Gastroenterology Flashcards
Features of Wilson’s disease?
Low caeruplasmin and deranged LFTs
KF rings
Older children may have neuropsychiatric symptoms
Features of NAFLD
Most common cause of liver disease in children
Associated with obseity
Hepatomegaly may be present (but difficult to note in obese children)
Definitive diagnosis can only be made with biopsy but rarely needed, elevated LFTs and suggestive USS are usually enough
Thin projection of the right lower lobe of the liver, easily palpable within the lateral right abdomen
Riedel lobe
Tissue absent in aganglionic segments of bowel, diagnostic of Hirschsprung’s disease
Meissner’s plexus
Tissue usually extending from caecum to RUQ, that cross the duodenum
Ladd bands
Fascia of the anterior abdominal wall, just superficial to the external oblique muscle
Scarpas fascia
Ligamentum teres
The remnant umbilical vein
Uncinate process
Hook shaped process, found in the pancreas, the ethmoid bone and ribs
Liver segment 2
The superior lateral segment of the left lobe of the liver
Vermiform appendix
Narros, worm-shaped structure that extends from the posteromedial surface of the caecum
First condition to exclude in a neonate with bilious vomiting?
Malrotation and midgut volvulus until proven otherwise
- upper and lower contrast study (often missed on XR)
- bilious gastric aspirates/emesis suggest obstruction distal to the ampulla of Vater
What do fat globules in the stool indicate?
Intraluminal problem e.g. failure of enzyme process or bile to suspend fats, i.e. maldigestion
What do fatty acid crystals in the stool indicate?
Mucosal/brush border problem (fatty acid not absorbed), i.e. malabsorption
Relevance of chymotrypsin?
Chymotrypsin and elastase-1 are enzymatic products of pancreatic secretion that remain relatively stable during transport through the GIT
Sensitivity of 85% for advanced pancreatic exocrine insufficiency, but only 49% for mild and moderate (it may be diluted in the presence of concomitant diarrhoea. Exogenous enzymes interfere with the test)
Overview of primary intestinal lymphangiectasia
Characterised by diffuse or localised ectasia of enteric lymphatics. Obstruction of the intestinal lymphatics impairs lymph flow and increases pressure in the intestinal lymphatics. This leads to leakage of lymph into the intestinal lumen, reduced recirculation of intestinal lymphocytes into the peripheral circulation, and decreased absorption of fat-soluble vitamins.
Is a protein-losing enteropathy, you would expect low protein and albumin in the LFTs
Overview of Meckel’s diverticulum
Common cause of significant GI bleeding, with 60% presenting before 2 years
Due to erosion of intestinal mucosa from ectopic gastric mucosa, found within the MD in 25% of cases
The ectopic mucosa can be detected by Technecium-99m scan (“Meckel’s scan”)
Age of presentation of food protein induced colitis?
Usually presents by 18 months
The most common triggers are milk and soy proteins
Overview of juvenile polyps
Juvenile polys are one of the most common causes of significant PR bleeding, with peak presentation at 3-4 years of age
Most often pedunculate hamartomas, which can be both diagnosed and removed during colonoscopy
Presentation of very early onset IBD in young children (<6 years)?
Usually accompanied by growth failure and systemic symptoms
Strong genetic component, often linked to messengers involved in immune regulation (such as IL-10), and associated immunodeficiencies occur in 25% of cases
Causes of PR bleeding in children
Meckel’s, colitis (inflammatory/infective), juvenile polyps, IBD, anal fissures, intussusception, HSP, lymphonodular hyperplasia, rectal ulcer syndrome
Oesophagus muscle types?
Upper 1/3 - striated, innervated by spinal accessory nerves, allows for voluntary initiation of swallowing
Middle 1/3 - mixed, innervated by dorsal motor nerve of vagus
Distal 1/3 - smooth muscle, innervated by dorsal motor nerve of vagus
Orophrayngeal dysphagia
Refers to inability to transfer food to the oesophagus
Neurological causes of oropharyngeal dysphagia?
Cortical - pseudo bulbar palsy (UMN lesion) due to bilateral stroke
Bulbar - ischaemia, tumour (LMN)
Peripheral - polio, ALS
Muscular causes of oropharyngeal dysphagia?
Muscular dystrophy
Cricopharyngeal incoordination - failure of UES to relax with swallowing
Zenker’s diverticulum
Types of dysphagia?
Oropharyngeal
Oesophageal (mechanical or non-mechanical)
Difference between dysphagia and dysmotility?
Dysphagia to solids before liquids (can manifest when solids introduced to diet)
Dysmotility - liquids are affected as early as (or earlier) than solids
Embryologic origin of oesophagus?
Post pharyngeal foregut, distinguished from the stomach by 4 weeks
Investigations for oesophageal obstruction?
Fluoroscopy - may include video evaluation of swallowing, often first line test
Endoscopy - if intrinsic lesion is suspected
Manometry - if dysmotility is suspected
Oesophageal duplication cysts
Occur from foregut duplication, affect distal oesophagus on the right side
Commonly present with respiratory distress due to airway compression
Dysphagia more common in older children
Upper GI bleeding can occur due to acid from gastric mucosa
Neuroenteric cysts
May contain glial elements and are associated with vertebral anomalies
Diagnosed using barium swallow, chest CT and MRI
Surgical excision
Most common masses which compress the oesophagus and produce obstructive symptoms?
Mediastinal lymph nodes: infective (TB, histoplasmosis), neoplasm (lymphoma)
Most common cause for oesophageal obstruction symptoms?
Eosinophilic oesophagitis
Cricopharyngeal achalasia
Failure of complete relaxation of the upper oesophageal sphincter
Cricopharyngeal incoordination
Full relaxation of the UES but incoordination of the relaxation with the pharyngeal contraction
Systemic causes of swallowing dysfunction?
