1B upper GI tract Flashcards
Label these diagrams of oesophageal anatomy
What are the 4 anatomical contributions to the lower oesophageal sphincter (LOS)’s effectiveness?
- 3-4cm of the distal oesophagus is within the abdomen so if there’s an increase in intraabdominal pressure there’s also increase in LOS pressure
- Diaphragm surrounds LOS (left and right crux)- contract like a pair of scissors around LOS when diaphragm contracts and contribute to its effectiveness
- An intact phrenoesophageal ligament
- Angle of His
Describe the intact phrenoesophageal ligament
- It’s an extension of inferior diaphragmatic fascia
- It has 2 limbs:
- One goes superiorly and attaches to lower part of oesophagus
- Other goes inferiorly and attaches to cardia of stomach
What is the angle of His?
Normally there’s an acute angle between the abdominal oesophagus and fundus of stomach at oesophageal junction that prevents reflux disease
What are the 4 stages of swallowing?
- Stage 0: Oral phase
- Stage 1: Pharyngeal phase
- Stage 2: Upper oesophageal phase
- Stage 3: Lower oesophageal phase
What happens in the oral phase?
- Chewing and saliva prepare bolus
- Both oesophageal sphincters constricted
What happens in the pharyngeal phase?
- Pharyngeal musculature guides food bolus towards oesophagus
- Upper oesophageal sphincter opens reflexly
- LOS opened by vasovagal reflex (receptive relaxation reflex)
What happens in upper oesophageal phase?
- Upper sphincter closes
- Superior circular muscle rings contract and inferior rings dilate
- Sequential contractions of longitudinal muscle
What happens in the lower oesophageal phase?
Lower sphincter closes as food passes through
How is the motility of the oesophagus determined?
- By pressure measurements (manometry)
- Peristaltic waves are around 40 mmHg
What is the LOS resting pressure and how does that change during receptive relaxation?
- Resting pressure is 20 mmHg
- Decreases by <5 mmHg during receptive relaxation
What mediates the LOS resting pressure?
Inhibitory noncholinergic nonadrenergic (NCNA) neurones of myenteric plexus
What is a functional disorder of the oesophagus?
Absence of an oesophageal stricture (abnormal narrowing of oesophagus)
What are the causes of an oesophagus stricture absence?
- Abnormal oesophageal contraction
- Failure of protective mechanisms for reflux
What are some examples of abnormal oesophageal contraction?
- Hypermotility
- Hypomotility
- Disordered coordination
What is an example of a failure of protective mechanism for reflux?
Gastro-Oesophageal Reflux Disease (GORD)
What is dysphagia?
Difficulty in swallowing
What is important when describing dysphagia?
To describe the localisation- cricopharyngeal sphincter or distal
What types of dysphagia are there?
- For solids and fluids
- Intermittent or progressive
- Precise or vague in appreciation
What is odynophagia?
Pain on swallowing
What is regurgitation?
- Return of oesophageal contents from above an obstruction
- May be functional or mechanical
What is reflux?
Passive return of gastroduodenal contents to the mouth
Define achalasia
- Hypermotility of oesophagus due to loss of ganglion cells in Aurebach’s myenteric plexus in LOS wall
- Leads to decreased activity of inhibitory NCNA neurones
What does achalasia lead to?
- Increased resting pressure of LOS
- Receptive relaxation sets in late and is too weak so during reflex phase the LOS pressure is much higher than stomach
- Swallowed food collects in oesophagus causing increased pressure throughout with dilation of oesophagus
- Propagation of peristaltic waves cease
What is primary achalasia?
- Majority of achalasia is primary
- Aetiology is unknown
What is secondary achalasia?
Diseases causing oesophageal motor abnormalities similar to primary achalasia
What are examples of secondary achalasia?
- Chagas’ Disease - chronic infection of a parasite
- Protozoa infection
- Amyloid/Sarcoma/Eosinophilic Oesophagitis
What is the course of achalasia?
- Insidious onset- symptoms for years prior to seeking help
- Without treatment there’s progressive oesophageal dilation of oesophagus
What does achalasia increase the risk of?
- Increases risk of oesophageal cancer by 28 fold
- Annual incidence is only 0.34%
What are the two main treatments of achalasia?
- Pneumatic dilatation (PD)
- Surgery
What happens in pneumatic dilatation (PD)?
