Fetal circulation

Fetal circulation Which blood vessel in the fetus contains blood with the highest oxygen content? A. Inferior Vena Cava B. Descending Aorta
C. Pulmonary Trunk
D. Aortic Arch
Provide a short justification for your answer.
The Aortic arch is the blood vessel in the above choices that contain the highest oxygen content. The highest oxygenated blood in the fetus comes from the umbilical vein after gaseous exchange in the placenta. Blood from the umbilical vein is often 80-90% saturated. 50-60% of the umbilical vein blood flows to inferior vena cava through ductus venosus (Mark & Hanson 2000, p. 3). Oxygenated blood flowing in the given inferior vena cava flows with the deoxygenated towards the right atrium. The oxygenated part of the inferior vena cava gets directed from the right atrium through the left atrium via foramen ovale (Blackburn 2007, p. 267). Blood in the left atrium is about 65% saturated. From left atrium, blood flows to the given left ventricle and leaves through the aorta to supply vital structure like the brain and myocardium (Mark & Hanson 2000, p. 6).
2. After birth there are several changes to the circulatory system. If either the foramen ovale or the ductus arteriosus remain patent after birth, this can result in pulmonary hypertension.
A patent ductus arteriosus often can result in pulmonary hypertension. After birth, normally, ductus arteriosus has to close and channel all its blood to the pulmonary system instead of the descending thoracic aorta (Mark & Hanson 2000, p. 8). When patent after birth, it results to left to right shunt, therefore allowing blood to move systemic circulation to the given pulmonary circulation resulting in high volume (Blackburn 2007, p. 267). With the high volume, pulmonary artery pressures increase eventually leading to pulmonary hypertension.
Mark A. Hanson, J. A., 2000, Fetus and Neonate: Physiology and Clinical
Applications, Cambridge: Cambridge University Press.
Blackburn, S. T., 2007, Maternal, Fetal, & Neonatal Physiology: A Clinical
Perspective, New York: Elsevier Health Sciences.