Large Bowel Pathology Flashcards
How common is colorectal cancer?
4th most common cancer behind breast, prostate and lung
What is the most common classificaton of colorectal cancer?
Adenocarcinoma. (98%)
What sex is colorectal cancer more common in?
M > F
What causes colorectal cancer?
IBD
FH
Genetics
Alcohol
Obesity
Smoking
Diabetes
>Age
Diet
- Decreased fibre
- Increased red meat
What are the genetic causes of colorectal cancer?
Familial Adenomatous Polyposis
HNPCC
What is Familial Adenomatous Polyposis?
Rare autosomal dominant condition in which adenomatous polyps form in the colon epithelium due to mutation of APC gene, located on chromosome 5
What is HNPCC?
Autosomal dominant disorder of gene mutations in MSH2 and MLH1, causing mainly right-sided carcinoma
Also known as Lynch syndrome
How does colorectal cancer present?
Right
- Weight loss
- Iron deficiency anaemia
Left
- Persistent rectal bleeding mixed with stools
- Altered bowel habit, usually to loose frequent stools
- Abdominal pain
- Tenesmus
Both
- Palpable lower abdominal mass
- Cachexia
What investigation is used in colorectal cancer diagnosis?
FBC
- Hypochromic microcytic anaemia/iron deficiency anaemia
Colposcopy with biopsy, gold standard
Biomarkers
- CEA
- CA19-9
CT chest, abdomen pelvis for staging
CT colonography when colonoscopy fails
What investigation is used in colorectal cancer screening?
Faecal Immunochemical Testing (FIT)
adults 50-74 every 2 years
What procedure can be done for those at risk of HNPCC?
Prophylactic Proctocolectomy
Name complications of colorectal cancer?
Acute bowel obstruction
Iron deficiency anaemia
What criteria is used for colorectal cancer stageing?
Modified Duke’s Classification
However, TNM is now more commonly used
Describe Duke’s stage A colorectal cancer
Confined to bowel wall
Describe Dukes stage B colorectal cancer
Growth through bowel wall (muscle)
Describe Dukes stage C colorectal cancer
Regional lymph node involvement
Describe Dukes stage D colorectal cancer?
Distant metastases
What is used to monitor disease progression in colorectal cancer?
CEA (carcinoembryonic antigen)
Not helpful in screening, but it may be used for predicting relapse of previously treated for bowel cancer
What are the locations of colorectal cancer?
(from most common to least common)
Rectal
Sigmoid
Ascending colon and caecum
Transverse colon
Descending colon
What is the most common location for colorectal cancer?
Rectal
What is HNPCC also associated with?
Endometrial cancer
What is FAP also associated with?
Duodenal tumours
What is the most common type of inherited colorectal cancer?
HNPCC
What criteria is used to help diagnose HNPCC?
Amsterdam criteria
What is involved in the Amsterdam criteria?
At least 3 members with colorectal cancer
Cases span 2 generations
At least one case diagnosed before 50
When should an urgent 2 week colposcopy referral be offered?
Over 50 with unexplained hypochromic microcytic anaemia
Over 40 years with abdominal pain and unexplained weight loss
Over 50 years with unexplained rectal bleeding
Over 60 years with a change in bowel habit
What is the management of upper rectum colorectal cancer?
Anterior resection
What is the management of caecal, ascending or proximal transverse colon colorectal cancer?
Right hemicoloectomy
What is the management of distal transverse and descending colon colorectal cancer?
Left hemicoloectomy
What is the management of sigmoid colon colorectal cancer?
High anterior resection
What is the management of anal verge colorectal cancer?
Abdominal-perineal excision of rectum
What is the management of lower rectum colorectal cancer?
Anterior resection
When is Hartmann’s procedure performed?
Performed as an emergency procedure, ie perforation of rectosigmoid colon
The sigmoid colon and upper rectum are removed and an end colostomy formed
Give complications of bowel cancer surgery
Bleeding, infection and pain
Damage to nerves, bladder, ureter or bowel
Post-operative ileus
Anaesthetic risks
Laparoscopic surgery converted during the operation to open surgery
Leakage or failure of the anastomosis
Requirement for a stoma
Failure to remove the tumour
Change in bowel habit
DVT and PE
Incisional hernias
Low anterior resection syndrome, causing incontinence
Intra-abdominal adhesions
How is curative bowel cancer surgery followed up?
CT chest, abdomen, pelvis
CEA
What is appendicitis?
Inflammation of the vermiform appendix, which arises from the caecum
What is the peak age of appendicitis?
10-20 years
What causes appendicitis?
As there is a single entrance and exit to the appendix, pathogens can get trapped due to obstruction at the point where the appendix meets the bowel, leading to infection and inflammation secondary to luminal obstruction
How does appendicitis present?
Colicky central abdominal pain due to inflammation of the appendix, followed by localization of pain to right iliac fossa due to inflammation of overlying peritoneum
McBurney’spoint/RIF tenderness
N&V
Low grade pyrexia
Guarding on abdominal palpation
Rebound tenderness (increased pain when releasing pressure), suggesting peritonitis
Percussion tenderness, suggesting peritonitis
Rovsing’s sign
What is Rovsing’s sign?
Palpation of LIF causes pain in RIF
What investigations are used in appendicitis diagnosis?
