Neonatal

Question 1

Describe genes associated with Hirschsprung disease (9)

Answer 1

• Genes thought to contribute to early cell death
  
  • RET proto-oncogene (thought to contribute to early cell death)
  • Neurturin
  • Glial cell-line derived neurotrophic factor (GDNF) + GFRA1 (GDNF family receptor alpha 1)
• Genes thought to trigger early maturation or differentiation of neural crest cells
  
  • SOX-10
  • Endothelin-3
  • Endothelin-B
• Other genes implicated
  
  • ZFHX1B
  • Phox2B
  • Hedgehog-Notch complex

Question 2

What is the neonatal blood volume (mL/kg)?

Answer 2

Neonatal blood volume = 80ml/Kg.

30mL blood loss in a term neonate = 10% total blood volume.

Question 3

What are the main physiological effects of CDH (5)?

Answer 3

Pulmonary Hypoplasia (fewer bronchial divisions, bronchioles and alveoli)

Pulmonary hypertension (thick walled, low compliance pulmonary arterioles throughout)

Right ventricular hypertrophy (secondary to high pulmonary vascular resistance)

Left ventricular hypoplasia

Reduced surfactant - low pulmonary compliance (fewer type 2 pneumocystes)

Question 4

What are the findings on biopsy of Hirschsprung disease?

Answer 4

• Absence of ganglion cells in submucosal plexus
• Nerve trunk hypertrophy
• Calretinin staining (negative)
• Acetylcholinesterase staining (positive) - increased cholinergic fibres.

Question 5

Describe complications of gastroschisis in antenatal (3), neonatal (6) and childhood/adolescents (4).

Answer 5

• Antenatal:
  
  • Simple versus complex gastroschisis (including vanishing) - may be associated with atresia and short bowel syndrome.
  • Associated with prematurity, foetal demise, intestinal rotational anomaly.
• Neonatal/Infant:
  
  • Neonatal hypovolaemia/sepsis - associated with risk of dehydration and sepsis from birth (exposed organs).
  • Risk of abdominal compartment syndrome with reduction of contents +/- primary closure = >20mmHg.
  • Reduced intestinal function - associated with ‘peel’ and exposure to amniotic fluid/urine (collagen deposition, reduced interstitial cells of Cajal).
  • Gastro-oesophageal reflux
  • Failure to thrive/intestinal failure
    
    • Requiring TPN
      
      • Catheter associated complications (thrombosis, CABSI)
      • Liver dysfunction associated with TPN.
• Childhood/Adolescence:
  
  • Persistent intestinal failure common → most common reason for intestinal transplantation.
  • Worse cognitive outcomes.
  • Persistent abdominal pain (40%) of adolescents.
  • Normal height and weight but higher BMI in adulthood (thought due to social status).

Question 6

Name 4 abnormalities of the lower oesophageal sphincter that contribute to reflux (4)

Answer 6

1. Shortened lower oesophageal sphincter length.
2. Malposition of the lower oesophageal sphincter (must be partially intrathoracic, partially intra-abdominal) - suspended in place by the phreno-oesophageal membrane.
3. Abnormal sphincter function (as seen with TOF/OA)
4. Increased frequency of lower oesophageal sphincter transient relaxations.

Question 7

Describe foetal circulation

Answer 7

• Foetal circulation has several right to left shunts to bypass liver and non-functioning lungs.
  
  • Ductus venosus (left umbilical vein to left portal vein to IVC) - bypass liver.
  • Foramen ovale (right atrium to left atrium) - bypass pulmonary circulation.
  • Ductus arteriosus (pulmonary artery to distal aortic arch) - bypass pulmonary circulation
  • Final shunt is from internal iliac arteries to umbilical arteries → placenta

Question 8

What are the causes of chylothorax?

Answer 8

• Traumatic:
  
  • Most commonly occurs after thoracic surgery
    
    • Cardiac surgery
    • CDH
    • TOF/OA
• Non-traumatic:
  
  • Lymphatic malformation
  • Congenital/Foetal chylothorax - most common pleural effusion in the neonatal period.
    
