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Foundation Sciences · Embryology

Foetal Circulation

⏱️ 30 mins read 📖 Embryology 🎯 MLA Relevance: High

Foetal circulation includes three shunts (ductus venosus, foramen ovale, ductus arteriosus) that bypass the non-functional lungs and liver.

📌 Learning Objectives

  • Describe the underlying mechanism of Foetal Circulation.
  • Identify the key clinical features and complications of Foetal Circulation.
  • Outline the appropriate investigations and management of Foetal Circulation.
  • Discuss the implications for patients and families of Foetal Circulation.
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Curriculum Mapped
UK MLA Curriculum

📋 Overview

Oxygenated blood from the placenta enters via the umbilical vein, bypasses the liver via the ductus venosus, and is preferentially streamed across the foramen ovale into systemic circulation. At birth, increased pulmonary blood flow and removal of placental circulation close these shunts.

🔬 Basic Science

Oxygenated blood from the placenta enters via the umbilical vein, bypasses the liver via the ductus venosus, and is preferentially streamed across the foramen ovale into systemic circulation. At birth, increased pulmonary blood flow and removal of placental circulation close these shunts.

🏥 Clinical Relevance

Prostaglandin E1 keeps the ductus open in duct-dependent cyanotic heart disease until surgery.

🧪 Investigations

Investigation depends on clinical context: relevant blood tests, imaging, and specific genetic or histopathological tests as appropriate. Refer to specialist services where indicated.

💊 Management

Management is condition-specific and typically multidisciplinary, combining medical therapy, surgical intervention where appropriate, supportive care, and family/genetic counselling.

Revision Resources – expand the sections below for high-yield notes, exam pearls, key facts and further reading.

🎯 MLA High-Yield Notes & Quick Revision
Common SBA themes: recognising the underlying mechanism, identifying classic clinical features, and choosing the first-line investigation or management step. Watch for inheritance pattern and characteristic associations.
fetal circulation ductus arteriosus foramen ovale pda umbilical vein
  • The umbilical vein carries oxygenated blood from the placenta to the foetus.
  • The ductus venosus bypasses the foetal liver.
  • The foramen ovale shunts blood right-to-left across the atrial septum.
  • The ductus arteriosus shunts blood from the pulmonary artery to the aorta.
  • PDA can be closed with indomethacin (prostaglandin inhibitor) in preterm infants.
Exam Pearls
⭐ High Yield
The umbilical vein carries oxygenated blood from the placenta to the foetus.
The ductus venosus bypasses the foetal liver.
The foramen ovale shunts blood right-to-left across the atrial septum.
The ductus arteriosus shunts blood from the pulmonary artery to the aorta.
PDA can be closed with indomethacin (prostaglandin inhibitor) in preterm infants.
💡 Clinical Pearl
Fetal Circulation: Prostaglandin E1 keeps the ductus open in duct-dependent cyanotic heart disease until surgery.
⚠️ Exam Tip — Common Mistakes
Confusing the mechanism of Foetal Circulation with related conditions.
Missing classic clinical features of Foetal Circulation in SBA stems.
Failing to consider Foetal Circulation in the differential diagnosis.
🔑 Key Facts
The umbilical vein carries oxygenated blood from the placenta to the foetus.
The ductus venosus bypasses the foetal liver.
The foramen ovale shunts blood right-to-left across the atrial septum.
The ductus arteriosus shunts blood from the pulmonary artery to the aorta.
PDA can be closed with indomethacin (prostaglandin inhibitor) in preterm infants.
🔗 Related Topics
📚 References
  1. GMC MLA Content Map
  2. NICE Clinical Knowledge Summaries
  3. BMJ Best Practice

Further Resources

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