Power Doppler and 3-dimensional sonographic diagnosis of multiple separate true knots of the umbilical cord

T he reported incidence of a true knot of the umbilical cord is approximately 1.2 % of all deliveries. 1,2 Prenatal sonographic diagnoses of cases of a true knot of the umbilical cord have been reported infrequently.(3-6) Ramon y Cajal and Martinez(7) recently reported characteristic sonographic findings of this condition, in which a detailed investigation disclosed a transverse section of the umbilical cord surrounded by a loop of umbilical cord. This finding, noted in 5 cases, was termed the "hanging noose" sign. We present an unusual case in which 2 true knots of the umbilical cord were noted by power Doppler sonography in close proximity to each other at 33 weeks' gestation and were confirmed as separate true knots of the umbilical cord by 3-dimensional sonographic imaging.