    • CPAM
    • CDH
      
      • Congenital chylothorax usually associated with dysmorphic syndromes.
      • Thought to be caused by structural defect in the lymphatic drainage system.

Higher risk of congenital chylothorax in: Trisomy 21, Turner’s Syndrome, Noonan Syndrome, Ehlers-Danlos as they all have increased risk of lymphatic disorders.

Question 9

What diseases/syndromes are associated with Hirschsprung disease?

Answer 9

Trisomy 21

Waardenburg Syndrome

Congenital central hypoventilation syndrome

Goldberg Spritzen Syndrome

Smith-Lemli-Opitz Syndrome

Neurofibromatosis

Neuroblastoma

Question 10

What are the findings on anorectal manometry in Hirschsprung disease?

Answer 10

1. Loss of the recto-anal inhibitory reflex (reflex relaxation of internal sphincter associated with distension on the rectum)

Question 11

What are the mechanisms for oesophageal clearance to minimise reflux associated injury (3)?

Answer 11

• Oesophageal motility - minimise exposure time of oesophageal mucosa to refluxate.
  
  • Primary peristalsis - associated with ingestion of food and swallowing (clears reflux 90% of the time).
  • Secondary - reactive to refluxate requiring clearance. Occurs especially during sleep.
  • Tertiary - sporadic, non-propagating contractions.
• Saliva neutralises refluxed material.
• Upright posture

Question 12

Describe foetal interventions for CDH and how they may change pathogenesis

Answer 12

• Foetoscopic tracheal occlusion (FETO) is the main foetal intervention being utilised in CDH.
  
  • Involves foetoscopically passing a balloon into the trachea, and obstructing the trachea. This usually occurs after 27 weeks gestation.
    
    • Tracheal occlusion blocks outflow of pulmonary fluid and is thought to improve foetal lung growth and development.
• Large European trial (TOTAL) - found FETO improved survival if done between 27 and 29 weeks.
  
  • Associated with premature rupture of membranes and premature delivery.

Question 13

Describe the physiological mechanisms that prevent gastro-oesophageal reflux (7).

Answer 13

1. Lower oesophageal pressure - Reflux associated with transient relaxations (pressure < 6mmHg).
2. Lower oesophageal length
3. Lower oesophageal position - positioned partly in the thorax, partly in the abdomen. Essential for preventing reflux.
4. Intra-abdominal length of the oesophagus
5. Angle of His - usually acute, creating a flap valve effect with a prominent mucosal fold.
6. Intra-abdominal pressure (low protective against reflux). Conditions with high intra-abdominal pressures (retching, coughing, obesity, gastroschisis, exomphalos, CDH) associated with higher rates of GORD.
7. Oesophageal function - affects oesophageal peristalsis AND LES function (i.e. OA/TOF → high rates of reflux).

Question 14

Describe the pathophysiology of caustic stricture. What are the three phases?

Answer 14

• Caustic stricture - ingestion of caustic product (i.e. bleach) or button battery.
  
  • Ingestion:
    
    • Alkaline solutions combine with oesophageal tissue proteins → liquefactive necrosis and saponification.
      
      • Necrosis can be full thickness.
    • Alkaline solutions are absorbed and cause vascular thrombosis → impaired blood supply to damaged tissue.
  • Button batteries:
    
    • Forms circuit with mucus. Forms hydroxide radicals and liquefactive necrosis within 15 minutes → erosion through wall.
• 3 phases of caustic injury:
  
  • Liquefactive necrosis - rapid deep injury, until alkali neutralised by tissue fluid.
  • Reparative phase - Between day 5 and 14. Sloughing of necrotic debris and formation of granulation tissue and collagen deposition → oesophageal wall thinnest and most prone to perforation during reparative phase.
  • Scar retraction - begins after 2 weeks → collagen deposition → oesophageal stricture.

Question 15

How does botulinum toxin work?

