GI Flashcards
What is helicobacter pylori? Key biochem feature? Spread? Higher colonisation where?
Gram -ve, curve motile rod, microaerophilic, related–> campylobacter genus and spirochetes, polar sheathed flagella= corkscrew motion
Urease positivity- used in testing, person-to-person spread
In developing countries
Pathogenesis of helicobacter pylori?
Adapted to living gastric mucus–> microaerophilic, motile, urease generates ammonium to buffer acidity, need ectopic gastric mucosa for duodenal/ oesophgeal colonisation, induces inflammation–> mononuclear and neutrophilic cellular infiltrate in lamnia propria, Treg and Th17 responses, stimulates increased gastrin–> increased parietal mass but may also modulate gastric acid production
Natural history of campylobacter pylori?
Acquisition usually asymptomatic- may cause nausea and epigastric pain, chronic diffuse superficial gastritis, followed by period of achlrorrydria
Persistent colonisation in most, might clear if not host adapted or antibiotics, eradication if HP+ controversial often no benefit and might only benefit select sub-population
% duodenal ulcers associated with HP? Duodenal colonisation associated with what? Increased with what strains? % gastric ulcers? What increases healing and reduces relapse?
90% Gastric metaplasia and duodenitia cagA+ strains 50-80% gastric ulcers Antimicrobials
Gastric cancer associated with reduced what? What does this? Gastric lymphoma leads to what? Other disease associations?
Gastric acid
H.pylori
Chronic antigen stimulation causing mucosal associated lymphoid tumours
Oesophageal disease–> gastro-oesophageal reflux, Barrett’s oesophagus and oesophageal adenocarcinoma, increased asthma, height and ITP all linked
Investigation for h.pylori?
Serology- rapid but no assessment of clinical state, lower sensitivity
Stool antigen- can assess response to therapy after 6-8 weeks, urea breath test- only 60% sensitivity- need equipment, more invasive but quantitative and rapidly responsive to Tx, endoscopy with urease test, histology +/- culture= best if symptoms, more invasive, can allow culture and antibiotic sensitivity but not widely available
Tx for h.pylori?
Omeprazole, amoxicillin IV/oral- inhibits enzymes for peptidoglycans in bacterial cell walls–> lysis, clarithromycin ORAL/IV- inhibit protein synthesis–> 50S subunit of ribosome and block translocation- stops bacterial growth
Causes of infectious diarrhoea (gastroenteritis)? How will c.diff infection differ? Pt w/ severe B cell immunodeficiency may get what? Transplant pt may get what? Non-infectious causes? Diagnose in stool by what for what and what?
Viral (rotavirus,) foodborne (s.aureus,) travel related (e.coli, giardiasis)–> watery diarrhoea, bloating and malabsorption
More severe/ prolonged
Severe giardiasis
Cytomegalovirus/ parasites or feature of systemic infection with sepsis or malaria, potential HIV infection
Malignancy, overflow with constipation, endocrine
Microscopy for ova and parasites or antigen, Tx= metronidazole
History for infectious diarrhoea?
Work, acute/ chronic- acute< 2 weeks, risk factors, HIV, may be non-infectious, achlorhydia- absence of HCl in gastric secretions, on PPIs, travel, diet change, contact with D&V, any fever/ pain, chronic diarrhoea alternating with constipation= irritable bowel, weight loss, nocturnal diarrhoea and anaemia= close follow-up
Bloody diarrhoea also known as what? Organisms? Diagnosis? Tx?
Dysentry
Shigella/ salmonella, campylobacter, e.coli, amoebiasis, abdo pain
Examination of cysts in stool, antigen, PCR or serology
Metronidazole and intraluminal agent, UC, Crohn’s, colorectal cancer, colonic polyps, pseudomembranous colitis, ischaemic colitis
Mucus in stool occurs in what conditions? Frank pus suggests what? White cells are microscopically absent in what 4 things?
IBS, colorectal cancer and polyps
IBD, diverticulitis or a fistula/ abscess
Amoebiasis, cholera, e.coli and viruses
Explosive diarrhoea in what? Large bowel diarrhoea organisms? Features?
Cholera, giardia, yersinia; rotavirus
Salmonella, shigella, c.diff and entamoeba
Watery stool+/- blood/ mucus; pelvic pain relieved by defecation; tenesmus; urgency
Small bowel symptoms? Travellers diarrhoea most commonly due to what? Also caused by what? Symptoms?
Periumbilical/ RIF pain not relieved by defecation
Salmonella/ campylobacter/ shigellosis, also cryptosporidiosis, giardiasis, amoebiasis
Dehydration, decreased skin turgor, capillary refill>2s, shock, fever, weight loss, clubbing, anaemia, oral ulcers, rashes, abdo masses
Do rectal exam for masses/ impacted faeces, any goitre?
