Table 1
sFGR definition in twins among societies.
| Society | Date of publication | Definition of sFGR | Growth charts | Other twins recommendation |
|---|---|---|---|---|
| NICE | 2019 | ≥25% EFW discordance and EFW of one foetus <10th centile for GA | Undefined | |
| ACOG | 2019 | One foetus has EFW <10th centile and disproportion between EFW >20% | Undefined | |
| ISOUG | 2016 | One foetus has EFW <10th centile and the intertwin weight discordance >25% | Singleton | |
| RAN-ZOG | 2017 | Undefined | Undefined | Recommendation about MC twins but without definitions of FGR |
| SOGC | 2017 | AC and/or EFW of one or both twins are <10th centile or when growth discordance is identified | Singleton | |
| ACR | 2017 | One foetus EFW <10th centile and the intertwin EFW discordance >25% | Singleton | |
| FIGO | 2019 | One foetus EFW <10th centile and the intertwin EFW discordance >25% | Twin | |
| Delphi consensus | 2019 | Separates MC and DC twins, EFW <3rd centile or contributory factors | Singleton |
[i] AC, abdominal circumference; ACOG, American College of Gynecologists; ACR, American College of Radiology; DC, dichorionic; EFW, estimated foetal weight; GA, gestational age; FIGO, International Federation of Gynecology and Obstetrics; ISOUG, International Society of Ultrasound in Obstetrics and Gynecology; MC, monochorionic; NICE, National Institute for Health and Care Excellence; RANZOG, Royal Australian and New Zealand College of Obstetricians and Gynaecologists; sFGR, selective FGR; SOGC, Society of Obstetricians and Gynaecologists of Canada.
Table 2
sFGR definition by expert consensus: A Delphi procedure.
| DC twins | MC twins |
|---|---|
| EFW <3rd centile or | |
| EFW of one foetus <10th centile | EFW of one foetus <10th centile |
| AC is not taken into account | AC of one foetus <10th centile |
| The disproportion between foetal weight ≥25% | The disproportion between foetal weight ≥25% |
| UAPI of smaller foetus >95th centile | UAPI of smaller foetus >95th centile |
| 2/3 have to be present to recognise sFGR | 2/4 have to be present to recognise sFGR |
Figure S1
Ultrasound images of umbilical flow according to the classification of FGR in MC twins by Gratacós et al.20 FGR, foetal growth restriction; MC, monochorionic.
Table S1
Assessment of hypertrophic twin pregnancies depending on chorionicity.
| sFGR twins | Color Doppler | Foetal growth assessment |
|---|---|---|
| DC | Biweekly or more frequent | Biweekly |
| MC | Once a week or more frequent |
Table 3
Recommended GA at delivery in stable twins pregnancies complicated by sFGR according to Doppler assessment compared with FGR singleton pregnancies.
| sFGR Type | ||||
|---|---|---|---|---|
| Chorionicity | I | II | III | IV |
| DC | UAPI >95th centile CPR <5th centile | AEDF | REDF, DV PI >95th centile | DV a wave reversed |
| MC | I | II | III | |
| UAPI >95th | AREDF | iAREDF | DV a wave reversed (it is not stage IV in MC) | |
| Recommended GA at delivery (weeks) | ||||
| DC | 34–36 | 30–32 | 30–32 | >26 <26 expectant management or selective termination* |
| MC | 34–36 | 30–32 | 30–32 | >26 <26 SLPCV, selective termination (RFA, cord occlusion) |
| Singletons | 37 | 34 | 30 | 26 <26 expectant management |
Data reproduced from Figueras and Gratacós,19 Gratacós et al.,20 ISUOG guideline and Khalil et al.7
AEDF, absent EDF; AREDF, absent/reverse EDF; DC, dichorionic; DV, ductus venosus; DV PI, ductus venosus pulsatility index; EDF, end-diastolic flow; FGR, foetal growth restriction; GA, gestational age; iAREDF, intermittent AREDF; MC, monochorionic; REDF, reverse EDF; sFGR, selective FGR; SLPCV, selective laser photocoagulation of placental connecting vessels; RFA, radiofrequency ablation; UAPI, umbilical artery pulsatility index.