Many - CP, Arnold-Chiari malformation, bulbar palsy or cranial nerve defects, transient pharyngeal muscle dysfunction, SMA, muscular dystrophy, MS etc
Differentiating muscle types in motility disorders
Upper oesophageal and upper oesophageal sphincter dysmotility = striated muscle
Lower oesophageal and lower oesophageal sphincter dysmotility = smooth muscle
Overview of achalasia
Primary oesophageal motor disorder characterised by loss of LES relaxation (resting pressure >30mmHg) and loss of oesophageal peristalsis
Damage to smooth muscle innervation: loss of myenteric ganglion cells
Triple A syndrome
Achalasia, ACTH insensitivity (low BSL), alacrima
Associated with 12q13 deletion
Clinical features of achalasia
Regurgitation and dysphagia with solids and liquids
May have malnutrition or chronic cough
Retained oesophageal foot can produce oesophagitis
Gold standard investigation for achalasia
Manometry/motility study
- peristalsis in distal oesophagus, incomplete or absent LES relaxation = diagnostic
Treatment of achalasia
Goals: relieve symptoms, improve emptying, prevent megaoesophagus
Medical = CCB (nifedipine), PDE inhibitors, nitrates
Endoscopy = injection of botulinum toxin, pneumatic dilatation
Surgical = Heller myotomy (reflux is complication)
Complications of achalasia
Respiratory - aspiration, bronchiectasis, lung abscess
GIT - malnutrition, increased risk of oesophageal cancer (secondary to chronic inflammation)
Diffuse oesophageal spasm
= normal peristalsis with abnormal high pressure waves
Present with chest pain
Barium oesophagogram: corkscrew pattern
No treatment, can try CCB or anticholinergics or nitrates
Classification of hiatal hernia
Type 1 = sliding: gastroesophageal junction slides into thorax, often associated with reflux
Type 2 = paraoesophagheal: fungus insinuated next to oesophagus, fullness after eating/upper abdominal pain are common symptoms
Type 3 = combination
Investigation/treatment of hiatal hernia
Upper GI series and upper GI endoscopy
Treatment involves managing reflux, surgical correction with fundoplication only if reflux not well controlled
Causes of ‘pill oesophagitis’?
Tetracycline
KCl
Ferrous sulphate
NSAIDs
Alendronate
Causes of oesophagitis?
= histological diagnosis of inflammation
GORD
Eosinophilic oesophagitis
Infectious oesophagitis
Pill oesophagitis
Caustic ingestion
Radiation
Sclerotherapy
Mechanisms of GORD
Hiatus hernia
Increased frequency of LOS relaxation
Decreased LOS pressure
Decreased oesophageal motility
Gastric emptying time altered
Definition of GORD
Reflux PLUS one of:
1. histopathological changes of oesophageal epithelial lining
2. symptoms of reflux (FTT, oesophagitis, episodes of aspiration pneumonia)
Natural history of reflux in infants
Becomes evident in the first few months of life, peaks at 4 months and resolves in 90% by 12 months
Clinical manifestations of infantile reflux
Regurgitation and vomiting
Oesophagitis features - pronounced irritability with arching, refusal to feed, weight loss, haematemesis
Respiratory features - chronic cough and wheeze, obstructive apnoea, stridor
Sandifer syndrome
Food refusal and neck contortions, presenting in older children as signs of reflux
Normal values of distal oesophageal acid exposure (on pH monitoring)?
Normal values of distal oesophageal acid exposure (pH<4) are <5-8% of the total monitored time
Indications for fundoplication in GORD?
Neurological disease
Not responding to medical therapy
Complications - peptic strictures, Barrett’s oesophagus
Gastrostomy feeds
Respiratory disease
Overview of eosinophilic oesophagitis
= chronic oesophageal disorder characterised by infiltration of the oesophageal epithelium with eosinophils
Most patients male, mean age at diagnosis 7 years
More common in those with atopy
Clinical manifestations of eosinophilic oesophagitis?
Infants = vomiting, feeding problems and poor weight gain
Older children and adolescents = food dysphagia with occasional food impactions or strictures, and may complain of chest or epigastric pain, slow eating
Pathogenesis of eosinophilic oesophagitis?
T helper type 2 cytokine mediated pathways leading to production of a potent eosinophil chemoattractant, eotaxin-3, by oesophageal epithelium
Diagnostic criteria for eosinophilic oesophagitis
> 15 eosinoophils/hpf on biopsy
Persistence of eosinophilia after a PPI trial
Secondary causes excluded
Dietary management of eosinophilic oesophagitis?
Successful in 60-80% of children
Target elimination diet = remove foods known to be allergic for patient
Six food elimination diet = eliminate foods commonly associated with allergy (milk and wheat most frequently impacted, also eggs, soy, nuts, seafood)
Elemental diet = all food intake changed to liquids (not practical)
Treatment of eosinophilic oesophagitis?
PPI = 40-50% of patients respond
Topical steroids = fluticasone and budesonide (swallowed inhaled corticosteroids)
Biological agents = anti-IL5 antibodies (mepolizumab, relizumab)
Complications of eosinophilic oesophagitis?
Stricture
Oesophageal perforation
No long term risk of cancers identified
Risk factors for infectious oesophagitis?
Diabetes
Alcohol
Glucocorticoids
Immunosuppressants
Broad spectrum antibiotics
Pathogens in infectious oesophagitis?
Candida albicans (most common)
Viral - HSV, CMV
Bacterial - uncommon (trypanosoma cruzie, cryptosporidium)
Clinical features of infectious oesophagitis?
Odynophagia +++ (pain on swallowing)
Dysphagia (solids and liquids)
Fevers and bleeding (but uncommon)
Four points of anatomic narrowing of the oesophagus which are at risk for FB?
Cricopharyngeus (upper oesophageal sphincter)
Aortic arch
Left main stem bronchus
Diaphragmatic hiatus
Medication used for treatment in oesophageal obstruction?