Investigations for travellers diarrhoea?
FBC- decreased MCV/ Fe deficiency, increased if alcohol abuse or B12 absorption decreased, eosinophilia if parasites, ESR/CRP raised- infection, Crohn’s/ UC, cancer
U&E- K+ decreased= severe D&V, TSH decreased–> thyrotoxicosis, coeliac serology
Stool: MC&S–> bacterial pathogens, ova cysts, parasites C.diff toxin, faecal fat excretion or chiolein breath test
Other investigations for infective diarrhoea?
Rigid sigmoidoscopy- with biopsy of normal and abnormal looking mucosa- 15% of patients with Crohn’s disease have macroscopically normal mucosa
Colonoscopy/ barium enema- avoid if acute, normal= consider small bowel radiology (Crohn’s) +/- ERCP (chronic pancreatitis)
Management of infectious diarrhoea?
Treat cuases, food handlers- no work until stool samples -ve, close wards, oral rehydration better than IV, if dehydrated and bloody diarrhoea> 2 weeks= IV fluids may be needed
Codeine phosphate PO or loperamide PO after each loose stool decrease stool freq- avoid in colitis
Avoid antibiotics unless systemic upset
Antibiotic associated may respond to probiotics (lactobacilli)
What is deontology based on? May compile what? What about consequentialism?
Based on belief that we owe a duty of care to each other
Telling of whole truth in a way which is unkind
Consequences matter- how you get there doesn’t
Hard to know what they will be, some actions= wrong, even if consequences good
What are virtue ethics? Centres ethics on what? Cons? 5 Cs of ethical duties?
Characteristics that promote human flourishing: compassion, patience, kindness, fidelity
Centres ethics on whole person and what it means to be human
No clear guidance for moral dilemmas, no agreement on what virtues are, relative to culture
Candour, consent, capacity, confidentiality, communication
What is the clinical truth? Truth-telling needs to be sensitive to what things?
Contextual, circumstantial and personal, cannot ignore objective truth, must be relegated to it either
Culture, time, person and amount
What is teamwork? What are the Belbin team roles?
Work done by several associates with each doing a part but all subordinating personal prominence to the efficiency of the whole
Plant- creative, imaginative, unorthodox
Resource- extrovert, enthusiastic, develops contacts
Coordinator- mature, chairperson
Shaper- dynamic, challenging
Monitor evaluator- strategic
Teamworker- cooperative
Implementer- disciplined
Completer- painstaking, conscientious
Specialist- single-minded, skill and knowledge
Teamwork issues? 6 components of teamwork?
Lack of teamwork- lack of working together, lack of leadership, lack of effort- ‘social loafing’
Communication/SBARR, leadership, authority gradient, situational awareness, declaring an emergency, training together- stimulation
What is a doctor’s obligations? What is Hippocratic paternalism?
Duty to patient, accountable–> employer and regulator, responsible to each other, profession, matters of public health, moral obligations
Medicine had little to offer but hope, ‘bad news’ destroyed hope, concealment= was in patient’s best interests, doctors and medicines rep was at stake
Examples of end of life care? What is whistleblowing?
Euthanasia, DNAR, advance directives, withholding and withdrawing Tx, assisted suicide
Raising concerns about a person, practise/ organisation, GMC= patient care first concern, duty to report- harm to pt may occur
What are Immanuel Kent’s 2 formulas?
1) Of universal law- before acting, consider whether could live in world where everyone acted in this way
2) Formula of humanity- people are always treated as ends in themselves, never as means to an end
What is the gut? GIT occupies where? What is an intestinal obstruction? A Volvus? Adhesions?
Digestive tract mouth–>anus
Through head, neck, thorax and abdomen
Blockage to the transit of intestinal contents through the gut
Twist/ rotation of segment of bowel
Sticking together- abdominal structures, bowel loops or omentum, other solid organs, abdominal wall
What is intesussuption? Atresia? Hernia?
Telescoping of one hollow structure into its distal hollow structure
Absence of opening or failure of development of hollow structure
Abnormal protrusion through normal/ abnormal defects of body cavity
Features of obstruction? Fermentation of the intestinal contents in established obstruction causes what? Colic occurs when? May be absent in what? Constipation need not be what?
Vomiting, nausea and anorexia
‘Faeculent’ vomiting- when there is a colonic fistula with the proximal gut
Early- absent in long-standing complete obstruction
Absolute if obstruction is high- i.e. no faeces or flatus passed- one off movement doesn’t exclude SBO
In distal obstruction what will happen? Abdominal distension is more marked as what happens? There are what sounds? 3 key decisions in intestinal obstruction?
