospital stay, no difference in path margins, number of nodes, or mobility/mortality
method for controlling bleeding of pelvic venous plexus
bone wax or sterile thumbtacks
Treatment for ureter injury
<7 days post op- reoperate and repair
<= 7 days post op- place percutaneous drain and wait 6-8 weeks before repair
damage to which nerves causes bladder dysfunction
pelvic splanchnic plexus (parasympathetic)
damage to which nerves causes sexual dysfunction
erectile- pelvic splanchnic plexus (parasympathetic)
retrograde ejaculation- damage to hypogastric plexus (sympathetic, T10-L2)
Ejaculatory failure- damage to pudendal nerve (sympathetic, S2-4) in pelvic sidewall
Course of type 1 branchial cleft cyst
From angle of mandible to external auditory canal
Course of type 2 branchial cleft cyst
From anterior SCM to tonsillar pillar
Course of type 3 branchial cleft cyst
Deep SCM to pyriform sinus
Rate of wound infection in colorectal surgery
10%
MC location for head and neck cancer of unknown origin
tonsils
MC malignant parotid tumor
mucoepidermoid
Electrolyte derangements in primary hyperparathyroidism
Elevated PTH, Ca, renal cAMP, urine Ca
Cl:PO4 ration >33
Phos will be normal to low
MCC of mortality in pts w parathyroid ca
Hypercalcemia
MEN 1
Pancreatic tumors (MC is gastrinoma) Parathyroid hyperplasia Pituitary tumors (MC is prolactinoma)
MC endocrine pancreatic tumor
Insulinoma
Genetic defect in MEN 1
MEN1
Genetic defect in MEN2a and MEN2b
Ret proto oncogene
Major side effect of Herceptin (trastuzumab)
Cardiac toxicity
Major side effect of taxol
Neurotoxicity
The greatest change in lung dimension during inspiration is in which direction?
superior-inferior due to diaphragm movement
where does the thoracic duct cross the mediastinum?
thoracic duct crosses right to left at T4-5 level
Which pneumocytes produce surfactant?
Type II
What is the most commonly involved structure in thoracic outlet syndrome?
brachial plexus– usually involving C8-T1/ulnar distribution
location of phrenic nerve to the scalenes?
anterior to the anterior scalene muscle
location of long thoracic nerve to the scalenes?
posterior to the middle scalene muscle
Superior vena cava syndrome
apical lung ca grows into SVC causing acutely swollen face, arms, hands. Tx is emergent XRT; MC small cell lung ca
Horners syndrome
ptosis, miosis, anhydrosis due to invasion of the sympathetic chain at T1
What ca releases PTH-rp?
squamous cell lung ca
MC location of significant hemoptysis
bronchial arteries
Horners syndrome
ptosis, miosis, anhydrosis due to invasion of the sympathetic chain at T1
Pancoast tumors
apical lung tumors in superior sulcus; invasion into sympathetic chain or brachial plexus
MC congenital heart defect
ventricular septal defect
primary blood supply to the trachea
inferior thyroid and bronchial arteries
Overall MC mediastinal tumors
neurogenic tumors
Treatment for carotid stenosis due to medial fibromuscular dysplasia
percutaneous transluminal angioplastydmr [78
MC type of endoleak
Type 2
Types of endoleak
Type 1: leak at proximal or distal graft attachment site
Type 2: back filling from collateral branches
Type 3: leak at junction bt stents
Type 4: porous graft material
Type 5: endotension
Treatment for carotid stenosis due to medial fibromuscular dysplasia
percutaneous transluminal angioplasty
Types of endoleak
Type 1: leak at proximal or distal graft attachment site
Type 2: back filling from collateral branches
Type 3: leak at junction bt stents
Type 4: porous graft material
Type 5: endotension
What do the parietal cells of the stomach secrete?
HCl and intrinsic factor
What do chief cells of the stomach secrete?
Pepsinogen
What surgical conditions can lead to B12 deficiency?
