The March issue of Ultrasound in Obstetrics & Gynecology has a special focus on management of prenatally diagnosed spina bifida, with relevant articles on neurodevelopmental outcome following prenatal vs postnatal closure, insufflation of heated and humidified, rather than cold and dry, CO2 in fetoscopic repair of spina bifida, and prenatal brain imaging for predicting the need for postnatal hydrocephalus treatment following prenatal repair of a neural tube defect.
Management of prenatally diagnosed spina bifida
The usual protocol for postnatal treatment of open spina bifida is early postnatal surgical repair. More recently, attempts have been made to improve the prognosis of spina bifida using fetal open or laparoscopic prenatal surgical repair. While prenatal closure of spina bifida aperta has been proposed to reduce the impact of in-utero neurological damage, fetal surgery increases risk of premature delivery, which may impact negatively on cognitive outcome.
Masini et al. report on the prenatal diagnosis of spina bifida, and its natural history, postnatal treatment and long-term outcome in a tertiary referral center. It was found that the prenatal detection rate was close to 100%, and advances in conventional neonatology and pediatric neurosurgery have allowed increased life expectancy and improved quality of life in patients with spina bifida. Sileo et al. report the long-term physical and neurological outcomes of infants with prenatally diagnosed isolated spina bifida that underwent postnatal surgical repair, concluding that neurodevelopmental and neurological outcomes between prenatal and postnatal repair are similar. In a Systematic Review, Inversetti et al. compared neurodevelopmental outcome between prenatal and postnatal repair, finding that the risk of impairment was similar, despite an increased risk of prematurity in the prenatally repaired group.
In an Editorial, Michael Bebbington disputes the validity of the conclusions of these studies, arguing that that a lack of information on which to stratify outcome represents a potential major source of bias in the study of Sileo et al., with similar methodological flaws in the study of Masini et al., and that the Systematic Review of Inversetti et al. is underpowered.
Fetoscopic closure of spina bifida has been proposed as a less invasive approach to prenatal repair than open surgery that may reduce obstetric and maternal risks while preserving the central nervous system benefits. However, there are concerns regarding CO2 insufflation during fetoscopic myelomeningocele repair, given its association with fetal acidosis and hypercapnia. In an Editorial, Magdalena Sanz Cortes discusses whether heated, humidified, compared with cold, dry, CO2 for uterine insufflation in humans may improve outcome. This topic is discussed in relation to the study of Amberg et al., in which insufflation of heated and humidified, rather than cold and dry, CO2 was assessed for its impact on the fetus and fetal membranes in sheep.
Fetal surgery itself and/or exposure to a CO2 environment during spina bifida repair may affect placental function and impair fetal growth. Sanz Cortes et al. compared growth in fetuses, neonates and infants who underwent prenatal fetoscopic or open myelomeningocele repair, finding no significant differences in fetal or postnatal growth parameters.
Also on this topic…
Prenatal brain imaging for predicting need for postnatal hydrocephalus treatment in fetuses that had neural tube defect repair in utero
Leakage of cerebrospinal fluid in fetuses with a neural tube defect may result in hydrocephalus, which is commonly treated by placement of a ventriculoperitoneal shunt, requiring lifelong monitoring. In this study, Zarutskie et al. assessed if brain imaging in fetuses that underwent prenatal repair of neural tube defect can predict the need for hydrocephalus treatment in the first year postpartum. Persistence of hindbrain herniation on magnetic resonance imaging 6 weeks after prenatal neural tube defect repair independently predicted the need for postnatal hydrocephalus treatment better than any ultrasound- or other magnetic resonance imaging-derived measurements of ventricular characteristics.
Also included in this issue…
Levator ani muscle morphology and function in women with obstetric anal sphincter injury
While obstetric anal sphincter injury (OASI) can be identified clinically by inspection and palpation immediately after delivery, levator ani muscle (LAM) trauma is often occult. If OASI is associated with a high prevalence of LAM injury, the identification of OASI at delivery could be a marker for occult levator trauma. In this study, Volløyhaug et al. estimated the prevalence of major LAM injury in women with clinically diagnosed OASI and explored the risk factors associated with LAM injury. Operative vaginal delivery was found to be a risk factor for LAM injury in women with OASI, and LAM injury was associated with weaker pelvic floor muscle contraction (download the accompanying Journal Club slides).
The next issue of UOG has a special focus on the cerebroplacental ratio: normal values and use in management of labor.