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True knot of the umbilical cord: transient constrictive effect to umbilical venous blood flow demonstrated by Doppler sonography
Author(s) -
Gembruch U.,
Baschat A. A.
Publication year - 1996
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1046/j.1469-0705.1996.08010053.x
Subject(s) - medicine , umbilical cord , blood flow , fetus , constriction , ultrasound , cord , surgery , pregnancy , anatomy , cardiology , radiology , genetics , biology
True knot of the umbilical cord is a rare occurrence, which is difficult to diagnose antenatally, even with the use of ultrasound. Constriction of a true knot of the umbilical cord may lead to obstruction of the fetal circulation and subsequent intrauterine death. We present a singleton pregnancy, in which the antenatal diagnosis of a true knot of the umbilical cord with entanglement of the cord around the fetal neck and body was made at 23 + 4 weeks' gestation. With the use of color‐coded Doppler followed by pulsed wave Doppler spectral analysis, a stenotic effect on the umbilical venous blood flow, with normal arterial blood flow, was demonstrated for the first time. Marked acceleration of umbilical venous blood flow velocities from 15 cm/s pre‐stenotically to 100 cm/s post‐stenotically was demonstrated. This presented as an aliasing phenomenon and a mosaic pattern on color flow imaging in the variance mode. This phenomenon was only transient and could not be demonstrated again at follow‐up examinations. A healthy newborn was delivered by Cesarean section at 33 + 1 weeks' gestation. The presence of a single knot was confirmed at delivery. Copyright © 1996 International Society of Ultrasound in Obstetrics and Gynecology