Gastric bypass (lose intrinsic factor)
Terminal ileum resection (where B12 gets absorbed)
Blind loop syndrome (bacteria consume all the B12)
Where is gastrin produced?
By G cells in the antrum and duodenum
UES pressures at rest and during early swallow
at rest: 60mmHg
early swallow: 15mmHg
LES pressures at rest and during earl swallow
at rest: 15mmHg
early swallow: 0mmHg
Diffuse esophageal spasm
high amplitude repetitive NON peristaltic contractions
nutcracker esophagus
high amplitude peristaltic contractions
scleroderma esophagus
peristalsis and low LES pressure with massive reflux and severe esophagitis
achalasia
high LES pressure and absence of peristalsis
Tx for Schatzki’s rings
occur in pts with hiatal hernias; tx is ring dilatation and PPI. (NEVER resect)
MC location for Boerhaave’s
left lower esophagus; left thoracotomy is usually best incision for repair; repair should be multiple layers bc mucosal tear is usually longer than the muscular tear
Best test to find esophageal tear
gastrograffin swallow study followed by barium swallow study
Where do the adrenal veins drain?
RIGHT adrenal vein drains into IVC
left adrenal vein drains into left renal vein
Pylephlebitis
infection of the portal system that can occur after diverticulitis or appendicitis- fever, elevated LFTs, air in portal system. Liver abscess and portal thrombosis can occur
MCC of upper GI bldg in children >1
portal vein thrombosis
Schistosomiasis
RUQ pain and maculopapular rash- tx w praziquantelghx
Dx of amebic liver abscess
symptoms, CT scan (large single abscess with peripheral rim of enhancement), serology
Focal nodular hyperplasia on imaging
CT- hypervascular lesion with enhancing central stellate scar
positive lesion on technetium labeled albumin scan
Where does active reabsorption of conjugated bile acids occur?
in terminal ileum
most sensitive indicator of obstructive jaundice
alk phos
DNA polymerase is involved in
duplication of DNA– polymerase chain reactions
RNA polymerase is responsible for
transcription – copying DNA into mRNA
proteins are translated from
mRNA (ribosomes translate mRNA into amino acid sequences which make up proteins)
How do steroids work to create proteins?
bind a receptor in the cell cytoplasm, enter the nucleus as s steroid-receptor complex, then affect transcription of mRNA for protein synthesis.
How does thyroid hormone work to create proteins?
crosses into the nucleus then binds a receptor to affect transcription of mRNA
What activates protein kinase A?
cAMP
What activates protein kinase c?
Ca or DAG
How does thromboxane increase platelet adhesion?
increases Ca release inside of platelets which then triggers expression of GpIIB/IIIa on plts to allow plts to bind
Which clotting factors are contained in cryoprecipitate
contains highest levels of Factor 8, vWF, and fibrinogen; use when fibrinogen levels are low
What treatment can cause a relative anti-thrombin 3 deficiency?
heparin– if a pt is on heparin course and then quits responding, give anti-thrombin 3 or FFP
How do thrombolytics work?
convert plasminogen to plasmin; plasmin degrades fibrin
How does prostatectomy cause bleeding issues?
prostatectomy/TURP can release urokinase which causes fibrinolysis and bleeding. Give aminocaproic acid
What are the types of intestinal atresia?
Type I: mucosal atresia w intact bowel and no mesenteric defect
Type II: two separate atretic segments of bowel connected by a fibrous cord
Type III: two segments separated by a V-shaped mesenteric defect
Type IIIb: apple-peel or Christmas tree anomalies
Type IV: multiple atresias
where is the highest incidence of biliary atresia?
asia
Does biliary atresia occur more frequently in males or females?
biliary atresia occurs more frequently in females
Does biliary atresia occur more frequently in males or females?
biliary atresia occurs more frequently in females
Prothrombin complex concentrate
plasma mix of Vit K dependent factors
- 3 factor type has low levels of Factor VII and requires additional FFP to reverse warfarin
black widow spider venom
alpha-latrotoxin is neurotoxic
brown recluse spider
sphingomyelinase-D causes local skin necrosis with ulceration
