A molded and undivided medical penetrating device comprising: a first portion of the device adapted for insertion into the interior of a body through an opening in a body and for retention in the body cavity following insertion; a second portion of the device integrally joined to the first portion of the device by a joining portion of the device and adapted to be maintained essentially outside the body while the first portion of the device is retained within the body, the second portion of the device having a substantially tubular configuration and including an outer surface, a proximal end adjacent the first portion of the device and a distal end removed from the first portion of the device; and an opening extending through the first portion of the device and the second portion of the device and providing access to the interior of the body from outside the body, the outer surface of the substantially tubular second portion of the device and the opening extending through the substantially tubular second portion of the device forming a wall therebetween, wherein the first portion of the device comprises two external surfaces (42,44) that oppose one another, one of the external surfaces being substantially convex and integrally joined to the outer surface of the substantially tubular second portion of the device by the joining portion of the device and the other of the external surfaces being substantially concave, characterized in that the thickness of the wall, at the location where the first portion of the device and the tubular second portion of the device are integrally joined to one another by the joining portion of the device, being less than the thickness of the wall nearer its distal end. a first portion of the device adapted for insertion into the interior of a body through an opening in a body and for retention in the body cavity following insertion; a second portion of the device integrally joined to the first portion of the device by a joining portion of the device and adapted to be maintained essentially outside the body while the first portion of the device is retained within the body, the second portion of the device having a substantially tubular configuration and including an outer surface, a proximal end adjacent the first portion of the device and a distal end removed from the first portion of the device; and an opening extending through the first portion of the device and the second portion of the device and providing access to the interior of the body from outside the body, the outer surface of the substantially tubular second portion of the device and the opening extending through the substantially tubular second portion of the device forming a wall therebetween, wherein the first portion of the device comprises two external surfaces (42,44) that oppose one another, one of the external surfaces being substantially convex and integrally joined to the outer surface of the substantially tubular second portion of the device by the joining portion of the device and the other of the external surfaces being substantially concave, characterized in that the thickness of the wall, at the location where the first portion of the device and the tubular second portion of the device are integrally joined to one another by the joining portion of the device, being less than the thickness of the wall nearer its distal end.