Ἰσχύρια (formed from ἰσχυρός "I stop," and ὑγρός "wet, urine," in physic), a disease consisting in an entire suppression of urine. See Medicine Index.

It is occasioned by anything which may obstruct the passages of the reins, ureters, or the neck of the bladder, as sand, stone, mucus, &c. It may also arise from an obstruction of the nerves which pass to the reins or bladder, as we see it does in a palsy of the parts below the diaphragm. The too great distention of the bladder may also produce the same effect; for the fibres being much lengthened, and consequently condensed, the spirits necessary for their contraction cannot get admittance; whence it is that persons who have retained their urine a long time, find a great deal of difficulty in discharging it.