The Colon Flashcards
What is a sigmoid volvulus?
Sigmoid colon twisting around itself
What are haustra?
Visible tonic contractions of teniae coli
What are the branches of the sup. mesenteric artery?
Jejunal and ileal arteries Inf. pancreaticoduodenal a. Middle colic a. Right colic a. Ileocolic a.
What are the branches of the inf. mesenteric artery?
Left colic a.
Sigmoid arteries
Sup. rectal a.
What is the main anastomosis prevent bowel ischaemia?
Marginal artery (of Drummond)
What is the blood supply of the distal half of the anal canal?
Middle rectal a. (Branch of internal iliac a.)
Inf. rectal a. (Branch of pudendal a.)
Clinical presentation of portal hypertension?
Caput medusae - dilated collateral epigastric veins
Oesophageal/Rectal varices
What is the vertebral level of the pelvic cavity?
L5
What is the levator ani?
Pelvic floor muscle
At what vertebral level does the sigmoid colon become the rectum?
S3
When does the anal canal start?
Anterior to the tip of the coccyx
Where does the rectal ampulla lie?
Immediately sup. to levator ani
What is the role of the levator ani muscle?
Supports pelvic organs
- Tonic contractions prevent prolapse
- Increased contractions during coughing/sneezing
What is the levator ani supplied by?
Nerve to levator ani
What is the puborectalis muscle?
A muscle wrapped around anal canal
What is the nerve supply to the rectum and anal canal?
SNS - T12-L2 - Synapse at inf. mesenteric ganglia - periarterial plexuses PNS - S2-S4 - Via pelvic splanchnic nerves Visceral afferents - Enter at S2-S4 - Run along PNS fibres Somatic motor - Leave in pudendal nerve (S2-S4) - Also in levator ani nerve (S3 and S4)
What makes diverticular disease complicated?
Inflammation Rupture Abscess Fistula Massive bleed
What is diverticular disease related to?
Low fibre diet
High intralumenal pressure
Symptoms of colitis?
Diarrhoea (+/- blood) Abdo cramping Dehydration Sepsis Weight loss Anaemia
Clinical features of small bowel ischaemia and infarction
Severe, poorly localised pain
Elderly
Arteriopaths
What is the Rome III criteria for IBS?
Recurrent abdo pain/discomfort for >3 days per month for 3 months and two or more of the following:
- Improvement on defecation
- Onset associated with change in stool frequency
- Onset associated with change in stool form
What symptoms are present in IBS?
Bloating Urgency Tenesmus PR mucus Nocturia Stress aggravation
Treatment of IBS
Regular meal times
Decreased fibre intake
Plenty of fluids (but not caffeine)
Try 4 weeks of probiotics
Common causes of small bowel obstruction
Adhesions
Hernias
Malignancy
What are the non-infectious causes of diarrhoea?
GI bleed Ischaemia Diverticulitis Endocrine disorder Drugs Toxins (fish) Withdrawal
Infectious causes of bloody diarrhoea?
Campylobacter
Shigella
E. coli 0157
Amoebiasis
Treatment of campylobacter infection?
Clarithromycin
Azithromycin
Key features in the examination of infectious diarrhoea
Fever Rashes Dehydration - Pulse - Mental state - BP Abdo tenderness PR exam
What two causative agents is stool microscopy used to diagnose for?
Giardia
Amoeba
What organisms does stool culture test for in blood diarrhoea?
Salmonella
Campylobacter
Shigella
How do we test for E. coli and C. diff?
Stool toxins
How do we test for norovirus?
PCR
How is the severity of a C. diff infection calculated?
One or more of:
- Pseudomembranous colitis/toxic megacolon/ileus/colonic dilation >6cm
- WCC >15cells/mm3
- Creatinine > 1.5xbaseline
Risk factors for a C. diff infection?
Antibiotics
PPIs/H2RAs
Age >65
Chemo/Renal disease/IBD
Therapy for Pseudomembranous colitis
Metronidazole (non-severe) PO vancomycin (if severe)
Clinical features of UC?
Bloody diarrhoea Urgency Tenesmus Incontinence LIF pain
How do we assess UC?
CRP Albumin AXR Endoscopy Histology
What signs of UC can be seen on an AXR?
No stool distribution
Thumb printing (mucosal oedema)
Toxic megacolon
What are the extra intestinal manifestations of UC?
Arthritis Uveitis Deranged LFTs Primary sclerosing cholangitis - Itch - Rigors
Symptoms of CD?
Cramps Diarrhoea Wgt loss Mouth - Painful ulcers - Swollen lips - Angular stomatitis
How do we asses CD?
Clinical exam - Wgt loss - RIF mass - PR signs Bloods - CRP - Albumin - Platelets - Vitamin B12 - Ferritin
Drug therapy for UC?
5ASA (Mesalazine)
Steroids
Immunosuppressants
Anti-TNF
Drug therapy for CD?
Steroids
Immunosuppressants
Anti-TNF
What are the side effects of 5ASA?
Diarrhoea
Idiosyncratic nephritis
Side effects of Azathioprine?
Pancreatitis
Leukopaenia
Hepatitis
Lymphoma
What are the types and examples of Anti-TNF drugs?
