GI Flashcards
Define intestinal obstruction
Blockage of the lumen of the gut
Arrest of onward propulsion of intestinal contents
Name 3 broad types of causes of intestinal obstruction
- Intraluminal obstruction = something in the bowel
- Intramural obstruction = something in the wall of the bowel
- Extraluminal obstruction = something outside of the bowel
Give 3 causes of intraluminal obstruction of the intestine
- Tumour
- Diaphragm disease
- Meconium ileus
- Gallstone ileus
What is diaphragm disease?
Mucosa/submucosa fold due to fibroid diaphragm leaving a pinhole lumen
What is thought to cause diaphragm disease?
NSAIDs
Give 3 causes of intramural obstruction of the intestine
- Inflammatory disease = Chron’s, Diverticular disease
- Tumours
- Neural = Hirschsprung’s disease
Describe how Crohn’s disease can cause intestinal obstruction
Crohn’s disease –> fibrosis –> contraction –> obstruction
Describe how diverticular disease can cause intestinal obstruction
Out pouching of mucosa –> faeces trapped –> inflammation in bowel wall –> contraction –> obstruction
What is Hirschsprung’s disease?
A congenital condition where there is a lack of nerves in the bowel –> no ganglion cells –> no contraction –> distal obstruction and gross dilation of the bowel
Give 3 causes of extraluminal obstruction of the intestine
- Adhesions
- Volvulus
- Peritoneal tumour
What are adhesions?
Fibrous bands stick 2 bits of bowel together so bowel is pulled and distorted
What causes adhesions?
Often formed after abdominal surgery (pelvic, gynaecologist, colorectal)
What is volvulus?
Bowel twisting around each other cuts off blood supply/ lumen
Risk of ischaemia, necrosis and perforation
Which areas of the bowel are most likely to be affected by volvulus?
Occurs in areas of bowel that have mesentery
Often in the sigmoid colon
Give 4 common causes of small bowel obstruction in adults
- Adhesions
- Hernias
- Crohn’s disease
- Malignancy
Give 3 common causes of small bowel obstruction in children
- Appendicitis
- Volvulus
- Intussusception
What is intussusception?
One part of the intestine telescopes into another section of the intestine
Caused by force in-balances
Give 5 symptoms of small bowel obstruction
- Nausea and anorexia
- Early feculent vomit
- Diffuse colicky pain
- Late constipation
- Distention
- Tenderness
Does abdominal distension occur more distal or proximal to an intestinal obstruction?
More distal = greater distension
Give 4 signs of small bowel obstruction
- Vital signs - increased HR, hypotension, raised temp
- Tendernes and swelling
- Resonance
- Bowel sounds
What investigations might you do in someone who you suspect to gave a small bowel obstruction?
- Take a good history - ask about previous surgery
- FBC, U+E, lactate
- X ray
- CT, USS, MRI
What is the management/treatment for small bowel obstruction?
- Fluid resuscitation
- Bowel decompression
- Analgesia and antiemetics
- Antibiotics
- Surgery - laparotomy, bypass segment, resection
Which is more common, small or large bowel obstruction?
Small bowel obstruction = 60-75% of intestinal obstruction
What can untreated intestinal obstruction lead to?
- Ishcaemia
- Necrosis
- Perforation
Give 2 common causes of large bowel obstruction
- Colorectal malignancy
2. Volvulus
Where is the usual site of perforation in large bowel obstruction if the ileocaecal valve is competent?
Caecum
How long does acute prevention of large bowel obstruction last?
Average of 5 day of symptoms = abdominal pain and obstipation
Give 5 symptoms of large bowel obstruction
- Bloating
- Late vomiting
- Colicky pain
- Distension
- Blood in stool
- Volvulus = sudden, pain, localised tenderness and distension
What investigations might you do in someone who you suspect to gave a large bowel obstruction?
- Digital rectal examination
- Sigmoidoscopy
- Plain X ray
- CT scan
Describe the management for a large bowel obstruction
- IV fluid replacement - replace loss and correct electrolyte imbalance
- Bowel decompression
- Surgery
Define hernia
Abnormal protrusion of an organ into a body cavity it doesn’t normally belong
What are the risks of hernia’s if left untreated?
Become strangulated
Give 2 symptoms of hernias
- Pain
2. Palpable lump
Describe the progression from normal epithelium to colorectal cancer
Normal epithelia –> adenoma –> colorectal adenocarcinoma –> metastatic colorectal adenocarcinoma
Define adenocarcinoma
A malignant tumour of glandular epithelium
What is familial adenomatous polyposis?