Nothing will be passed
As the obstruction progresses
Active, ‘tinkling’ bowel sounds
1) Is obstruction small or large bowel? 2) Is there an ileus or mechanical obstruction? 3) Is the obstructed bowel simple/ closed loop/ strangulated?
What happens in SBO? What is shown on AXR? What is ileus obstruction?
Vomiting occurs earlier, distension is less, pain higher in abdomen
AXR= central gas shadows with valvulae conniventes that completely cross the lumen and no gas in large bowel, LBO= pain is more constant
Functional obstruction from reduced bowel motility, no pain and bowel sounds= absent
What are simple, closed loop and strangulated obstructions?
Simple= one obstructing point and no vascular compromise, closed loop= at 2 points, risk of perforation usually at caecum, strangulated= blood supply compromised and patient is more ill than expected, sharper more localised pain, peritonism= cardinal sign, may be fever and WCC increase with other mesenteric ischaemia signs
SBO causes?
SBO= adults= adhesion- previous surgery, increased incidence= pelvic, gynaec, colorectal surgery, hernia, strangulation groin hernia, Crohn's, malignancy, children= appendicitis, intesussuption, volvulus, atresia, hypertrophic pyloric stenosis Uncommon= radiation, gallstones, diverticulitis, appendicitis, sealed small perforation, intraabdominal collection/ abscess, foreign bodies
LBO causes? Pathophysiology?
Age and race dependent- US/Europe= 90% colorectal malignancy, Africa= 50% volvulus, paed= anatomical development, diverticular stricture, volvulus
Colon proximal to obstruction dilates- increased colonic pressure w/ decreased mesenteric blood flow, mucosal oedema, arterial blood supply compromised
Bacterial translocation causes what? If ileocaecal valve competent? If ileocaecal valve incompetent? Management of obstruction?
Sepsis
Caecum is the usual site of perforation
There is faeculent vomiting
General principles= cause, site, speed of onset, completeness of obstruction
Strangulation and LBO= surgery, ileus and incomplete SBO= managed conservatively at least initially
Immediate action for obstruction? Further imaging? Surgery?
‘Drip and suck’- NGT and IV fluids, analgesia, blood tests, AXR, erect CXR, catheterise to monitor fluid status
Early CT if clinical and radiographic= inconclusive, case for LBO by colonoscopy
Oral gastrografin= partial SBO, mild action against mechanical obstruction
Strangulation= emergency and closed loop, stents= obstructing large bowel malignancies in palliation/ bridge to surgery
Untreated obstruction–>? Intestinal obstruction can be what, what or what? 3 causes of intraluminal obstruction?
Ischaemia, necrosis, perforation
Intraluminal, intramural or extraluminal
Tumours (carcinoma, lymphoma,) diaphragm disease- can be NSAIDs caused, gallstone ileus
4 causes of intramural obstruction? What is diverticulosis? Diverticular disease? Diverticulitis? Diverticulum?
Inflammation–> Crohn’s disease, diverticular disease, tumours, Hirschsprung’s disease
Outpouching of gut wall, usually at sites of entry of perforating arteries
Diverticula= present, disease= symptomatic
Inflammation of the diverticulum
Can be acquired/ congenital, may occur elsewhere, most important= acquired colonic diverticula
Pathology of diverticulosis? Diagnosis?
Most in sigmoid colon, lack of dietary fibre–> high intraluminal pressure, force mucosa to herniate through muscle layers of gut at weak points adjacent to penetrating vessels, majority= asymptomatic
Incidental at colonoscopy, barium enema if altered bowel habit and abdominal pain, CT abdomen= confirm acute diverticulitis, extent and complications, AXR= obstruction, free air or vesicle fistulae
Complications of diverticulosis?
Altered bowel habit+/- left-sided colic received by defecation; nausea and flatulence, high fibre diet try, antispasmodics may help, surgical resection resorted to
Diverculitis, perforation, haemorrhage, fistulae, abscesses
4 causes of extraluminal obstruction? 2 volvulus types?
Adhesions, volvulus, peritoneal tumour, ovarian carcinoma
Sigmoid- bowel twists on its mesentery–> strangulated obstruction, AXR= ‘inverted U’ loop of bowel looks like coffee bean
Gastric- rare, typically 180 degrees rotation–> pylorus and oesophagus–> incarceration and strangulation–> vomiting, pain and failed attempts to pass an NG tube
Presenation of hernias? What does irreducible and incarceration mean? Obstructed and strangulated hernias?
