Is notching in the umbilical artery Doppler waveform a benign finding?

A diastolic notch in the uterine artery Doppler flow velocity waveform (FVW) is associated with an increased uterine vascular impedance, impaired uterine blood flow, and adverse perinatal outcome.(1) Likewise, uterine artery notching combined with an abnormal FVW of the umbilical artery (UA) is considered a predictor of adverse neonatal outcome.(2) Unlike data regarding the uterine artery, data are rare regarding the clinical importance of notching in the UA as an isolated finding. A few case reports have described the association between umbilical cord notching (with or without an abnormal FVW) and cord entanglement in monoamniotic twins,(3) fetal gastroschisis,(4) and fetal intra-abdominal vein dilatation.(5) Recently, Abuhamad et al(6) prospectively evaluated 1857 pregnancies and found UA notching in 29 (1.6%) fetuses. They showed that UA notching is associated with both cord and placental abnormalities, including abnormal cord insertion, cord stricture, and false or true knots in the cord.(6) Furthermore, they suggested that this finding may have important clinical implications, such as cord and placental abnormalities and a high prevalence of nonreassuring fetal heart rate abnormalities during labor. We present a case in which UA notching was detected in an impaired fetus with a single umbilical artery (SUA) whose umbilical cord was wrapped around its body. On the basis of this case and our review of the literature, we recommend increased fetal surveillance whenever FVWs display a notch in the UA.