Antenatal corticosteroid for metal lung maturation

Question 1

Under what conditions are pregnant ladies advised to have corticosteroid administration before anticipated preterm birth?

Answer 1

A single course of coroticosteroids (betamethasone) is recommended for pregnant women between 24 0/7 weeks and 33 6/7 weeks of gestation who are at risk of preterm delivery within 7 days
Under the following conditions
* Multiple pregnancy where preterm birth is anticipated before 34+0 weeks of gestation
* Pregnancies where late preterm birth between 34+0 and 36+6 weeks of gestation is anticipated

Question 2

What are some causes of intrauterine growth restriction?

Answer 2

• Placental insufficiency: unexplained elevated maternal AFP, preeclampsia
• Chronic maternal disease: CVD, DM, HT
• Abnormal placentation: abruptio placentae, placenta previa, infarction, circumvallate placenta, placenta accretia, haemangioma
• Genetic disorders: family history, trisomy 13, 18,21, triploidy, turner syndrome
• Malformations
• Immunologic: antiphospholipid syndrome
• Infections: CMV, Rubella, herpes, toxoplasmosis
• Metabolic: phenylketonuria, poor maternal nutrition
• Substance abuse (smoking, alcohol, drugs)
• Multiople gestation

Question 3

Define IUGR

Answer 3

Estimated fetal weight below the 10th percentile for its gestational age and whose abd circumference is below the 2.5th percentile.

At term, the cutoff birth weight for IUGR is 2,500g.

Question 4

Define symmetric vs asymmetric IUGR

Answer 4

Symmetric growth restriction implies a fetus whose entire body is proportionally small.

Asymmetric growth restriction implies a fetus who is undernourished and is directing most of its energy to maintaining growth of vital organs, such as the brain and heart, at the expense of the liver, muscle and fat. This type of growth restriction is usually the result of placental insufficiency.
Has normal head dimension but a small abd circumference (decreased muscle mass) and thinned scan (because of decreased fat). If the insult causing asymmetric growth restriction is sustained long enough or is severe eniough, the fetus may lose the ability to compensate and will become symmetrically growth restricted. Arrested head growth is of great concern to the developmental potential to the fetus.

Question 5

What is the value for symphysiofundal height that raises suspicion of IUGR?

Answer 5

A fundal height that lags by more than 3cm or more is increasing in disparity with the gestational age may signal IUGR
A lag of 4cm or more certainly suggests growth restriction.

Question 6

How can USG be used to assess for growth restriction?

Answer 6

Fetal biparietal diameter and head circumference(top), fetal abd circumference (center), fetal abd circumference (bottom)

Ratio of the head circumference to the abd circumference (HC/AC). Between 20 and 36 weeks of gestation, the HC/AC ratio normally drops almost linearly between 1.2 to 1. The ratio is normal in the fetus with symmetric growth restriction and elevated in the infant with asymmetric growth restriction.

USG can also be used to assess amniotic fluid index value (oligohydramnios + IUGR is a bad combination and early delivery should be considered): calcualted by summing the largest cord free vertical pocket in each 4 quadrants of an equally divided uterus.

Question 6

How to decide the timing of delivery in preeclampsia patient?

Answer 6

There is a balance between preventing intrauterine demise because of chronic oxygen deprivation and giving birth too preterm.
Preterm delivery is indicated if the growth restricted fetus demonstrates abnormal fetal function tests, and is often advisable in the absence of demonstrable fetal growth.
* Risks of prematurity must be weighed against the complications unique to IUGR

Question 7

How can doppler ultrasound be used to assess fetal compromise?
What features indicate poor perinatal outcome?

Answer 7

• Umbilical artery dopppler velocimetry measurements reflect resistance to blood flow from the fetus to the placenta. It is an indirect measure of placental function and fetal status.
• Because of placental capacitance, the umbilical artery is one of the few arteries that has forward diastolic flow.
• Decreased diastolic flow with a resultant increase in systolic to diastolic ratio suggests increased placental vascualr resistance and fetal compromise. Also pulsatility index and resistance index are measures of resistance to blood flow of the placental vasculature.
• Severely abnormal umbilical artery doppler velocimetry (define as absent or reversed diastolic flow) is associated with poor perinatal outcome, particularly in the setting of fetal growth restriction. (if there is no fetal growth –> indication for considering preterm delivery)

Question 8

What are the factors that affect placental resistance?

Answer 8

• GA (gestational age)
• Placental location
• Pregnancy complications (placental abruption, preeclampsia)
• Underlying maternal disease (chronic hypertension)

Question 9

What are the indications for using umbilical artery (UA) doppler velocimetry?

Answer 9

• Fetal growth restriction
• Cord malformations
• Unexplained olighydramnios
• Suspected or established preeclampsia
• Possibly fetal cardiac anomalies

Should not be performed routinely on low risk women

Question 10

What is the management approach in a pregnancy demonstrating fetal growth restriction

Answer 10

Question 11

How long is the effect of corticosteroids for antenatal administration?
What is the max number of cycles of administration?

Answer 11

Lasts for 2 weeks
2: rarely will give 2 (there is increased chance of neurological complications)

Question 12

What is management for mother with signs of labor before <34 weeks?

Answer 12

Tocolysis with betamethasone given. Allow 24 hours after first dosage before inducing labor to allow effect of steroids to mature the fetal lung.