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DOI: 10.1055/a-2280-8772
Firsttrimester Diagnosis and Therapy @ 11 – 13+6 Weeks of Gestation – Part 1
Guideline of the DEGUM, ÖGUM, SGUMGG, DGGG, ÖGG, Gynecologie Suisse, DGPM, DGPGM, BVF, ACHSE (AWMF S2e LL 085-002 1.1.2024) (https://register.awmf.org/de/leitlinien/detail/085-002) Artikel in mehreren Sprachen: English | deutsch- Abstract
- 1 Intention and Scope
- 2 Introduction
- 3 Legal Basis
- 4 Screening for Malformations @ 11 – 13+6 Weeks of Gestation (Biometry and Anatomy)
- Note
- References
Abstract
This extensive AWMF 085-002 S2e-guideline “First Trimester Diagnosis and Therapy @ 11 – 13+6 of Gestation” has systematically analyzed high-quality studies and publications and the existing evidence (evidence tables) and produced recommendations (level of recommendation, level of evidence, strength of consensus).
This guideline deals with the following topics in the context of the 11 – 13+6 weeks scan: the legal basis, screening for anatomical malformations, screening for chromosomal defects, quality assessment and audit, screening for preeclampsia and FGR, screening for preterm birth, screening for abnormally invasive placenta (AIP) and placenta accreta spectrum (PAS), screening for velamentous cord insertion and vasa praevia, screening for diabetes mellitus and LGA.
Screening for complications of pregnancy can best be carried out @ 11 – 13+6 weeks of gestation. The issues of how to identify malformations, chromosomal abnormalities and certain disorders of placentation (high blood pressure and proteinuria, intrauterine growth retardation) have been solved. The problem of how to identify placenta percreta and vasa previa has been partially solved. What is still unsolved is how to identify disorders of glucose metabolism and preterm birth.
In the first trimester, solutions to some of these problems are available: parents can be given extensive counselling and the risk that a pregnancy complication will manifest at a later stage can be delayed and reduced. This means that screening is critically important as it helps in decision-making about the best way to manage pregnancy complications (prevention and intervals between follow-up examinations).
If no treatment is available and if a termination of pregnancy is considered, the intervention can be carried out with far lower complications compared to the second trimester of pregnancy. In most cases, further examinations are not required and the parents can be reassured. A repeat examination at around week 20 of gestation to complete the screening for malformations is recommended.
Note: The guideline will be published simultaneously in the official journals of both professional societies (i.e. Ultraschall in der Medizin/European Journal of Ultrasound for the DEGUM and Geburtshilfe und Frauenheilkunde for the DGGG).
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Keywords
first trimester screening - nuchal translucency - chromosomal disorders - malformation - preeclampsia1 Intention and Scope
1.1 Purpose and objectives
The pace of change in sonographic, biochemical and molecular screening methods @ 11 – 13+6 weeks of gestation (GW) has made it necessary to present suggestions for a structured and quality-assessed approach in order to offer patients the best possible advice, diagnosis, screening and prevention.
Purpose: to provide clear information which is easy to understand about the methods currently available in screening for
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malformations,
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chromosomal abnormalities,
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disorders of placentation (preeclampsia, growth restriction, fetal death, miscarriage),
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preterm birth,
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abnormally invasive placenta (AIP)/placenta accreta spectrum disorder (PAS),
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velamentous cord insertion, vasa praevia,
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diabetes mellitus and macrosomia;
to outline the capabilities of the individual sonographic, biochemical and molecular methods; to describe the currently recommended standard approach as well optional approaches. The purpose is also to provide information about how later manifestations of high risks identified in the first trimester of pregnancy can be reduced by taking preventive measures as well as providing information on how an individually tailored management of pregnancy would look like.
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2 Introduction
2.1 Screening and diagnosis @ 11 – 13+6 weeks of gestation
The aim of screening in the first trimester of pregnancy @ 11+0 – 13+6 weeks of gestation is to identify risk factors which require a further diagnostic workup and/or an intervention at an early stage in pregnancy in a self-selected population.
This screening should be understood as an offer to provide examinations without cause undertaken voluntarily (opportunistically).
Screening includes taking the medical history of the mother and fetus, carrying out ultrasound scans, and reviewing the biochemical, biophysical and genetic factors of mother and fetus.