Glucagon 1mg IV - relaxes LES enough to allow passage of food in 50% of patients, affects only smooth muscles (so not helpful for proximal obstructions or strictures)
Boerhaave syndrome
Spontaneous oesophageal perforation associated with sudden increase in intra-oesophageal pressure (vomiting, coughing, straining)
Location of oesophageal perforations?
Perforation in proximal thoracic oesophagus - pneumothorax, effusions LEFT side of chest
Signs of more distal tears manifest on the RIGHT
Foregut/midgut/hindgut
Foregut: upper GI tract to the level of the bile duct insertion
Midgut: rest of small bowel and large bowel to the midtransverse colon
Hindgut: colon and upper anal canal
Common inhibitory factors for the stomach
- Reverse enterogastric reflex (presence of acid/protein in small intestine/small bowel distension)
- Secretin
- Gastric inhibitory peptide
- VIP
- Somastatin
Parietal cell functions?
Secrete HCl acid
Intrinsic factor for B12 absorption
Overview of omeprazole
Blocks acid secretion in response to all stimuli
Dose dependent irreversible inhibition with increasing effect over days (max effect by day 5)
>20mg inhibit all intragastric acidity in most individuals
Binds to hepatic CYP450 - inhibits oxidative metabolism of some drugs (e.g. phenytoin)
Most common cause of duodenal ulcers?
H pylori
Clinical features of duodenal ulcer?
Abdominal pain - worst before a meal, relieved by a meal
Clinical features of gastric ulcer?
Abdominal pain (epigastric usually)
Usually worse 2-4 hours after meal
Often pain at 2-3am (Hal secretion highest)
Relieved by antacids
First line treatment for H. pylori eradication?
Amoxicillin + clarithromycin + omeprazole for 10-14 days
Overview of Zollinger-Ellison syndrome
= rare syndrome characterised by severe PUD
Neuroendocrine tumour -> gastrin -> autonomous gastric acid secretion
Usually also have diarrhoea
98% of patients have elevated gastrin levels
Associated with MEN-1 and rare with NF and TS
Risk factors for H. pylori
SES most important predictor
Household crowding
Ethnicity
Migration from high prevalence areas
Infected parent (especially mum)
Contaminated water
Transmission: faecal-oral, oral-oral or gastric-oral
Which immunoglobulin in breastmilk is the most immunoprotective?
IgA - in breastmilk is secretory IgA, and is important as infant intestinal IgA production does not begin until several months of age
What are the pathways via which calcium is absorbed?
The paracellular pathway or the transcellular route
Paracellular is the primary pathway: passive absorption when the luminal concentration of calcium is high, enhanced by 1, 25-dihydroxyvitamin D which makes the junction more permeable to calcium
Which vitamins are likely to be deficient in short bowel syndrome?
Fat soluble vitamins: Vitamin A, D, E, K
Trace element deficiencies (iron, zinc, selenium) due to increased faecal losses
Vitamin B12 (as is absorbed in the ileum)
Magnesium
Where is vitamin C absorbed?
Passively in the proximal small bowel
Which organism is likely to cause diarrhoea and malabsorption in patients with CVID?
Giardia lambila (treat with metronidazole)
Which omentum attaches the stomach and duodenum to the liver?
Lesser omentum
Which omentum attaches the stomach to the transverse colon?
Greater omentum
Overview of Behcet disease?
Diagnosis: ulcers (oral or genital) occurring 3 times per year, plus 2 of the following: pathergy, uveitis and erythema nodosum
Pathergy = pustular reaction 24-48 hours after sterile needle puncture
Frequency of ulcers in PFAPA syndrome?
2-4 weekly, associated with fevers
PFAPA = Periodic fever, aphthous stomatitis, pharyngitis, adenitis
Features of splenic sequestration?
Vaso-occlusion in the spleen, and RBC pool in spleen. Causes marked drop in Hb, a persistent reticulocytosis and a rapidly enlarging spleen. There is a risk of hypovolaemic shock, and an associated mortality rate of 10-15%
Overview of aplastic crisis
Transient arrest of erythropoiesis and a sudden reduction in Hb concentration and RBC precursors in the bone marrow. This most often follows parvovirus B19 infection
Risk of parvovirus in sickle cell disease?
Limits reticulocyte production
Infliximab mechanism of action?
Binds to tumour necrosis factor
Infliximab is a monoclonal antibody
TNF-a is thought to be directly related to the pathogenesis of IBD, and blocking this can stop the inflammatory process
Overview of gastroschisis?
Protruding intestines with no covering membrane, usually to the right of the umbilicus
The protruding intestines are often thickened, fibrous and poorly functioning
Requires immediate surgery, complications include midgut volvulus, NEC and short bowel syndrome
Overview of omphalocele
Midline defect in the umbilical region which is >4cm
Often contained both solid organs and intestines
50-75% of neonates with omphalocele have another congenital anomaly
Overview of diastasis recti?
A vertical bulge noted when intra-abdominal pressure is raised, due to weakness of the fascia between the rectus abdominal muscles
= normal finding in neonates
Overview of umbilical hernia
<4cm, midline at the umbilicus, contains only intestines
Rarely cause incarceration and often self-resolve, although some require surgical closure
Elevated tissue transglutaminase (tTG) with normal IgA?
Coeliac disease
Diagnostic test for hereditary spherocytosis?
Osmotic fragility test - spherocytes have a reduced SA:V ratio therefore increased susceptibility to osmotic lysis in hypotonic solutions.
The osmotic fragility test detects haemolysis by measuring the fraction of total Hb released from red cells at progressively more dilute salt concentrations
GI problems associated with autosomal recessive polycystic kidney disease?
Biliary issues, as the protein fibrocystic is found in the epithelial cells of the hepatic bile duct (as well as in the kidneys). Most patients with ARPKD are born with some evidence of fibrosis on biopsy.
