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

This is the authors' abstract. We don't add key points for this paper.

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. Letter to this article: Reply to the letter of Ebbing Ultraschall Med 2020; 41(01): 81-81 DOI: 10.1055/a-0771-1365