Tumescence

Tumescence is the quality or state of being tumescent or swollen. Tumescence usually refers to the engorgement with blood (vascular congestion) of the erectile tissues, marking sexual excitedness and possible readiness for sexual activity. The tumescent sexual organ in men is the penis and in women is the clitoris.

Regularly, men who experience erectile dysfunction are given a nocturnal penile tumescence (NPT) test, usually over a three day period. Such a test detects the presence of an erection occurring during sleep using either (1) a small, portable computer connected to two bands placed around the shaft of the penis which records penile tumescence, or (2) a band of paper tape with perforations (like postage stamps) that is fit snugly around the shaft of the penis and will break at the perforations during penile tumescence.

The goal of nocturnal penile tumescence testing is to determine whether a man can experience an erection while sleeping after reporting he is unable to experience any while awake. If a man does obtain an erection while sleeping, but cannot obtain one while awake, a psychological cause is usually suspected. Else, if a man does not obtain an erection in either state, a physiological cause is usually suspected. Usually, a patient suffers from the former.

The opposite term is detumescence.