Hepatomegaly and portal hypertension develop over time in most patients.
Carol disease occurs in later stages
Cut off dose for investigation of paracetamol overdose?
> 10g or >200mg/kg
- would start NAC regardless if presenting >8 hours after ingestion
Conditions with increased risk of developing coeliac disease?
T1DM
Selective IgA deficiency
First degree relative with coeliac
Turner syndrome
Williams syndrome
Down syndrome
Autoimmune thyroiditis
Possible diagnosis for hypoalbuminaemia, oedema, pleural/pericardial effusions?
Think of protein-losing enteropathies - particularly with no evidence of liver or renal disease
Can test with A1AT clearance, as this protein is a similar molecular weight as albumin and not actively secreted, absorbed or digested.
Supplementation with what micronutrient is most effective in treating chronic diarrhoea in malnourished children?
Zinc
Which nutrients are absorbed in the duodenum/proximal jejunum?
Calcium, magnesium, phosphate, iron, folic acid
Which nutrients are absorbed in the distal ileum?
Vitamin B12, bile acids
Rates of absorption of calcium at different locations?
The duodenum is the region of most efficient absorption (active transport), however most calcium is likely absorbed in the ileum (passive transport)
Key feature of diencephalic syndrome
Significant absence of subcutaneous adipose tissue
Diencephalic syndrome occurs when benign astrocytomas affect the hypothalamus and thalamus, causing failure to thrive in a happy patient with preserved appetite and grossly normal development
Most common dietary factor associated with iron deficiency in infancy?
Introduction of unmodified cow’s milk prior to eight months
Typical age of occurrence of splenic sequestration?
Infancy (as early as 5 weeks)
Precipitants of splenic sequestration?
URTI, bacteraemia, viral infection
Features of Campylobacter food poisoning?
Seen in undercooked poultry, unpasteurised milk and contaminated water.
Incubation period 2-5 days
Causes inflammatory gastro: fever, diarrhoea (may be bloody) and vomiting
Supportive care
Can be associated with development of Gullain-Barre (usually a few weeks after infection)
Features of salmonella enteritidis food poisoning?
From contaminated eggs, poultry, cheese, juice and vegetables such as bean sprouts and melons.
Incubation period of 1-3 days
Fever, bloody diarrhoea, vomiting.
Antibiotics if <3 months (due to meningitis risk) or systemically unwell older children
Features of salmonella typhi food poisoning?
aka typhoid fever
Fever, headache, malaise and vomiting.
Constipation seen more often than diarrhoea
Complications include bacteraemia and meningitis, therefore antibiotics recommended
Features of bacillus cereus food poisoning?
A toxin mediated cause of gastro
Seen following improperly stored rice and meats
Associated with rapid onset of vomiting and/or watery diarrhoea
No fevers or invasive disease in immunocompetent patients
Supportive management
Most common type of oesophageal atresia?
Type C - oesophageal atresia with a distal TOF (85% of cases)
Which autoantibody is most specific for coeliac disease?
IgA endomysial antibodies
(however, these are expensive and have largely been replaced by anti-tissue transglutaminase IgA antibody tests, as these have similar value but are simpler to perform)
What is the predominant mechanism of action of phototherapy as treatment for jaundice?
Geometric photo-isomerisation of unconjugated bilirubin to more soluble isomers
The go to test (with highest PPV) for coeliac disease?
IgA anti TTG (Immunoglobulin A Anti Tissue Transglutaminase)
What condition can cause false negatives in anti-endomysium IgA and anti-tissue transglutaminase tests?
IgA deficiency - therefore serum IgA concentration is mandatory, to ensure false-negative results in IgA deficient individuals are excluded
Which disaccharide is produced by decomposition of starch?
Maltose
The combination of glucose and galactose makes which disaccharide?
Lactose - contains a beta bond making digestion harder for some individuals
What is the most common cause of asymptomatic indirect jaundice?
Gilbert syndrome
Which anatomical site in the oesophagus is the most likely for a foreign body to become impacted?
Oesophagus at level of the cricoid
Thin projection of the right lobe of the liver, easily palpable within the lateral right abdomen?
Riedel lobe
Absent in ganglionic segments of bowel (diagnostic of Hirschsprung’s disease)?
Meissner’s plexus
Tissue usually extending from the caecum to RUQ, that cross the duodenum?
Ladd bands
Fascia of the anterior abdominal wall, just superficial to the external oblique muscle?
Scarpas fascia
The remnant umbilical vein?
Ligamentum teres
A term meaning ‘hook shaped process’, found int he pancreas, the ethmoid bone and ribs?
Uncinate process
Superior lateral segment of the left lobe of the liver?
Liver segment 2
A narrow worm-shaped structure that extends from the posteromedial surface of the caecum?
Vermiform appendix
Overview of glucose-galactose malabsorption
More than 30 mutations of sodium/glucose co-trasnporter gene (SGLT1)
Result in AR disorder of intestinal glucose and galactose/Na+ cotransport, leading to osmotic diarrhoea
Presents with severe life-threatening dehydration during the neonatal period
Symptomatic with ingestion of glucose/breastmilk/formula, symptoms resolve promptly with IV fluids
Rx: fructose-based formula, and lifelong dietary restriction of causative sugars
Overview of Caroli disease?
Imaging studies (USS, MRCP) show bile duct ectasia and irregular cystic dilatation of intrahepatic bile ducts
Frequently associated with ARPKD and ADPKD, also with nephrons-thesis 13, Meckel-Gruber syndrome, Joubert syndrome, Bardet Biedl and COACH syndrome
Which cells produce hydrochloric acid and intrinsic factor?
Parietal cells
Which cells secrete pepsinogen?
Chief cells
Which cells produce gastrin?
G-cells (enteroendocrine cells)
Which cells are mucin producing cells?
