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General Surgery > Colorectal > Flashcards

Colorectal Flashcards

1
Q

LBGIT is bleeding from a source distal to ___

A

Ligament of Treitz

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2
Q

What is haematochezia?

A

Gross, fresh blood seen on toilet paper after defecation or mixed with stools

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3
Q

All patients over __ with PR bleed should be scheduled for ___

A

50, colonoscopy

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4
Q

Differentials for different PR bleed occurrence patterns

A

On toilet paper, dripping into bowl: haemorrhoids

Coating stools: distal bleed

Mixed into stools: proximal bleed

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5
Q

Ddx for different bloody stool colours

A

Frank red: left colon bleed
Maroon/mixed into stool: right colon
Melena: UBGIT/right colon

Clots: LBGIT, unlikely to be UBGIT

*Blood takes 14 hours to be broken down in the intestine. >14 hours = melena.

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6
Q

Pain on defecation can indicate

A

rectal tumours, anal fissures, ischemic colitis

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7
Q

What is spurious diarrhea?

A

occurs when the feces become so hard that they cannot be expelled and fecal fluid will flow around the block.

There are a number of features that clinically characterize overflow diarrhea, also called spurious diarrhea:
1. Only fluids are expelled.
2. It most often has the colour of feces.
3. It is not accompanied by abdominal pain.
4. It is often difficult for the patient to reach the toilet before it is expelled.
5. If a gloved finger is put down into the fluid it will feel threadlike due to mucus in the stool.
6. The patient does not have fever.

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8
Q

What is tenesmus & what can it indicate?

A

Frequent & urgent feeling of need to defecate even when bowels are already empty

Rectal tumours, infective/inflammatory colitis, radiation proctitis

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9
Q

What does age of pt presenting with LBGIT clue us in on?

A

Young: usually benign (haemorrhoids, fissures, inflammatory bowel disease)

Older: diverticular disease, colon cancer, ischemic colitis

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10
Q

Types of colitis

A

Infective - viral, bacterial, parasite
Inflammatory - UC, Crohns
Ischaemic - watershed areas
Chemical - NSAID, anti-angina
Radiation - radiation proctitis

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11
Q

Endoscopy is only useful in ___ pts with LBGIT as they can tolerate ___

A

haemodynamically stable
bowel prep

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12
Q

If pt is haemodynamically unstable, can use __ to diagnose bleeding site

A

CT mesenteric angiogram - content extravasation in bowel lumen

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13
Q

Urine output may drop below ___ in haemodynamically unstable pts

A

0.5ml/kg/hr

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14
Q

If bleeding is detected on CT mesenteric angiogram, a ___ can be performed for therapeutic intervention

A

Selective mesenteric angiography + angioembolisation

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15
Q

Indications for exploratory laparotomy in LBGIT

A

Persistent/recurrent PR bleed despite non-operative attempts to localise bleed

Haemodynamically unstable pts requiring >6 to 10 units of PCT

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16
Q

Risk factors for ischaemic colitis

A

1) Occlusive vascular disease
- thrombosis/emboli

2) Non-occlusive
- Hypotension
- Medication: chemo, OC
- Cardiac: atrial fib, atherosclerosis
- hypercoagulability states
- obstructions, vasculitis

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17
Q

Blood supply of colon & rectum

A

SMA: ileocolic, right colic, middle colic (supplies up to 2/3rd of transverse colon)

IMA: left colic, sigmoid, rectal

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18
Q

Watershed areas of the colon

A

Right colon - vulnerable in low flow states (ileocolic is a terminal branch of SMA)

Splenic flexure - supply from both SMA & IMA

Rectosigmoid junction - vulnerable in IMA stenosis

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19
Q

Clinical progression of ischemic colitis

A

1) Hyperactive phase: severe pain with loose, bloody stools

2) Paralytic phase: pain is more continuous & diffuse, abdomen tender & distended, no bowel sounds

3) Shock phase: massive fluid, protein, electrolytes leak through gangrenous mucosa. Severe dehydration + shock + metabolic acidosis develops

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20
Q

Transmural ischemia presents with __

A

intestinal pneumatosis - air in the walls of the bowel
portal venous gas
lack of bowel wall enhancement

