Management of SGA with 2SD increased UA PI and standard measurement 29/11/92Mojgan Barati

What is the optimal gestation to deliver the SGA fetus In the SGA fetus detected after 32

weeks of gestation with an abnormal umbilical artery Doppler, delivery no later than 37 weeks of gestation is recommended.

Purpose of SGA diagnosis unidentified SGA fetuses have a fourfold

greater risk of adverse fetal outcome Evidence level 2+

The purpose of surveillance is to predict fetal acidaemia thereby allowing timely delivery prior to irreversible end–organ damage and in–utero death

In pregnancies in which intrauterine growth restriction due to uteroplacental vascular insufficiency is diagnosed, maternal surveillance for the development of severe preeclampsia with adverse features is warranted

What is the optimal method and frequency of fetal surveillance in a SGA infant and what is/are the optimal test/s to time delivery?

-1 Umbilical artery Doppler -2 Cardiotocography (CTG) -3 Amniotic fluid volume -4 Biophysical profile (BPP) -5 Middle cerebral artery (MCA) Doppler -6 Ductus venosus (DV) and umbilical

vein (UV) Doppler - uterine art doppler (???)

SOGC Clinical Practice Guideline No. 295, August 2013

In cases in which the fetus measures < 10th percentile by estimated fetal weight or abdominal circumference measurement, the underlying cause of intrauterine growth restriction may be established by an enhanced ultrasound examination to include a detailed review of fetal anatomy, placental morphology, and Doppler studies of the uterine and umbilical arteries.

surveillance twice weekly When umbilical artery Doppler flow

indices are abnormal (pulsatility or resistance index > +2 SDs above

mean for gestational age) and delivery is not indicated repeat surveillance twice weekly in fetuses withend–diastolic velocities present

Evidencelevel 4 In SGA fetuses with abnormal umbilical

artery Doppler where there is not an indication for delivery the optimal frequency of surveillance is unclear. Until definitive evidence becomes available it is reasonable to repeat surveillance twice weekly in fetuses with end–diastolic velocities present and daily in fetuses with absent or reversed end–diastolic velocities (AREDV

Cardiotocography (CTG

CTG should not be used as the only form of surveillance in SGA fetuses A

Interpretation of the CTG should be based on short term fetal heart rate variation from computerised analysis. A

Amniotic fluid volume Ultrasound assessment of amniotic

fluid volume should not be used as the only form of surveillance in SGA fetuses.

Interpretation of amniotic fluid volume should be based on single deepest vertical pocket A

Interpretation of amniotic fluid volume should be based on single deepest vertical pocket A

The incidence of an AFI ≤ 5 cm in a low risk population is 1.5%.

Compared to cases with a normal AFI, the risk of perinatal mortality and morbidity was not increased in cases with isolated oligohydramnios nor in those with associated conditions, including SGA fetuses

Notably over the 8 weeks after the initial diagnosis of oligohydramnios, mean EFW centile did not change significantly

Evidencelevel 1+compared to a SDVP < 2 cm, when

an AFI ≤ 5 cm was used more cases of oligohydramnios were diagnosed and more women had induction of labour without an improvement in perinatal outcome.

Evidencelevel 1+ Oligohydramnios is associated with labour

outcome; a systematic review of 18 studies involving 10 551

women, found an AFI ≤ 5 cm was associated with an increased risk of caesarean section for fetal distress and an Apgar score < 7 at 5 minutes but not acidaemia.

Although older studies in high risk pregnancies have shown that a reduced SDVP is associated with increased perinatal mortality, limited information is available about the accuracy of oligohydramnios to independently predict perinatal mortality and substantive perinatal morbidity in non–anomalous SGA fetuses monitored with umbilical artery Doppler.

Biophysical profile (BPP) Biophysical profile should not be used

for fetal surveillance in preterm SGA fetuses.A

recent studies in preterm severely SGA fetuses suggest the BPP is not an accurate predictor of fetal acidaemia and that the test has much higher false negative rates (11%) in this group. BPP is not recommended for fetal surveillance in the preterm SGA fetus. Evidence level 2+

Middle cerebral artery (MCA) Doppler In the preterm SGA fetus, middle cerebral artery

(MCA) Doppler has limited accuracy to predict acidaemia and adverse outcome and should not be used to time delivery. B

In the term SGA fetus with normal umbilical artery Doppler, an abnormal middle cerebral artery Doppler (PI < 5th centile) has moderate predictive value for acidosis at birth and should be used to time delivery. C

Based on this (Evidence level 2–) evidence it is reasonable to use MCA Doppler to time delivery in the term SGA fetus with normal umbilical artery Doppler

Ductus venosus (DV) and umbilical vein (UV) Doppler Ductus venosus Doppler has

moderate predictive value for acidaemia and adverse outcome.

