1. Small for Gestational Age (SGA) Fetus
Small for Gestational Age (SGA) Fetus. Diagnostic and Management Dilemmas.
Dr. Dan Valsky
Fetal Medicine Unit
Department of Obstetrics and Gynecology
Hadassah University Hospital - Mt. Scopus
Jerusalem, Israel

2. SGA: Definition and Diagnosis
Before the early 1960s, it was assumed that a newborn with a birth weight less than 2500 g was “premature.”
Lubchenco recognized that there exists a cohort of newborns who do not achieve their growth potential, and that their failure to do so imparts a significant burden of increased perinatal mortality as well as short- and long-term childhood morbidity.
Hansmann in 1973 incorporated the concept of evaluating fetal growth in reference to percentiles

3. Early IUGR: Definition and Diagnosis

4. הגדרה הערכת משקל עוברית מתחת לאחוזון 10.
כל עובר בקטגוריה זו נכנס להגדרה של SGA (Small for Gestational Age)
אבחון SGA מתחת ל-32 שבועות נקרא SGA מוקדם.
אבחון SGA מעל 32 שבועות נקרא SGA מאוחר.
p10
p50
IUGR+SGA
NORMAL+IUGR

5. אבחנה
קליניקה – מדידת המרחק בין החלק העליון של הסימפיזיס פוביס עד לפונדוס. לאור רגישות נמוכה של שיטה זו היא אינה מהווה כיום נדבך חשוב באבחנה של SGA
אולטרה סאונד – הוא הכלי העיקרי באבחון ההערכה כוללת :
וידוא גיל ההריון.
ביצוע ביומטריה עוברית וחישוב משקל העובר.
קביעת אחוזון.

6. אבחנה: וידוא גיל ההריון
אבחנה: וידוא גיל ההריון
גיל ההריון נקבע על פי תאריך הוסת האחרונה במידה והוסתות סדירות ועל פי בדיקת אולטרה סאונד בשבועות מוקדמים כאשר הדיוק של מדידת האורך CRL של העובר הוא +/- 3 ימים.
תיקון לגיל ההריון ייעשה אם בדיקת על-קול שבוצעה ב-13 השבועות הראשונים תגלה פער של יותר מ-6 ימים, או אם בדיקת על-קול שבוצעה בין השבועות תגלה פער מעל 10 ימים.
בשבועות מתקדמים יותר של ההריון, כאשר אין US מוקדם לתארוך מדויק, יש להשתמש במדידה של הצרבלום. קוטר הצרבלום (TCD) אינו מושפע כמעט מקצב גדילת העובר.

7. אבחנה: ביומטריה עוברית
אבחנה: ביומטריה עוברית
אפשר לחשב את משקל העובר על פי נוסחאות שונות הכוללות בתוכן את מדדי הראש, הבטן והפמור של העובר.
HC & BPD AC FL +
=EFW

8. אבחנה: קביעת אחוזון
משקל העובר יתורגם לאחוזון על פי טבלה המייצגת גדילת עוברים בקרב האוכלוסיה הנבדקת.
p10
p50
IUGR+SGA
NORMAL+IUGR

9. + =EFW SGA: Definition and Diagnosis IUGR+SGA NORMAL+IUGR HC & BPD ACFL +
=EFW
p10
p50
IUGR+SGA
NORMAL+IUGR

10. Integrated Definition
Early IUGR: Definition and Diagnosis
Population references:
They provide birthweigh pecentile at each gestational week, but infants born preterm are more likely to be IUGRs.
Prospective studies:
They don’t give a longitudunal growth pattern and dont assess individual growth parameters
Retrospective ultrasound based:
They have a selection bias, eg, why some women receive US examination at non routine week?
The individualized approach:
Incorporate information about fetal growth potential based on maternal and fetal parameters ( race, BMI, sex, parity…)
So as fetal weight is not good enough for IUGR definition’ some other parameters should be used.
Fetal well being parameters are nor enough sensitive ( AF, NST, BPP)
But some Doppler parameters are good.
As fetal weight alone cannot predict accurately perinatal mortality and morbidity it shoul be integrated with other parameters of fetal or placental health.
Zhang J, Kramer M, AJOG, 2010

11. Abnormal Fetus SGA Constitutional IUGR SGA: Definition and Diagnosis
Fetal Abnormalities
Aneploidy
Malformations
Infections
Multiple Gestations
Maternal Diseases
Vascular/renal
Thrombophilias
Drugs
Extreme undernutrition
Placental Abnormalities
Chorioangioma
Confined placental mosaisism
Chronic placental abruption
Idiopathic Placental Insufficiency

12. בירור : גורמים עובריים שלילת מומים אנטומיים ביצוע אקו לב עוברי
הערכת שליה וחבל טבור
יעוץ גנטי
שלילת סימני זיהום תוך רחמי
בדיקת זרימות (דופלר)

13. 15% 85% Abnormal Fetus SGA Constitutional IUGR
Early IUGR: Definition and Diagnosis
Abnormal Fetus
IUGR
SGA Constitutional
15%
85%
Fetal Abnormalities
Aneploidy
Malformations
Infections
Multiple Gestations
Maternal Diseases
Vascular/renal
Thrombophilias
Drugs
Extreme undernutrition
Placental Abnormalities
Chorioangioma
Confined placental mosaisism
Chronic placental abruption
Idiopathic Placental Insufficiency
The differenciation between SGA and IUGR is ABNORMAL Doppler ( UA)

15. Placental compromise

16. Depending on the maternal history and ultrasound findings, further diagnostic evaluation may require any or all of the following:
● Fetal karyotyping.
● Maternal serum studies for evidence of seroconversion
when there is suspicion of viral infection, with
specific amniotic fluid viral DNA testing when indicated.
● Careful observation for early detection of preeclampsia.
● Evaluation of the congenital and acquired thrombophylic disorders, particularly if a previous pregnancy was complicated by early and severe preeclampsia.

