Presentation of Fetal Myelomeningocele

Symptoms and signs

• Ultrasonographic spinal abnormality: An open NTD is most commonly detected on routine prenatal ultrasonography.
• Progression of hydrocephalus and Chiari II malformation: Animal models suggest that as the gestation progresses, associated neurologic sequelae — including ventriculomegaly and hindbrain herniation — also progress (9).

Evaluation at Presentation

• Assess eligibility for fetal myelomeningocele repair: With regard to fetal intervention, evaluation of the mother and fetus upon presentation focuses on determining eligibility for intrauterine repair.
• Lesion level and concomitant anomalies: If an open NTD is observed during the diagnostic ultrasound, the spinal level should be approximated and a search for other anomalies undertaken. The presence of other structural anomalies, including cerebral malformations and limb defects, was exclusionary for enrollment in the MOMS trial and remains a relative contraindication to fetal repair.

Intervention at Presentation

Stabilization

• Patient support and counseling: The presence of an open NTD itself does not pose an immediate risk to the mother, nor does it render the fetus nonviable. Evidence of fetal distress or hemodynamic instability should trigger the workup of a separate pathologic process not directly related to myelomeningocele. In the immediate period following an open NTD diagnosis, the mother should be educated about the condition, advised on treatment options, and offered social and emotional support.

Preparation for definitive intervention, nonemergent

• MFM: When an open NTD is identified, a referral to an MFM specialist, who would then conduct an advanced (Level II) ultrasound should be considered.
• Advanced Fetal Center: If a mother is interested in fetal myelomeningocele repair after consulting with the MFM practitioner, she should be immediately referred to a fetal center that offers the procedure. Additional workup will be required.
• Less than 26 weeks of gestation: Fetal myelomeningocele repair is performed no later than 25 weeks, 6 days of gestation.
• Assess eligibility for fetal repair: Currently, a fetus is eligible for fetal repair if the mother is aged 18 or over, there is only one fetus in the pregnancy, the fetus has a normal karyotype, and the defect is between T1 and S1.
• Exclusion criteria: A fetus is ineligible for fetal closure of the myelomeningocele if the mother meets any of the following criteria: (a) has type 1 diabetes, hypertension, or a BMI over 40; (b) has aberrant anatomy (e.g., placental abruption, short cervix, or history of incompetent cervix) or uterine anomalies (e.g., multiple fibroids, Müllerian duct abnormality, bicornuate or unicornuate uterus, or uterine septum); or (c) tested positive for HIV, Hepatitis B or Hepatitis C. A fetus is also excluded if they have cardiac defects, intracranial hemorrhage, and other detectable anomalies. Finally, the surgery is not recommended if the family lacks adequate psychosocial support or is unwilling to relocate near the fetal center between fetal surgery and delivery.
• Alternative, postnatal repair: If excluded from fetal myelomeningocele repair, the mother may choose to deliver and plan for postnatal myelomeningocele closure.

Preparation for definitive intervention, emergent

• Gestational age window: Fetal surgery is offered between 22 weeks and 25 weeks, 6 days of gestation. Although emergent fetal repair of myelomeningocele is never indicated, the inherently narrow window between ultrasonographic diagnosis and proposed intrauterine intervention mandates swift multidisciplinary assessment and clearance.

Admission orders

See Presentation of Myelomeningoceles in Children, Admission Orders.