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The combination of extraordinary advances in molecular genetics,
prenatal genetic diagnosis,1 and the continuous
technologic innovations in prenatal imaging2,3 now
make it possible to diagnose prenatally virtually any condition
with high levels of confidence. This capability has afforded the
opportunity to consider prenatal treatment for an ever-expanding
list of conditions that in years past depended on postdelivery assessments.
In many instances, irreparable organ injury or even death occurred
as a result of this delay. Fetal therapy holds significant promise to
change the natural history and improve not only perinatal survival
but long-term outcomes as well.4 Fetal therapy has
expanded the conditions that may be considered for medical treatment,
including congenital pulmonary airway malformations (CPAM),5,6 fetal arrhythmias,7 congenital
adrenal hyperplasia,8 and even congenital diaphragmatic
hernia.9-11 Possible indications for open fetal
surgery have broadened to conditions such as myelomeningocele,12 sacrococcygeal
teratoma,13,14 bladder outlet obstruction,15,16 and
CPAM.6 But perhaps the most striking area of growth
in fetal intervention is for conditions that may be treated by fetoscopic
techniques,17 such as twin-twin transfusion syndrome,17-20 twin
reversed arterial perfusion sequence,21,22 and
congenital diaphragmatic hernia.9-11
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Fetal intervention is only possible with precise prenatal imaging,
a complete understanding of the maternal history, selection criteria for
the intervention, and techniques that are safe for both mother and
baby. Recent advances in ultrasound imaging, especially 3-dimensional and
4-dimensional scanning capabilities, have dramatically improved
the quality of ultrasound affording diagnostic precision and image-guided
capabilities not previously available.3 Ultrasound
imaging is complemented by the greater imaging capacity afforded
by fetal magnetic resonance imaging, particularly for the central
nervous system and chest. Similarly, fetal cardiac assessment has
benefited by technical advances not only in fetal echocardiographic
imaging but also in the development of fetal magnetocardiography
for the accurate diagnosis of tachyarrhythmias.23,24
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In the past, fetal intervention was limited to conditions in
singletons in which the life of the fetus was threatened. In recent
years, the indications for fetal intervention have been extended
to non–life-threatening conditions, such as myelomeningocele,12 and
to multiple gestations for twin-twin transfusion syndrome,18-20 which
in fact is currently the most common indication for fetal surgery.
The sophistication of the average expectant mother also has increased.
Expecting parents increasingly seek out expertise in fetal imaging,
prenatal diagnosis, and fetal intervention and are willing to travel
if expertise is not locally available. The evolution of fetal intervention holds
tremendous promise for altering prenatal natural history of a disorder
in ways not possible after delivery. It also is fraught with potential
risk for mothers considering interventions who derive no direct
benefit from these procedures. Critical appraisal of the potential
maternal and fetal risks of fetal intervention must be carefully
weighed by all parents considering these options.
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Medical treatment options still remain limited if one excludes
the use of corticosteroids ...