Diagnosis is mainly clinical
FBC
- Increased WCC
- Neutrophilia
>CRP
USS/CT, exclude other diagnosis
B-HCG, exclude ectopic pregnancy in females
Laparoscopy, diagnostic and therapeutic
How is appendicitis managed?
Laparoscopic/open appendicectomy
Prophylactic co-amoxiclav
Describe the pre-operative management for an appendicectomy?
Prophylactic IV antibiotics/Co-amoxiclav
Give differential diagnoses of appendicitis
Ectopic pregnancy
Ovarian torsion
Ruptured ovarian cyst
Diverticulitis
PID
What is a complication of appendicitis?
Perforation leading to generalized peritonitis or localized appendix abscess
Give complications of appendicectomy
Bleeding, infection, pain and scars
Damage to bowel, bladder or other organs
Removal of a normal appendix
Anaesthetic risks
PE or DVT
What is ischaemic colitis?
Acute disruption in blood supply to the colon, which may lead to inflammation, ulceration and haemorrhage
Give risk factors for ischaemic colitis
Age
AF, particularly for mesenteric colitis
Other causes of emboli
- Endocarditis
- Malignancy
CVD risk factors
- Smoking
- HTN
- DM
Cocaine
How does ischaemic colitis present?
Self limiting
Abdominal pain
- Crampy
- Generalised
Sudden bloating
Rectal bleeding
Diarrhoea
Fever
Dusky blue mucus
What investigations are used in bowel ischaemia diagnosis?
FBC
- Increased WCC
Increased Lactate
AXR
- Thumb printing in ischaemic colitis if haemorrhage or mucosal oedema
CT abdomen, makes diagnosis
What is the first line investigation for bowel ischaemia?
Lactate
What is the management for ischaemic colitis?
Supportive
Surgery if peritonitis, perforation or ongoing haemorrhage
Which part of the colon is most likely to be affected by ischaemic colitis?
Splenic flexure
What is sigmoid volvulus?
Describes large bowel obstruction caused by the sigmoid colon twisting on the sigmoid mesocolon
Where can volvulus also occur, less commonly?
Caecum (20% of cases)
Due to developmental failure of peritoneal fixation of the proximal bowel
Give risk factors for sigmoid volvulus
Increased age
Chronic constipation
Chagas disease
Neurological conditions
- Parkinson’s
- DMD
Psychiatric conditions
- Schizophrenia
Give risk factors for caecal volvulus
Adhesions
Pregnancy
All ages
How does volvulus/bowel obstruction present?
Vomiting, green billious
Diffuse abdominal pain
Abdominal ditention
Absolute constipation
Tinkling bowel sounds
History of malignancy/surgery
What investigations are used in bowel obstruction, generally?
AXR, initial investigation
Contrast abdominal CT confirms diagnosis and establoshes site
What AXR signs are seen in volvulus?
Large bowel obstruction
- Large, dilated/distended loop of colon
- Often with air-fluid levels
Coffee bean sign arrising from LLQ in sigmoid
Embryo sign arrising from RLQ in caecal
Small bowel obstruction and centrally dilated bowel may be seen in caecal
How is sigmoid volvulus managed?
Supportive with analgesia, fluids and NG tube insertion
Rigid sigmoidoscopy with rectal tube insertion for decompression
Urgent laparotomy if peritonitis or failed compression
How is caecal volvulus managed?
Right hemicolectomy
How is bowel obstruction managed, generally?
Nil by mouth
IV fluids
NG tube with free drainage, reducing risk of vomiting and aspiration
Laparoscopy to correct underlying cause
Give causes of bowel obstruction
Adhesions
Hernias
Malignancy
Volvulus
Diverticular disease
Strictures
Intussuception
What anti emetic should be avoided in bowel obstruction?
Metoclopramide
What is diverticular disease?
Protrusion of the inner mucosal lining through to the outer muscular layer of the bowel, forming pouches/bulges
What causes diverticular disease?
>50
Low fibre diet
Obesity
NSAIDS
Congenital/Meckel’s
Which part of the bowel is diverticular disease most common in?
Sigmoid
What is Meckel’s diverticulum?
Congenital outpouching or bulge in lower part of the small intestine due to left over umbilical cord
How does diverticular disease present?
Mainly self-limiting, can be asymptomatic
LLQ pain
Constipation/altered bowel habit
Rectal bleeding
What classification is used to assess the severity of diverticular disease?
Hinchey classification
How is diverticular disease managed?
Increase dietary fibre
Bulk forming laxatives, stimulant laxatives should be avoided
Surgical resection
Give complications of diverticular disease?
Diverticulitis
Haemorrhage
Fistula development
Abscess development
Perforation
Peritonitis
Ileus/obstruction
How does diverticulitis present?
Severe LLQ abdominal pain
N&V
Fever
Change in bowel habit, mainly diarrhoea
Rectal bleeding
Reduced bowel sounds
Guarding, rigidity and rebound tenderness suggests perforation
Increased inflammatory markers
How is diverticulitis managed?
Analgesia, avoiding NSAIDS
Oral co-amoxiclav for 5 days in mild disease
Admitted for IV if no improvement in 72 hours
Abscess drainage
What is melanosis coli?
Disorder of pigmentation of the bowel wall in which histology demonstrates pigment-laden macrophages, associated with laxative abuse