Goblet cells - located in the small and large intestines, as well as the respiratory tract
Overview of hereditary fructose intolerance
Deficiency of fructose-1, 6 diphosphate aldolase
Severe condition in infants with ingestion of fructose, caused by deficiency of fructose aldolase B in the liver, kidney and intestine
Clinical features of hereditary fructose intolerance?
Jaundice, hepatomegaly, vomiting, lethargy, irritability and convulsions
(resembles galactosemia)
Which deficiency causes angular cheilosis?
Vitamin B2 (riboflavin) deficiency
Iron deficiency anaemia
Zinc deficiency
Features of cobalamin deficiency?
Cobalamin = B12
Deficiency results in microcytic anaemia, elevated homocysteine, peripheral neuropathy, memory loss and other cognitive defects
Features of folate deficiency?
Folate = B9
Deficiency produces microcytic anaemia and elevated levels of homocysteine.
In pregnant women, deficiency can lead to birth defects
Features of niacin deficiency?
Niacin = B3
Deficiency causes pellagra
Symptoms include aggression, dermatitis, insomnia, weakness, mental confusion and diarrhoea
Advanced pellagra can lead to dementia and death
Features of riboflavin deficiency?
Riboflavin = B2
Deficiency causes ariboflavinosis
Symptoms include cheilosis, high sensitivity to sunlight, angular cheilitis, glossitis, dermatitis or pseudo-syphilis, or pharyngitis
Features of thiamin deficiency?
Thiamin = B1
Deficiency causes beriberi
Symptoms include weight loss, emotional disturbances, Wernicke’s encephalopathy (impaired sensory perception), weakness and pain in the limbs, arrhythmias and oedema
Criteria for liver transplant in acute liver failure?
Arterial pH <7.3
OR
- grade III or IV encephalopathy, and
- prothrombin time >100 seconds, and
- serum creatinine >3.4
Most common abnormality associated with refeeding syndrome?
Hypophosphataemia
Intestinal lymphangiectasia
= congenital acrasia of lymphatic system
Protein losing enteropathy with leakage of lymph into lumen of the bowel
Chronic loss of lymphocytes and Ig (increased infection risk)
Findings: steatorrhea, oedema, diarrhoea, abdominal distension, chylous effusion, repeated infections
Ix: low albumen, low IgG, LYMPHOCYTOPENIA, anaemia, increased faecal fat loss, hypocalcaemia, hypomagnesaemia
Increased faecal alpha antitrypsin
Complications: intestinal lymphoma of B cell type
Treatment of intestinal lymphangiectasia?
Supportive: high protein diet, medium chain TGL, vitamin and calcium supplements, IV albumin and intragam
Findings in osmotic diarrhoea?
Osmotic diarrhoea resulting in malabsorption results in acidic stool
Findings in secretory diarrhoea?
A secretory process produces stools with a neutral pH
Secretory diarrhoea = increase in secretion or inhibition of absorption (i.e. little to no structural damage)
Overview of cryptosporidiosis infection?
Mild, watery diarrhoea - self limiting
Can last for weeks +/- abdominal cramps
Diarrhoea ranges from intermittent and scant to continuous/watery/voluminous
Associated with low grade fever, nausea, vomiting, loss of appetite and malaise
Histopathology findings in rotavirus-induced gastro?
Jejunal and duodenal mucosa have patchy irregularities, with shortening/blunting of the villi, and increased infiltration of the lamina propria with mononuclear cells.
Rotavirus invades small intestine villous tip cells causing villous atrophy, loss of digestive enzymes and reduction of absorption, and therefore diarrhoea. There is also a secretory component. Diarrhoea persists until the villi are regenerated.
The most important pathophysiological factor in reflux?
Transient relaxations of the lower oesophageal sphincter
What are the acute indications for colectomy in a patient with UC?
Perforation
Acute severe colitis
Toxic megacolon
Physiology of kernicterus following jaundice?
Kernicterus = bilirubin encephalopathy
Causes sensorineural hearing loss (best detected on auditory brainstem responses - ABR)
Results from deposition of unconjugated bilirubin in the basal ganglia and brainstem nuclei.
Multifactorial pathogenesis: involves interaction between unconjugated bilirubin, albumin binding and unbound bilirubin levels, passage across the BBB and neuronal susceptibility to injury
Ongoing diarrhoea, oedema, fat globules in stool, lymphocytopenia, hypoalbuminaemia?
Intestinal lymphangiectasia
Features of PFIC?
PFIC = progressive familial intrahepatic cholestasis
1/3 of cases of childhood cholestasis
PFIC1 and PFIC2 are characterised by a low-normal GGT
Commonly associated with maternal history of pregnancy induced cholestasis
3 subtypes, autosomal recessive inheritance
Components of SMOF?
Soybean oil - provides essential fatty acids
MCT - rapidly oxidised in the body
Olive oil - mono-unsaturated fatty acids
Fish oil - EPA and DHA (used in cell membranes and precursor to prostaglandins)
Common bacteria causing cholangitis in patients post-Kasai procedure?
Enterococcus
Klebsiella
Pseudomonas
E. coli
SCL5A1 gene?
Codes for a sodium glucose cotransporter protein, found in the intestinal tract
Mutations cause glucose-galactose malabsorption as the sugars are unable to be transported across the intestinal epithelium
ALDOB gene?
Aldolase B enzyme, breaks down fructose, found in the liver
Is deficient in hereditary fructose intolerance
SPINK1 gene?
Codes for a trypsin inhibitor, which is secreted into pancreatic juice
Associated with hereditary pancreatitis
TCN2 gene?
Codes for transcobalamin, which binds to B12 in the blood
Allows B12 to enter the cell, mutations cause transcobalamin deficiency
Diagnostic findings of chyle?
Triglyceride count >1.1mmol/L
Cholesterol <5.18mmol/L
>80% lymphocytes
Adding starch to ORS increases water reabsorption by which mechanism?
