Investigating umbilical cord torsion as a cause of abortion

Approximately 1 in 25 Thoroughbred pregnancies in the UK result in pregnancy loss during mid to late gestation, a statistic that has not shown any significant improvement in the past three decades. 

In the UK, umbilical cord torsion (UCT) is recognised as the primary cause of this phenomenon, accounting for almost half of the cases that are sent for laboratory analysis. 

 

UCT occurs when there is excessive twisting of the umbilical cord, which restricts the blood supply to the foetus and eventually causes its death.

 

Interestingly, in all other countries (except Australia), the proportion of pregnancy loss attributed to UCT is much lower. In North America, the occurrence of UCT is one tenth of that in the UK. The rate of abortion attributed to umbilical torsion varies from 2.4% to 6.0% in studies conducted in the United States, while it reaches 35.7% in the United Kingdom. 

 

Umbilical cords from torsion cases tend to be longer than 85 cm on average. The reasons why certain pregnancies are more prone to develop long or excessively twisted umbilical cords, as well as the dramatic geographic variation in occurrence, are not well understood. 

 

Researchers at the Royal Veterinary College (RVC) are leading a collaboration with colleagues at Cornell University, Rossdales Laboratories and Hagyard Equine Medical Institute to explore the reason why the umbilical cord twists excessively mid-pregnancy. The research, funded by the Alborada Trust, continues the first ever comprehensive study of UCT in the world. Together, the research team hope to establish new ways of detecting the twisting prior to the pregnancy being aborted.

 

They will also characterise subcomponents and key proteins of the umbilical cord in both normal and diseased cords to identify any potential regions of the cord that could be monitored clinically. These areas will then be examined using ultrasonography in mid-gestation to assess the diagnostic potential for mares that are at risk of UCT abortion.

The researchers hope to develop novel diagnostic tools that will enable veterinarians to predict mares at risk of suffering a UCT pregnancy loss and monitor the efficacy of novel treatments for the condition. Ultimately, the findings from this project will push forward the understanding of this cause of equine pregnancy loss, and abortion more widely.    

 

Jessica Roach, Research Fellow at the RVC, said: “The generous funding from The Alborada Trust will allow us to build on our understanding of umbilical cord torsion, which is such a frustrating cause of abortion to breeders and veterinarians alike. This project brings together researchers who are leading their field and I hope that this will allow us to forward our understanding of this condition. Our aim is to develop novel diagnostic tools to identify pregnancies with a torsed umbilical cord, and ultimately prevent or decrease the risk of pregnancy loss.”

 

For more information on the study, see : https://www.rvc.ac.uk/research/projects/investigation-of-clinical-predictors-of-equine-umbilical-cord-torsion-and-abortion