Answer 15

• Botox is a neurotoxin,
  
  • it binds presynaptic cholinergic terminals in skeletal muscle,
  • inhibits release of acetylcholine at the NMJ
  • ‘chemical denervation’

Question 16

What is the pathophysiology and gene associated with cystic fibrosis?

Answer 16

• Cystic fibrosis occurs as an autosomal recessive genetic defect in the CFTR gene on chromosome 7q31.
  
  • CFTR = cystic fibrosis transmembrane regulator (most commonly delta F508 mutation) - codes for cAMP induced Cl channel on epithelial cells.
    
    • Impaired Cl secretion → hyper viscous mucosal secretions.
  • Affects:
    
    • Gut: Meconium ileus, DIOS
    • Exocrine pancreas: mucoviscidosis of exocrine sections → blocked pancreatic duct → pancreatitis and autodigestion of acinar cells (pancreatic insufficiency - occurs in 66% of CF children at birth).
    • Biliary system - inspissated bile, formation of gallstones.
    • Respiratory system - inspissated secretions, impaired mucociliary elevator, recurrent infections/inflammation → bronchiectasis.
    • Congenital bilateral absence of the vas deferens

Question 17

Describe the transition to post-natal circulation. How is this different in the child with CDH?

Answer 17

• At birth, two major events - clamping of umbilical cord AND child takes first breath → lungs expand.
  
  • Closure of ductus venosus (nil flow through left umbilical vein post clamping of cord)
  • First breath creates negative intrathoracic pressure and reduces pulmonary vascular resistance → increased pulmonary blood flow.
    
    • Increasing left atrial pressures → closure of foramen ovale.
  • Ductus arteriosus dependent upon maternal prostaglandins (via placenta) plus flow and low oxygen tension.
    
    • Clamping cord, plus decreased pulmonary vascular resistance (increased flow from pulmonary artery to pulmonary vasculature) PLUS increased oxygen tension causes ductus arteriosus to close.
• In CDH, due to pulmonary hypoplasia and foetal pulmonary hypertension, right to left shunts don’t close. Deoxygenated blood bypasses pulmonary circulation PLUS poor respiratory function → hypoxaemia.
  
  • High pulmonary pressures lead to right ventricular dysfunction post birth.

Question 18

Describe the stages of lung development and their timing.

Answer 18

• Embryonal stage (weeks 3-6)
  
  • tracheal bud forms as ventral diverticulum off foregut, basic lobes (6/40)
• Pseudoglandular stage (weeks 5-17) - CDH thought to occur around week 8. Affects all subsequent stages.
  
  • Formal lung buds and main terminal bronchi form.
  • Pre-acinar vasculature complete by the end of stage
• Cannalicular stage (weeks 16-25)
  
  • Formation of pulmonary vessels, bronchioles and alveolar ducts.
  • Type 1 pneumocytes all functional gas exchange, primitive Type 2 pneumocytes.
  • Major stage for pulmonary vasculature due to development of functional units (acinus - alveoli, etc)
• Saccular stage (weeks 24-40)
  
  • Maturation of alveolar sacs
  • Maturation of functional type 2 pneumocytes → surfactant production.
• Alveolar stage (Birth to 8 years)
  
  • Ongoing increases in functional alveoli.

Question 19

What are the findings on liver biopsy associated with biliary atresia?

Answer 19

Bile duct proliferation

Intraluminal bile plugs

Portal stromal oedema

Expansion of the portal tracts.

Fibrosis/cirrhosis of liver parenchyma.

Question 20

Describe physiological neonatal jaundice

Answer 20

• Neonates undergo transition from HbF to Hb (increased haemolytic)
• Immature liver unable to conjugate bilirubin for excretion at rate of bilirubin production → unconjugated hyperbilirubinaemia.
  
  • Peaks between days 3 and 10.
• Treatment depends of level of bilirubin and age of baby.
  
  • Persistently high bilirubin can result in kernicterus (neural toxicity secondary to high levels of unconjugated hyperbilirubinaemia)

Question 21

Discuss other forms of meconium disease seen in neonate

Answer 21

Meconium plug syndrome - occurs in 1 in 500.