Colonic fermentation to short chain fatty acid, and sodium and fluid absorption in the colon
Average age of onset of familial adenomatous polyposis?
16 years old
Location of polyps in familial adenomatous polyposis?
Polyps are often in the large intestine (usually many +++)
Genetic cause of familial adenomatous polyposis?
Caused by APC gene mutation that has autosomal dominant inheritance
Overview of omphalomesenteric duct?
Connects midgut to yolk sac
Involutes at 5-6 weeks (when the bowel has returned to the abdominal cavity)
Also known as vitelline intestinal duct
Supplied by vitelline artery
Aim of TMPT gene testing?
Predict the rate of thiopurine metabolism
- those who have two non-functioning alleles will almost always experience significant bone marrow suppression if given regular doses of thiopurines
- BM suppression is a dose dependent side effect, occurs in 2-5% of patients
Daily maintenance fluid calculations
<6 months = 120ml/kg/day
>6 months = 100ml/kg/day for the first 10kg, 50ml/kg/day for the next 10kg, and then 20ml/kg/day for each kg thereafter
Deficit calculation (if weight known)
(weight in kg) x (% of dehydration) x 10ml = mL of deficit
Mechanism of action of omeprazole in PUD?
Binds to hydrogen potassium ATPase pump in the acid environment of the intracellular canaliculi within the parietal cell
Reversible
No effect on acetylcholine or histamine receptors
GIT complications of CF?
Pancreatic insufficiency (15-20%), pancreatitis
Biliary colic
Intussusception
Spontaneous bacterial peritonitis (RARE)
Meconium ileus, distal ileal obstruction syndrome, rectal prolapse, fatty liver disease, biliary cirrhosis
Porto criteria?
Staging system for IBD
Rome criteria?
Used in the diagnosis of functional GI disorders
Paris criteria?
Used to detect cross over syndromes of autoimmune hepatitis and primary biliary cirrhosis
What kind of nasal tube is used in SMA syndrome?
Nastojejunal tube (to bypass the obstruction point)
Overview of SMA syndrome
- SMA compresses the third segment of duodenum between itself and the aorta
- risk factors are thin body habitus, abdominal surgery, deconditioning following bed rest
- diagnosis can be confirmed on CT/MRI/USS
In glucose-galactose malabsorption, ingestion of which carbohydrate is likely to cause severe diarrhoea and dehydration?
Sucrose
Fructose ingestion is normal
Which tests have the highest diagnostic accuracy for coeliac disease?
Serum IgA endomysial and tissue transglutaminase antibodies
What complication following a Kasai procedure is associated with a fever?
Ascending cholangitis - common complication (40-90%), most patients have at least one episode by two years of age.
Risk due to nature of the anatomy and bacterial stasis in the roux limb.
What is melanosis coli associated with?
The use of anthraquinone-containing laxative (e.g. Senna), not seen with osmotic or diphenolic agents.
Melanosis coli can develop within four months of laxative use and will disappear once ceased.
= dark brown discolouration of the colon with lymph follicles shining through as pale patches, usually seen in rectum and sigmoid colon
Best scan for Meckel’s diverticulum?
Meckel radionuclide scan, which is performed after IV infusion of technetium-99m pertechnetate
- mucous secreting cells of the ectopic gastric mucosa take up the pertechnetate, permitting visualisation of the diverticulum
Symptoms of Yersinia entercolitica?
Acute yersiniosis (acute febrile gastro)
Pseudoappendicitis syndrome (RIF pain, vomiting, fever, leukocytosis, diarrhoea)
Which immunological mechanism is the major cause of the destruction of the small intestinal villous architecture in coeliac disease?
Activation of T lymphocytes
Gluten/gliadin interacts with free tissue transglutaminase (tTG) -> binds to gene loci (HLA DQ2 or HLA DQ8) -> activates cytotoxic T cells which stimulates damage to the epithelium and production of antibodies to gliadin and tTG
Which of the following is most likely to be associated with fatty acid crystals on faecal microscopy?
Acute pancreatitis, chronic cholestasis, cystic fibrosis, giardiasis, intestinal lymphangiectasia
= Giardiasis
Presence of fat globules in stool?
Malabsorption due to pancreatic insufficiency, chronic cholestasis, rapid transit, overload
= fat not being digested
Presence of fatty acid crystals in stool?
Digestion/breakdown of fat but not being absorbed due to physical defect/metabolic cause e.g. celiac disease or infection (Giardia)
What is PNALD?
Parenteral nutrition-associated liver disease
= cholestasis occurring in the setting of parenteral nutrition (if other causes of liver injury have been excluded.
Seen in 40-60% of children who receive long-term PN
Management of PNALD?
Enteral feeding!
- exposes the GIT to nutrient and hormonal stimuli (which are not present when the tract is empty)
Particularly important to upgrade feeds to enteral in babies with short gut syndrome (particularly high risk for developing significant liver disease)
How does a portacaval shunt work?
Performed for portal hypertension
Diverts nearly all of the portal blood flow into the sub hepatic inferior right vena cava.
Although portal pressure is reduced significantly, the major diversion of blood flow from the liver results in an increased risk for hepatic encephalopathy (as the liver is less equipped to remove toxins from the blood)
Impact of absent HLA DQ2/DQ8?
Negative predictive value of absent HLA DQ2/DQ8 is very high, therefore a diagnosis of coeliac is very unlikely.
Is there any proven benefit to supplementing milk formula with long chain polyunsaturated fatty acids in term babies?
No
Where do the ventral and dorsal pancreatic buds arise from?
Both buds arise from the duodenum
Eventually these merge to form the pancreatic duct
Describe the process of rotation of the two buds which form the pancreas
As the duodenum moves towards the right, the ventral bud usually rotates dorsally to lie just superior (and in close proximity) to the dorsal bud.
The dorsal bud is initially superior but after rotation it lies just inferior to the ventral bud.
