Neurological and cardiovascular pathophysiological responses to monochorionic placentation

  • Sarah Newell

Student thesis: Doctoral ThesisDoctor of Medicine (MD)


Monochorionic twins have a unique set of complications, due to vascular anastomoses allowing interfetal transfusion. This results in episodes of haemodynamic instability, and as a result, they are at risk of various co-morbidities including cardiovascular and neurodevelopmental sequelae. The pathophysiology behind increased neurological morbidity in monochorionic twins is not fully understood. Therefore, in this thesis I have explored the neurological and cardiovascular effects of monochorionic placentation.

The impact of birthweight discordance on brain growth and brain volume was assessed in a cohort of twins (n = 96). Selective fetal growth restriction was associated with increased intertwin brain volume discordance and a trend towards a reduction in total brain tissue volume, after adjusting for birthweight. In both monochorionic and dichorionic twins, increasing birthweight discordance was associated with a reduction in absolute brain volume and an increase in brain volume discordance after controlling for various confounders including birthweight.

Quantification of left ventricular strain was assessed in a cohort of twins (n = 144). There was an increase in intertwin strain discordance and a reduction in left ventricular strain, driven by reduced strain in the recipient twin, in twinsets affected by twin-to-twin transfusion syndrome. This resolved promptly following successful laser treatment.

Prediction and early diagnosis of pathology remains a significant challenge in the management of monochorionic twins. This thesis provides evidence for the potential benefit of using left ventricular strain quantification to differentiate between and predict monochorionic pathologies, and evidence of a negative impact of intertwin growth discordance on brain growth and development.

Continued investigation into adjuncts to enhance the prediction, diagnosis, and understanding of the complications of monochorionicity, will improve management and counselling in these high risk pregnancies.
Date of Award23 Jun 2020
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorKaren Luyt (Supervisor), Christy Burden (Supervisor), Mark Denbow (Supervisor) & Adam Smith-Collins (Supervisor)

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