The concept presented here is evidence-based and is not part of the Maternity Guidelines.
First-trimester screening is quality assured.
This guideline aims to provide the persons providing care with a systematic overview of the current screening options @ 11 – 13+6 weeks of gestation.
When?
11+0–13+6 weeks of gestation (CRL45 – 84 mm)
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Who?
Specialists in Obstetrics and Gynecology who meet the standards described in this guideline (screening must be carried out by a physician).
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Ultrasound equipment
Minimum technical requirements for ultrasound equipment must comply with:
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real-time grey-scale ultrasound (2D, B-mode imaging),
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color Doppler (power Doppler), pulsed Doppler
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M-mode
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transabdominal ultrasound probes (electronic and/or mechanical curved array or linear, wideband, frequency range 3.0 – 7.5 MHz), if necessary.
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transvaginal ultrasound probes (electronic and/or mechanical, wideband, high frequency (4.0 – 10.0 MHz)
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adjustable acoustic power output control, standard parameters (TIs, TIb, MI)
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freeze-frame and online zoom capability
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video cineloop capability
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electronic calipers (minimum discrimination 0.1 mm)
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storage and print options for images
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regular technical inspections (refer to ultrasound agreement)
(EC, strong consensus 10/10)
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Documentation
The information provided to the patient along with the patientʼs written consent to the examination must be documented.
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Safety of ultrasound
Based on the ALARA principle (as low as reasonably achievable)
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Approach when the examination cannot be carried out in accordance with the standards of this guideline
If the examination cannot be carried out in accordance with the standards of this guideline:
the patient must be referred to an institution where screening can be carried out in accordance with this guideline,
the patient must be informed in detail about what is included in first-trimester screening:
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counselling before and after the examination
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screening for malformations
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screening for preeclampsia and growth restriction,
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screening for chromosomal disorders
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screening for further disorders of pregnancy (if indicated)
and what the potential results and consequences of first-trimester screening can be.
Counselling must ensure that first-trimester screening is offered to every patient in accordance with the standards in this guideline.
If one of the risks is found to be elevated following first-trimester screening or NIPT, the pregnant woman must be quickly transferred to an institution which can carry out further investigations to avoid unnecessary distress.
(EC, strong consensus 11/11)
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2.2 Multiple pregnancies
The AWMF 015 – 087 S2e-guideline on the monitoring and care of twin pregnancies (1.5.2020) [5] describes the care of twin pregnancies (chapter 3 and following).
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3 Legal Basis
3.1 Information and counselling
The requirement that screening is carried out by medical specialists means that if a service cannot be provided in accordance with state-of-the art science and technology, patients will be referred to an institution which is able to provide a state-of-the-art service. Not doing so amounts to falling below the required standard and would mean that the facility providing substandard services can be held liable.
Germany
Genetic Diagnosis Act (GenDG), Maternity Guidelines, Patient Rights Act (PRG), Act on Assistance to Avoid and Cope with Conflicts in Pregnancy (SchKG), German Civil Code (BGB).
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Austria
Mother-Child Booklet, Genetic Engineering Act (GTG)
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Switzerland
Federal Law on Genetic Testing in Humans (GUMG),
Swiss Health Care Benefits Ordinance (KLV)
Letter by Experts No. 52: Prenatal non-invasive risk estimation of fetal aneuploidies
Letter by Experts No. 80: First trimester screening for preeclampsia
Recommendations on ultrasound examinations in pregnancy
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3.2 Terminaton of Pregnancy
Germany: Strafgesetzbuch [= German Criminal Code] (StGB § 218)
Austria: Strafgesetzbuch [= Austrian Criminal Code] [§ 97 (1) Abs. 1 and Abs. 2 – 3]
Switzerland: Strafgesetzbuch [= Swiss Criminal Code] (§ 119, Abs. 1 and Abs. 2)
Laws and guidelines on first-trimester screening in Germany, Austria and Switzerland.