Straining event, sensation of discomfort, appearance of lump, discovery of painless lump
Can’t be pushed back into the right place
Contents of the hernia sac are stuck inside by adhesions
GI hernias obstructed if bowel contents can’t pass through due to pressure of hernia edges
Blood supply to hernia contents= impaired–> gangrene and perforation of hernia contents (urgent surgery!)
Where does an inguinal hernia pass through? Pre-disposing factors? Examination?
Through the deep inguinal ring (midway between pubic tubercle and anterior superior iliac spine) & through the external ring and present above and medial to the pubic tubercle
Male, age, chronic cough, constipation, urinary obstruction, heavy lifting, ascites, past abdominal surgery
Look for previous scars, feel the other side, examine external genitalia, ask:
is lump visible, pt to cough, repeat with pt standing
How do you distinguish between direct and indirect inguinal hernia? Management?
Reduce the hernia and occlude the deep ring w/ 2 fingers (add pressure,) ask pt to stand/ cough–> hernia restrained= indirect, if not= direct
Advise pt to diet if overweight and stop smoking pre-op, warn of recurrence, laparoscopic repair
Where does femoral hernia travel? Presdisposing factors? Diff diagnosis? Tx?
Bowel enters femoral canal- presents as mass in upper medial thigh points down leg, likely to be irreducible and to strangulate due to rigidity of canal’s borders
Women, Middle Ages, elderly
Inguinal hernia, Saphena varix, enlarged Cloquet’s node, lipoma, femoral aneurysm, psoas abscess
Tx= surgical repair recommended= herniotomy–> ligation& excision of the sac, herniorrhaphy- repair of hernia defect
Where does umbilical hernia travel? Risk factors? Tx?
When tissue protrudes around the umbilicus, momentum/ bowel herniates through the defect
Obesity, heavy lifting, persistent coughing, multiple pregnancies, ascites
Tx= surgery involving repair of the rectus sheath
Where does epigastric hernia travel? Incisional? Spigelian? Lumbar? Richter’s?
Through linea alba above the umbilicus
Follows breakdown of muscle closure after surgery, obese= repair isn’t easy, mesh repair= decreases recurrence but increases infection
Occurs through the linea semilunar is at the lateral edge of the rectus sheath, below and lateral to the umbilicus
Through the inferior/ superior lumbar triangles in posterior abdominal wall
Involves bowel only
What does Maydl’s hernia involve? Littre’s? Obturator? Sciatic? Sliding?
Herniating double loop of bowel, strangulated portion may reside as single loop inside abdominal cavity
Hernial sacs containing strangulated Meckel’s diverticulum
Through obturator canal, typically pain along medial side of thigh in thin woman
Through lesser sciatic foramen
A partially exztraperitoneal structure- caecum on R, sigmoid colon on L
What does sliding and rolling hiatus hernias involve? Imaging and tx?
Sliding= where GO junction slides up into chest, acid reflux, rolling= GO remain, bulge of stomach herniates up into chest alongside oesophagus, gross acid reflux= uncommon
30% pt> 50 y/o, 50%= symptomatic GO reflux
Barium swallow= best diagnostic test, upper GI endoscopy= visualises mucosa but can’t reliably exclude hiatus hernia
Tx= lose weight, treat reflux, surgery if symptomatic despite meds, repair rolling hiatus hernia prophylactically as it may strangulate
3 types of mesenteric ischaemia? What does acute almost always involve? Causes and most common?
1) Acute mesenteric ischaemia
2) Chronic mesenteric ischaemia
3) Chronic colonic ischaemia
Superior mesenteric artery thrombosis/ embolism, mesenteric vein thrombosis/ non-occlusive disease
Arterial thrombosis= becoming most common, venous= more in younger patients with hyper coagulable states and tends to affect smaller lengths of bowel
Non-occlusive disease= low-flow states, reflects poor CO, recent cardiac surgery or renal failure
Presentation, tests and Tx of acute mesenteric ischaemia?
Acute severe abdominal pain, no abdominal signs, rapid hypovolaemia–> shock, pain= constant, central or around RIF, degree of illness often far out of proportion with clinical signs
May be Hb increase, WCC increase, modestly raised amylase, persistent metabolic acidosis, early on= ‘gas-less’ abdomen, arteriography, CT/ MR angiography- provides a non-invasive alternative to simple arteriography
Resuscitation with fluid, antibiotics and usually heparin required, thrombolytics via catheter if arteriography, surgery= remove dead bowel, maybe revascularisation
Prognosis for acute mesenteric ischaemia? Presentation and tests for chronic mesenteric ischaemia?
