Correspondence

Complex Umbilical-Cord Knot

N Engl J Med 2003; 349:1389-1390October 2, 2003

Article

To the Editor:

The “compound” umbilical-cord knot reported by Camann and Marquardt (July 10 issue)1 is topologically two distinct knots that were probably “tied” at separate times. First, an overhand knot probably formed as the fetus passed through a loop in the cord, creating the lump at the upper left of the compound knot. Subsequently, a figure-eight knot2 probably formed when the fetus passed through a second loop whose base retained a half-twist. Not necessarily immediately, they snugged together into what presents as a compound knot.

Could the two component knots have been tied simultaneously? It is unlikely, but if so, it is most imaginable that this double tying occurred at delivery, with the two loops accidentally caught between the head of the fetus and the internal cervical os. This scenario would require a cord long enough for the simultaneous formation of two loops, each of which would have to be more than 30 cm long in order to fit around the head of the fetus. The average length of an umbilical cord is 55 to 60 cm, but some do measure 100 cm or more.3 This explanation is weak, however, because a nuchal cord would be far more likely to occur under these circumstances than would a compound knot, and the cord was not reported to be particularly long.

Norman A. Spencer, M.D.
217 Russell St., Hadley, MA 01035

3 References