After rotation, the two buds fuse and enclose the superior mesenteric artery
Typical history of food protein proctocolitis?
<6 months, fed for a few weeks with formula and then develops diarrhoea and eventually vomiting.
No weight loss and infant is otherwise healthy, stools often contain streaks of blood and some mucous.
If the infant has the enterocolitis syndrome, the infant can become dehydrated and lose weight
What are reducing substances?
Reflect unabsorbed sugars in the stool
0.25% = small
2% = large
Cause of Gilbert’s disease?
3-7% of population
Commonest inherited cause of hyperbilirubinaemia (AR) and benign
Caused by underactivity of conjugating enzyme system (bilirubin-UGT)
Presentation of Gilbert’s disease?
Intermittent jaundice with no haemolysis or liver disease
Episodes may be precipitated by fasting, dehydration, menstrual periods, stress (e.g. intercurrent illness/vigorous exercise).
May be associated with mild abdominal pain, but resolves spontaneously
Investigation findings in Gilbert’s syndrome?
Unconjugated hyperbilirubinaemia (intermittent)
LFTs otherwise normal
Normal FBC, reticulocyte count and film
Clinical features of lactose intolerance?
Most common inherited form of carbohydrate malabsorption
Presents with abdominal pain and diarrhoea, which occurs only with lactose consumption
Clinical features of UC?
Chronic condition involving inflammation of colonic mucosa (distal to proximal)
Haematochezia is common
Most common extraintestinal features are fever and arthritis, can also have erythema nodosum, pyoderma gangrenoum and primary sclerosing cholangitis
What are the blood gas findings in pyloric stenosis?
Hypochloremic, hypokalaemic metabolic alkalosis
(persistent vomiting causes progressive loss of fluids rich in HCl, therefore kidneys retain hydrogen ions over potassium)
Associations with coeliac disease?
Dermatitis herpetiformis
Dental enamel hypoplasia of permanent teeth
Osteopenia/osteoporosis
Short stature
Delayed puberty
Iron deficiency anaemia not responding to oral iron
Less strong evidence: hepatitis, arthritis, epilepsy with occipital calcifications
Transient hyperphosphataemia
Characterised by marked elevation of serum ALP in the absence of detectable liver or bone disease
Most cases in children <5 years
Gradually returns to normal within 2-3 months, can occur in isolation in viral infections/failure to thrive
Histological features of Crohn’s disease?
Transmural inflammation
Skip lesions
Complications include strictures, fistulae, perianal disease and growth failure
Granulomas - specific, but not present in all cases
Which carbohydrates are absorbed by the intestinal sodium-glocuse transporter 1 (SGLT-1)?
Glucose
Galactose
Infant with FTT, developmental regression, neurological signs (hypotonia with hyperreflexia, unusual movements), anaemia, low serum B12, UMS showing increased methylmalonic acid and homocystine?
Subacute combined degeneration of spinal cord due to Vitamin B12 deficiency
- next step: maternal serum B12 level
What is the Schilling test?
Used to determine if low B12 is due to deficiency or pernicious anaemia
Alagille syndrome can result in what deficiencies?
Alagille with cholestatic jaundice will mainly cause malabsorption (and probable deficiency) in fat-soluble vitamins (A, D, E, K)
Features of Vitamin A deficiency?
Ocular signs known as xerophthalmia (earliest sign is night blindness)
Features of Vitamin D deficiency?
Rickets
Hypocalcaemia
Hypophosphataemia
Features of Vitamin E deficiency?
Tocopherol (vitamin E) deficiency can lead to:
- progressive sensory and motor neuropathy (late finding)
- spinocerebellar ataxia
- retinal degeneration (pigmented retinopathy and loss of vision)
- haemolytic anaemia
Features of Vitamin K deficiency?
Bleeding diathesis
Features of folate deficiency?
Hypersegmentation of neutrophils, megaloblastosis and anaemia
Features of Vitamin B12 deficiency?
Deficiency uncommon unless exclusively breastfed by deficient mothers, or with malabsorption
Features include megaloblastic anaemia, atrophic glossitis, neuropathy and demyelination of CNS.
Neuropathy symptoms include areflexia and loss of vibration/position sense
Overview of clinical features of Vitamin B12 deficiency in an infant?
Developmental regression
Poor weight gain/FTT
Normal HC and length
Hypotonic, brisk reflexes
Hypersegmented neutrophils with macrocytic red cells
Methylmalonic acid and homocystine increased in the urine
What findings in the urine are typical for Vitamin B12 deficiency?
Methylmalonic acid and homocystine
Treatment for hydatid cysts?
Albendazole (parasitic infection) - can cause cysts in liver or lungs
Fat globules in stool
Maldigestion (intraluminal problem e.g. failure of enzyme process or bile to suspend fats)
Fat crystals in stool
Malabsorption (mucosal/brush border problem e.g. fatty acid not absorbed)
What is one of the more common medication used as maintenance therapy in Crohn’s disease?
Azathioprine - for maintenance and prolonging remission
Significance of tryptic activity in stool?
Excludes exocrine pancreatic disease
Autoimmune hepatitis type 1
Characterised by hepatitis and the presence of ANA and/or anti smooth muscle antibodies
- responsible for 2/3 of cases of autoimmune hepatitis
Autoimmune hepatitis type 2
Characterised by hepatitis and the presence of anti-liver kidney microsome antibodies and/or anti-liver cytosol type 1 antibodies
- tends to be more severe than AIH1
- Rx: steroids +/- azathioprine (second line mycophenolate)
How does transcobalamin II deficiency impact Vitamin B12?
Transcobalamin II deficiency is an inherited defect of a protein necessary for the transport of vitamin B12 from the intestine to the liver/BM/tissue storage sites.
Results in severe megaloblastic anaemia, FTT, neurological manifestations, glossitis, diarrhoea, vomiting.
