Colorectal Flashcards
Pathophysiology of Appendicitis
Appendix is blocked by:
Foecalith
Lymphoid
Neoplasms
IBS
The blocked appendix continues to secrete mucus and fluid, there is bacterial overgrowth and all this causes a cycle of luminal distension and inflammation increasing luminal pressure.
Luminal distension stimulates affarent visceral nerve fibres from T8-T10= vague periumbilical pain
Breech in epithelium lead to translocation of enteric bacteria
Transmural inflammation follows and inflamed outer serous layer of appendix irritates parietal peritoneum producing more localised pain at McBurney point.
With increased pressure, impaired venous and lymphatic drainage, then ongoing Ischemia + infection = perforation and contamination of peritoneal cavity
Organisms associated with/w appendicitis
E.Coli
Bacteroides
Enterococcus
(Gram neg) so Augment good cover
Which signs are elicited when examining for appendicitis
Rovsing: pain in RIF when palpating LIF
Dunphy: Pain in RIF when coughing
Iliopsoas: Pain in RIF on hyper extension of the R hip
Obturator: Pain in RIF on internal and external rotation of R hip
Appendicitis is complicated by what
Appendix abscess
Phlegmon (appendix mass) give Ab
Why is it difficult to diagnose appendicitis in pregnancy
Appendix is displaced up by uterus
WCC of up to 12000 is normal in pregnancy
Tachycardia is normal physiological change
N&V are presumed to be from hyperremesis gravidum
Assessment of stoma
- Viability of the stoma (if it’s the right stoma, specific pouch type, one way valve in urine stoma and clip in colon/ileostomy, check any leakages etc)
- Size (measure all the time as it changes, pouching system needs to be cut to accommodate size of stoma measured)
- Consistency
- Skin peristomal and parastomal (adjust ouch if skin is sore, assess for infections, no oil based creams)
Stoma complications
- Faecal contamination on the skin
Can also be due to
a) I’ll fitting stoma pouch system
b) incorrect size of stoma
c) allergy or skin irritation to product appliance - Adhesive pouch/ tape allergy
- Fungal infections (tx topical water based antifungal creams)
Surgical
1. Parastomal hernia
2. Stenosis: cutaneous and deep fascia (dilate with Hagar dilators)
3. Retraction (tx convex pouch systems)
4. Prolapse (try reduce, admit if strangulated)
5. Peristomal granulation (tx with silver nitrate)
6. Ischemia/necrosis
7. Bolus obstruction (hard foods, can also be adhesions/scar tissue
8. Stoma separation
Mechanisms responsible for progression of volvulus to gangrene/necrosis
Ischemia of mesenteric from torsion and strangulation.
Distension of bowel causes intraminal pressure to exceed diastolic and systolic pressure, leading to arterial and venous obstruction
pathophysiology of sigmoid volvulus
Torsion occurs as the base of loop causing obstruction
Ischemia due to 2 things: mesenteric obstruction and increased intraluminal pressure past the BP
Necrosis
Aetiology if volvulus
Chronic constipation
High fibre diet
Use of enemas
Bowel habits
Length of sigmoid colon
Presenting features of sigmoid vulvulus
- Pain, generally mild colicky or severe if gangrene. Radiate to the Back.
- Constipation
- Abdominal distension
- Vomiting
- Passing of flatus instead of reaches after attack
- Relief with enema
Clinical features of sigmoid volvulus
Abdo distension
Dyspnoea
Remarkably little tenderness unless gangrene
Outline of distended bowel ‘Motorcycle tyre’
Tympanic abdomen
Visible peristalsis
Empty rectum on rectal exam
Clinical features of sigmoid volvulus
Abdo distension
Dyspnoea
Remarkably little tenderness unless gangrene
Outline of distended bowel ‘Motorcycle tyre’
Tympanic abdomen
Visible peristalsis
Empty rectum on rectal exam
Investigations to confirm sigmoid volvulus
- Abdo Xray (plain with pt upright)
- Bent inner tube
- Coffee been sign
- Summation line
- Walls of volvulus appear smooth
w’ no haustrations
-absent rectal gas
- Barium Enema
In cases where dx is difficult on AXR,
a limited barium enema will confirm
the dx.
Bird’s beak sign due to obstruction
Barium contraindicated in pts w’ suspected colon infarction or perforation.
