fmf certificate of competence in measurement of the facial angle

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FMF Certificate of competence in measurement of the facialangleThe findings of recent studies suggest that fetuses withtrisomy 21 have a flat profile because the maxilla (upper

jaw) is small and set back. This produces a wide angle in aline drawn over the palate and between the maxilla andthe forehead (facial angle). Measurement of the facialangle at 11-13 weeks improves the performance of screening for trisomy 21 by maternal age and fetal NT.

Protocol for measurement of the fetal facial angley The gestational period must be 11 to 13 weeks and six

days.

y The magnification of the image should be such thatthe fetal head and thorax occupy the whole image.

y A mid-sagittal view of the face should be obtained.This is defined by the presence of the echogenic tip of the nose and rectangular shape of the palateanteriorly, the translucent diencephalon in the centreand the nuchal membrane posteriorly. Minordeviations from the exact midline plane would causenon-visualization of the tip of the nose and visibility of the zygomatic process of the maxilla.

y The facial angle should be measured between a line

along the upper surface of the palate and a line whichtraverses the upper corner of the anterior aspect of the maxilla extending to the external surface of theforehead, represented by the frontal bones or anechogenic line under the skin below the metopicsuture that remains open.



Clinical application of fetal facial angle measurementThe fetal facial angle decreases with CRL and is wider infetuses with trisomy 21 than in chromosomaly normalfetuses. It is essential that in adjusting the risk for trisomy

21 using the measurement of the facial angle the softwaretakes into account the fetal CRL.

The FMF software firstly calculates a risk based onmaternal age, fetal NT and maternal serum free -hCGand P A PP- A . If the risk is more than 1 in 50 and and thefacial angle is within the normal range the risk does notchange. If the risk is 1 in 50 to 1 in 1,000 and the the facialangle is within the normal range the risk is usually reduced. If the facial angle is above the bormal range the

risk is always increased.

Protocol for the assessment of the ductus venosusy The gestational period must be 11 to 13 weeks and six

days.

y The examination should be undertaken during fetal

quiescence.y The magnification of the image should be such that

the fetal thorax and abdomen occupy the wholeimage.

y A right ventral mid-sagittal view of the fetal trunk should be obtained and color flow mapping should beundertaken to demonstrate the umbilical vein, ductus

venosus and fetal heart.

y The pulsed Doppler sample volume should be small(0.5-1.0 mm) to avoid contamination from theadjacent veins, and it should be placed in the

yellowish aliasing area.

y The insonation angle should be less than 30 degrees.

y The filter should be set at a low frequency (50-70 Hz)so that the a-wave is not obscured.



y The sweep speed should be high (2-3 cm/s) so thatthe waveforms are spread allowing better assessmentof the a-wave.

y W hen these criteria are satisfied, it is possible to

assess the a-wave and determine qualitatively whether the flow is positive, absent or reversed.

Clinical application of ductus venosus flow findingsThe incidence of reversed ductus venosus a-wave isrelated to NT and CRL as well as aneuploidy, being morecommon when the NT is high and the CRL is low.Therefore it is not possible to give simple numbers by

which the presence of normal flow will reduce the risk for

trisomy 21 and the presence of reversed a-wave willincrease the risk.

The FMF software firstly calculates a risk based onmaternal age, fetal NT and maternal serum free -hCGand P A PP- A . If the risk is more than 1 in 50 and ductus

venosus flow is normal the risk does not change. If therisk is 1 in 50 to 1 in 1,000 and the ductus venosus flow isnormal the risk is usually reduced. If there is reversed a-

wave the risk is always increased. In addition, there is an

increased risk for cardiac defects and therefore suchpatients should have a follow up specialist fetal cardiacscan.



