What is the normal oxygen saturation of the Aorta?

• A. 95-99%
• B. 72-75%
• C. 88-92%
• D. 100%

Answer: (A)

Oxygen saturation in the aorta reflects systemic arterial blood after it’s been oxygenated by the lungs. In a healthy adult, arterial blood remains very high in oxygen, so systemic arterial saturation is normally about 95–99% (often cited as 97–99%). The aorta carries this oxygen-rich blood to the tissues, where oxygen is extracted, but the arterial blood entering the tissues stays near the high end of the saturation range.

Why this fits best: values around 95–99% represent oxygenated arterial blood, which is what the aorta should contain after left ventricular ejection. A reading near 100% is ideal but not usually exactly achieved; the key is that arterial saturation stays high.

The other ranges don’t fit arterial blood: around 72–75% corresponds to mixed venous blood returning to the heart and represents deoxygenated blood; 88–92% is not typical for arterial blood in a normal state; 100% is possible with perfect oxygenation but is not the standard normal range.