CT scan
-Whirl sign which lead to the point of obstruction
Management of Sigmoid Volvulus
Conservative
Sigmoidoscopy
-in patients with viable bowel
-diagnostic and therapeutic
-gently pass scope and relieves the torsion, passing of large flatus and fluid faeces
-site of torsion about 15cm above anal verge
-after detorsion pass a flatus tube and stitch to anal ring and leave for 2-3 days
Surgical Management (Mandatory after decompression)
1. Urgent laparotomy if:
-failed decompression
-features suggestive of peritonitis
-presence of gangrene seen on sigmoidoscopy
-features suggestive of perforation eg blood stained effluent from scope, fever, leukocytes after decompressions
After urgent Laparoscopy, Primary anastomosis or Colostomy and Hartman’s procedure
Elective surgery
2. Laparoscopic Resection of sigmoid colon after decompressed sigmoid volvulus.
Nonresectional surgery
3. Colopexy (Sigmoidopexy)
Suture sigmoid into anterior abdominal wall, less likely to twist.
4. Mesocoloplasy (Mesosigmoidoplasty)
Contraindications of decompression with sigmoidoscopy
Features of gangrene eg peritonitis, unstable vitals
Presence of a compound vulvulus (knot !)
Failed attempt as sigmoidoscopy
Complications of sigmoidoscopy in volvulus
Perforation
Reducing gangrene bowel
Aetiology of ileo-sigmoid knot
Hyper mobile small intestine
Elongated mesentery having great breath and narrow base
Unusually redundant (big) mesocolon having narrow base of attachment
Management of ileosigmoid knot
Resect both small and large bowel
Anastomoses if there is gangrene or colostomy and Hartman’s procedure
Which polyps are high risk for malignancy
Large polyps >1cm
Villous polyps
Sessile/immobile
High grade dysplasia
Risk factors for colon cancer
- Diet high in animal fat and meat
- Obesity (insulin resistance then insulin ⬆️=cancers)
- Family history (FAP, Attenuated FAP, Lynch syndrome,
- IBS
- Gardeners syndromes (linked to FAP also)
Screening for colorectal cancer
At risk individuals (family hx)
1. Faecal Immunohistochemical Testing (FIT) (detects occult blood doesn’t tell you if it’s cancer)
2. Colonoscopy in First degree relatives of colon cancer patients 10years prior to their onset of disease.
Presenting features of colonic cancer
General:
1. Bleeding/mucoid
2. Pain
3. Obstructive symptoms
4. Change in bowel h habits
5. Constitutional: LOW, Anaemia
6. Mass
Rectosigmoid (present earlier, more common 50-60%)
Left sided
Right sided (least distinct presentation)
Investigations for colon cancer
You have to Biopsy to make the diagnosis
- Colonoscopy (Gold standard)
- Protosigmoidoscopy
-sufficient to confirm dx in distal colonic lesions histological, only tells you level of tumour or whether or not it occupies part of the lumen
For staging
CXR
CT scan chest abdo and pelvis and features of the cancer
-size and primary depth of invasion
-involvement of adjacent structures
-nodal involvement
Mets signs on CT
-liver lesions, bone or lung lesions (opacities)
-pleural effusions
-ascites
US of abdo also used for assessment of metastatic disease
MRI for all rectal cancers
PET scan if still in doubt, isotope based study,isotope rapidly taken up by cancer cells
How to stage colorectal cancer
TNM
TX-T4
NX-N2
MX-M2
How to stage colorectal cancer
TNM
TX-T4
NX-N2
MX-M2
Management of colorectal cancer
Right hemi-colectomy
Left hemicolectomy
Sigmoid colectomy
Anterior resection and APR
Factors that determine resectibility in colon cancer
Will there be complete resection
Adequate nests of the resection (yield sufficient lymph nodes)
Features of advances disease (mets), can we resect them (eg lung, liver)
What determines the type of resection for colon cancer
Anatomical location
Blood supply
Size of tumour
Anatomical location and blood supply determines which segment will be respected
Size of tumour determines how radical the resection will be eg whether or not the adjacent organs will be respected eg uterus, small bowel.
What is an adenoma
Being epithelial neoplasm
FAP is caused by which gene mutation
APC gene on chromosome 6 (5)
Diverticulitis clinical presentation (6)
- Left iliac fossa pain (it’s commonly in the sigmoid) pain may be colicky in nature
- Bloating
- Flatulence
- Rectal bleeding in diverticula’s bleed (rare)
- Altered bowel habit (constipation/diarrhea)
- Sx dissapearing after defeacation of flatulence
- Fever and leukocytosis on investigations
Investigations for diverticulitis
Best: CT SCAN
CT surpercedes colonoscopy and is being increasingly used, may be used to supplement colonoscopy
Colonoscopy supercedes barium enema (useful also if you suspect malignancy)
Barium enema is useful in planning surgery as it shows severity and extent of disease
Always do the colonoscopy after acute episode settles after some time.
Complications of diverticulitis
(Think of your 4s- perforation, obstruction, infection, bleeding)
- Perforation
- Bowel obstruction (structures)
- Abscess formation (local or walled off pelvic abscess) then fistula
- Bleeding