Feasibility and limitations of the prenatal sonographic assessment of choanal flow and neonatal implications.

Abstract

ObjectiveTo evaluate the factors associated with the prenatal detection of choanal flow (CF) in a normal population.MethodsFifty pregnant women underwent CF evaluation using B-Mode and color Doppler. Screening for CF began at 22 weeks, standardized according to two section planes: sagittal and transverse. CF was considered positive when flow was seen, and negative if no flow was detected after 1 minute. The screening was repeated monthly until flow was observed. We assessed maternal BMI, fetal gender, gestational age at the first detection of flow, placental site, visibility noted by the sonographer, nasal asymmetry, and possible nostril dilatation.ResultsChoanal flow was established in all patients except two cases where the fetal face was consistently downwards (48/50). The gestational age at first detection of choanal flow was 28 weeks ± 3.5 weeks. Flow was unilateral in 56.3% of cases and bilateral in 43.8% of cases. Visibility assessed by the operator was rated as good in 72% of cases, average in 20%, and poor in 8%. The only factor significantly associated with the gestational age at first detection of choanal flow was visibility (p = 0.006).ConclusionThe average gestational age for the detection of choanal flow is 28 weeks. Relying solely on second-trimester morphological ultrasound may result in missed detections.