If the elderly have edema in the external genitalia and perineal area, then the possible causes are: 1. Prostatic hyperplasia, elderly patients with prostatic hyperplasia may have water retention in the body and show edema. The patient’s urination is poor and a large amount of water accumulates in the body, which can lead to water retention in the kidneys, lower body edema, and lower limb edema. 2. If the kidney function is poor, then water cannot be filtered out of the body and accumulates in the body, which can lead to edema in the low hanging parts of the body. The edema is often manifested as non-depressed edema, self-conscious swelling of both lower limbs, swelling of the perineal area, etc. The appearance of edema is more obvious. 3. Malnutrition and low protein edema. In elderly patients, if the nutrition is poor and the body consumes too much protein, the body albumin may drop and water may easily enter the tissue interstitial space and manifest as edema, which is sunken edema, and when pressed by hand, the lower body or lower limbs are seen to be sunken and cannot be rebounded. It is common in patients who are bedridden for a long time, have poor diet, and are severely malnourished.