• Whitish firm cap within terminal 2cm of meconium → obstruction.
• Normally relieved by PR with normal colonic function post.
  
  • Associated with:
    
    • Cystic fibrosis.
    • Hirschsprung disease.
    • Hypothyroidism
    • Maternal narcotic use
    • Neuronal intestinal dysplasia.

Question 22

Create a management plan to address metabolic and physiological derangements seen in infantile hypertrophic pyloric stenosis.

Answer 22

Derangement - hypochloraemic, hypokalaemic metabolic alkalosis PLUS hypovolaemia.

• Management:
  
  • ABCD + Assess severity of hypovolaemia, gain IV access, NBM, IDC if severe.
    
    • Fluid resuscitation + maintenance fluids
      
      • 20ml/kg bolus of N.Saline
      • Maintenance fluids - N.Saline + 5% dextrose. Add K+ once adequate urine output.
    • Monitor urine output,
    • Q6hrly VBG to assess for resolution of alkalosis.
  • Consider surgical intervention ONLY once HCO3- normalised.

Question 23

What is the pathophysiology of abdominal compartment syndrome? What are potential causes?

Answer 23

Abdominal compartment syndrome is characterised by increased abdominal pressure (as measured by urinary catheter or gastric probe) resulting in reduced organ perfusion and end organ dysfunction.

• Abdominal pressures 10-15mmHg - reduced renal and splanchnic circulation.
• Abdominal pressures > 20mmHg - renal perfusion reduced by > 75%, associated with organ dysfunction.
  
  • Kidneys first to fail - ATN and oliguria.
• Often also associated with ventilatory difficulties and decreased venous return → low cardiac output.

Abdominal compartment syndrome occurs with:

• Reduced abdominal wall compliance - Reduction of gastroschisis or CDH.
• Increased intra-abdominal contents - Intra-abdominal tumours, bleeding, ascites.
• Increased intra-luminal pressure - intussusception, ileus, obstruction.

Question 24

What is meant by syndromic biliary atresia versus non-syndromic biliary atresia?

Answer 24

• Syndromic biliary atresia (accounts for 10-20%) - associated with other congenital anomalies such as interrupted vena cava, pre duodenal portal vein, intestinal malrotation, situs inversus, cardiac defects, polyspenia.
  
  • Thought to occur due to insult occurring during differentiation of the hepatic diverticulum from the foregut.
• Non-syndromic biliary atresia (perinatal type) - may have origins later, tends to be progressive.
• Cystic biliary atresia - cystic structure at porta hépatis. Cholangiogram shows absent or abnormal intrahepatic ducts (choledochal cyst would should normal, dilated or cystic intrahepatic ducts).

Question 25

Describe the proposed aetiologies of torticollis and management options

Answer 25

• Aetiologies of congenital torticollis = trauma vs tumour.
  
  • Trauma - injury to the SCM during the birthing process (higher rates in breech presentations)
  • Tumour - benign ‘tumour’ of shortened and fibrotic SCM.
    
    • Pathology: endomysial fibrosis (collagen and fibroblast deposition around atrophied muscle fibres)
    • DDx: ocular pathology, vertebral anomalies, clavicle fracture, plagiocephaly, craniosynostosis, CNS lesion.
• Aetiologies of acquired torticollis
  
  • Ocular muscle imbalance.
  • Cervical hemivertebrae
  • Infection
  • Trauma
  • Neoplasm
  • Inflammatory
• Management:
  
  • Physiotherapy - successful in >90%
  • Botulinum toxin if physiotherapy fails
  • Surgical management.

Question 26

Describe the types of stomas traditionally used in meconium ileus.

Answer 26

• Temporary stomas have traditionally been used in meconium ileus to allow downstream post operative irrigations.
  
  • Bishop-Koop:
    
    • End to side anastomosis with end stoma - Proximal limb anastomosed to distal limb which forms stoma.
  • Santulli and Blanc:
    
    • Proximal end stoma, distal end to side anastomosis.
  • Mikulicz:
    
    • Double barrelled end stoma with side to side anastomosis between proximal and distal limbs.
  • Tube enterostomy:
    
    • Loop with no stoma but tube to allow downstream wash.

