Prediction of selective fetal growth restriction and twin-to-twin transfusion syndrome in monochorionic twins.
OBJECTIVE
To study the correlation of discrepancy between crown-rump length (CRL) and nuchal translucency (NT) in monochorionic twins at 11-14 weeks of gestation and subsequent development of twin-to-twin transfusion syndrome (TTTS) and selective fetal growth restriction (sFGR).


METHODS
Retrospective cohort study.


METHODS
Tertiary-care Fetal Medicine Unit, London.


METHODS
Monochorionic twin pregnancies with known outcome.


METHODS
Inter-twin discrepancy was calculated as a percentage of the larger CRL and smaller NT and compared among those developing TTTS, those with sFGR and those with normal outcome. Receiver operating characteristic (ROC) curves were constructed to evaluate the performance of inter-twin discrepancy in prediction of sFGR and TTTS.


METHODS
Development of TTTS and sFGR.


RESULTS
A total of 242 monochorionic twin pregnancies were studied (102 TTTS, 36 sFGR and 104 controls). The median CRL discrepancy in the sFGR group (11.9%) was significantly higher (P < 0.001) than in the TTTS group (3.8%) and control group (3.5%). Median inter-twin NT discrepancies were not significantly different (P = 0.869) between sFGR and both TTTS and control groups (15.6%, 16.7% and 14.8%, respectively). Discrepancy in CRL performs well as a screening test for sFGR (area under ROC curve = 0.89), but not for TTTS (area under ROC curve = 0.58).


CONCLUSIONS
First-trimester CRL discrepancy in monochorionic twins is a marker for subsequent development of sFGR rather than TTTS. Inter-twin NT discrepancy does not appear to be significantly different in these two groups from those with normal outcome.
Fetal Medicine Unit, St George's University of London, London, UK.
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Memmo
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Dias
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Mahsud-Dornan
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Papageorghiou
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Bhide
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Thilaganathan
D000328:Adult; D015331:Cohort Studies; D018568:Crown-Rump Length; D005260:Female; D005317:Fetal Growth Retardation / Q000000981:diagnostic imaging*; D005330:Fetofetal Transfusion / Q000175:diagnosis / Q000000981:diagnostic imaging*; D005865:Gestational Age; D006771:Hospitals, Maternity; D006785:Hospitals, University; D006801:Humans; D008131:London; D048208:Nuchal Translucency Measurement; D011237:Predictive Value of Tests; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D059285:Pregnancy, Twin; D012372:ROC Curve; D012189:Retrospective Studies; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D014430:Twins, Monozygotic; D016216:Ultrasonography, Prenatal