Laser ablation for vasa previa shows promising results

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A recent study highlighted the potential of fetoscopic laser ablation in improving perinatal outcomes for vasa previa, reducing risks associated with this condition affecting approximately 5 in 10,000 pregnancies.

Laser ablation for vasa previa shows promising results | Image Credit: © MQ-Illustrations - © MQ-Illustrations - stock.adobe.com.

Laser ablation for vasa previa shows promising results | Image Credit: © MQ-Illustrations - © MQ-Illustrations - stock.adobe.com.

Favorable outcomes generally occur when treating types 2 and 3 vasa previa with laser ablation at 31 to 33-weeks’ gestation, according to a recent study published in the American Journal of Obstetrics & Gynecology.

Takeaways

  1. The study suggests that treating types 2 and 3 vasa previa with laser ablation at 31 to 33 weeks' gestation leads to favorable outcomes.
  2. Vasa previa, characterized by fetal vessels near the internal cervical without placental support, is linked to substantial perinatal morbidity and mortality.
  3. There are 3 types of vasa previa: type 1, where there's velamentous placental cord insertion near the cervix; type 2, where fetal vessels connect to an accessory placental lobe; and type 3, where neither type 1 nor 2 are present.
  4. Approximately 5 in 10,000 pregnancies are affected by vasa previa, and it's often challenging to diagnose. Cases without prenatal diagnosis have a low survival rate of 28.1%.
  5. Fetoscopic laser ablation, known to improve outcomes in twin–twin transfusion syndrome, may similarly enhance vasa previa management. The study evaluated outcomes from fetoscopic laser ablation at 31 to 33 weeks' gestation for types 2 and 3 vasa previa, showing successful occlusion and favorable results.

Vasa previa, which presents as fetal vessels near the internal cervical without support from underlying placenta, is associated with significant perinatal morbidity and mortality. These risks are decreased by early detection because of preterm cesarean delivery timed to avoid membrane rupture.

There are 3 types of vasa previa: type 1 where there is a velamentous placental cord insertion near the cervix, type 2 where fetal vessels connect to an accessory placental lobe, and type 3 where neither types 1 nor 2 are present.

Approximately 5 in 10,000 pregnancies are impacted by vasa previa and it is often difficult to diagnose. Patients with persistent type 2 or type 3 vasa previa are often managed through measures which reduce the risk of fetal exsanguination, such as planned early cesarean delivery. However, cases without a prenatal diagnosis have a low survival rate of 28.1%.

Fetoscopic laser ablation of placental vascular communications, which improves outcomes in twin–twin transfusion syndrome, may similarly improve vasa previa management. To evaluate perinatal outcomes from fetoscopic laser ablation at 31 to 33-weeks’ gestation in patients with types 2 and 3 vasa previa, investigators conducted a retrospective cohort study.

Surgeries occurring at Los Angeles Fetal Surgery between 2006 and 2022 were included in the analysis. Participants had vasa previa identified at the center or were referred for laser ablation, and all received preoperative ultrasound examination. Fetal anatomy, fetal Doppler waveforms, and cervical length were evaluated.

Endovaginal ultrasound images were correlated with transabdominal ultrasound findings to determine vasa previa type. Color and pulsed-wave Doppler examination was used to classify the vessel type as artery or vein. 

A vasa previa within 2.5 cm of the internal cervical os was classified as type 2 or type 3, and patients with these presentations were offered laser ablation. These participants were offered expectant management starting at 28 to 32 weeks’ gestation and early cesarean delivery, pregnancy termination, or diagnostic fetoscopy and possible laser ablation.

To evaluate placental territory, investigators measured the placental tissue perfused by the aberrant fetal vessels. Participants received corticosteroids prior to the surgery for fetal lung maturation. Local anesthesia and maternal sedation were provided during fetoscopy, with a warm lactated Ringer’s solution through an 18-gauge needle used to perform amnioinfusion.

There were 20 patients with type 2 or type 3 vasa previa receiving laser ablation for a singleton pregnancy at 31 weeks’ gestation or later included in the final analysis. Type 2 vasa previa was reported in 70% of these patients, and the mean observed distance from the internal cervical os of the closest vesselwas 0.90±0.57 cm.

One to 4 vessels were lasered, with the largest vessel diameter being 2.9±0.8 mm. Patients underwent fetoscopic laser ablation at a mean gestational age 32.0±0.6 weeks, which lasted for a mean duration of 63.4±19.6 minutes.

A fetal artery and vein were both involved in 45% of surgeries, while 30% only involved a vein and 25% only an artery. Successful occlusion was achieved in all patients, with no cases of perioperative cesarean delivery. All but 1 patient had a hospital stay duration of 2 days, while 1 who needed a second procedure for reperfusion of the vasa previa had a duration of 3 days.

Neonatal intensive care unit admission was observed in 3 newborns, 1 for respiratory distress syndrome and 2 for hyperbilirubinemia. Sepsis, neonatal transfusion, patent ductus arteriosus, intraventricular hemorrhage, and death were not observed, nor were there maternal delivery complications.

These results indicated favorable outcomes from fetoscopic laser ablation against type 2 and type 3 vasa previa at 31 to 33 weeks’ gestation. Investigators recommended further research to determine the benefits of this procedure to mothers and fetuses.

Reference

Chmait RH, Monson MA, Chon AH, et al. Third-trimester fetoscopic ablation therapy for types II and III vasa previa. Am J Obstet Gynecol. 2024;230:87.e1-9. doi:10.1016/j.ajog.2023.09.015

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