1. ISUOG Basic Training
Distinguishing between Normal & Abnormal Fetal Size
& Growth Patterns in Singleton & Twin Pregnancies
Trish Chudleigh, UK

2. Key questions
which maternal conditions are most frequently associated with abnormal fetal growth patterns?
which measurements should be taken to assess fetal growth correctly?
what are the typical ultrasound features of poor fetal growth?
what are the typical ultrasound features of macrosomic fetal growth?
how is fetal growth assessed in twin pregnancies?

3. Learning objective At the end of the lecture you will be able to:
use ultrasound to distinguish between normal & abnormal growth patterns in singleton & twin pregnancies

4. Growth patterns appropriate growth fetal growth restriction (FGR)
macrosomia
31 w ; 40w 1000 gram; 40w 3150 gram w 3150 gram; 40 w 4700 gr
Intrauterine growth restriction (IUGR) is one of the most common and complex problems in modern obstetrics. Diagnosis an management are complicated by the use of ambiguous terminology and lack of uniform diagnostic criteria….
Size alone is not an indication of a complication. As a result of this confusion, underintervention and overintervention can occur
Macrosomia
Comparison between a normal two-day-old baby (right) with two low birthweight babies (left and centre). The baby on the left was born nine weeks preterm; the baby in the centre was born full term but weighed only 1000 g. Science Photo Library.

5. Detecting, & interpreting, growth patterns
clinical assessment
maternal &/or fetal risk factors
measurement of fundal height
ultrasound
biometry (HC + AC [FL, BPD])
estimation of fetal weight (BPD, HC, AC, FL )
measurement of amniotic fluid (AFI or DVP)
umbilical & fetal Doppler studies
Symfyseal fundal height Low sensitivity, high false positive rates, significant intra- and inter-observer variation make this test alone unsuitable for diagnosis. 50% FGR missed

6. Risk factors SGA/FGR SGA / FGR Fetal: Maternal: chomosome anomaly
genetic syndrome
congenital anomaly
Maternal:
idiopathic
chronic disease
abnormal implantation
(PE, HELLP, antiphospholipid FGR
SGA / FGR
Placenta:
mosaicism
uterine anomaly
velamentous insertion
External factors:
smoking
infection
psycho / social

7. Outcome severe FGR
retrospective cohort study of 110 fetuses a very low birth weight (<1500 g)
survived
died within 1 week
died at 1-4 weeks
died at 4 weeks-1 year
Baschat 2011 these observations suggest that early onset growth delay, severity of FGR and prematurity significantly increase the risk for neurological sequelae and motor and cognitive delay. Slowing of head growth in particular is associated with decrease in perceptional performance, motor ability, cognition, concentration ability and defects in short-term memory, with subsequently poorer school achievement95. Studies with a higher proportion of patients delivered formaternal deterioration fail to demonstrate consistent differences compared with AGA controls (Table S1). One significant confounder of studies that consider growth parameters in isolation is that the degree of fetal compromise is not accounted for.
Birthweight
Chalubinski et al UOG 2012; 39: 293–298

8. Early FGR & late FGR early FGR, easy to diagnose, difficult to treat
late FGR, difficult to diagnose, easy to treat
Baschat 2011 Once the clinical diagnosis of FGR has been made, the progression differs in preterm and term pregnancies. In early-onset FGR before 34 weeks, late cardiovascular manifestations of placental dysfunction become more likely when the UA end-diastolic velocity is reversed (UAREDV). The typical pattern of deterioration progresses from escalating abnormalities in UA and venous Doppler parameters to abnormal biophysical parameters.
In contrast, in late-onset FGR presenting after 34 weeks, cardiovascular abnormalities do not extend beyond the cerebral circulation. As placental vascular dysfunction is less severe, a decreased CPR, with either normal or only minimally elevated UA Doppler indices, may be observed

9. Small for gestational age - SGA
newborn birth weight < 10th centile for GA
low-birth weight (< 2500 gms)
- preterm AGA: delivery < 37 weeks, appropriate size for GA
- preterm & growth restricted: delivery < 37 weeks, FGR
- term & growth restricted: delivery > 37 weeks, FGR
Intrauterine growth restriction (IUGR) is one of the most common and complex problems in modern obstetrics. Diagnosis an management are complicated by the use of ambiguous terminology and lack of uniform diagnostic criteria….
Size alone is not an indication of a complication. As a result of this confusion, underintervention and overintervention can occur

10. Macrosomia Definition Cut-off Prevalence neonate at term > 4.5 kg
1.3 – 1.5%
gestational age dependent
> 97th centile
birth weight at term
> 4.0 kg 7%
> 90th centile
Important is to realize
Campbell S. UOG 2014; 43: 3–10

11. Risk factors for macrosomia
maternal diabetes
gestational diabetes
maternal obesity
family history
genetic syndromes
Beckwith-Wiedemann
Sotos
Riskfactor 5-10% of macrosomia associated with maternal or gestational diabetes, recognized during pregnancy Macrosomic fetuses of non-diabetic women can be identified as being at risk by factors such as maternal obesity and family history but are generally unsuspected until the possibility of a big baby is raised by antenatal clinical or ultrasound examination.
BMI > 30 uit Campbell
BWS 1:13000 mutatie deletion Ch 11 but also other chroom, omphalocele, tumors
SGB x-linkedmutatie GPC3gen HD ventriculomeg polydactylie, corvitium
Sotos ccagen mutatie chrom 5spychomotor developm varieert sterk.
Okun et al. J Matern Fetal Med 1997;6:285–290