Question 27

Name 3 congenital and 3 acquired causes of oesophageal stricture.

Answer 27

• Congenital:
  
  • Congenital oesophageal stenosis
    
    • 1 per 25000-50000, ⅓ associated with OA
    • 3 variants - tracheobronchial remnant, oesophageal web, diffuse fibrosis
    • Become clinically apparent with commencement of solid feeds.
  • Oesophageal duplication cyst
    
    • 1 per 8000, accounts for 15% of all GI duplications.
    • Shares common wall, 2 muscle layers, lined with GI epithelium.
  • Achalasia
    
    • 1 per 1000000, chronic motility disorder - poor or absent peristalsis, failure of lower oesophageal sphincter to relax.
    • Associated with Trisomy 21, congenital hypoventilation syndrome, glucocorticoid insufficiency.
• Acquired:
  
  • Caustic stricture
  • Inflammatory (eosinophilic oesophagitis)
  • Peptic stricture
  • Anastomotic stricture (post OA/TOF repair)

Question 28

Describe the metabolic derangements seen in infantile hypertrophic pyloric stenosis

Answer 28

• Metabolic derangements (hypochloraemic, hypokalaemic metabolic alkalosis)
  
  • Repeated vomiting (loss of H+, Cl-, K+) coupled with inadequate oral intake (hypovolaemia)
    
    • Metabolic alkalosis
      
      • Fasting state → decreased pancreatic exocrine HCO3- secretion - retained HCO3-
  • Acid-base buffers
    
    • Cellular - H+/K+ exchange - worsens serum K+ (as moves intracellular)
    • Renal
      
      • Attempted excretion of HCO3- (coupled with Na+ and H2O)
      • RAAS retention of Na+ and H2O = at expense of K+ (worsens hypokaelamia)
      • Severe hypokalaemia → aldosterone mediated reabsorption of K+ in exchange for H+ → paradoxical aciduria

Question 29

What are 3 causes of intestinal failure not associated with short bowel syndrome?

Answer 29

• Motility disorders
  
  • Intestinal pseudo-obstruction
• Mucosal enteropathies
  
  • Microvillous inclusion disease
  • Tufted enteropathy

Question 30

What are the risk factors and pathogenesis for Hirschsprung associated enterocolitis?

Question 31

Which factors are thought to contribute to the formation of biliary atresia (6)?

Answer 31

• Foetal viral infection/exposure - CMV, EBV, reovirus have all been implicated in the formation of biliary atresia
• Genetic predisposition
• Abnormal ductal plate remodelling
  
  • Normally occurs centrally and expands peripherally. Immature/embryonic appearing bile ducts seen in biliary atresia.
• Immune mediated inflammation
  
  • HLA-B12 antigens and MHC-class II have both been implicated in an immune mediated destruction of bile ducts.
• Intra and extra hepatic duct malunion (pancreaticobiliary ductal malunion)
  
  • Biliary tree forms in two parts (extra hepatic from diverticulum, intrahepatic corresponds to portal vasculature development - they normally fuse in 12/40. Abnormalities in the union of the two components may result in BA.
• Environmental exposure
  
  • Environmental toxins such as biliasterone (found in several Australian plants) have been implicated in the formation of BA in animal models.

Question 32

Describe 3 theories associated with the formation of CDH

Answer 32

• Failure of muscularisation of the diaphragm
  
  • Failed closure of pleuroperitoneal canal prior to midgut returning → diaphragmatic hernia → space occupying lesion in thoracic cavity → abnormal lung development and subsequent abnormal pulmonary vascular development.
• Abnormal lung development results in abnormal diaphragmatic development.
  
  • Abnormal lung buds effect post-hepatic mesenchymal plate and disturb diaphragm development.
• Teratogen exposure
  
  • Nitrofen dosing in rodent embryos → formation of CDH
• Retinoic acid/Vitamin A deficiency
  
  • Associated with formation of CDH in rodents.
• Likely two hit model - Abnormal lung development AND abnormal diaphragm development.