First-trimester screening must be carried out in accordance with the following laws and codes of practice:
Germany
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Maternity Guidelines [9]
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Guidelines on prenatal risk evaluation/examinations [7, 8]
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Genetic Diagnosis Act (GenDG) [6]
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Patient Rights Act (PRG) § 630 BGB [10]
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Act on Assistance to Avoid and Cope with Conflicts in Pregnancy (SchKG) [11]
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German Criminal Code (StGB § 218a Absatz 2) [15]
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Austria
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Mother-Child-Booklet Regulation (BGBl II Nr. 470/2001) [18]
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Genetic Engineering Act (GTG) [12]
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Austrian Criminal Code (StGB § 97) [16]
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Switzerland
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Federal Law on Genetic Testing in Humans (GUMG) [13]
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Swiss Criminal Code (StGB § 119) [17]
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Swiss Health Care Benefits Ordinance (KLV) [19]
(Strong consensus 10/10)
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4 Screening for Malformations @ 11 – 13+6 Weeks of Gestation (Biometry and Anatomy)
Certain malformations can always be detected in the first trimester of pregnancy, some malformations may be detected in part, and some cannot yet be diagnosed in the first trimester (direct screening) ([Tables 1] and [2]).
Always detectable |
DR (%) |
Potentially detectable |
DR (%) |
Not detectable |
DR (%) |
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anencephaly |
100 |
missing hand/foot |
77 |
agenesis of the corpus callosum |
0 |
alobar holoprosencephaly |
100 |
diaphragmatic hernia |
50 |
hypoplasia of the cerebellar vermis |
0 |
omphalocele |
100 |
skeletal dysplasias |
50 |
echogenic lung lesions |
0 |
gastroschisis |
100 |
polydactyly |
60 |
intestinal obstruction |
0 |
megacystis |
100 |
severe heart defects |
34 |
renal malformations |
0 |
body stalk anomaly |
100 |
facial cleft |
5 |
clubfeet |
0 |
generalized hydrops |
100 |
open spina bifida |
14 |
Always detectable |
DR (%) |
Often detectable |
DR (%) |
Rarely detectable |
DR (%) |
---|---|---|---|---|---|
anencephaly |
100 |
open spina bifida |
> 50 |
cerebral ventriculomegaly |
< 10 |
alobar holoprosencephaly |
100 |
HLHS |
> 50 |
agenesis of the corpus callosum |
< 10 |
encephalocele |
100 |
AV channel |
> 50 |
cleft lip (isolated) |
< 10 |
tricuspid/pulmonary atresia |
100 |
complex cardiac defects |
> 50 |
lung malformations |
< 10 |
pentalogy of Cantrell |
100 |
left isomerism |
> 50 |
VSDs |
< 10 |
ectopia cordis |
100 |
urogenital obstruction |
> 50 |
abdominal cysts |
< 10 |
omphalocele |
100 |
limb deficiencies |
> 50 |
renal agenesis (unilateral) |
< 10 |
gastroschisis |
100 |
FADS |
> 50 |
multicystic dysplastic kidney |
< 10 |
body stalk anomaly |
100 |
lethal skeletal dysplasias |
> 50 |
hydronephrosis |
< 10 |
duplex kidney |
< 10 |
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hypospadias |
< 10 |
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clubfeet |
< 10 |
4.1 Fetal biometry
The reference curves (formulas) of one of the five authors listed below must be used to determine gestational age between 11 – 13+6 GW based on crown-rump length (CRL): Robinson et al., 1975, McLennan et al., 2008, Sahota et al., 2009, Verburg et al., 2008, or Papageorghiou et al., 2014.
Measurement of the CRL must always be used to determine gestational age except for IVF pregnancies.
The date of conception must be used to determine the gestational age of IVF pregnancies.