12. Macrosomia risk for mother risk for Infant emergency CS mortality
instrumental delivery
shoulder dystocia
trauma to birth canal
bladder, perineum & sphincter injury
risk for Infant
mortality
brachial plexus injury
facial nerve injury
fracture humerus / clavicle
birth asphyxia
If screening for the large-for-gestational age infant is to be attempted, it might be a good option to undertake a two-stage operation, i.e. a screening scan at around 32–34weeks’ gestation to identify a high-risk group, followed by a detailed scan at 39 weeks in those identified
as being large. The object of the earlier or triage scan
would be to achieve as high a sensitivity as possible so that
most large fetuses are in the screen-positive group.
Shoulder dystocia – more common in macrosomic infants – may contribute to perineal and anal sphincter trauma. Campbell 2014
Basso et al Am J Epidemiol 2006;164:303–311

13. Fetal growth/weight estimationHC
BPD AC
Femur
International standards for fetal growth based on serial ultrasound measurements: the Fetal Growth Longitudinal. Study of the INTERGROWTH-21st Project
A list of search terms used has been published previously. We found 337 studies, which had substantial methodological heterogeneity, and none
met the WHO recommendations for monitoring fetal anthropometric measurements. The large number of charts available, the reference nature of their design (ie, they are related to a given place and time), and the variation in the cutoff points used to define abnormal growth, make it difficult in routine clinical practice to identify fetal growth restriction (FGR). International From our cohort of healthy, well nourished pregnant women prospectively enrolled from 8 geographically diverse populations, and whose risk of adverse maternal and perinatal outcomes (including FGR) was low, we have generated the fi rst international standards for fetal growth based on the primary ultrasound measures of HC BPD OFD, AC, Femur length, according to gestational age. Combined with our newborn standards,45 the new fetal standards are for use worldwide to diagnose FGR uniformly and monitor growth from early pregnancy through to the neonatal period. We recommend these tools for the interpretation of routine ultrasound measurements and comparisons across populations.
Papageorghiou et al Lancet 2014;384:869-79

14. Fetal growth/ weight estimation

15. Estimated fetal weight
Hadlock (HC, AC, FL +/- BPD) - most reliable formulae
estimating fetal weight >3 kg - unreliable
Kurmanavicius et al J Perinat Med 2004;32:155-61

16. Normal growth (3rd, 50th ,97th, centile)X X X X X X X X X X X X X X X X X X X X X X X X

17. Symmetrical reduction in growth velocity
reduction or restriction?

18. Asymmetrical reduction in growth velocity

19. Asymmetrical reduction in growth velocity

20. Asymmetrical increase in growth velocity

21. HC/AC ratio H/A falls during pregnancy HC>AC up to 38wks
HC<AC after 38 weeks

22. Growth patterns using H/A ratio
Asymmetrical growth restriction
Normal,
Symmetrical growth restriction
Large HC with small AC
Small HC with normal AC
Poor diabetic control,
Microcephaly

23. Ultrasound detection of FGR
serial biometry superior to single estimates in prediction of FGR
combine with assessment of amniotic fluid
time interval, at least two weekly for biometry
normal growth - value of umbilical & fetal Doppler?
ultrasound screening after 24 weeks in low-risk pregnancies does not improve perinatal outcome
Ultrasound has a maximum random error of approximately 100 g/kg,
which means that weight predictions in grams for small fetuses appear to be more clinically useful. Uit Campbell macrosomia uog 2014
Need to allow the fetus an opportunity to grow…. 23

24. Assessing growth in practice
HC AC
EFW
admitted for pre-eclampsia & FGR at 29w, CS maternal indication at 32w+5d
Bwt 1419gr (~15th percentile)
last EFW 1098gr (~2nd percentile) at 30w+5d
Via portfolio pim schol Echo TKD jan 2016

25. Ultrasound detection of macrosomia
assess risk factors
US for fetal size at weeks
If > P90 repeat US at weeks
Campbell UOG 2014
If screening for the large-for-gestational age infant is to be attempted, it might be a good option to undertake a two-stage operation, i.e. a screening scan at around 32–34weeks’ gestation to identify a high-risk group, followed by a detailed scan at 39weeks in those identified as being large. The object of the earlier or triage scan would be to achieve as high a sensitivity as possible so that
most large fetuses are in the screen-positive group
Campbell UOG 2014; 43: 3–10

26. Assessing growth in practice
IVF
BMI 28.6
30w
BPD HC AC
AFI
BPD HC AC
FL EFW BWt
38w
female, 4205g
no anomalies
57203 IVF, bmi 28,6 induced 38w2d 4205 gram no anomalies

27. Khalil et al ISUOG Practice Guidelines Twins
Monochorionic twin pregnancy
Monitoring twins
Dichorionic twin pregnancy
Khalil et al ISUOG Practice Guidelines Twins
UOG 2016; 47: 247–263.

28. Twins – early growth patterns
25% difference in size in MZ & DZ
DZ difference in growth potential MZ
unequal placental sharing
blood vessel anastomoses
structural anomaly
chromosomal anomaly
CRL
Already in 1st trimester

29. Monitoring later growth in twins
Dichorionic twins
US every 4 weeks from 20 weeks
when size difference > 20%, every 2 weeks
Monochorionic twins
US every 2 weeks from 14 weeks
biometry
deepest vertical pool
Doppler UA-PI & MCA PS velocity
Khalil et al ISUOG Practice Guidelines Twins
UOG 2016; 47: 247–263.

30. Polyhydramnios & oligohydramnios
DVP
≥ 8
<2
AFI
≥ 24
<5

31. Key points use HC & AC to assess growth velocity
use BPD, HC, AC & FL to assess EFW
leave at least 14 days between scans
be aware of causes of impaired & increased fetal growth
chorionicity determines when, & how frequently, serial scans should be performed
assess amniotic fluid at each scan (deepest pool)