True knot of the umbilical cord: Transient constrictive effect to umbilical venous blood flow demonstrated by Doppler sonography

U. Gembruch, Ahmet Baschat

Research output: Contribution to journalArticle

Abstract

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+1 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.

Original languageEnglish (US)
Pages (from-to)53-56
Number of pages4
JournalUltrasound in Obstetrics and Gynecology
Volume8
Issue number1
StatePublished - Jul 1996
Externally publishedYes

Fingerprint

Umbilicus
Doppler Ultrasonography
Umbilical Cord
blood flow
Pregnancy
Nuchal Cord
Color
color
Blood Flow Velocity
pregnancy
Prenatal Diagnosis
Constriction
death
Cesarean Section
spectrum analysis
delivery
constrictions
Neck
flow velocity
examination

Keywords

  • Doppler sonography
  • Fetal surveillance
  • True knot of the umbilical cord
  • Umbilical venous stenosis
  • Venous pulsations

ASJC Scopus subject areas

  • Obstetrics and Gynecology
  • Radiology Nuclear Medicine and imaging
  • Reproductive Medicine
  • Acoustics and Ultrasonics
  • Radiological and Ultrasound Technology

Cite this

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abstract = "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+1 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.",
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N2 - 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+1 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.

AB - 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+1 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.

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