PD weakens LOS by circumferential stretching and in some cases, tearing of muscle fibres- done by inserting balloon and expanding it in LOS
What is the efficacy of PD?
71-90% of patients respond initially but many patients subsequently relapse
What happens in surgery for achalasia?
- Heller’s myotomy- a continuous myotomy (cutting of musculature and exposing mucosa) performed for 6cm on the oesophagus and 3cm onto stomach
- Dor fundoplication then done- anterior fundus folded over oesophagus and sutured to right side of myotomy
What are the risks of surgery for achalasia?
- Oesophageal and gastric perforation- 10-16%
- Division of vagus nerve- rare
- Splenic injury- 1-5%
Define scleroderma
Autoimmune disease where hypomotility happens in early stages due to neuronal defects leading to atrophy of smooth muscle of oesophagus
What does scleroderma cause?
- Peristalsis in distal portion ultimately ceases fully
- Decreases resting pressure of LOS
- GORD develops
What is scleroderma often associated with?
CREST syndrome
- Calcinosis- deposits of calcium in soft tissue
- Raynaud’s phenomenon- constriction of peripheral blood vessels, can lead to problems with hands
- Esophageal problems
- Sclerodactyly- thickening of digits of hands and toes
- Telangiectasia- dilated or broken blood vessels near surface of skin
What is the treatment for scleroderma?
- Exclude organic obstruction and make sure they don’t have malignancy
- Improve of peristalsis with prokinetics (cisapride). This doesn’t work too well because once peristaltic failure occurs it’s usually irreversible
What is corkscrew oesophagus?
- Disordered coordination of contraction of oesophagus
- Leads to dysphagia and chest pain
- Pressures of 400-500 mmHg
What can we see when investigating corkscrew oesophagus?
- Marked hypertrophy of circular muscle
- Corkscrew shaped oesophagus on Barium
What is the treatment for corkscrew oesophagus?
- May respond to forceful PD of cardia
- Results not as predictable as achalasia
What three areas of anatomical constriction occur in the oesophagus?
- Cricopharyngeal constriction
- Aortic and bronchial constriction
- Diaphragmatic and sphincter constriction
What are the causes of oesophageal perforations?
- Iatrogenic (>50%)
- Spontaneous; Boerhaave’s (15%)
- Foreign body (12%)
- Trauma (9%)
- Intraoperative (2%)
- Malignant (1%)
Where does iatrogenic oesophageal perforation usually happen?
- At OGD
- More common in presence of diverticula or cancer
- Most commonly in Killian’s triangle
How does Boerhaave’s happen?
- Sudden increase in intra-oesophageal pressure with negative intra thoracic pressure
- Vomiting against a closed glottis occurs
- 3.1 per 1,000,000
Where does Boerhaave’s happen?
Usually in left posterolateral aspect of distal oesophagus
What foreign bodies can cause oesophageal perforations?
- FoDisk batteries- a growing problem and it causes electrical burns if it embeds in the mucosa
- Magnets
- Sharp objects
- Dishwasher tablets
- Acid/alkali
What types of trauma are there for oesophageal perforations?
- Neck- penetrating force needed
- Thorax- blunt force needed
As oesophageal perforation caused by trauma can be difficult to diagnose, what do we check for?
- Dysphagia
- Blood in saliva
- Haematemesis (vomiting blood)
- Surgical emphysema
How do patients with oesophageal perforation present?
- Pain- 95%
- Fever- 80%
- Dysphagia- 70%
- Emphysema- 35%
What investigations are done for oesophageal perforation?
- CXR
- CT
- Swallow (gastrogaffin contrast given)
- OGD- only do endoscopy if really needed because it can make it worse
How is oesophageal perforation mainly treated?
Surgery- it’s a surgical emergency and increased mortality by 2x if 24h delay in diagnosis
Describe the initial management of oesophageal perforation
- Nil by mouth (NBM)
- IV fluids
- Broad spectrum A/Bs and antifungals
- Bloods (including G&S)
- ITU/HDU level care
- Have to refer to tertiary referral centre
What definitive management is there for oesphageal perforation?
- Conservative management with a metal stent covering oesophagus- only if it’s a small contained perforation that hasn’t leaked
- Operative management should be default as primary repair is optimal
- Oesophagectomy is the definitive solution and may happen
What is a protective mechanism against reflux?