Ductus venosus Doppler should be used for surveillance in the preterm SGA fetus with abnormal umbilical artery Doppler and used to time delivery A

What is the optimal gestation to deliver the SGA fetus? At present there is no effective

intervention to alter the course of FGR except delivery.

Timing delivery is therefore a critical issue in order to balance the risks of prematurity against those of continued intrauterine stay; death and organ damage due to inadequate tissue perfusion.

sequence of changes Several studies have reported the sequence of

changes in Doppler and biophysical parameters as FGR worsens.

While most fetuses showed a deterioration of arterial Doppler indices before the occurrence of an abnormal DV PIV or biophysical abnormalities

the relationship between venous Doppler and biophysical abnormalities was not consistent. For example, more than 50% of fetuses delivered because of cCTG abnormalities had a normal DV PIV

What is the optimal gestation to deliver the SGA fetus

In the SGA fetus detected after 32 weeks of gestation with an abnormal umbilical artery Doppler, delivery no later than 37 weeks of gestation is recommended. RCOG

If > 34 weeks. •• If abnormal fluid (AFV < 5 cm or DVP < 2 cm), BPP, and/or Doppler studies: consider delivery. SOGC

Delivery at 34 0/7-37 6/7 weeks of gestation in cases of FGR with additional risk factors for adverse outcome ( eg, oligohydramnios, abnormal umblical artery doppler velocimetry results ,maternal risk factors, or co-morbidities

ACOG

After 34 weeks : high PI in the umblical arteries or DV or low PI in the MCA or AFI below the 5th centile FMF

How should the SGA fetus be delivered? In the SGA fetus with normal

umbilical artery Doppler or with abnormal umbilical artery PI but end–diastolic velocities present, induction of labour can be offered but rates of emergency caesarean section are increased and continuous fetal heart rate monitoring is recommended from the onset of uterine contractions.

Ultrasound Obstet Gynecol 2013

ISUOG Practice Guidelines: use of Doppler ultrasonography in obstetrics

What is the appropriate technique for obtaining umbilical artery Doppler waveforms?

There is a significant difference in Doppler indices measured at the fetal end, the free loop and the placental end of the umbilical cord

The impedance is highest at the fetal end, and absent/reversed end-diastolic flow is likely to be seen first at this site

Reference ranges for umbilical artery Doppler indices at these sites have been published.

For the sake of simplicity and consistency, measurements should be made in a free cord loop.

However, in multiple pregnancies, and/or

when comparing repeated measurements longitudinally,

recordings from fixed sites, i.e. fetal end, placental end or intraabdominal portion, may be more reliable.

Figure 3 Acceptable (a) and unacceptable (b) umbilical arterywaveforms. In (b), waveforms are too small and sweep speed tooslow.

Figure 4 Umbilical artery waveforms obtained from same fetus,within 4 min of each other, showing: (a) normal flow and (b)apparently very low diastolic flow and absent flow signals atbaseline, due to use of incorrect vessel wall filter (velocity reject isset too high).

Note: 1) In multiple pregnancy, assessment of umbilical

artery blood flow can be difficult, since there may be difficulty in assigning a cord loop to a specific fetus. It is better to sample the umbilical artery just distal to the abdominal insertion of the umbilical cord. However, the impedance there is higher than at the free loop and the placental cord insertion, so appropriate reference charts are needed.

2) In a two-vessel cord, at any gestational age, the diameter of the single umbilical artery is larger than when there are two arteries and the impedance is thus lower .

Management of SGA with 2SD increased UA PI

Maternal surveillance Maternal monitoring for hypertention

Fetal surveillance twice weekly When umbilical artery Doppler flow

indices are abnormal (pulsatility or resistance index > +2 SDs above

mean for gestational age) and delivery is not indicated repeat surveillance twice weekly in fetuses withend–diastolic velocities present

What is the optimal gestation to deliver the SGA fetus

In the SGA fetus detected after 32 weeks of gestation with an abnormal umbilical artery Doppler, delivery no later than 37 weeks of gestation is recommended. RCOG

If > 34 weeks. •• If abnormal fluid (AFV < 5 cm or DVP < 2 cm), BPP, and/or Doppler studies: consider delivery. SOGC

Delivery at 34 0/7-37 6/7 weeks of gestation in cases of FGR with additional risk factors for adverse outcome ( eg, oligohydramnios, abnormal umblical artery doppler velocimetry results ,maternal risk factors, or co-morbidities

ACOG

After 34 weeks : high PI in the umblical arteries or DV or low PI in the MCA or AFI below the 5th centile FMF

Standard UA doppler The impedance is highest at the

fetal end, and absent/reversed end-diastolic flow is likely to be seen first at this site

For the sake of simplicity and consistency, measurements should be made in a free cord loop.