Question 33

Describe the two common types of CDH

Answer 33

• Posterolateral - “Bochdalek” - 90% of all CDH.
  
  • Usually left sided (85%) - right pleuroperitoneal canal closes first (liver)
    
    • Failure of closure of the pleuroperitoneal canals by the pleuroperitoneal membrane (usually occurs in the lumbocostal triangle).
• Anterior - “Morgagni” - 10% of all CDH

Question 34

Discuss the pathogenesis of complicated and uncomplicated meconium ileus.

Answer 34

• Meconium ileus occurs due to:
  
  • Inspissated mucosal secretions PLUS viscid, protein reach, low water content pancreatic exocrine secretions → intraluminal intestinal obstruction.
• Complicated meconium ileus = inspissated meconium PLUS volvulus, gangrene, perforation, atresia, peritonitis:
  
  • Obstructed lumen perforates → atresia, meconium peritonitis, meconium ascites, meconium cyst.
    
    • Atresia - usually due to a segmental volvulus in utero - approx 15% of neonates with jejunal atresia have CF.
    • Meconium peritonitis (up to 40% CF) - four types:
      
      • Adhesive meconium peritonitis.
      • Giant cystic meconium peritonitis
      • Meconium ascites
      • Infected meconium peritonitis

Question 35

What mechanisms limit oesophageal injury once exposed to refluxate?

Answer 35

• Saliva - neutralises refluxate, but also acts as a lubricant to assist clearance of refluxate.
• Reduction in acid volume (PPI)
• Avoiding reflux of bile acids, pepsin and trypsin.

Question 36

Describe the physiological derangements in infantile hypertrophic pyloric stenosis

Answer 36

• Main metabolic derangement is hypochloraemic, hypokalaemic metabolic alkalosis PLUS decreased loss of volume and decreased oral intake → hypovolaemia.
  
  • Physiological change:
    
    • Respiratory buffer - decrease respiratory rate in attempt to preserve CO2.
    • Tachycardia - maintain cardiac output in context of hypovolaemia.
    • Decreased urine output - maintain volume in context of hypovolaemia.
  • If metabolic derangement severe and prolonged:
    
    • Decreased level of consciousness/seizure - secondary to hypoglycaemia +/- hyponatraemia.
    • Cardiac arrhythmias - hypokalaemia
    • Hypotension and tachycardia, anuria - hypovolaemic shock
    • Respiratory depression - severe metabolic alkalosis (loss of CO2 mediated respiratory drive).

Question 37

What are the types (Kasai) of biliary atresia?

Answer 37

Type 1 = CBD atresia only

Type 2a = Common hepatic duct atresia

Type 2b = CBD and common hepatic duct atresia (plus cystic)

Type 3 = All extrahepatic ducts affected

Type 3 accounts for 90% of all biliary atresia

Question 38

What is achalasia, what conditions is it associated with (5) how does it present and what is its natural history?

Answer 38

• Achalasia is a congenital oesophageal motility disorder characterised by poor or absent oesophageal peristalsis coupled with a failure to relax the lower oesophageal stricture with swallowing.
  
  • Associated with: Trisomy 21, central hypoventilation syndrome, glucocorticoid deficiency, Chagas disease, Allgrove Syndrome (achalasia, alacrima - lacrimal secretory disorders, adrenocorticotropic hormone insensitivity).
• Presentation:
  
  • Infants - regurgitation, choking, pneumonia and FTT
  • Older Children - dysphagia, regurgitation, retrosternal chest pain, weight loss.
• Diagnosis:
  
  • Barium swallow - dilated (mega)oesophagus, minimal or no opening of lower oesophageal sphincter (“birds beak”)
  • Oesophageal manometry - elevated LOS pressure, failure of coordinated relaxation with swallowing, abnormal or absent peristalsis.
• Natural history:
  
  • Infants - some will spontaneously resolve (treatment usually non-operative, botox or temporary gastrostomy)
  • Older children - progressive, incurable (treatment - calcium channel blockers, botox, pneumatic dilatation, oesophagomyotomy → coupled with anti reflux procedure (partial fundoplication).

