Fetal circulation sumi

Fetal Circulation - OBG Nursing

1. FETAL CIRCULATION Mrs. Sumi Mathew HOD, OBG Nursing, GCON, Jodhpur

2. definition The  Fetal Circulation  is defined as- The blood circulation in the  fetus or in other words it is  the  circulatory  system of a  fetus . The term usually encompasses the entire feto -placental  circulation , which includes the umbilical cord and the blood vessels within the placenta that carry  fetal  blood .

3. CHARACTERTICS The fetal circulation system is distinctly different from adult circulation, It facilitates the exchange of materials between fetus and mother. It allows the fetus to receive oxygenated blood and nutrients from maternal blood circulation and elimination of CO2 & waste through the placenta, There are three bypasses or shunts in this circulation which is specific to this circulation.

4. ANATOMY & PHYSIOLOGY Placenta - Site where exchange of gases, nutrients and waste take places with maternal circulation.

5. ANATOMY & PHYSIOLOGY – ( conti .) Umbilical Cord – consists of 3 blood vessels – 2 arteries and 1 vein

6. Bypasses - Ductus Venosus – carries oxygenated blood from umbilical vein to inferior venacava bypassing fetal liver Foramen Ovale – connects the right and left. It pushes blood from right atrium to the left atrium bypassing the pulmonary circulation. Ductus Arteriosus - carries oxygenated blood from pulmonary artery to aorta bypassing fetal lung.

7. Flow Chart of Fetal Circulation

8. AT BIRTH - As the baby is born, the cardiovascular system undergoes a quick, drastic change. With its first breath, the baby's pulmonary vascular resistance substantially drops, which is in response to the oxygen now present in the lungs and the physical act of breathing. With the clamping of the umbilical cord after birth, the systemic vascular resistance increases helping the blood flow towards the lungs .

9. AT BIRTH - The ductus arteriosus has a left-to-right flow within 10 minutes. The smooth muscle in the ductus arteriosus responds to the oxygen by increasing calcium channel activity causing constriction and ultimately closure of the shunt. The increased systemic resistance also raises the pressure in the left atrium to be higher than the right atrium, and this causes the foramen ovale to close.

10. AT BIRTH - The ductus arteriosus becomes the ligamentum arteriosum , The foramen ovale becomes the fossa ovalis , The umbilical vein becomes the ligamentum teres (round ligament).

11. SUMMARY The fetal circulatory system provides the fetus with nutrients and oxygen, while also removing waste products and carbon dioxide from fetal circulation. The umbilical cord develops from the placenta and is attached to the fetus. Oxygenated blood from the mother in the placenta flows through the umbilical vein and into the inferior vena cava (IVC), bypassing the liver via the ductus venosus .

12. SUMMARY– ( conti .) From the IVC, oxygenated blood travels to the right atrium of the heart. There is greater pressure in the right atrium compared to the left atrium in fetal circulation; therefore most of the blood is shunted from the right atrium to the left atrium through an opening called the foramen ovale . Once in the left atrium, blood travels through the left ventricle into the aorta and the systemic circulation.

13. SUMMARY– ( conti .) The deoxygenated blood travels back to the placenta via the umbilical arteries to be oxygenated by the mother. Additionally, some oxygenated blood in the right atrium can also enter the right ventricle and then the pulmonary artery.

14. SUMMARY– ( conti .) Because there is high resistance to blood flow in the lungs, the blood is shunted from the pulmonary artery into the aorta via the ductus arteriosus , hence bypassing the lungs. Blood then enters the systemic circulation, and the deoxygenated blood is recycled back to the mother via the umbilical arteries.