Fetal growth restriction

Question 1

Definitions of:

1. Small for dates
2. Large for dates
3. Low birthweight
4. Fetal macrosomia
5. Fetal growth restriction

Answer 1

1. Below 10th centile at birth for that gestational age
2. Above 90th centile at birth for that gestational age
3. Below 2.5kg at birth
4. Above >4kg at birth
5. Below the 10th centile at birth for that gestational age and doesn’t reach its own growth potential

Question 2

What are the different ways in which fetal surveillance may be carried out?
Give what time they are used

Answer 2

1. Ultrasound of fetal growth- from first trimester
2. Doppler umbilical artery waveform- 3rd trimester
3. Doppler waveform of fetal circulation- only used in high risk pregnancies
4. Biophysical profile- used from 28 weeks onwards
5. CTG
6. Kick chart ie cardiff count to 10

Question 3

In the ultrasound of fetal growth, what can be measured?

Answer 3

Head circumfrence
Abdominal circumfrence
Femur length
Biparietal diameter

Question 4

What would you see in an abnormal umbilical artery doppler waveform? What is normal pattern?

Answer 4

Normal pattern is saw tooth pattern with forward direction of flow
Abnormal waveform may be absent or have reversed end diastolic flow

Question 5

In a growth ultrasound what are the three ways in which you can distinguish a healthy fetus from an growth restricted one?

Answer 5

1. Rate of growth using previous scans
2. Pattern of smallness- ie head sparing
3. Compared actual growth to expected growth using centile charts

Question 6

What is included in the biophysical profile on ultrasound?

What are the normal values of the Amniotic fluid index?

Answer 6

1. Amniotic fluid index
2. Fetal breathing
3. Fetal tone- ie slowed extension to partial flexion is abnormal
4. Fetal movement- <2 episodes of limb movements in 30 minutes is abnormal

Each pararemeter score 2, 4/8 is abnormal

AFI- 5-25cm, if below then oligohydroamnios or above then polyhydroamnios

Question 7

In terms of disease, what is the definition of intrauterine growth restriction?

Answer 7

When fetus is born with clinical features of malnutrition, or when they don’t reach their growth potential

Question 8

What are the 3 types of intrauterine growth restriction?

Answer 8

1. Symmetrical- circumfrences are all reduced, along with postnatal weight and length and HC
2. Assymmetrical- circumfrences all normal, and postnatal weight and length reduced but HC normal
3. Mixed IUGR

Question 9

Why is the post-natal HC normal in asymmetrical IUGR?

Answer 9

Because of headsparing effect, reduced resistance in the MCA

Question 10

What is important to conduct in the examination of someone carrying an IUGR fetus?

Answer 10

• Symphysis- fundal height done every time from 28 weeks- growth reduced
• BP and urine- exclude pre-eclampsia as this often causes it

Question 11

What are the investigations and management of IUGR

• if doppler normal
• Abnormal

Answer 11

• Doppler normal- then ultrasound and umbilical artery doppler waveform every 2 weeks
• Doppler abnormal but EDF present- then serial surveillance twice a week
• EDF absent or reversed- then serial surveillance every day

In preterms also do doppler waveform of ductus venosus

Question 12

Management of IUGR

• at term
• preterm

Answer 12

• Induction or C-section before 36 weeks, monitor with CTG when contractions begin
• preterm if previously normal doppler but abnormal now then admit to hospital, cortisosteroids <36 weeks,, when abnormal ductus venosus then C-section should be no later than 32 weeks

Question 13

What are the risk factors for IUGR? (maternal, placental, fetal)

Answer 13

Placental: multiple pregnancy, pre-eclampsia/other hypertensive diseases throughout pregnancy, APH, placental abruption, site of implantation

Fetal factors: Chromosomal abnormality, genetic syndromes, congenital structural defects, intrauterine infections eg TORCH, malaria, HIV, syphillis

Maternal: Extremes of age, alcohol, smoking, drugs, low socioecnomic class, maternal disease (type II diabetes, CKD, SLE, antiphospholipid syndrome), maternal infection- TORCH, HIV, syphillis

Question 14

In addition to growth ultrasounds and umbilical artery doppler waveform what other investigations would you conduct?

Answer 14

• karyotyping- especially if early symmetrical IUGR ie <23 weeks espeically if uterine artery doppler is normal
• Serological screening for CMV and toxoplasmosis- especially if structural abnormality

Question 15

What are the short term and long term concequences of IUGR fetus?

Answer 15

Short term- Hypoglycaemia, hypothermia, hypoxia, meconium aspiration, pneumonitis, pulmonary haemorrhage, cerebral palsy

Long term- poor growth and neurodevelopmental outcome, lower scores on cognitive testing, learning difficulties, more likely to get adult onset diseases during childhood ie type 2 diabetes, chronic hypertension

Question 16

What is an alternative definition of macrosomia?

Answer 16

Excessive intrauterine growth beyond the expected gestation

Question 17

What are the main causes of macrosomia?

Answer 17

Maternal diabetes 
Maternal obesity 
Male fetus 
Maternal age 
Overdue pregnancy >42 weeks delivery

Question 18

What are the complications associated with a macrosomic child?

Answer 18

• Shoulder dystocia
• Lung hypoplasia (cortisol inhibits surfactant production)
• Hypoglycaemia- have to be fed early
• Jaundice (birth trauma-RBC breakdown)