Serum vitamin B12 levels are NORMAL, but do not transport to sites of use
GIT associations of autosomal dominant polycystic kidney disease?
Liver/pancreas/spleen cysts
Colonic diverticula in 80%
Urine electrolytes in pyloric stenosis?
Urinary losses of Na and HCO3 (to compensate for Cl- losses)
Secondary hyperaldosteronism develops due to hypovolaemia, high aldosterone causes the kidneys to retain Na (to correct intravascular volume depletion) and excrete potassium.
= urinary chloride is low, urinary potassium increased, urine pH will be relatively alkaline
Alternative term for alpha1-antitrypsin?
Protein Z - secreted by hepatocytes
Calculation of faecal osmolality?
2 x (Faecal Na + K) = faecal osmolality
The presence of reducing substances suggests what kind of malabsorption?
Carbohydrate malabsorption
Medical management of perianal Crohn’s disease causing fistula?
Metronidazole and infliximab
Always initially managed with anti-TNF alpha agents (such as infliximab) - if there is an abscess, start with just the antibiotic and start the biologic agent once the infection has cleared
Site of folate absorption?
Jejunum
Where are proteins, amino acids and vitamin B12 absorbed?
Ileum
Where is calcium, magnesium, iron, fat-soluble vitamins A and D, and glucose absorbed?
Duodenum
Where are water, potassium, sodium chloride, and fatty acids absorbed?
Colon
What is the ideal screening test for asymptomatic siblings of a child with Wilsons disease?
ATP7b gene mutation
Blood markers and biopsy results are unlikely to be abnormal before the child is symptomatic
HbsAg positive, anti-HBc positive, IgM anti-HBc positive
Acute hepatitis B
HBsAg positive, anti-HBc positive, IgM anti-HBc negative
Chronic hepatitis B infection
HBsAg negative, anti-HBc positive, anti-HBs positive
Previous hepatitis B infection
HBsAg negative, anti-HBc negative, anti-HBs positive
Immunity due to hepatitis B immunisation
HBsAg
= hepatitis B surface antigen
- protein on the surface of HBV, detectable during acute or chronic infection, presence means a person is infectious
Anti-HBs
= hepatitis B surface antibody
Indicates immunity to hepatitis B
Anti-HBc
= total hepatitis B core antibody
Appears at the onset of symptoms and persists for life, it indicates any previous or current infection
IgM anti-HBc
= IgM antibody to hepatitis B core antigen
Indicates acute infection (<6 months)
Osmotic vs secretory diarrhoea re fasting?
Osmotic diarrhoea stops when fasting (secretory diarrhoea continues)
Features of secretory diarrhoea
Stool Na >70
Low osmotic osmolality
Low stool osmolar gap <50
pH >6
No reducing stubstances
High volume >200ml/day
Continues when oral intake is stopped
Features of osmotic diarrhoea
Stool Na <70
High stool osmolality
High stool osmolar gap >125
pH <5 (bacterial fermentation)
Reducing substances (all sugars except sucrose)
Low volume
Ceases when oral intake stopped
Organisms which can cause bloody diarrhoea?
Salmonella, shigella, clostridium difficile, Campylobacter and certain strains of E. coli
Organism associated with gastro following ingestion of reheated rice?
Bacillus cereus
Organism with similar presentation to appendicitis?
Yersinia enterocolitica
Cause of traveller’s diarrhoea?
E. coli
Common causes of food poisoning?
Staph aureus
Bacillus cereus (reheated rice)
Diarrhoea from contaminated poultry?
Campylobacter
Cause of diarrhoea and seizures?
Shigella
Causes of brisk GI bleeding
Meckel diverticulum
AV malformation
Oesophageal or gastric varices
Causes of painful GI bleeding
Intussusception
Volvulus
Small bowel obstruction
Inflammatory bowel disease
Ischaemic colitis
Pseudomembranous colitis
Causes of painless GI bleed
Meckel diverticulum
Juvenile polyps
Pathophysiology of eosinophilic oesophagitis
Chronic antigen mediated immune disorder
Pill oesophagitis
Due to insufficient water intake with swallowing pill rather than oesophageal pathology
Most common with tetracycline and ferrous sulfate
Achalasia
Oesophageal motility disorder, with impaired movement of the oesophagus and inability of the LES to relax
“birds peak” appearance at LES on imaging
Rx: endoscopic dilatation, or Heller myotomy (surgical opening)
RF for pyloric stenosis
Maternal smoking
Bottle feeding
Family history
Macrolide antibiotic use under 2 weeks of age
Menetrier disease
Presents around 4 years of age, a/w CMV infection
DDx: lymphoma, H. pylori, CMV
Presents with vomiting, oedema
Giant gastric folds on scope
Usually self limiting in children
Boerhaave syndrome
Spontaneous rupture of oesophagus due to vomiting
- develop subcutaneous emphysema
Classic triad of symptoms with gastric volvulus
- Sudden severe epigastric pain
- Intractable emesis
- Inability to pass a tube into the stomach
Causes of osmotic diarrhoea
Osmotic laxatives (lactulose, sorbitol)
CHO malabsorption (glucose/galactose transport defect, lactase, sucrase def)
Coeliac disease
Auto-immune enteropathy
Inflammatory
Infection
Bacterial overgrowth
Causes of secretory diarrhoea
Infection (cholera, E. coli, salmonella)
Mucosal necrosis or atrophy
Stimulant laxatives (e.g. coloxyl)
Bile acid malabsorption
Congenital electrolyte transport defect
Tumours (VIPoma, gastrinoma, carcinoid)
Pheochromocytoma
Mastocytosis
Melanosis coli
Lesion that occurs only with use of Senna laxatives (contains anthraquinone)
Develops within 4 months of ingestions, resolves in similar timeframe once ceased
= dark brown discolouration of colon with lymph follicles visible as pale patches
