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Predictive Outcomes of Fetal Micrognathia: One Fetal Center's Experience

Prenatal Genetics
  • Primary Categories:
    • Prenatal Genetics
  • Secondary Categories:
    • Prenatal Genetics
Introduction:
Fetal micrognathia is a common prenatal craniofacial abnormality. Micrognathia may have multiple implications for the pregnancy and the neonate, as there is an increased risk of tongue-based airway obstruction, impeding pulmonary development, and affecting nutrition intake. There are multiple genetic syndromes known to cause micrognathia but differ in terms of neonatal outcome. Additionally, sometimes micrognathia is seen as an isolated finding with or without a family history of the same trait. Therefore, it becomes difficult to counsel families prenatally on potential neonatal outcomes. Here we present a retrospective review of prenatal imaging and postnatal outcomes in hopes to aid counseling.

Methods:
114 cases of prenatally ascertained micrognathia were retrospectively identified at a single tertiary care center. A chart review was performed to record the following: prenatal outcome, gestational age and method of delivery, presence of polyhydramnios, neonatal respiratory support needed at delivery, status of the child, severity of micrognathia, additional anomalies appreciated on prenatal imaging, and genetic testing results. Any cases where there was incomplete information were excluded.

Results:
The average age of the pregnant person at the time of evaluation was 31 years. Most pregnancies either resulted in a live born child (64.9%) or were terminated (30.7%), and a subset resulted in an intrauterine fetal demise (IUFD) (4.4%). The majority of pregnancies were delivered by C-section (55.7%). A subset (12.2%) of the delivered pregnancies resulted in neonatal demise, the most common cause being respiratory compromise. 7/9 neonatal deaths were in the setting of palliative care, with the majority (5/7) of these fetuses with a diagnosis of Trisomy 13 or 18 on diagnostic testing or through prenatal cell-free DNA (cfDNA) screening. The average GA at delivery was 36.1 weeks. 11/67 (16.5%) were delivered by Procedure Requiring Second Team in OR (PRESTO), where Neonatology, Otolaryngology, the airway team, and anesthesia were present in the operating room at delivery. Excluding neonatal demise, there were 19 deceased children included in this cohort. The average age at death was 150 days.



32% of cases were defined as mild on prenatal imaging. The 16.5% of cases that were delivered by PRESTO were deemed severe enough to be delivered in this way. Severity was not consistently quantified for the remaining patients.



76.9% of live births required respiratory intervention at delivery. Of those, 26.2% required positive pressure ventilation (PPV), 43% continuous positive airway pressure (CPAP), and 35.4% endotracheal tube (ETT) placement. 15 cases did not require any intervention.



In 22.8% of cases, polyhydramnios was present between the 2nd-3rd trimester of pregnancy. 85.6% of cases had additional ultrasound anomalies outside of micrognathia, of which skeletal (57.9%), neurological (50.9%), and cardiac anomalies (39.5%) were the most common. 9 cases had a positive family history of micrognathia, where the finding in the fetus was thought to be constitutional.



89.5% (102) cases had diagnostic genetic testing, 72 of which had a genetic finding. Genetic testing explained the ultrasound findings in 60.8% of cases that underwent diagnostic genetic testing.

Conclusion:
Prenatal micrognathia is a common ultrasound finding that warrants additional investigations to better inform prognosis. 85.6% of the presented group had additional ultrasound anomalies and 60.8% had a genetic etiology, supporting a detailed anatomy ultrasound and consideration of genetic testing. Further, 76.9% of cases required respiratory intervention at delivery, about a third of which required ETT placement. Finally, while 12.2% of the delivered pregnancies resulted in neonatal demise, most of these were in the setting of palliative care. Altogether, this supports that while micrognathia can have poor prognosis, preparation with respiratory assistance at delivery may greatly improve morbidity and mortality.

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