Placental fetal thrombotic vasculopathy in severe congenital anomalies prompting EXIT procedure

The ex-utero intrapartum treatment (EXIT) procedure is used to secure fetal airway, cannulate for extracorporeal membrane oxygenation (ECMO), or resect a tumor during partial delivery in a modified cesarean section. This is a retrospective study of placental pathology from EXIT procedures.

Placental reports and glass slides from 36 placentas delivered by EXIT procedure (study group SG) and 36 placentas from pregnancies without perinatal mortality and delivered by cesarean sections and matched for gestational age were blindly reviewed. Indications for EXIT procedures were: 11 cervical teratomas, 9 diaphragmatic hernias, 4 pulmonary airway malformations, 4 micrognathias, 3 vascular malformations, 3 CHAOS, and 2 aortic stenoses. 22 clinical and 43 gross and histological placental features were compared using the analysis of variance or Yates χ(2) with Holm-Bonferroni correction, where appropriate.

The average gestational age in the SG and the CG was 34.9 weeks. Histological features of fetal thrombotic vasculopathy were more frequently seen in the SG. Of the placental features, statistically significant differences were found in, partial fibrosis of chorionic villi (9.7 ± 7.9 vs. 6.1 ± 5.3 villi per placental section) [p = 0.035], clusters of at least 3 avascular chorionic villi (33 v. 6%) [p = 0.042], and abnormal umbilical cord insertion (8% vs. 0% (p = 0.045), in the SG and the CG respectively.

To the best of our knowledge, this is the first study to describe the placentas from EXIT procedures. The presence of increased frequency of fetal thrombotic vasculopathy on histology indicates an underlying chronic and on-going stasis in fetal circulation due to the presence of conditions which were indications for the EXIT procedures. The possibility of coagulopathy should be considered in management of the fetuses and neonates undergoing EXIT procedure. Detailed examination of the placenta is of utmost importance in order to recognize and treat potentially life-threatening complications.