Neonatology 6 Flashcards
What are the features of ambiguous genitalia?
Male: o Severe hypospadias with bifid scrotum o Undescended testis/testes with hypospadias o Bilateral non-palpable testes Female: o Clitoral hypertrophy of any degree o Non-palpable gonads o Vulva with a single opening
What can a disorder of sexual differentiation be secondary to?
o Excessive androgens producing virilisation in female- congenital adrenal hyperplasia
Inadequate androgen in males- abnomralities with conversion or synthesis from cholesterol
o Gonadotrophin insufficiency- seen in Prader-Willi syndrome and congenital hypopituitarism – small penis & cryptorchidism
o Ovotesticular disorder of sex development (DSD)- caused by XX & Y containing cells being present in the foetus leading to both testicular and ovarian tissue being present and complex external phenotype
What is congenital adrenal hyperplasia?
Number of autosomal recessive disorders of adrenal steroid biosynthesis result in congenital adrenal hyperplasia
1 in 5000
• Over 90% have a deficiency in the enzyme 21-hydroxylase- which is needed for cortisol biosynthesis
• About 80% are unable to produce aldosterone- leading to low sodium and high potassium
• In the foetus, the resulting cortisol deficiency stimulates the pituitary to produce ACTH- which drives overproduction of adrenal androgens
How does congenital adrenal hyperplasia present?
o Virilisation of the external genitalia in female infants- with clitoral hypertrophy and variable fusion of the labia
o In the infant males, the penis may be enlarged and the scrotum pigmented, but these changes are seldom indentified
o A salt-losing adrenal crisis in the 80% of males who are salt losers will occur at 1-3 weeks of age and present with vomiting, weight loss, floppiness and circulatory collapse
o Tall stature in the 20% of male non-salt loser- both male and female non-salt losers also develop a muscular build, adult body odour, pubic hair and acne from excess androgen production – leading to precocious puberty
How is congenital adrenal hyperplasia diagnosed?
- There may be a family history of neonatal death if a salt losing crisis has not been recognised and treated, diagnosis is made by finding markedly raised levels of the metabolic precursor 17 alpha-hydroxyprogesterone in the blood
- In salt loser- the abnormalities are low sodium, high potassium, metabolic acidosis and hypoglycaemia
What is the management for congenital adrenal hyperplasia?
corrective surgery in females
Salt losing crisis- IV saline, dextrose & hydrocortisone are needed
o Lifelong glucocorticoids to suppress ACTH levels and to allow normal growth & maturation
o Mineralocorticoids if there is salt loss
o Monitoring growth, skeletal maturity and plasma androgens insufficient HRT will lead to increased ACTH, rapid initial growth and stunted end height
o Hormones are needed for illness or surgery as the patient cannot mount a cortisol response
What is Potter’s syndrome?
A typical physical appearance- which is the result of a dramatically decreased amniotic fluid volume (oligohydramnios) secondary to renal diseases such as bilateral renal agenesis (BRA)
• Intrauterine compression of the foetus from oligohydramnios caused by lack of foetal urine causes a characteristic facies, lung hypoplasia and postural deformities including severe talipes, the infant may be stillborn or die soon after birth from respiratory failure
What are the features of Potter facies?
Low-set ears
Beaked nose
Prominent epicanthic folds and downward slant eyes
Pulmonary hypoplasia causing respiratory failure
Limb deformities
What can Potter’s syndrome also be due to?
o Polycystic kidney disease
o Renal hypoplasia
o Obstructive uropathy
• Any disease that impairs urine production causes oligohydramnios whilst disease that impairs foetal swallowing (eg. TOF or atresia) causes polyhydramnios
• Amniotic fluid is critical to pulmonary development- without it the consequences are pulmonary hypoplasia and respiratory distress at birth
How do the kidneys develop?
kidneys develop between weeks 5-7 with ongoing urine production from about week 14- amniotic fluid is a dynamic product and foetal urine is a major contributor to its production from the 2nd trimester- foetal swallowing recycles amniotic fluid
What are the causes of haemolytic anaemia?
o Immune- haemolytic disease of the newborn
o Red cell membrane disorders- hereditary spherocytosis
o Red cell enzyme disorders- glucose-6-phosphate dehydrogenase deficiency
o Abnormal haemoglobins- alpha-thalassaemia major
What is haemolytic disease of the newborn?
autoimmune condition that develops in a foetus, maternal IgG pass through the placenta including some which attack RBCs in the foetal circulation leading to haemolysis-foetus can develop reticulocytosis and anaemia
Moderate or severe– erythroblasts found in foetal blood- sometimes called erythroblastosis fetalis
What is foetal maternal haemorrhage?
if similar incompatibility occurs in subsequent pregnancies (eg. Rhesus D)
Abortion
Childbirth
Rupture in placenta during pregnancy
Medical procedures during pregnancy that breach the uterine wall
o Mother has received a therapeutic blood transfusion- ABO blood groups and Rh typing is routine prior to transfusion to try to prevent this
o Mothers with type O blood group- more prone to make IgG anti-A & anti-B antibodies which can cross the placenta
What are the causes of hypoxic ischaemic encephalopathy?
o Reduced umbilical blood flow- cord compression including cord prolapse and shoulder dystocia
o Reduced placental gas exchange- placental abruption, excessive/prolonged uterine contractions, ruptured uterus
o Reduced maternal placental perfusion-IUGR
o Maternal hypoxia
o Compromised foetus- anaemia or IUGR
o Inadequate postnatal cardiopulmonary circulation- failure to breath
What are the symptoms of hypoxic ischaemic encephalopathy?
o Level of consciousness
o Muscle tone
o Posture
o Tendon reflexes
o Suck
o Heart rate
o CNS homeostasis
Renal failure, DIC, hypotension, PPHN, hypoglycameia/calcaemia/natraemia
• Clinical manifestations start immediately (<48hrs) after asphyxia- may be from primary neuronal death (immediate) or reperfusion injury causing secondary neuronal death (delayed)
there should be respiratory depression at birth and a need for resuscitation, including IPPV- there should be moderate-severe acidosis soon after birth (pH <7)