LOS usually closed as a barrier against reflux of harmful gastric juice (pepsin & HCl)
What is LOS pressure increased by?
- Acetylcholine
- Alpha adrenergic agonists
- Hormones
- Protein-rich food
- Histamine
- High intraabdominal pressure
- PGF2alpha etc
What is LOS pressure decreased by?
- VIP (vasoactive intestinal polypeptide)
- Beta adrenergic agonists
- hormones, dopamine
- NO
- PGI2
- PGE2
- chocolate
- acid gastric juice
- Smoking etc
When does sporadic reflux occur?
- Pressure on full stomach
- Swallowing
- Transient sphincter opening
What 3 mechanisms protect following reflux?
- Volume clearance- oesophageal peristalsis reflex
- pH clearance- saliva
- Epithelium- barrier properties
What different ways can GORD protective mechanisms fail?
- Decrease in sphincter pressure
- Increased transient sphincter opening (happens if you drink too much fizzy drink)
- Hiatus hernia
- Abnormal peristalsis leading to decreased volume clearance
- Decreased saliva production (in sleep, xerostomia) leading to decreased pH clearance
- Decrease in buffering capacity of saliva (e.g. through smoking) leading to decreased pH clearance
- Defective mucosal protective mechanism e.g. alcohol
What are the two types of hiatus hernia?
- Sliding hiatus hernia- ligament holding distal oesophagus down gives way so whole stomach slides up into chest
- Rolling/paraoesophageal hiatus hernia- portion of stomach sticks up side- it’s an emergency
What happens if a hernia gets strangulated?
The blood supply to it is cut off and then the stomach/oesophagus can become ischaemic
What investigations are done for GORD?
- OGD to exclude cancer and to look for oesophagitis, peptic stricture and Barrett’s oesophagus
- Oesophageal manometry (pressure measurement)
- 24-hr oesophageal pH recording
What medical treatment is there for GORD?
- Lifestyle changes (weight loss, smoking cessation, teetotaling)
- PPIs
What surgical treatment is there for GORD?
- Dilation of peptic strictures
-
Laparoscopic Nissen’s fundoplication- stitch up the perforation then wrap fundus around oesophagus and put stitches in
- If you do it too tight the person can’t swallow
What are the functions of the stomach?
- Break food into smaller particles (acid and pepsin)
- Holds food, releasing it in controlled steady rate into duodenum
- Kills parasites and certain bacteria
What do the cardia and pyloric regions produce?
- Cardia and pyloric region- mucus only
- Body and fundus- mucus, HCl, pepsinogen
- Antrum- gastrin
What things can cause erosive and haemorrhagic gastritis?
- NSAIDs, alcohol
- Multi-organ failure, burns
- Trauma
- Ischaemia
What do erosive and haemorrhagic gastritis cause?
Acute ulcer- massive gastric bleeding and perforation
Where does erosive and haemorrhagic gastritis occur?
Anywhere in stomach
What can cause non-erosive, chronic active gastritis?
Helicobacter pylori
What does non-erosive, chronic active gastritis cause?
- Increase in gastrin
- Acid secretion is normal or increased
- Leads to chronic gastric and duodenal ulcer
- Leads to reactive gastritis → epithelial metaplasia → carcinoma
Where does non-erosive, chronic active gastritis occur?
Antrum
How is non-erosive, chronic active gastritis treated?
Triple antibiotics (amoxicillin, clarithromycin and pantoprazole) for 2 weeks
What can cause atrophic (fundal gland) gastritis?
Autoantibodies against parts and products of parietal cells e.g. gastrin receptor/carbonic anhydrase/H+-K+ ATPase
What problems can atrophic gastritis cause?
- Decreased acid secretion → G cell hyperplasia (gastrin secretion) → epithelial metaplasia → carcinoma
- Decreased acid secretion → increased gastrin to counteract this → ECL (endochromaffin cell like) cell hyperplasia (histamine secretion) → carcinoid (neuroendocrine tumour)
- Decreased IF secretion → decreased cobalamine (B12) absorption → long term leads to cobalamine (B12) deficiency → pernicious anaemia
What do parietal cells produce?
Hydrogen ions
What do chief cells do?
Enrich glands with pepsinogen
What are 3 ways of stimulating gastric secretion?
