Gastroenterology Flashcards
Cystic fibrosis predominantly affects which ethnicity?
Caucasian
How is cystic fibrosis inherited?
Autosomal recessive
Which gene is affected in cystic fibrosis?
CFTR (cystic fibrosis transmembrane conductance regulator)
What is meconium ileus?
Failure to pass the first stool in neonates (usually passes within 24-48 hours)
CF is the most common cause
Bilious vomiting, abdominal distension, no meconium
What is the primary screening test for CF?
Immunoreactive trypsinogen (IRT; elevated) on a heel-prick blood
Why is immunoreactive trypsinogen elevated in CF?
IRT has not been converted to its active form due to impaired release of pancreatic enzymes
What test is used to confirm CF after abnormal IRT?
DNA assay to identify common CFTR mutations
What is the diagnostic criteria for CF?
Typical clinical manifestations of CF
AND
Evidence of CFTR dysfunction
Sweat chloride > 60 mmol/L on two occasions
OR
CFTR gene mutation
OR
Abnormal nasal potential difference test
What is the most important factor in CF prognosis?
Severity of pulmonary disease
Chronic respiratory infections and mucus plugging → irreversible bronchiectasis → progressive respiratory failure → death
Is physiological neonatal jaundice conjugated or unconjugated?
Unconjugated
When does physiological neonatal jaundice occur?
Between days 3-8 of life
Give 3 causes for physiological neonatal jaundice
- HbF replaced with HbA (haemolysis)
- Immature hepatic conjugation and elimation pathways → impaired metabolism
- Less bacteria in the GIT → less conversion of bilirubin to urobilin → less excretion of bilirubin
Where is the vomiting (emetic centre)?
In the medulla
Which autonomic nerve mediates emesis?
Vagus
What electrolyte changes are seen in children with pyloric stenosis?
Metabolic acidosis (low H+, high HCO3- to compensate)
Low Cl-
Low K+
What surgical procedure is done for pyloric stenosis?
Pyloromyotomy
Incision is made through the pyloric sphincter and the lumen can bulge through this opening
What is the feed test in the context of suspected pyloric stenosis?
Shortly after eating, peristalsis may be visible
Which type of inguinal hernia involves protrusion of the bowel through the internal inguinal ring, external inguinal ring and into the scrotum?
Indirect inguinal hernia
Which type of inguinal hernia herniates lateral to the inferior epigastric artery?
Indirect
Which type of inguinal hernia herniates medial to the inferior epigastric artery?
Direct
Which type of inguinal hernia protrudes through the inguinal (Hesselbach’s) triangle?
Direct
Which type of inguinal hernia involves herniation through the external (superficial) inguinal ring only?
Direct
What is the best method of assessing dehydration?
% loss of body weight
What is the role of anti-diarrhoeal drugs in infants and children with gastroenteritis?
NO role - do not use
What is the role of anti-emetic drugs in infants and children with gastroenteritis?
Ondensetron may be used
Reduces vomiting
Improves intake of oral rehydration solutions
Reduces the need for IV fluids and hospitalisation
Can worsen diarrhoea
When is the peak incidence of intussusception?
3-12 months
What is this?
Target sign of intussusception
From what age/weight can ondansetron be used?
6 months/8kg
Acute abdominal pain with legs drawn up and with asymptomatic intervals is characteristic of which condition?
Intussusception
What is perferred treatment of intussusception?
Air enema
What investigations should be performed for intussusception?
- AXR (exclude perforation and obstruction)
- US
- Air enema (diagnostic and therapeutic)
What pathogen is associated with reptiles?
Salmonella
Why do children with pyloric stenosis have high bicarbonate?
The kidneys reabsorb bicarboante to maintain fluid volume despite the metabolic alkalosis
If bicarbonate is loss, sodium follows, then water
What is breastfeeding jaundice?
The persistence of physiologic jaundice beyond the first week of life
Exclusive breastmilk intake may increase intestinal absorption of bilirubin
List 4 causes of neonatal conjugated hyperbilirubinaemia
- Hepatitis A/B
- Cystic fibrosis (decreased bilirubin excretion)
- Biliary atresia
- TORCH infections
- Choledochal cyst
- Dubin-Johnson syndrome
- Rotor syndrome
- Alpha-1-antitrypsin deficiency
List 4 causes of neonatal unconjugated hyperbilirubinaemia
- Haemolytis disease of the newborn
- Spherocytosis
- Thalassemia
- G6PD deficiency
- Crigler-Najjar syndrome
- Glucuronyl transferase deficiency
- Hypothyroidism
- High GI obstruction
What is kernicterus?
Chronic bilirubin encephalopathy
Rare complication of uncongugated hyperbilirubinaemia
Cerebral paresis, vertical gaze palsy, hearing impairment, athetosis (movement disorder)
When might bilirubin be positive on urinalysis?
Failure of conjugated bilirubin to reach the intestines → bilirubin is not converted to urobilinogen
Biliary obstruction
Hepatic disease; hepatocellular disease, cirrhosis, hepatitis
What might cause an elevated urobilinogen on urinalysis?
Conjugated hyperbilirubinaemia
Impaired hepatic reabsorption of urobilinogen; liver disease
Absent or decreased in obstructive jaundice
What causes steatorrhoea?
Pancreatic e.g., chronic pancreatitis, CF
Malabsorption e.g., coeliac, giardiasis, Whipple’s disease, Crohn’s
Biliary e.g., PBC, PSC
What are the two main diagnostic laboratory tests for coeliac disease?