Poor for arterial thrombosis and non-occlusive disease<40% survive, though not so bad for venous and embolic ischaemia
Triad of severe, colicky post-prandial abdominal pain, decreased weight (eating hurts,) upper abdominal bruit may be present+/- PR bleeding, malabsorption, nausea and vomiting, AF
CT angiography and contrast enhanced MR angiography replacing traditional angiography, Doppler USS may be useful
Surgery considered due to ongoing risk of acute infarction
Perc transluminal angioplasty and stent= replacing open revascularisation= less post-op morbidity and mortality, higher restenosis rates
Chronic colonic ischaemia usually follows what? Presentation, tests and tx?
Low flow in inferior mesenteric artery territory and from mild ischaemia–> gangrenous colitis
Lower left-sided abdominal pain+/- bloody diarrhoea
CT may be helpful, colonoscopy and biopsy= ‘gold-standard’, barium enema= ‘thumb-printing’ of submucosal swelling
Usually conservative with fluid replacement and antibiotics, strictures common but most recover
Gangrenous ischaemic colitis= prompt resuscitation followed by resection of affected bowel and stoma formation, mortality= high
Epidemiology of colorectal carcinoma? Risk factors? Reduce risk?
Usually adenocarcinoma, 3rd most common worldwide, majority= distal colon, those >60 y/o, more in males than females, in Western countries than in Asia or Africa
Increasing age, low fibre diet, saturated animal fat and red meat, sugar consumption, colorectal polyps, alcohol and smoking, obesity, adenomas, UC, family history, genetic disposition: FAP, HNPCC, 1st degree relative<40 y/o
Veg, garlic, milk, exercise, low-dose aspirin
Pathophysiology of colorectal carcinoma? Clinical presentation of L and R-sided?
Normal epithelium–> adenoma–> adenocarcinoma
Nearly all= adenocarcinoma, polypoid mass with ulceration, spreads by direct infiltration through bowel wall then to lymphatic and blood vessels and metastasis to liver and lung
Closer cancer to outside= more blood and mucus visible
Left-sided= altered bowel habit, PR mucus/ bleeding or obstruction, pass PR, tenesmus
Right-sided= weight loss, low Hb, abdominal pain, blood with poo so can’t see if you see pt w/ iron deficiency anaemia, colonoscopy? Anaemia and mass
Emergency presentation of colorectal carcinoma? Diff diagnosis? Investigations?
Obstruction (absolute constipation- no air coming out, Colicky abdominal pain, abdominal distension, vomiting)
Anorectal pathology- haemorrhoids, anal fissure etc, colonic pathology- polyp/ cancer, diverticulitis, colitis
SI and stomach pathology- massive upper GI bleed, Meckel’s diverticulum, small bowel angiodysplasia
Faecal occult blood following symptoms- good for screening, not diagnosis- dietary restrictions 3 days before
Tumour markers, colonoscopy- gold standard, double contrast barium enema, CT colonoscopy
2 types of hereditary polyps? Reasons for identifying HNPCC cancers? Macroscopic features of colorectal cancer?
1) Familial adenomatous polyposis- normal colon born, teens= 1000s polyps, few/1000 become cancerous
2) Hereditary non-polyposis colorectal cancer HNPCC- mutation in one of mismatch repair genes- earlier age onset cancer, DNA damage not recognised
Risk of further cancers in index patient and relatives, possible therapy implications, apoptosis not activated
38% in rectum, anus, recto-sigmoid junction–> all palpated with finger, all adenocarcinoma from glandular epithelium
If you find a cancer, who in MDT meeting? Spread via what in colorectal carcinoma? Staging? Prognosis?
Colorectal surgeon, oncologist, radiologist, gastroenterologist, colorectal nurse practitioner, stomatherapist
Local, lymphatic, by blood- to liver, blood, bone or transcolemic
TNM preferred to old Dukes’ criteria
A= restricted to muscularis mucosae, B= extension through this, C= involvement of regional lymph nodes
5 yr for stage 1 75%, drops to 5% for stage 4 - hence imperative for screening
Staging investigations for colorectal carcinoma? Operative technique?
Bloods, CT chest, abdomen and pelvis, surgery or no surgery? Only if chance of cure, offered if no metastatic spread and no inoperable intraperitoneal disease
Laparoscopic= as safe as open, same survival, shorter length of stay
R hemicolonectomy- for caecal, ascending, proximal transverse
L hemicolectomy- distal transverse or descending colon
Sigmoid colectomy- for sigmoid tumours
Anterior resection- for low sigmoid/ high rectal
Abdomen-perineal resection for tumours low in rectum