- Neural: ACh acting on M1 receptors through postganglionic transmitter of vagal parasympathetic fibres
- Endocrine: Gastrin produced by G cells of antrum
- Paracrine: Histamine made by ECL cells and mast cells of gastric wall on H2 receptors
What are three ways of inhibiting gastric secretion?
- Endocrine: Secretin produced by small intestine
- Paracrine: Somatostatin
-
Paracrine and autocrine:
- PGs (E2 and I2)
- TGFalpha
- adenosine
What are four ways in which the mucosa is protected?
- Mucus film
- HCO3- secretion
- Epithelial barrier
- Mucosal blood perfusion
How does mucus film protect mucosa?
- Epithelial cells make mucus
- Mucus protects against Pepsin and H+ ions
How does HCO3- secretion protect mucosa?
- HCO3- buffers against action of acids
- Needs prostaglandins however- if we take non steroidals this attacks COX and decreases production of HCO3-
How does epithelial barrier protect mucosa?
- Apical membrane and tight junctions are barriers
- Prevent penetration of H+ ions
How does mucosal blood perfusion protect mucosa?
- Good perfusion means even if H+ ions do get through, they’re quickly taken away by blood
- This is how ischaemia causes problem in ulcers because there isn’t good mucosal blood perfusion so mucosa is open to attack by H+ ions
What are 3 mechanisms of epithelial repair and wound healing?
- Migration
- Gap closed by cell growth
- Acute wound healing
What is migration in wound healing?
Adjacent epithelial cells flatten to close gap via sideward migration along basement membrane (BM)
What factors stimulate cell growth in wound healing?
- EGF
- TGFalpha
- IGF-1
- GRP
- Gastrin
Acute wound healing- when and how does this occur?
BM destroyed:
- Attraction of leukocytes and macrophages
- Phagocytosis of necrotic cells
- Angiogenesis
- Regeneration of ECM after repair of BM
- Epithelial closure by restitution and cell division
What are causes of ulcer formation?
- Helicobacter pylori
- Non steroidals and smoking
- Stress
- Psychogenic components, smoking and gastrinoma
- Secretion of gastric juice
- Less HCO3- secretion
- Less cell formation
- Less blood perfusion
How does helicobacter pylori cause ulcer formation?
- Disturbs barrier function
- Causes gastritis which also disturbs barrier function
- Increases H+ and pepsinogen secretion which increases chemical aggression
How do non steroidals and smoking cause ulcer formation?
- Decreased prostaglandin synthesis → less mucosal protection → barrier function disturbed
- Decreased prostaglandin synthesis → increased H+ and pepsinogen secretion → increased chemical aggression
How does stress (shocks, burns, operation) cause ulcers?
Decreased blood perfusion → less mucosal protection → barrier function disturbed
How do Psychogenic components, smoking and gastrinoma cause ulcers?
Increased H+ and pepsinogen secretion → increased chemical aggression
How do ulcers form?
- Chemical aggression and barrier function being disturbed leads to epithelial damage
- Epithelial damage → wound → can lead to ulcer if not healed
What do we look to diagnose if there’s a young person who develops an ulcer with no risk factors?
Gastrinomas- neuroendocrine tumours that produce gastrin
These can be caused by Zollinger-Ellison syndrome
What are the different clinical outcomes of H pylori infections?
- 80% are asymptomatic or chronic gastritis
- 15-20% get chronic atrophic gastritis/intestinal metaplasia/gastric or duodenal ulcer
- <1% get gastric cancer or MALT lymphoma
What medical treatment is given to ulcers?
- PPI or H2 blocker
- Triple antibiotic if h pylori is proven (amoxicillin, clarithromycin, pantoprazole) for 7-14 days
What are the elective surgery procedures for gastritis and why is it rarely done?
- Check serum gastrin (antral G-cell hyperplasia or gastrinoma (Zollinger-Ellison syndrome))
- OGD- biopsy all 4 quadrants of ulcer (rule out malignant ulcer) if refractory
- Rarely done because most ulcers heal within 12 weeks and if they don’t you change medication
What are the surgical indications for ulcers?
- Intractability (after medical therapy)- they still have symptoms after therapy so e.g. might have to consider fundoplication
- Relative- continuous requirement of steroids therapy/NSAIDs
- Complications from ulcer: haemorrhage, obstruction, perforation