Autosomal dominant condition where you develop thousands of polyps in your teens
Describe the pathophysiology of familial adenomatous polyposis
Mutation in APC protein –> beta catenin not broken down –> beta catenin upregulates epithelium proliferation genes –> adenomas form
Describe the pathophysiology of HNPCC
Loss of both DNA repair genes –> cellular genetic damage
What are the implications of having HNPCC?
- Risk of further cancers
2. Can’t use DNA damaging chemo
What are precursors to colorectal cancer?
Polyploid adenomas
Describe the epidemiology of colorectal cancer
Normally adenocarcinoma
Incidence peaks around 60-70 years
Males > females
Give 5 risk factors for colorectal cancer
- Increasing age
- Family history
- Western diet
- Alcohol
- Smoking
Give 3 reasons why bowel cancer survival has increased over recent years
- Introduction of the bowel cancer screening programme
- Colonoscopic techniques
- Improvements in treatment options
What can affect the clinical presentation of a colorectal cancer?
How close the cancer is to the rectum
Give 2 signs of a left sided/sigmoid colorectal cancer
- Altered bowel habit
- PR bleeding
- Colicky pain
Give 3 signs of a right sided colorectal cancer
- Iron deficiency anaemia
- Right iliac fossa mass
- Weight loss
Give 4 signs of colorectal cancer
- Abdominal mass
- Perforation
- Haemorrhage
- Fistulae
What investigations might you do in someone who you suspect might have colorectal cancer?
Colonoscopy = gold standard, biopsy and removal of small polyps
Tumour markers are good for monitoring progress
CT/MRI for staging
How can adenoma formation be prevented?
NSAIDs
What screening programme is used to identify bowel cancer?
Faecal occult blood (FOB) screening
For over 65s
+ve result = biopsy
What is the treatment for adenoma?
Endoscopic resection
What is the treatment for colorectal adenocarcinoma?
Surgical resection
What is the treatment for metastatic colorectal adenocarcinoma?
Chemotherapy and palliative
Explain resection coding
R0 = tumour completely excised locally R1 = microscopic involvement of margin by tumour R2 = macroscopic involvement of margin by tumour
Explain Dukes staging and prognosis
A = limited to muscularis mucosae = 95% 5-year survival B = extension through muscularis mucosae (not lymph) = 75% 5-year survival C = involvement of regional lymph nodes = 35% 5-year survival D = distant metastases = 25% 5-year survival
What does T refer to in the staging of cancer?
T = refers to primary tumour and suffixed by number that denotes tumour size
What does N refer to in the staging of cancer?
N = refers to lymph node status and is suffixed by numbers that denotes number of lymph nodes or group of lymph nodes containing metastases
What does M refer to in the staging of cancer?
M = refers to anatomical extent of distant metastases
What does the T mean for colorectal cancer staging?
T1 = invades submucosa T2 = Muscularis propria T3 = Bowel wall T4 = Peritoneum
What does the N mean for colorectal cancer staging?
N1 = spread to lymph nodes N2 = spread to lymph nodes above the diaphragm
What does the M mean for colorectal cancer staging?
M1 = surrounding structure involvement (liver)
Name 5 things that can break down the mucin layer in the stomach and cause gastritis
- Mucosal ischameia
- H. pylori
- Aspirin, NSAIDs
- Increased acid (stress)
- Bile reflux
- Alcohol
Give 3 symptoms of gastritis
- Epigastric pain
- Nausea and vomiting
- Indigestion
- Haematemesis
What investigations are done with someone you suspect has gastritis?
Endoscopy (erythema) Biopsy (histology change) Blood tests (inflammation)
Describe the treatment for gastritis
- Decrease alcohol and smoking
- Antacid (magnesium carbonate)
- PPI (omeprazole)
- H2 receptor antagonist (ranitidine)
- Enteric coated aspirin
How do you treat H. pylori?
Triple therapy:
Normal –> amoxicillin, omeprazole and clarithromycin/metronidazole
Penicillin resistance –> clarithromycin, omeprazole and metronidazole
Give 4 causes of peptic ulcers
- NSAIDs
- Mucosal ischaemia
- Increased acid production (stress)
- Bile reflux
- Alcohol
- H. pylori
How does mucosal ischaemia cause ulcer formation?
Lack of blood flow to cells –> no mucin production = no mucosal protection –> ulcer formation
How does increased acid production (stress) cause ulcer formation?
Mucosa overwhelmed –> corrosion –> ulcer formation
How does NSAIDs cause ulcer formation?
Reduced prostaglandin synthesis due to salicylic acid release –> cell death –> no mucin production = no mucosal protection –> ulcer formation