Protocol for the assessment of tricuspid flow y The gestational period must be 11 to 13 weeks and six

days.

y The magnification of the image should be such thatthe fetal thorax occupies most of the image.

y A n apical four-chamber view of the fetal heart should be obtained.

y A pulsed-wave Doppler sample volume of 2.0 to 3.0mm should be positioned across the tricuspid valve sothat the angle to the direction of flow is less than 30degrees from the direction of the inter-ventricularseptum.

y Tricuspid regurgitation is diagnosed if it is foundduring at least half of the systole and with a velocity of over 60 cm/s, since aortic or pulmonary arterial bloodflow at this gestation can produce a maximum velocity

of 50 cm/s.y The sweep speed should be high (2-3 cm/s) so that

the waveforms are widely spread for betterassessment.

y The tricuspid valve could be insufficient in one ormore of its three cusps, and therefore the sample

volume should be placed across the valve at leastthree times, in an attempt to interrogate the complete

valve.Clinical application of tricuspid flow findingsThe incidence of tricuspid regurgitation is related to NTand CRL as well as aneuploidy, being more common whenthe NT is high and the CRL is low. Therefore it is notpossible to give simple numbers by which the presence of



normal flow will reduce the risk for trisomy 21 and thepresence of tricuspid regurgitation will increase the risk.The FMF software firstly calculates a risk based onmaternal age, fetal NT and maternal serum free -hCG

and P A

PP- A

. If the risk is more than 1 in 50 and tricuspidflow is normal the risk does not change. If the risk is 1 in50 to 1 in 1,000 and the tricuspid flow is normal the risk isusually reduced. If there is tricuspid regurgitation the risk is always increased. In addition, there is an increased risk for cardiac defects and therefore such patients shouldhave a follow up specialist fetal cardiac scan.



FMF Certificate of competence in measurement of uterineartery PIThe Fetal Medicine Foundation has now establishedsoftware for the calculation of risk for preeclampsia. The

software is provided free of charge to those who comply with the FMFregulation of NT screening and havedemonstrated competence in the Doppler assessment of the uterine arteries at the 11-13 weeks scan.

Preeclampsia, which affects about 2% of pregnancies, is amajor cause of perinatal and maternal morbidity andmortality. Routine antenatal care has evolved with theaim of identifying women at high-risk for subsequentdevelopment of preeclampsia. The likelihood of

developing preeclampsia is increased by a number of factors in the maternal history, including A fro-Caribbeanrace, nulliparity, high body mass index and personal orfamily history of preeclampsia. However, screening by maternal history may detect only about 30% of those that

will develop preeclampsia for a false positive rate of 5%.

A more effective method of screening for preeclampsia isprovided by measurement of the uterine artery pulsatility

index (PI) at 11-13 weeks' gestation in combination withmaternal history, blood pressure and serum P A PP- A andplacental growth factor (PLGF). For a false-positive rateof 5% it has been estimated that the new combinedmethod of screening can predict 90% of preeclampsiarequiring delivery before 34 weeks and 45% of latepreeclampsia. There is extensive evidence that it is early rather than late preeclampsia which is associated with anincreased risk of perinatal mortality and morbidity and

both short-term and long-term maternal complications.Identification of women at high-risk for preeclampsiaduring the first trimester could potentially improvepregnancy outcome because intensive maternal and fetalmonitoring in such patients would lead to an earlierdiagnosis of the clinical signs of the disease and theassociated fetal growth restriction and avoid the



development of serious complications through suchinterventions as the administration of antihypertensivemedication and early delivery.

It is imperative that, as for the NT scan, sonographers

undertaking risk assessment of preeclampsia by examination of the uterine arteries must receiveappropriate training and certification of theircompetence.

Requirements for Certification in measurement of uterineartery PIThe requirements for certification are:1. FMF certification in the measurement of nuchal

translucency.2. A ttendance of the internet based course on the 11-13

weeks scan.3. Submission of a logbook of 3 images demonstratingcolor flow mapping and waveforms of the uterine artery at11-13 weeks.

Protocol for first-trimester measurement of the uterineartery PIy The gestational age must be between 11 weeks and 13

weeks and six days.

y Sagittal section of the uterus must be obtained andthe cervical canal and internal cervical os identified.Subsequently, the transducer must be gently tiltedfrom side to side and then colour flow mappingshould be used to identify each uterine artery alongthe side of the cervix and uterus at the level of theinternal os.

y Pulsed wave Doppler should be used with thesampling gate set at 2 mm to cover the whole vesseland ensuring that the angle of insonation is less than30º. W hen three similar consecutive waveforms areobtained the PI must be measured and the mean PI of the left and right arteries be calculated.

fmf certificate of competence in measurement of the facial angle

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