17. MANAGEMENT Risk factors assessment and modification
Interval growth evaluation
NST
BPP
Doppler studies

19. Types of Doppler
Pulse Doppler
Color Doppler
Power Doppler

20. Doppler systolic-diastolic waveform indices of blood flow velocity.
S/D Ratio
(S-D)/S - resistance index (RI)
(S-D)/mean – pulsatility index (PI)

21. Umbilical Artery 21

22. Umbilical Artery

23. Early IUGR: Definition and Diagnosis
Umbilical artery
UA Doppler indices correlate with fetal levels of glucose, AA,blood gases, and could be a surrogate measurement of placental function *
UA is a risk discriminator tool in the management of SGA fetuses**
Increased UA impedance (AREDF) is associated with an increased risk for perinatal mortality, morbidity and long term abnormal neurodevelopment***
The use of UA Doppler associated with 30% reduction in perinatal mortality and improvement of number of perinatal outcomes ****
To give an example of Umbilical art flow, normal and abnormal. So explain PI, to tell how the measurement should be done
** those studies show that the outcome of small fetuses with normal UA is the same like AGA. So it rised a question if these fetuses should be monitored at all. In this aspect UA is discriminatory, as shows us, who are at risk for adverse outcome ( abnormal UA) and who are not ( normal UA )
*** It does not mean that each fetus with such pattern should be delivered, as there is onothe rmore important factors which should be considered ( as gestational age, by being more strong, or DV , by being more specific )
**** it was based on the data from several studies included 7000 fetuses
* Karsdorp, Eur J Obstet Gynecol Reprod Biol, 1994, Nicolaides, BMJ,1998
** Ott WJ, JUM, 2000, Bashat AA, AJOG, 2000
*** Cosmi E, Obstet Gynecol, 2005, Valcamonico, AJOG, 1994
**** Nelson JP, Cochrane Database, 2000

24. Early IUGR: Definition and Diagnosis
85-90%
10-15%
PEG

25. Middle Cerebral Artery (MCA)

26. Ductus venosus (DV)

27. Placental Resistance Early IUGR: Doppler Assessment
Subclinical placental disease
Compensated hypoxia
Decompensated hypoxia (acidosis)
Fetal death

28. Placental Resistance Early IUGR: Doppler Assessment
Subclinical placental disease
Compensated hypoxia
Decompensated hypoxia (acidosis)
Fetal death

29. Placental Resistance Early IUGR: Doppler Assessment
Subclinical placental disease
Compensated hypoxia
Decompensated hypoxia (acidosis)
Fetal death
When 30% of placenta ill- UAPI wil increase
Brain redistribution
Fetal developmant- delay in achievement of develpmental milestones:
- increased HR
- lower variability
- delayed reactivity 29

30. Placental Resistance Early IUGR: Doppler Assessment
Subclinical placental disease
Compensated hypoxia
Decompensated hypoxia (acidosis)
Fetal death
When villous oblitaration is more than 50% of placental area
First clinical sign is AEDF in UA
Risk of acidemia increases
2 Doppler parameters should be mentioned here as they are critical for severity assessment at this stage ant as we will see for prognosis:
- DV
- Aoi 30

31. Placental compromise

32. Placental Resistance Early IUGR: Intervention threshold C B A
Subclinical placental disease
Compensated hypoxia
Decompensated hypoxia (acidosis)
Fetal death
Where shoul be the intervention threshold be?
A - Risk of fetal death vs severe prematurity
B - Less risk of death, less decompensative hypoxia period but still prematurity
C- No risk of death, theoretically small risk of neurological influence, but highr risk of prematurity, so could be appropriate policy from some week of pregnancy, where the risk of prematurity complications is small
How this cut off should be defined ( DV?? Which changes, BPP, which changes ??) 32

33. Placental Resistance Early IUGR: Intervention threshold >32w 28-32w
Abnormal BPP
>32w
28-32w
<28w
Subclinical placental disease
Compensated hypoxia
Decompensated hypoxia (acidosis)
Fetal death
In BCN – before 28 weeks of gestation, according to the literature ( Bashat) when the most important factor is GA, only severe DV changes are considered abnormal – Reversed a wave
week when the risk of prematurity is less- absent A vawe will be considered as abnormality of DV, which nessesitates delivery
- after 32 week – when the risk of prematuruty is low, any abnormality of DV, for example elevated PI, will be considered as a reason for delivery.
BPP lost in sequential manner, which is determined by differemt sensitivity on pH
Loss of reactivity, breathing movement, gross movement, tone.
AF in mostly dependent on cardiac function and not a part of neural system deterioration. 33