Chimeric
- Infliximab (IV infusion)
Humanised
- Adalimumab (SC injection)
When is Anti-TNF therapy recommended?
If long term immunosuppression is needed: - Surgery - Support In refractory or fistulating disease If a current infection is excluded
What do I cells secrete and where do they secrete it?
CCK
Duodenum and jejunum
What do S cells secrete and where do they secrete it?
Secretin
Duodenum
What do M cells secrete and where do they secrete it?
Motilin
Duodenum and jejunum
What do K cells secrete and where do they secrete it?
Glucagon-like insulinotropic peptide
Duodenum and jejunum
What do L cells secrete and where do they secrete it?
Glucagon-like peptide 1
What is the migrating motor complex and what affects it?
Peristalsis between meals Inhibited by - Feeding - Vagal tone Triggered by - Motilin Suppressed by - Gastrin - CCK
What surgical operations can be carried out for Crohn’s disease?
Resection
Stricturoplasty
What operations can be carried out in UC?
Protocolectomy +
- End ileostomy
- Ileorectal anastomosis
Features of a colostomy
Usually left
Usually flush
Stool
Features of an ileostomy
Usually right
Usually sprouted
Usually effluent
Surgeries available for colonic Cancer?
Right hemicolectomy Transverse colectomy Left hemicolectomy Sigmoid colectomy Subtotal colectomy
What are the available surgeries for rectal Cancer?
Abdominal-perineal excision of the rectum (APER)
Anterior resection
What is the commonest cause of food poisoning?
Campylobacter
How is a campylobacter infection treated?
Ciprofloxacin
Erythromycin
How is salmonella typed?
Via O-antigens and slide agglutination
How is salmonella food poisoning treated?
Ciprofloxacin
What can cause haemolytic ureamic syndrome?
E. coli 0157
Presentation of HUS?
Symptoms - Abdo pain - Fever - Pallor - Petechiae - Oliguria Signs - High WCC - High urea - Low platelets - Low Hb
What causes enteric Fever?
Salmonella typhi
Salmonella paratyphi
What conditions result in both Fever and jaundice?
Pre-hepatic: - Malaria - HUS - Sickle cell crisis Intra-hepatic: - Hep A and E - Leptospirosis - Weils diseases - Malaria - Enteric Fever - Typhus - Viral haemorrhagic Fever Post-hepatic: - Ascending cholangitis - Helminths
What is Chagas’ disease?
Trypanasoma cruzi infection
Results in PNS denervation of
- Colon
- Oesophagus
What is the causative organism of rectal gonorrhoea?
Neisseria gonorrhoea
Treatment of rectal gonorrhoea?
Cephalosporin
Chlamydia treatment
STI screen
What is the cause of rectal chlamydia?
Chlamydia trachomatis
Which is milder, rectal gonorrhoea or chlamydia?
Chlamydia
How do we treat rectal chlamydia?
Azithromycin
Doxycycline
What is telangiectasia visible in?
Radiation colitis
What is the histological appearance of Crohn’s disease?
Patchy and segmented
Transmural (entire thickness)
Non-caseating granulomas
What is the histological appearance of Ulcerative Colitis?
Diffuse Crypt branching Irregular crypts Cryptitis Massive inflammatory cell influx
True or false. Crohn’s disease can cause toxic megacolon (acute fulminant colitis).
False. UC can cause toxic megacolon
What is the initial treatment of diverticulitis?
IV fluids
Rest
IV antibiotics
Which of a proximal or distal small bowel obstruction causes distension?
Distal
How do we diagnose meckels diverticulum?
Technicium Tc 99m scan (detects ectopic gastric mucosa)
What is the empirical treatment for diarrhoea and at least one other symptom?
Ciprofloxacin 500mg BD for 3-5 days
If rapid bowel clearing is needed, would a bulk or osmotic laxative be used?
Osmotic
What type of laxative is methylcellulose?
A bulk laxative
Examples of osmotic laxatives?
Lactulose
Sorbitol
Glycerin (Sodium Stearate) suppositories
Examples of stimulant purgatives?
Bisacodyl
Senna
Sodium picasulfate
What is oral dorcusate sodium?
Faecal softener
What are some mechanisms of sodium reabsorption?
Sodium/Glucose co-transport Sodium/Amino acid co-transport Sodium/H+ exchange Parallel Sodium/H+ and Chloride/Bicarbonate exchange Epithelial sodium channels (ENaC)
Are sodium co-transporters regulated by cAMP or calcium ions?
Nope
What effect does aldosterone have on epithelial sodium channels?
Increased rate
Which is greater, chloride secretion or chloride absorption?
Absorption
What is the role of CFTR?
Chloride conductance - secretory diarrhoea
What bacterial infection causes secretory diarrhoea and how?
Cholera
Toxin inhibits GTPase resulting in increased cAMP and CFTR stimulation.
Chloride hypersecretion
What is rigler’s sign?
Gas outside of the bowel wall in toxic megacolon
What bacteria have short (1-6hr) incubation periods?
Staph aureus
Bacillus cereus
What bacteria have 12-48hr incubation times (medium)?
Salmonella
Clostridium perfringens
How long is the incubation period for Campylobacter and E. coli 0157?
2-14 days
What is the incubation period of enteric Fever?
7-18 days
