• DOI:10.1055/a-0571-8608
• Corpus ID: 4598349

True or false umbilical cord knot? Differentiation via 3D/4D color Doppler ultrasound.

@article{Merz2018TrueOF,
  title={True or false umbilical cord knot? Differentiation via 3D/4D color Doppler ultrasound.},
  author={Eberhard Merz and Sonila Pashaj},
  journal={Ultraschall in der Medizin},
  year={2018},
  volume={39 2},
  pages={
          127-128
        }
}

• E. Merz, S. Pashaj
• Published 1 April 2018
• Medicine
• Ultraschall in der Medizin

True umbilical cord knots are actual knots in the umbilical cord formed during pregnancy, while a false umbilical cord knot is a bulge in the umbilical cord due to twisting of the vein around the arteries or around an overlap of umbilical cord loops lying against one another. True umbilical cord knots are relatively rare. Based on births, an incidence of 0.3 – 1.2 % is specified [1, 2]. Various factors are associated with the occurrence of an umbilical cord knot: grandmultiparity, chronic hypertension, diabetes, a long umbilical cord, a small fetus, a male fetus, monoamniotic twins, and patients who had undergone amniocentesis [2– 7]. While the risk of intrauterine death is 4 times higher in the case of true umbilical cord knots [2], there is no risk to the fetus in the case of false umbilical cord knots. However, even in the case of a true umbilical cord knot, there is no risk to the fetus as long as the knot is loose and blood circulation is not restricted. Wharton’s jelly provides a significant protective layer in this case. True umbilical cord knots typically appear in the form of a single knot. However, up to four true knots in one umbilical cord have been described [8]. It is assumed that umbilical cord knots are formed between 9 and 12 gestational weeks [2]. At this time there is significant amniotic fluid and fetal movement so that the fetus can slip through a loop of the umbilical cord during corresponding movements and gyrations. It is difficult to detect a true umbilical cord knot via 2 D ultrasound since it is a three-dimensional structure. In a retrospective study including 18 cases in which a true umbilical cord knot was found at the time of birth, Sepulveda et al. [1] were able to show that an umbilical cord knot was not detected during routine second-trimester ultrasound examination in any of these cases. Bohîlea et al. [9] specify a prenatal detection rate of 12%. Sonographic differentiation between a true and a false umbilical cord knot is even more difficult. Individual sonographic signs of a true umbilical cord knot have been described in the literature: umbilical cord in the form a four-leaf clover [10], an unusual multicolor umbilical cord pattern [4], or the “hanging noose” sign [11]. All of these signs can be indications of a true umbilical cord knot but do not provide definitive proof. Already in 2010, Guzikowski et al. [7] noted the advantages of 3D/4D color Doppler ultrasound for verifying an umbilical cord knot. Given the current quality of 3D/ 4D color Doppler ultrasound, it is now possible to more clearly verify a true umbilical cord knot on the basis of the three-dimensional image and to determine the degree of constriction (▶ Fig. 1). Differentiation from a false umbilical cord knot is also possible. In the case of an overlap of the umbilical cord simulating an umbilical cord knot, the false umbilical cord knot can be detected by rotating the volume and visualizing the umbilical cord (▶ Fig. 2a) from a different angle (▶ Fig. 2b). When detecting a true umbilical cord knot, blood flow measurements on Dop▶ Fig. 1 3D image of a true umbilical cord knot in an umbilical cord with a single umbilical artery (3D HDlive power Doppler). There is no compression of the two umbilical vessels.