(Level of recommendation A, level of evidence 1a, strong recommendation 10/10)
The following must be measured between 11 – 13+6 GW: CRL, NT, BPD
The following should be additionally measured between 11 – 13+6 GW (optional): FHR, HC, AC, FL, NB, TR, DV, IT, UA, Cx
(Level of recommendation EC, level of evidence 5, strong recommendation 11/11)
Crown-rump length (CRL) ([Fig. 1])
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Biparietal diameter (BPD) and head circumference (HC) ([Fig. 2])
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Abdominal circumference (AC) ([Fig. 3])
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Femur length (FL) ([Fig. 4])
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4.2 Fetal anatomy
Review of the fetus and placenta
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Amniotic fluid and amnion ([Fig. 5])
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Head and brain ([Fig. 6])
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Face
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Neck ([Fig. 7])
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Thorax and heart ([Fig. 8])
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Gastrointestinal tract ([Fig. 9])
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Abdominal wall ([Fig. 10])
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Umbilical cord ([Fig. 11])
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Spine ([Fig. 12])
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Extremities ([Fig. 13])
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Genitals
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Role of three-dimensional (3D) and 4D ultrasound ([Fig. 14])
1 After the patient has been informed and given her consent (GenDG)/ NB: nasal bone, TR: tricuspid valve flow (insufficiency), DV: ductus venosus flow (reversed A-wave), IT: intracranial translucency |
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The following visualizations must be done at 11 – 13+6 GW as part of early structured screening for malformations ( obligatory ): |
The following visualizations should be additionally carried out at 11 – 13+6 GW as part of early structured screening for malformations ( optional ): |
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Skull and brain |
cranial vault, cerebral falx, choroid plexus |
intracranial translucency (IT), brainstem |
Face |
profile |
eyes, jaw, lips |
Neck |
nuchal translucency (NT)1 |
nasal bone (NB)1 |
Spine |
outline |
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Heart and thorax |
position, outline, four-chamber view, lungs |
outflow tracts (color), three vessel trachea view, tricuspid valve flow (TR)1 |
Abdomen |
stomach, abdominal wall |
diaphragm, ductus venosus flow (DV)1, umbilical cord arteries on either side of the bladder |
Extremities |
arms and legs |
hands and feet (femur, tibia, fibula, humerus, radius, ulna) |
Urogenital tract |
bladder |
kidneys |
Placenta |
chorionicity, amnionicity (multiple pregnancy), structure |
position, insertion of umbilical cord, uterine arteries1 |
(Level of recommendation EC, strong consensus 10/10) |
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4.3 Detection rates of non-chromosomal malformations
Screening for fetal malformations in an unselected population differentiates between malformations which are always detectable, those that are potentially detectable, and those which are not yet detectable using the available diagnostic methods in the first trimester of pregnancy.
(Level of evidence 1a, strong consensus 7/7) ([Tables 1] and [2])
The detection rate for non-chromosomal structural anomalies also depends on the prevalence of severe malformations in the investigated cohort.
It is 32% in low-risk and 60% in high-risk cohorts.
(Level of evidence 1a, strong consensus 10/10)
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4.4 Detection rates: structured vs. non-structured vs. no screening protocol
If a structured diagnostic screening is carried out at an early stage in pregnancy, it should follow a previously defined protocol.
(Level of recommendation B, level of evidence 1a, strong consensus 10/10) ([Tables 3], [4] and [5])
Subgroup |
Population |
Anomalies (n/100 fetuses) |
Sensitivity (%) |
Diagnosis in 11 – 13+6 GW (%) |
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(Numbers in brackets show 95% CI.) |
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1 |
Severe malformations/low risk unselected |
1.01 (0.95 – 1.07) |
46.10 (36.88 – 55.46) |
53.47 (43.42 – 63.37) |
2 |
All malformations/low risk unselected |
1.81 (1.72 – 1.90) |
32.35 (22.45 – 43.12) |
41.10 (32.13 – 50.38) |
3 |
All malformations/high risk |
6.55 (5.66 – 7.52) |
61.18 (37.71 – 82.19) |
66.29 (43.47 – 85.69) |
Region |
Minimum requirements for first-trimester ultrasound scans |
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General aspect |
Singleton/multiple pregnancy |
Head and brain |
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Neck |
Mid-sagittal plane of the head and neck (profile)
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Heart |
Axial plane of the heart, four-chamber view
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Abdomen |
Axial plane
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Extremities |
Four extremities with visualization of three segments per section |
Placenta |
Appearance normal with no cystic structures |
Biometry |
Sagittal view: crown-rump length and nuchal translucency Axial view: BPD |
Region |
Structures which can be visualized in sagittal, axial or coronal planes as required during the detailed anatomical examination |
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Head & brain |
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Face & neck |
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Thorax |
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Heart |
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Abdomen |
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Spine |
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Extremities |
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Placenta |
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Amniotic fluid & amnion |
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The protocol for early structured screening for malformations should include at the very least:
biometry, head, brain, face, nuchal translucency, spine, extremities, thorax, heart, abdomen, placenta with umbilical cord and amniotic fluid
(Level of recommendation A, level of evidence 1a, strong consensus 10/10)
The following malformations can be almost always detected @ 11 – 13+6 weeks of gestation and should therefore be diagnosed:
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acrania/exencephaly/encephalocele (large)
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alobar holoprosencephaly
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omphalocele/exomphalos
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gastroschisis
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body stalk anomaly/ectopia cordis
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megacystis
(Level of recommendation A, level of evidence 2b, strong consensus 10/10)
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4.5 Indirect vs. direct screening for malformations
Open spina bifida can be detected @ 11 – 13+6 weeks of gestation in up to 79% of cases using indirect parameters such as intracranial translucency.
