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Swelling can appear on legs and feet sfter siiting in one posture with hanging legs for long duration as while travelling.
However, this kind of swelling is relieved after taking rest.
If the swelling persists and is also seen on the face then there is some other pathology in the body.
Under normal conditions all the tissue fluid is prevented from accumulating in the tissue by a normal functioning heart and normal functioning kidney
Dysfunctioning of kidney causes edema (swelling) which starts from face and then moves to other parts of body like chest, abdomen and then lower limbs
Cardiac abnormalities cause edema (swelling) which begins in lower limb and then upper part of body.
So, renal function tests and examination of cardiac system need to be done.
Also get your blood pressure measured as edema may develop in high bp
Dr Shailja P Wahal