Colon & Rectum Flashcards
Define:
Diverticulosis
Diverticular disease
Diverticulitis
Diverticulosis = diverticula are present
Diverticular disease = diverticula are present and symptomatic
Diverticulitis = inflammation of a diverticulum
What is diverticulosis and what causes it?
Mucosal herniation through muscle coat
Found in the sigmoid colon
Low fibre intake is thought to lead to high intraluminal pressures which force the mucosa to herniate through the muscle layers of the gut at weak points
Most commonly an incidental finding
What are the typical clinical features of diverticular disease?
LIF pain/tenderness
Sepsis
Altered bowel habit
What are some common complications of diverticular disease?
Pericolic abscess Perforation Haemorrhage Fistula Stricture
Treatment of uncomplicated diverticulitis
IV fluids
Bowel rest
IV antibiotics
Treatment of complicated diverticulitis
Hartmann’s procedure - resection of the rectosigmoid colon with closure of the rectal stump and formation of an end colostomy
Percutaneous drainage
Laparoscopc lavage and drainage
Acute & Chronic colitis
Causes?
Symptoms?
Dianosis?
Infective colitis; UC; Crohn’s; ischaemic
Diarrhoea + blood; abdo cramps; dehydration; sepsis; weight loss; anaemia
Diagnosis - plain AXR; sigmoidoscopy with biopsy; stool cultures barium enema
Ischaemic colitis Who does it tend to occur in? Most common artery? Presentation? Gold standard test? Treatment
Elderly, arteriopaths
Inferior mesenteric artery - ranges from mild ischaemia to gangrenous colitis
Lower left sided abdo pain +/- bloody diarrhoea
Colonoscopy with biopsy
Barium enema shows characteristic “thumb print” of submucosal swelling
Fluid and IV antibiotics; embolisation
Sigmoid volvulus What is this? Who does it occur in? What is seen on AXR? Treatment?
The bowel twists on its mesentery, which can produce severe, rapid, strangulated obstruction
Occurs in elderly, constipated, co-morbid patient
“Inverted u” loop of bowel that can look like a coffee bean
Treatment is flatus tube, sigmoid colectomy is also sometimes required
What is peristalsis in the colon initiated by?
Peristalsis is induced by the release of serotonin (5-HT) from neuroendocrine cells in response to luminal distension.
Serotonon activated 5-HT4, which in turn results in the activation of sensory neurones
What are the three types of constipation?
Briefly describe each.
- Normal transit through the colon - there is normal rate and stool frequency, but patients believe they are constipated
- Defecatory - a paradoxical contraction rather than the normal relaxation of the puborectalis and external anal sphincter during straining may prevent defecation
- Slow transit constipation - occurs predominantly in young women who have infrequent bowel movements
Megacolon
What is it?
What causes it?
What disease should be ruled out in young patients with this?
A number of congenital and acquired conditions in which the colon is dilated.
In many cases, it is secondary to chronic constipation and in some parts of the world Chagas’ disease (caused by a blood sucking bug) is a common cause.
Hirschsprung’s disease - a disease which presents in the early years of life, where an aganglonic segment of the rectum (megarectum) gives rise to constipation and subacute obstruction
What is the management of faecal incontinence?
Initial management is bowel habit regulation
Loperamide is the most potent antidiarrhoeal agent which also increases internal sphincter tone
What site is most commonly affected in ischaemic colitis?
Splenic flexure
Colonic polyp
What is this?
Benign or malignant?
An abnormal growth of tissue projecting from the colonic mucosa
They can be benign or malignant - need histology to tell them apart
What is the top four differential of a colonic polyp?
- Adenoma
- Serrated polyp
- Polyploid carcinoma
- Other
Name three macroscopic appearances of polyps
- Pendunculated - hanging like an upside mushroom
- Sessile - produce a carpet like flat growth
- Flat - barely protudes above the epithelial surface
What are adenomas always?
Dysplastic and benign - they do not invade other tissues and do not metastasize, but they can progress to adenocarcinomas
How does an adenoma progress to become an adenocarcinoma?
The epithelium gets a few mutations, causing an adenoma to develop, which accumulates more mutations, causing an adenocarcinoma
All adenomas must be removed before this process occurs, this is either done endoscopically or surgically
Describe Dukes staging for carcinomas
Dukes A - confined to muscularis propria
Dukes B - through muscularis propria
Dukes C - metastatic to lymph nodes
How does the presentation of colonic adenocarcinoma relate to the site?
Left sided (75%) - blood PR, altered bowel habit, obstruction Right sided (25%) - anaemia, weight loss
Patterns of spread of colorectal cancer -
Local invasion?
Lymphatic spread?
Haematogenous?
Local invasion - mesorectum, peritoneum, bladder
Lymphatic spread - mesenteric nodes
Haematogenous - liver, distant sites
Risk factors for colorectal cancer?
Age >55 yo
Neoplastic polyps
IBD
Genetic e.g. FAP, HNPCC
Diet - low fibre, high red/processed meat
Alcohol, smoking
LACK OF EXERCISE - involved with AMP-kinase
What is the most common colorectal cancer?
Adenocarcinoma
How does colorectal cancer present?
Left sided
Right sided
Both
Left sided - bleeding/mucus PR, altered bowel habit or obstruction, tenesmus, mass PR, pseudo diarrhoea
Right sided - weight loss, lob Hb, abdo pain, obstruction less likely
Either - abdo mass, perforation, haemorrhage, fistulae
What is the most common mutated gene in colorectal cancer?
APC
Others include Kras, p53, 18q loss
Which parts of the colon and rectum are most and least associated with colorectal cancer?
Rectum & sigmoidal –> most common
Caecum and ascending –> relatively common
Transverse and descending –> least common
Inherited colorectal cancer
Characteristics of HNPCC and FAP
HNPCC
- Late onset
- Autosomal dominant
- Right sided
- 100 polyps
- Associated with thyroid carcinoma
What is the main radiological investigation used in colorectal cancer?
What is the gold standard used for diagnosing colorectal cancer?
CT colography
Colonoscopy
How is radiotherapy used in colorectal cancer?
Adjuvant -reduces local recurrence after rectal excision
Palliative - inoperable primary rectal cancer or recurrent rectal cancer
Chemotherapy for colorectal cancer
Reduced Dukes C mortality
FOLFOX regimen has become standard - 5-FU, folinic acid and oxaliplatin
What causes anal fissure??
How is it treated?
Often follows a period of constipation - the passage of a hard stool produces a fissure, the pain of which causes anal spasm and further consipation
The vicious cycle is broken with stool softeners and local anaesthetic preparations
