Urethral catheter

A urethral catheter comprising a tube having openings at both ends, and having in at least a portion of the length of the tube to be situated within the urethra, a thin flexible wall having a smooth inner surface of elliptical or oval form in cross-section such that, in said portion, the wall will undergo substantially complete collapse under normal urethral pressure, characterized by at least one zone of increased wall thickness extending around a selected part of the cross-sectional periphery of the tube and extending longitudinally in said portion to prevent the wall from collapsing completely other than by normal urethral pressure or from folding longitudinally, according to the part selected and wherein said thin flexible wall portion of said tube outside said zone of increased wall thickness has flexural and resilient properties which permit elastic expansion of the tube wall when normal urethral opening occurs during expulsion of urine through the tube, with said thin flexible wall portion being formed of a material having a lateral compliance such that the maximum transmural pressure required to collapse a tube formed entirely of such material to half its normal cross-sectional area would be 100 cm water guage.