Question 39

What are the risk factors for infantile hypertrophic pyloric stenosis (8)?

Answer 39

• Male > female
• First born
• Family history
• Caucasian
• Young maternal age
• Breastfed vs formula
• Erythromycin exposure
• Transpyloric feeding in premature neonates

Question 40

What are the most common causes of short bowel syndrome (5)?

Answer 40

Necrotising enterocolitis (30-35%)

Intestinal atresia (25%)

Gastroschisis (including vanishing) (18%)

Malrotation with volvulus (14%)

Long segment Hirschsprung disease (2%)

Older children/adults - Crohn’s disease

Question 41

What are the cells associated with healing of the liver in response to injury?

Answer 41

• Two tiered response to injury:
  
  • Hepatocytes -
    
    • Associated with increased proliferation and regeneration.
  • Hepatic stem cells -
    
    • Plentiful in the liver, usually activated when significant hepatocellular damage OR to replace hepatocyte loss through senescence or arrest (toxin mediated).
    • Stem cells differentiate into hepatocytes or bile duct cells.
    • If stem cells cannot regenerate faster than loss of cells, then hepatocytes are replaced by fibrosis → cirrhosis.

Question 42

Why does portal hypertension occur? What is its definition? What are 5 porto-systemic shunts?

Answer 42

Portal hypertension occurs when there is resistance to portal venous (mesenteric) flow through the liver.

Occurs when portal pressures > 5-8cm H20 or a pressure gradient > 5cm H20 between hepatic veins and portal circulation.

Portosystemic Shunts:

Re-opening/canalisation of left umbilical vein → caput medusae

Haemorrhoidal plexus (between systemic middle and inferior rectal veins and portal superior rectal vein)

Between left gastric vein (portal) and hemiazygous (systemic) - Oesophageal varices

Retroperitoneal - splenorenal shunt

Bare area of the liver

Question 43

Describe 5 complications of portal hypertension

Answer 43

• Oesophageal varices - haematemesis.
• Portal hypertensive gastropathy - Upper GI bleed/melaena.
• Haemorrhoids/rectal varices - haematochezia
• Ascites (associated synthetic dysfunction - hypoalbuminaemia = decreased oncotic pressure, coupled with increased hydrostatic pressure).
• Splenomegaly - thrombocytopaenia and leukopaenia
• Pulmonary disorders
  
  • Pulmonary hypertension (vasoactive substances shunted away from liver into systemic circulation)
  • Hepatopulmonary syndrome

Question 44

Describe ways in which cystic fibrosis affects patients outside the neonatal period (10)

Answer 44

• Respiratory:
  
  • Thick secretions → impaired clearance due to blocked mucociliary escalator → mucus and bacterial proliferation → chronic inflammation and recurrent infection → bronchiectasis (irreversible dilation of the airways).
  • Mucus plugging → obstruct bronchiole → segmental collapse.
• Pancreatic:
  
  • Thick secretions block the pancreatic duct → pancreatic autodigestion → pancreatitis + pancreatic destruction → pancreatic insufficiency.
• Biliary:
  
  • Increased rates of gallstones (25%).
  • Obstructed biliary system + hepatocellular damage secondary to free radicals → biliary cirrhosis (hepatic stellate cells become activated and produce collagen and cytokines (worsens inflammation) → cirrhosis.
• Gastrointestinal:
  
  • GORD (50-80%) - worsens pulmonary function.
  • Distal intestinal obstruction syndrome (DIOS) - 15-25%
    
    • Slow motility, undigested protein/fats + low water content of exocrine secretions → recurrent episodes of partial or complete obstruction - usually teenage and young adults - usually ileocaecal.
  • Rectal prolapse (15%)
  • Atypical appendicitis (4%) - less frequent than normal population but usually atypical because of ABx use.
  • Intussusception (1%)