Low birth weight and prematurity II Flashcards
Using doppler ultrasound to diagnose IUGR: which arteries could you use to diagnose IUGR? [2]
What ratio could you also use? And what would indicate brain sparing? [1]
Umbilical artery
Middle cerebral artery
Cerebral / placenta ratio: 1.0 - 1.1 = brain sparing
How would IUGR impact umblical and middle cerebral artery flow (especially type 2) [1]
- Normal: no diastolic backflow (means that there is blood flow through all points of cardiac cycle)
- IUGR (esp. type 2): umbilical flow restricted so that more blood is directed to brain. Vasodilation of the cerebral circulation causes brain sparing effect
in the normal situation the fetal MCA has a [high / low] resistance flow which means there is minimal antegrade flow in fetal diastole
in pathological states this can turn into a [high / low] resistance flow mainly as a result of the fetal head sparing theory
in the normal situation the fetal MCA has a high resistance flow which means there is minimal antegrade flow in fetal diastole
in pathological states this can turn into a low resistance flow mainly as a result of the fetal head sparing theory
What is normal v abnormal cerebral: placenta ratio? [2]
What does this indicate? [1]
cerebroplacental ratio: >1:1 is normal and <1:1 is abnormal
<1 = abnormal
Indicates more flow to cerebral atery than placenta (and therefore brain sparing)
Explain how you manage IUGR [5]
Identify etiology of IUGR then treatment of underlying cause:
Stop smoking, alcohol, protein energy supplementation, hypertension
Bed rest in left lateral position increases uteroplacental blood flow
Maternal oxygen therapy
55% O2 at 8L/min round the clock decreases perinatal mortality rate
No pharmacological therapy which can reverse IUGR
Delivery
Risk of prematurity versus risk of intrauterine death has to be judged
Antenatal steroids reduces incidence of respiratory distress syndrome, intraventricular hemorrhage and death for fetus of <1500g
Giving which vitamin can reduce incidence of pre-term babies and decreases mobiditiy and complications? [1]
Vitamin D
Adequate vitamin D reduces which pathologies? [3]
Adequate vitamin D reduces:
- sepsis
- ROP
- delayed retinal maturation
Why does giving cortiosteroids to neonate decrease impact of respiratory distress syndrome? [1]
Stimulates type 2 pneumocytes to develop quicker and produce surfactant
Explain the pathophysiology of respiratory distress syndrome
Inadequate surfactant leads to high surface tension within alveoli.
This leads to atelectasis (lung collapse), as it is more difficult for the alveoli and the lungs to expand.
Leads to inadequate gaseous exchange: causing hypoxia, hypercapnia (high CO2) and respiratory distress.
Describe the pathology of Intraventricular hemorrhage / periventricular leukomalacia:
What birth weight babies most likely? [1]
What is pathophysiology? [1]
Which disease is a risk factor for this? [1]
Intraventricular hemorrhage / periventricular leukomalacia:
- VLBW (less than 1500g) at greatest risk
- Resp. distress syndrome 4x more likely
- Pathology: blood vessels in the preterm may be more fragile and immature and cause small to large bleeds in brain ventricles
What does Intraventricular hemorrhage / periventricular leukomalacia look like on ultrasound? [1]
Honeycombed
Describe physiology of retinal blood vessels in normal fetus:
- when does it normally start & complete by? [2]
- Which directions do the retinal blood vessels grow? [1]
- What condition within the eye controls normal retinal development? [1]
Retinal blood vessel development starts at around 16 weeks and is complete by 37 – 40 weeks gestation.
The blood vessels grow from the middle of the retina to the outer area.
This vessel formation is stimulated byhypoxiawhich is a normal condition in the retina during pregnancy
Explain pathology behind retinopathy of prematurity
Normal conditions: vessel formation is stimulated byhypoxiawhich is a normal condition in the retina during pregnancy
Pre-term baby causes exposure to higher oxygen concentrations, particularly with supplementary oxygen during medical care, the stimulant for normal blood vessel development is removed
When the hypoxic environment recurs, the retina responds by producing excessive blood vessels (neovascularisation), as well as scar tissue.
These abnormal blood vessels mayregressand leave the retina without a blood supply. The scar tissue may causeretinal detachment.
Why do pre-term babies lose more heat than normal size baby? [4]
- large surface area relative to body mass
- Subcutaneous fat is less and less brown fat
- Inadequate thermal response (unstable)
- Skin may not be fully keratinised and thinner and poor capillary response to environmental changes
How do you treat pre-term babies who lose heat? [1]
Put in plastic bag
Explain pathophysiology of necrotising enterocolitis [2]
How serious? [1]
Part of the bowel becomes necrotic due to bacterial invasion of ischaemic bowell wall:
Causes large amount of gas in bowel: can cause perforation of bowel: leads to peritonitis & sepsis
It is a life threatening emergency
Label A-D of this Doppler ultrasound of an artery [4]
A: Systole
B: Average
C: Diastole
D: Diastolic notch
How does the A-wave in a ductus venosus doppler ultrasound present in a normal and IUGR fetus? [2]
Normally ductus venosus shows positive A wave.
Reversal of the A wave may be seen in severe intrauterine growth restriction as well as in tricuspid regurgitation.
Compare the flow between A & C of this doppler ultrasound.
A: showing normal flow
C: severely reduced flow with severe notch (see arrows).
