Reversed blood flow in the superior sagittal sinus in hydrops fetalis.

Abstract

Hydrops fetalis is a term that describes the accumulation of fluid in two or more soft tissues and cavities and is one of the main factors that predispose to adverse neonatal outcome, in terms of both survival and neurodevelopment. Its etiology is highly variable and includes structural cardiac malformation, chromosomal abnormality, severe fetal anemia, mediastinal compression secondary to a thoracic mass or massive pleural effusion, fetal or placental tumor and twin-to-twin transfusion syndrome. Fetal brain circulation on Doppler ultrasound can be considered a predictor of postnatal neurodevelopment1. Cerebral blood flow has been shown to be altered in fetuses with growth restriction2, in which vasodilatation of the main arteries and increased resistance in the cerebral venous sinuses occur as a result of the brain-sparing effect3. Aside from intrauterine growth restriction and pregnancy-induced hypertension4, there is a paucity of evidence regarding fetal cerebral Doppler changes associated with fetal pathologies, and research has long been focused only on the main cerebral arteries, such as the middle cerebral artery (MCA). Preliminary research in fetuses with thoracic abnormality, such as congenital diaphragmatic hernia, has demonstrated cerebral blood flow changes, including decreased vascular resistance, but their clinical significance remains unclear5. No previous study has evaluated the potential changes in cerebral venous blood flow in fetal hydrops secondary to the mediastinal shift associated with a large lung mass. We present the case of a 30-year-old pregnant woman, gravida 2 para 0, with one previous termination of pregnancy, who was referred to our fetal surgery center in Querétaro, Mexico, due to a prenatal diagnosis of macrocystic congenital cystic adenomatoid malformation (CCAM) at 22 + 3 weeks of gestation. Fetal ultrasound revealed a macrocystic CCAM volume ratio of 6.15, severe mediastinal shift and hydrops fetalis (subcutaneous edema and ascites) (Figure 1). In the midsagittal view of the brain on HDflow color Doppler (Figure 2a,b), intermittent bidirectional blood flow in the fetal intracerebral venous system, including both the superior sagittal and straight sinuses, was observed in conjunction with reversed a-wave in the posterior portion of the superior sagittal sinus (Figure 2c). Evaluation of the umbilical artery and ductus venosus demonstrated positive diastolic blood flow, and MCA pulsatility index was within the normal range for gestational age. Following parental counseling regarding the poor prognosis, a thoracoamniotic shunt was placed at 23 weeks of gestation in an attempt to reduce the hydrops and improve fetal prognosis. Notably, normalization of cerebral venous blood flow was observed at prenatal follow-up, and a positive a-wave in the superior sagittal sinus was documented 1 week after shunting. Cesarean section was performed at 35 weeks following rupture of membranes, resulting in delivery of a liveborn, male neonate without respiratory morbidity. Pulmonary lobectomy was required at 3 days postpartum. We believe that cerebral venous Doppler adaptation to hydrops fetalis and its normalization following fetal intervention represent an area of opportunity for future research. To our knowledge, these observations have not been documented previously. Evaluation of cerebral venous blood flow may be useful for prenatal follow-up following intervention in hydropic fetuses and as a tool for prediction of neonatal survival and abnormal postnatal neurodevelopment. According to our observations, cerebral blood flow abnormalities may be independent of the changes observed in the MCA and precordial veins, such as the ductus venosus. Our findings should be confirmed by further studies in fetuses with hydrops and subcutaneous cranial edema, such as those with massive pleural effusion due to primary fetal hydrothorax or solid intrathoracic tumor. R.C.-M. wishes to thank the Fetal Medicine Foundation of Mexico for supporting the National Project of Fetal Surgery at Querétaro, Mexico. The data that support the findings of this study are available on request from the corresponding author.