True Cord Knot Means True Fetal Risk – Comment on the Title Image of Ultraschall in Med 2018; 39(02):127–128

Dear Editor,

Thank you for the title page with comments by Merz and Pashaj [1] showing an ultrasound image of a true umbilical cord knot in a single umbilical artery cord. We would like to add some comments and new findings from our nationwide population-based study on the umbilical cord including cord knots [2] and have utilized our dataset to explore the occurrence and risk in cases with the combination of a single umbilical artery and a knot not previously published. We found that in our population of more than 900 000 singleton births, the occurrence of a combination of a cord knot and a single umbilical artery is a very rare condition (0.014 %). There was an increased risk of perinatal death in these cases, but the confidence intervals were wide, reflecting the rarity of the condition. For the total group of single umbilical artery with knot, the odds ratio for perinatal death was 5.26 (95 % CI 2.15–12.85). Since the condition shown on the title page (Ultraschall in Med 2018; 39(02)) is very rare, we are curious to learn how this pregnancy was handled and if the outcome was good.

• References

• 1 Merz E, Pashaj S. True or false umbilical cord knot? Differentiation via 3D/4D color Doppler ultrasound. Ultraschall in Med 2018; 39: 127-128
• 2 Linde LE, Rasmussen S, Kessler J. et al. Extreme umbilical cord lengths, cord knot and entanglement: Risk factors and risk of adverse outcomes, a population-based study. PloS one 2018; 13: e0194814 . Epub 2018/03/28. doi: 10.1371/journal.pone.0194814. PubMed PMID: 29584790; PubMed Central PMCID: PMCPMC5870981
• 3 Moessinger AC, Blanc WA, Marone PA. et al. Umbilical cord length as an index of fetal activity: experimental study and clinical implications. PediatrRes 1982; 16: 109-112
• 4 Gembruch U, Baschat AA. True knot of the umbilical cord: transient constrictive effect to umbilical venous blood flow demonstrated by Doppler sonography. Ultrasound Obstet Gynecol 1996; 8: 53-56 . Epub 1996/07/01. doi: 10.1046/j.1469-0705.1996.08010053.x. PubMed PMID: 8843621
• 5 Baergen RN, Malicki D, Behling C. et al. Morbidity, mortality, and placental pathology in excessively long umbilical cords: retrospective study. PediatrDevPathol 2001; 4: 144-153 . doi: 10.1007/s100240010135 [pii]