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21
Q

___ is gold standard for diagnosing ischemic colitis

A

Endoscopy
(colonoscopy/sigmoidoscopy)

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22
Q

Colon cancer pts diagnosed mostly at ___ years old. Younger must suspect ___

A

60-70

HNPCC, FAP, pre-existing IBD

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23
Q

Risk factors for colon CA

A

Modifiable:
1) Diet - red/processed meat, alcohol
2) Smoking
3) Obesity

Non-modifiable
1) Age
2) Ethnicity (chinese)
3) Family history
4) Hereditary CRC - FAP, peutz-jeghers
5) Familial cancer - HNPCC (Amsterdam criteria)
6) Personal history - IBD, large polyps, radiation

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24
Q

HNPCC (familial) & right sided CA (sporadic) associated with ____

FAP (familial) & left sided CA (sporadic) associated with ___

A

microsatellite instability

chromosomal instability

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25
Q

85% of sporadic CRC caused by ___, 15% caused by ___

A

chromosomal instability (loss of APC, KRAS, p53)

microsatellite instability (defect in DNA mismatch repair genes MSH2, MSH6, MLH1, PMS1, PMS2)

**sporadic cancers that have microsatellite instability have better prognosis

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26
Q

In general, ___ CRC more common

A

left sided

27
Q

Red flags symptoms for colon cancer

A

PR Bleeding
Spurious diarrhea
Diminished stool calibre - pencil thin stools
Tenesmus
Alternating constipation & diarrhea

28
Q

RIght sided CRC more likely to present with ___

A

symptomatic anaemia - bleeding from right side is usually occult

29
Q

___ CRC more likely to cause intestinal obstruction. Why?

A

Left sided

Stools are more well formed + competent ileocaecal valve = closed loop obstruction

30
Q

Rectal tumours tend to present with ___

A

tenesmus, diminished stool calibre, mucoid stools

31
Q

Complications of colon tumours

A

1) Bleeding - anaemia
2) Obstruction - cardinal symptoms of IO (abdominal distension, pain, vomiting, obstipation)
3) Perforation - peritonitis, intra-abdominal sepsis
4) Fistula - fecaluria, pneumaturia, recurrent UTI, recto-vagina fistula
5) Invasion - pain, LUTS (bladder)

32
Q

Most common metastasis site of CRC

A

Liver

Then lung

33
Q

Important to measure ___ levels preoperatively as it is ___

A

carcinoembryonic antigen (CEA)

useful prognostic and surveillance tumour marker in CRC (level correlates with disease burden)

34
Q

Investigation modality

Diagnosis of CRC by ____
Staging by ___

A

Colonoscopy
CT TAP - to determine depth of invasion and metastasis to other organs

35
Q

Types of colectomy on location of primary tumour

A

Right hemi: caecum, AC, hepatic flexure tumour

Extended right hemi: everything above + mid TC

Left hemi: distal TC, splenic, DC, sigmoid

Sigmoid colectomy: sigmoid colon

Anterior resection: Partial or complete removal of rectum

36
Q

What is Hartmann’s procedure?

A

Surgical resection of colon, closure of rectal stump

Temporary end colostomy opened

Used in emergency settings when immediate anastomosis is not possible

37
Q

Lung protective measures to prevent post-op complications (atelectasis, pneumonia)

A

Incentive spirometry
Chest physiotherapy

38
Q

Where does rectal cancer occur? How to define the border?

A

within 15cm of anal verge

anal verge: junction between stratified squamous non-keratinising & stratified squamous keratinising epithelium in the anal canal

39
Q

Blood supply to rectum

A

superior rectal artery (from IMA)
middle & lower rectal artery (from internal iliac artery)

40
Q

What divides the anal (rectal) canal? Epithelium, venous drainage, nerve supply, lymphatic drainge of each

A

Pectinate (dentate) line - divides upper 2/3rd from lower 1/3rd

Upper 2/3: simple columnar epithelium, portal venous drainage, autonomic nerves (inf hypogastric plexus), drains to abdominal nodes

Lower 1/3: stratified squamous epithelium, systemic venous drainage, somatic nerve (inferior rectal nerve), drains to superficial inguinal

41
Q

Imaging: ____ is superior to ___ for rectal cancer staging

A

MRI > CT

42
Q

What is an anterior resection?

