This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in

Foramen ovale (changes after birth)

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

The foramen ovale closes after birth. Initially, this is due to a functional equalization of pressures within the atria that apposes the septum primum and the septum secundum. Equalization of pressure occurs because of:

  • lung inflation leading to reduced pulmonary vascular resistance
    • foramen ovale is an interatrial communication that permits blood from the inferior vena cava to freely enter the left atrium in utero (right-to-left shunt)
    • at birth, the left atrial pressure exceeds the right atrial pressure (thus reversing the right-to-left shunt of the fetal circulation)
      • this forces the septum primum against the septum secundum, functionally closing the foramen ovale
    • the duct closes by a prostaglandin dependent mechanism, the signal for closure being a rise in circulating oxygen levels
    • eventally the septa eventually fuse and leave a remnant of the foramen ovale, the fossa ovalis

Functional closure can be reversed during the immediate neonatal period; this occurs during bouts of crying when cyanosis may be seen and there is a re-emergent right-to-left shunt.

Anatomical fusion of the septum primum and secundum occurs by one year of age in 80% of the population. Fibrosis results in the fossa ovalis of the interatrial septum. The remaining 20% have a foramen which is only potentially patent. The normal pressures within the atria ensure that it remains closed; the septum primum acts as a flap-valve against the septum secundum due to the greater pressures within the left atrium compared to the right atrium.


Create an account to add page annotations

Annotations allow you to add information to this page that would be handy to have on hand during a consultation. E.g. a website or number. This information will always show when you visit this page.

The content herein is provided for informational purposes and does not replace the need to apply professional clinical judgement when diagnosing or treating any medical condition. A licensed medical practitioner should be consulted for diagnosis and treatment of any and all medical conditions.

Connect

Copyright 2024 Oxbridge Solutions Limited, a subsidiary of OmniaMed Communications Limited. All rights reserved. Any distribution or duplication of the information contained herein is strictly prohibited. Oxbridge Solutions receives funding from advertising but maintains editorial independence.