A targeted examination, e.g., if there is a prior history of spina bifida, should include the following sonographic parameters:
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direct imaging of the spine (frontal, sagittal view)
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sagittal view: intracranial translucency, brain stem, cisterna magna
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axial view: cerebral peduncles, aqueduct of Sylvius
(Level of recommendation B, level of evidence 1a, strong consensus 10/10) ([Fig. 15])
Cleft lip and palate (CLP) is detectable @ 11 – 13+6 weeks of gestation in 65% or 96% of cases through observation of a maxillary gap (isolated CLP vs. additional malformations).
The targeted examination, e.g., if there is a prior history cleft lip and palate, should include the following sonographic parameters:
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mid-sagittal plane showing the maxilla and maxillary gap
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frontal and oblique plane with visualization of the retronasal triangle
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axial view of the maxilla
(Level of recommendation B, level of evidence 2b, strong consensus 10/10) ([Fig. 16])
Sonographic markers such as nuchal translucency and flow through the tricuspid valve and the ductus venosus should be used to carry out indirect screening for fetal cardiac defects and should be combined with a four-chamber view.
(Level of recommendation B, level of evidence 4, strong consensus 10/10)
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4.6 Indirect vs. direct screening for cardiac defects
Findings of increased NT, reverse flow through the tricuspid valve and/or in the ductus venosus or an abnormal four-chamber view should lead to targeted fetal echocardiography carried out by a specialist.
(Level of recommendation A, level of evidence 1+, strong consensus 10/10)
Fetal echocardiography in 11 – 13+6 GW should consist of an examination of the heart using standard scanning planes and color Doppler.
(Level of recommendation B, level of evidence 1+, strong consensus 10/10)
Fetal echocardiography in 11 – 13+6 GW should include the following scanning planes using B-mode imaging and color Doppler:
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cardiac position
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cardiac axis
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four-chamber view
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right ventricular outflow tract
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left ventricular outflow tract
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three vessel trachea view with aortic and ductal arches
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search for ARSA (optional)
(Level of recommendation A, level of evidence 1a, strong consensus 10/10) ([Fig. 17])
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4.7 Diagnostic screening for malformations in the second trimester after early ultrasound scan for malformations in the first trimester of pregnancy
Diagnostic screening for malformations at 11 – 13+6 GW must be followed by organ screening in the second trimester of pregnancy @ 18 – 23 weeks of gestation.
(Level of recommendation A, level of evidence 1b, strong consensus 10/10)
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4.8 Importance of ultrasound scans to detect malformations @ 11 – 13+6 weeks of gestation vs. in 18 – 23 weeks of gestation: benefit for the parents
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4.9 Psychological aspects of first-trimester screening
Prior to carrying out first trimester screening, the pregnant woman should be informed about possible psychological and emotional consequences of abnormal findings.
(Level of recommendation B, level of evidence 1a, strong consensus 10/10)
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Note
The guideline will be published simultaneously in the official journals of both professional societies (i.e., Geburtshilfe und Frauenheilkunde for the DGGG and Ultraschall in der Medizin/European Journal of Ultrasound for the DEGUM).
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References
- See also the long version of the guideline: https://register.awmf.org/de/leitlinien/detail/085-002</uri>
Correspondence
Publikationsverlauf
Eingereicht: 17. Februar 2024
Angenommen: 01. März 2024
Artikel online veröffentlicht:
01. Oktober 2024
© 2024. Thieme. All rights reserved.
Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany
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References
- See also the long version of the guideline: https://register.awmf.org/de/leitlinien/detail/085-002</uri>