A

Anterior approach to resect the recto-sigmoid colon with primary anastomosis between descending colon and rectum

Low anterior resection occurs below peritoneal reflection, spares the anal sphincters

43
Q

What is a diverting/defunctioning ileostomy used for?

A

Loop of ileum that is opened up into the surface of the abdomen, to divert faecal matter out. Used after distal colon/anterior resection to prevent anastomotic leaks while the surgical site is healing.

44
Q

When is an abdominoperineal resection indicated?

A

Removal of sigmoid colon, rectum, anal sphincter complex

When tumour involves sphincter complex with inadequate distal margins

45
Q

What laxative is given for bowel prep prior to colonoscopy?

A

Polyethylene Glycol (PEG) - 3-4L over 2 doses

46
Q

What kind of colon polyps have malignant potential/are malignant?

A

Sessile serrated polyps - pre-malignant

Adenomas - Larger size, more villous features are more pre-malignant risk (2/3 of polyps are these)

Adenocarcinomas - malignant, invades through muscularis mucosa and into submucosal layer of bowel wall

47
Q

Most common type of non-neoplastic (benign) polyps found

A

Hyperplastic polyps - normal epithelial cells accumulating on mucosal surface

48
Q

How often to do colonoscopy if polyps are found?

A

Low risk polyps - 5 years
High risk polyps - 3 years

49
Q

How often to do colonoscopy if first degree relative had colon cancer before 60yo OR 2 or more 1st deg relatives with colon cancer?

A

Starting from 40 OR 10 years prior to age of diagnosis (whever earlier)

once every 5 years

50
Q

How often colonoscopy if first degree relative had colon cancer after 60?

A

starting from 50 years old, once every 10 years

51
Q

When is colonoscopy indicated every 1-2 years

A

family history of FAP (annually)
family history of HNPCC
personal history of IBD

52
Q

What is Peutz-Jeghers Syndrome?

A

AD condition, multiple hamartomatous polyps (colon, small intestine, stomach), muco-cutaneous pigmentation around perioral & buccal mucosa

High risk of CRC, breast, pancreatic, lung, uterine, gastric cancers

53
Q

What is Juvenile Polyposis Syndrome?

A

AD condition - multiple harmatomatous polyps in colon & upper GI

Increased risk of other GI malignancies: small bowel, pancreatic, stomach cancer

54
Q

What is familial adenomatous polyposis?

A

AD condition - mutations in APC tumour suppressor gene

Patients have >100 adenomatous polyps by age 35, 100% of pts develop CRC

55
Q

What is Lynch syndrome?

A

AD condition - mutations in DNA mismatch repair genes

Lynch syndrome I - familial
Lynch syndrome II - Associated with HNPCC

56
Q

What are end, loop, barrel stomas?

A

End - end of the intestine is transected, exteriorised and fashioned as a stoma
Loop - loop of intestine is exteriorised and fashioned a stoma

Barrel - intestine is severed, brought out as 2 ends to fashion a stoma (eg. ileo-colic stoma)

57
Q

Colostomy commonly located at ___, ileostomy located at ___

A

left iliac fossa
right iliac fossa

58
Q

A bowel in a stoma that forms a raised spout above the skin is like to be a ___

A

ileostomy
sometimes urostomy

59
Q

A loop ileostomy/colostomy would present with ___ ___ lumens

A

two adjacent lumens

60
Q

What is diverticular disease?

A

Psuedo-diverticular outpouching of colonic mucosa & submucosa at antimesenteric side

Diverticulitis - when the diverticula becomes inflamed

61
Q

What causes diverticular disease?

A

Increased intraluminal pressure
Degenerative changes in colonic wall - weakening of collagen structure w age

62
Q

Complications of diverticular disease

A

1) Acute diverticulitis
- underlying macro/micro perforation of diverticulum secondary to inflammation & focal necrosis

2) Chronic diverticulitis

3) Complicated diverticulitis
- LGIT haemorrhage
- Fistula
- Perforation
- Bowel obstruction

63
Q

Gold standard in diagnosing diverticulitis

A

CT AP

General Surgery (13 decks)

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