IgA anti-tissue transglutaminase antibody
IgG deamidated gliadin peptide (test of choice for children < 2)
Do perianal fistulae or abscesses suggest UC or CD?
Crohn’s disease
What is the most common cause of acute abdomen in premature infants?
Necrotising enterocolitis
What is the proposed pathophysiology of necrotising enterocolitis?
Mucosal damage and enteral feeding → bacterial growth → bowel necrosis/gangrene/perforation
How is necrotizing enterocolitis diagnosed?
AXR
What is this radiographic sign?
Pneumatosis intestinalis (necrotising enterocolitis)
Bubbles of gas within the wall of the intestine
“string of pearls” sign
What is Dance’s sign?
RUQ mass (intussusception) with RLQ empty space (movement of cecum out of normal position)
Which immunisation has been linked to intussusception?
Rotavirus
Intussusception more common following immunisation
What often preceeds intusucception?
Viral infection
Enlarged lymph nodes can act as a lead point
Which part of the GIT is affected by rotavirus?
Jejunum and duodenum
What % of conjugated bilirubin as a proportion of total bilirubin suggests conjugated hyperbilirubinaemia?
20%
What transcutaneous bilirubin (TcB) is an indication for serum bilirubin measurement?
> 250 micromol/L
What are the potential side effects of phototherapy?
Overheating
Water loss from increased peripheral blood flow and diarrhoea (if present)
Diarrhoea from intestinal hypermotility
Ileus (preterm infants)
Rash
Retinal damage
‘bronzing’ of neonates with conjugated hyperbilirubinaemia
Temporary lactose intolerance
What is defective in Crigler-Najjar syndrome?
UDP-glucuronosyltransferase activity
Liver enzyme responsible for conjugating bilirubin
What is defective in Dubin-Johnson syndrome?
MRP2 transporter
Impaired movement of conjugated bilirubin from the hepatocyte to the bile canaliculi
Which syndrome is most strongly associated with duodenal atresia?
Down syndrome
What might cause bilious vomiting in a neonate?
Volvulus
Intestinal atresia
What might cause haematemesis in infants?
Oesophageal varices (severe)
Mallory-Weiss tear
Erosive esophagitis or gastritis
Peptic ulcer
What is the most common presentation of a Meckel diverticulum?
Painless rectal bleeding
How does age at presentation affect the likelihood of Crohn’s disease vs ulcerative colitis?
< 8 - UC/Crohn’s, usually isolated colonic disease
> 8 - most likely Crohn’s disease
What are the most useful indicators of possible IBD in a child with abdominal pain?
Diarrhoea
Growth failure
Pubertal delay
Weight loss
Rectal bleeding
Pallor/fatigue
Perianal skin tags/fistulae
Family history of IBD
What are the classic features of abdominal pain from Crohn’s disease?
Localised in the RLQ
May be peritonitic
Is hematochezia and the passage of mucus or pus characteristic of UC or CD?
Ulcerative colitis
Are bowel obstructions characteristic of UC or CD?
CD
Which antibodies are most commonly used to support an IBD diagnosis?
Perinuclear antineutrophil cytoplasmic antibodies (P-ANCA)
Anti-saccharomyces cerevisiae antibodies (ASCA)
What is the usefulness of antibody tests in distinguishing CD and UC?
Perinuclear antineutrophil cytoplasmic antibodies (P-ANCA) - weakly associated with CD
Anti-saccharomyces cerevisiae antibodies (ASCA) - weakly associed with UC
Is transmural inflammation characteristic of CD or UC?
CD
Are granulomas characteristic of CD or UC?
Crohn’s disease
What is the prognosis for a congenital umbilical hernia?
90% spontaneously resolve by 5 years
What is aphthous stomatitis?
Small, shallow, non-infectious and painful oral ulcers
“canker sores”
Which nutritional deficiency is most strongly linked with aphthous stomatitis?
B12
Also folate and zinc
Food poisoning from reheated rice and food kept warm but not hot is characteristically from which pathogen?
Bacillus cereus
What exposure characteristically leads to Staphylococcus auerus food poisoning?
Inadequately refrigerated food (canned meats, mayonnaise/potato salad, custards)
How is mesenteric adenitis diagnosed?
Ultrasound showing abdominal lymph nodes > 8mm
Small appendix must be demonstrated to rule out appendicitis
What causes a congenital indirect inguinal hernia?
Failure of the processus vaginalis to obliterate
What is encopresis?
Faecal incontinence in a child > 4 years old
At least 1 per month for 3 months
What may cause encopresis?
Chronic constipation
Hirschsprung disease
Hypothyroidism
Hypercalcaemia
Spinal cord lesions
Anorectal malformations
Bowel obstruction
What are the characteristics of the abdominal pain in HSP?
Colicky
+/- nausea and vomiting
+/- bloody stools or melena
Where is the most common site of intussusception?
Ileocecal junction
What causes current jelly stools in intussusception?
Sloughed mucosa following ischaemia
What are the DDx for bilious vomiting in a neonate?
Midgut volvulus
Intestinal atresia (distal to empying of the bile duct)
Hirschsprung’s disease
Where is the most common location of a Meckel’s diverticulum?
2 feet proximal to the ileocecal valve
At what age can elective surgery for an unresolved umbilical hernia be performed?
5 years
- High chance of self-resolution before this age*
- 2-3 years if large or symptomatic*
