Risk Factors Associated With Spontaneous Preterm Delivery Status Post Open Fetal Myelomeningocele Repair
Condition: Myelomeningocele
MeSH terms: Meningomyelocele; Spina Bifida Cystica; Premature Birth
Study type: Observational

Summary: 
      This is a chart review of all patients who have underwent open prenatal repair of fetal
      myelomeningocele. Although prenatal repair is associated with improved neurologic outcomes
      and a decreased need for cerebrospinal fluid shunting after birth, one of the major risks is
      preterm delivery. This study is intended to identify maternal, fetal or intraoperative risk
      factors associated with preterm delivery.
    

Detailed description: 
      Myelomeningocele encompasses the most common form of spina bifida. The incidence ranges from
      2.73-3.80 per 10,000 births in the United States. The extent of neurologic sequela is
      correlated with the level of the lesion but frequently involves a spectrum of motor
      dysfunction including paralysis of the lower extremities, contractures in addition to lack of
      bladder and bowel control. These result in significant lifestyle limitations for survivors.
      Additionally, hydrocephalus, brainstem herniation and Chiari II malformations are commonly
      noted. Ventriculoperitoneal shunts are commonly placed in childhood to redirect cerebrospinal
      fluid and can require revisions later in life.

      The Management of Myelomeningocele Study (MOMS) trial revolutionized management of fetuses
      with myelomeningoceles by demonstrating that prenatal compared to standard postnatal repair
      resulted in decreased need for cerebrospinal fluid shunts and improved motor function at
      thirty months. As a result, various centers around the United States began offering prenatal
      repair to patients less than twenty-six weeks gestation with prespecified maternal and fetal
      characteristics.

      Prenatal repair is not without risk to both the mother and the fetus. The mother must undergo
      a laparotomy and accept the risks involved with any intraabdominal surgery including
      bleeding, infection, adhesion formation and damage to nearby organs. Unique to this
      procedure, a hysterotomy is typically created in the active segment of the uterus to allow
      for sufficient exposure of the fetal lesion. Like those women who undergo classical Cesarean
      sections, these patients must undergo Cesarean sections around 37 weeks gestation for all
      future pregnancies secondary to concern of uterine dehiscence in the setting of labor. This
      has major implications for the mother's future childbearing potential, as the number of
      previous Cesarean sections increases the risk of intraoperative complications and invasive
      placentation in subsequent pregnancies. A fetoscopic approach has reemerged in the United
      States as an alternative to the aforementioned open approach and is currently under further
      investigation.

      Intraoperative fetal distress has been reported and can lead to loss of the pregnancy.
      Additionally, fetal surgery carries the risks of spontaneous preterm birth and preterm
      premature rupture of membranes, which subject the fetus to the morbidity of prematurity. This
      risk of spontaneous preterm delivery is one of the more common and significant drawbacks to
      the procedure and represents a major hurdle to overcome. In the MOMS trial, 46% of those in
      the study group compared to 8% in the postnatal repair group experienced spontaneous rupture
      of membranes. Thirty-eight percent of prenatal repair versus 14% of postnatal repair patients
      went into spontaneous labor prior to scheduled delivery. The average gestational age at birth
      was 34 weeks for the prenatal surgery group and 37 weeks for the postnatal surgery group. In
      another study following the MOMS trial, 100 patient underwent prenatal repair with a reported
      32.3% rate of preterm premature rupture of membranes(PPROM) and 37.5% rate of preterm labor.
      Also reported a modified surgical approach to the hysterotomy and closure among 43 patients
      and found a 22% rate of PPROM. Thirty-nine percent delivered at 37 weeks or later compared
      with 21% of the MOMS cohort.

      Although the increased risk of preterm delivery is reported, little is known regarding risk
      factors associated with preterm delivery following this procedure. Soni et al. found that
      chorioamniotic membrane separation was a risk factor for subsequent PPROM. No studies have
      been published that assess risk factors for all spontaneous preterm deliveries including both
      preterm labor and PPROM. The objective of this study is to determine if any maternal, fetal
      or intraoperative factors can be identified that increase the risk of spontaneous preterm
      delivery in patients who undergo prenatal open myelomeningocele repair. With the
      identification of such factors, counseling of the patient and potentially patient selection
      could be refined in the future.
    

Intervention name(s): Chart review
Intervention type(s): Other
Intervention description(s): This is a chart review of all patients who have underwent open prenatal repair of fetal myelomeningocele. Although prenatal repair is associated with improved neurologic outcomes and a decreased need for cerebrospinal fluid shunting after birth, one of the major risks is preterm delivery. This study is intended to identify maternal, fetal or intraoperative risk factors associated with preterm delivery.
Observational model: Cohort
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        patients who underwent open fetal myelomeningocele repair Ethnicity: Any