Surgery - Lower GI Flashcards
What can cause failure of fascia closure in ab surgery?
Infection in abdomen
Can have hernia w/ fascia open – need to go to OR to fix ASAP
Most common causes of lower GI bleeding
1) Diverticulosis
2) Andiodysplasia
Ischemic colitis
Happens in setting of
- hypoTN
- vasculitis
- atherosclerosis
Present w/:
- ab pain (pain out of proportion of PE)
- —usually pain after eating –> wt loss
- fever
- vomitting
Bleed b/c of ischemia of watershed areas of the colon
Acute mesenteric thrombosis
Ab pain out of proportion of physical findings
N/V
Bloody diarrhea b/c mucosal sloughing
Numerous athero risk factors
Usually SMA is occluded –> distal duodenum –> transverse colon
Common causes of pelvic abscesses
- male
- female
Male
- appendicitis
- rupture of appendix –> form pelvic abscess from fluid draining into rectovesical pouch
Fem:
- gyn issues
Drain these abscesses!
Pelvic abscess vs anorectal abscess
Pelvic
- tender fluctuant mass palpable only w/ tip of examing finger on rectal
- painful defecation
- diarrhea
Anorectal
- perineal pain
- fluctuant mass palpable on perineum
- pain w/ ambulation + defecation
- urinary retention
Rovsing sign
RLQ pain w/ deep palpation of LLQ
Sign of Appendicitis
How do you dx appendicitis?
CLinically!
Don’t need further imaging to confirm dx if classic signs, sx, and lab data are present
Get CT if person has suspected appendicitis w/ atypical presentation
Need surgery ASAP
Give Abx pre and postop
Isolated duodenal hematoma
Mostly in kids after BAT
Usually have blood b/n submucosal and muscular layers of duodenum –> obstruction
Most will resolve by itself in 1-2 wks
Tx:
- nasogastric suction w/ TPN
- if need surgery, can do laparotomy or laparoscopic procedure
Uncomplicated vs complicated diverticulitis
- tx?
Uncomplicated
- colonic diverticular inflamamation
- tx: outpt, bowel rest, oral abx, observation
Complicated
- diverticulitis + abscess, perf, obstruct, or fistula formation
- if fluid collection < 3 cm, tx w/ IV abx
- if fluid > 3cm, CT guided drainage
- surgery (drainage + debridement) if drainage does not fix
Ab aorta operations - what is an early complication?
Bowel ischemia and infarction
How long do you give a pt who went under ab surgery that is now third spacing?
48-72 hrs
At this time, they will reabsorb edema and pee it all out
Pathophys of dumping syndrome
Rapid emptying of hypertonic gastric content into duodenum + SI
causes fluid shift from intravascular space –> SI
Then release intestinal vasoactive polypeptides and stimulation of autonomic reflexes
When do you use technetirum-99 labeled RBC scintigraphy?
IN cases of lower GI bleeding where source can’t be ID’d by colonoscopy
Mesenteric ischemia
inflammation and injury of the small intestine result from inadequate blood supply
Different severities of hernias
Reducible
Incarcerated = not reducible
Strangulated = not reducible + ischemic
Minimize post op infection for elective colonic surgery
What can you use to decrease bacterial load in bowel before GI surgery?
Mechanical cleansing
Oral Abx
Periop parenteral abx (anaerobes and aerobes)
Oral nonabsorbable abx
- neomycin
- erythromycin
Risk factors associated with colorectal cancer
Strong risk
- advanced age
- country of birth (eg Korea, Scandanavians)
- FAP/HNPCC
- long standing UC
Moderate risk
- previous adenoma or cancer
- 1st degree relative w/ adenoma or cancer
- pelvic irradiation
Protector factors assoc w/ colorectal cancer
Moderate
- physical activity
- aspirin/NSAIDs (Nurses study)
- high Ca intake (Nurses study)
Genetics of colon cancer - what can be mutated?
Tumor suppressors
- APC
- Chr 18
- p53
Oncogenes
- k-ras
DNA repair genes
- hMLH1
- hMSH2
Where do adenocardionmas of colon come from?
Glandular tissue of mucosa (#1)
Familial adenomatous polyposis
APC gene mutation
Chromosome 5 location
AD inheritance
100% colon cancer risk
Total proctocolectomy in early 20s
- ileostomy
- or J pouch (ileoprocto anastamoses)
Still early death b/c more susceptible to other adenomas, esp in duodenum
What is double contrast barium enema?
2 contrasts:
- Barium
- Air
Air to disperse barium
Gardner’s syndrome
Osteomas
variant of FAP
Classic for peutz-jegher’s?
Buccal pigmentation
HNPCC (Lynch syndrome)
AD inheritance
Not hundreds of adenomas like FAP but will still get polyps
Mismatch repair gene mutation
Higher risk for other cancers:
- stomach
- SI
- renal
- ovarian
- pancreatic
Where are most hereditary colon cancers?
R side
Watershed areas of Colon
Lives off collateralization of arteries for supplying area
Griffith’s point = splenic flexture
- Arch of Reiling
- SMA - marginal A branch of IMA
Sudek’s point
- superior hemorrhoidal A (IMA) - middle and inferior rectal A (internal iliac)
- mets to lung and liver for rectal cancer
Microsatellite instability
When 2 bases don’t line up, you get a break = MI
condition of genetic hypermutability that results from impaired DNA Mismatch Repair (MMR).
Microsatellite stable vs. unstable - which has better prognosis?
Microsatellite unstable cancer has better prognosis!
- less biologically active
But more resistant to 5-flurouracil chemo
Molecular pathogenesis of colorectal cancer
MIcrosatellite stable cancer:
Loss of APC gene –> k-ras mutation –> DCC deletion –> p53 deletion
Microsatellite unstable cancer:
MSH2/ MLH1 abnormality –> k-ras mutation –> DCC deletion –> p53 deletion
What do you look for in FOBT?
Iron!
THIS IS NOT SPECIFIC OR SENSITIVE!
Guiaic test:
- 3 separate stool samples collected by patients and tested for blood
Screening recommendations for CRC
- what tests do you do?
Annual FOBT + sigmoidoscopy / 5 years
Colonoscopy every 10 years
Double contrast barium enema every 10 years