The balloon technique-termed etal endoscopic tracheal occlusion (FETO)-uses a 3-mm operating sheath and fetoscopes as small as 1 mm (Depresr, 2011; Ruano, 2012). he procedure is generally performed between 27 and 30 weeks' gestation, with the goal of removing the balloon at approximately 34 weeks, either through a second fetoscopic procedure or by ultrasound-guided puncture Gimenez, 2017). If these are unsuccessful, the balloon is removed during an ex-utero intrapartum treatment procedure at delivery (p. 327).
FIGURE 16-6 Fetoscopic tracheal occlusion (FETO). The endoscope enters the fetal oropharynx and advances down the trachea. Inset: The balloon is inflated to occlude the trachea, and then the endoscope is removed. (Reproduced with permission from Shamshirsaz AA, Ramin, SM, Belfort MA: Fetal therapy. In Yeomans ER, Hoffman BL, Gilstrap LC III, et al: Cunningham and Gilstrap's Operative Obstetrics, 3rd ed. New York, McGraw-Hili Education, 2017.)
In 2003, a randomized trial of the FETO procedure in pregnancies with isolated CDH, liver herniation, and LHR < 1.4 did not identiY a benefit from fetal therapy (Harrison, 2003). Survival rates 90 days after birth were unexpectedly high in both groups and approximated 75 percent. Following this study, however, enthusiasm for the technique continued, particularly outside the United States. Using a lower LHR threshold of 1.0 in addition to liver herniation as prerequisites for inclusion, signiicantly higher postnatal survival rates have been reported. Rates improved from <25 percent with postnatal therapy to approximately 50 percent with FETO Gani, 2009; Ruano, 2012). In a recent metaanalysis of five trials that included 21i1 pregnancies, those treated with FETO were 13 times more likely to survive (Al-Maary, 2016). At present, FETO is available in the United States only in research trials.
After publication of the MOMS indings, research eforts focused on whether maternal morbidities associated with open fetal myelomeningocele repair might be mitigated if the procedure was accomplished endoscopically. Araujo Junior and associates (2016) conducted a systematic review that included 456 open cases and 84 endoscopic surgeries. he endoscopic procedures were generally performed by inserting instruments through the maternal abdominal wall and then through the uterine wall, with partial carbon dioxide insuiation of the uterus. he rate of maternal myometrial dehiscence or attenuation was only 1 percent following endoscopy compared with 26 percent following open procedures. However, endoscopy was associated with significantly increased rates of preterm delivery before 34 weeks-80 versus 45 percent, and of perinatal mortality-14 versus 5 percent.
Belfort and colleagues (2017) recently described their outcomes in 22 pregnancies with fetal myelomeningocele using a technique in which the maternal abdomen was opened, the uterus exteriorized, and the procedure then performed endoscopically using warmed carbon dioxide insuiation. In contrast with earlier endoscopic reports, most treated pregnancies were delivered at term, with no perinatal losses. Further, the proportion of infants requiring hydrocephalus treatment prior to 1 year of age-approximately 40 percent-was similar to that with open fetal surgery in the MOMS trial (Adzick, 2011; Belfort, 2017). Research eforts in this area will undoubtedly continue.