Pitting edema of both lower extremities is most commonly related to which origin?

Pitting edema in both lower extremities is most commonly related to a cardiac or systemic origin due to various physiological mechanisms associated with heart function and fluid balance. When the heart is unable to effectively pump blood, as in conditions such as congestive heart failure, it can lead to fluid retention and increased venous pressure. This results in the accumulation of fluid in the tissues, particularly in the lower extremities, where gravity exacerbates the situation.

Systemic conditions, such as renal or liver disease, can also contribute to pitting edema. They can disrupt the body's fluid management, leading to an imbalance in blood volume and pressure, promoting fluid leakage into the interstitial spaces.

In contrast, while venous obstruction may lead to edema, it typically presents as non-pitting edema or has a more localized effect, and lymphatic obstruction usually results in non-pitting edema due to protein-rich lymphatic fluid accumulation. Arterial insufficiency commonly leads to indicators like claudication or coldness in the extremities rather than bilateral lower extremity edema. Therefore, the systemic nature of the pathophysiology involved in cardiac conditions makes option B the most appropriate origin for pitting edema in this scenario.