Dichorionic-triamniotic triplets with the mono-di pair impacted by open neural tube defects: a case study

Additional Authors

Shreya Visvanathan, Department of OBGYN, East Tennessee State University, Johnson City, TN. Ashlyn Hodges, Department of OBGYN, East Tennessee State University, Johnson City, TN. Martin Olsen, MD, Department of OBGYN, East Tennessee State University, Johnson City, TN. Lori Moore, MPH, Department of OBGYN, East Tennessee State University, Johnson City, TN.

Abstract

Background: Myelomeningocele impacts 3 in every 10,000 children ages 0-19 years old according to the most recent available data. Concordance of myelomeningoceles (MMCs) in the setting of twin and triplet pregnancies is an incredibly rare phenomenon, with less than 30 cases of twins with concordant MMCs having been reported in the literature. We discuss in this case report a rare case of dichorionic-triamniotic triplets in which the monochorionic-diamniotic pair were diagnosed antenatally with myelomeningocele. Case Summary: The mother presented for routine prenatal care at 11 weeks of gestation as a 31 year-old G5P4003. Dating ultrasound at 18 week and 6 days gestation confirmed her estimated due date and three fetal poles were observed. She was found to have dichorionic-triamniotic triplets with Triplet A and Triplet B sharing a placenta while Triplet C had a distinct placenta. Level II complete anatomy scan undertaken at 22 weeks and 5 days gestation demonstrated myelomeningocele of twin B at L4-S2 and suspected open neural tube defect in Triplet A based upon lemon-shaped calvarium, “banana sign” of the cerebellum, and collapsed posterior fossa. Triplets A and B were also found to have ventriculomegaly. Triplet B was diagnosed with fetal growth restriction at that time as well. Triplet C was appropriately grown and had no apparent defects on ultrasound. Discussion: Most of the cases of MMC in monozygotic twins are non-concordant, the role of genetic etiology remains ambiguous. Our case differs from this trend the monochorionic-diamniotic pair were both impacted, suggesting perhaps a novel mutation. Though one instance of identical twins (in this set of triplets) does not prove that a single mutation can cause MMC, it raises the compelling possibility of a single gene or locus responsible.Future studies may investigate the feasibility of in-utero repair of MMC for multifetal gestations as well as the potential for a single-gene mutation driving the development for MMC.

Start Time

16-4-2025 1:30 PM

End Time

16-4-2025 4:00 PM

Presentation Type

Poster

Presentation Category

Health

Student Type

Clinical Resident or Fellow

Faculty Mentor

Aleksander Fuks

Faculty Department

Obstetrics and Gynecology

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Apr 16th, 1:30 PM Apr 16th, 4:00 PM

Dichorionic-triamniotic triplets with the mono-di pair impacted by open neural tube defects: a case study

Background: Myelomeningocele impacts 3 in every 10,000 children ages 0-19 years old according to the most recent available data. Concordance of myelomeningoceles (MMCs) in the setting of twin and triplet pregnancies is an incredibly rare phenomenon, with less than 30 cases of twins with concordant MMCs having been reported in the literature. We discuss in this case report a rare case of dichorionic-triamniotic triplets in which the monochorionic-diamniotic pair were diagnosed antenatally with myelomeningocele. Case Summary: The mother presented for routine prenatal care at 11 weeks of gestation as a 31 year-old G5P4003. Dating ultrasound at 18 week and 6 days gestation confirmed her estimated due date and three fetal poles were observed. She was found to have dichorionic-triamniotic triplets with Triplet A and Triplet B sharing a placenta while Triplet C had a distinct placenta. Level II complete anatomy scan undertaken at 22 weeks and 5 days gestation demonstrated myelomeningocele of twin B at L4-S2 and suspected open neural tube defect in Triplet A based upon lemon-shaped calvarium, “banana sign” of the cerebellum, and collapsed posterior fossa. Triplets A and B were also found to have ventriculomegaly. Triplet B was diagnosed with fetal growth restriction at that time as well. Triplet C was appropriately grown and had no apparent defects on ultrasound. Discussion: Most of the cases of MMC in monozygotic twins are non-concordant, the role of genetic etiology remains ambiguous. Our case differs from this trend the monochorionic-diamniotic pair were both impacted, suggesting perhaps a novel mutation. Though one instance of identical twins (in this set of triplets) does not prove that a single mutation can cause MMC, it raises the compelling possibility of a single gene or locus responsible.Future studies may investigate the feasibility of in-utero repair of MMC for multifetal gestations as well as the potential for a single-gene mutation driving the development for MMC.