The sleep laboratory NPT testing today is used in only selected cases. Thus, sleep lab data was used more to rule out a primary psychological problem, preventing an unnecessary surgical procedure on someone who might benefit from a course of psychological counseling. At that time, for a large number of patients the choice of treatment was between psychological counseling and penile implant surgery. As mentioned earlier, the advent of sleep lab studies in the 1970s provided the urologists who were doing penile implant surgery with very important information. While the Rigiscan monitor certainly provides a lot more information about numbers of erections and duration of each erection, along with degree of rigidity, there have been objections from physiologists who feel the lack of accurate sleep stage simultaneous information may lead to some misinterpretation. This device combines complicated monitoring with the convenience and economic advantage of an ambulatory monitoring system. Even though the snap-gauge test is very economical, its accuracy in distinguishing physical erectile dysfunction from psychological erectile dysfunction has been questioned.'; Ultimately, concerns over the accuracy of rigidity monitoring and the cost of sleep laboratory evaluation led to the development of Rigiscan, a small, portable monitoring system, which continuously measures the rigidity of the erect penis as well as records the number and duration of each tumescent episode.

In patients with normal nighttime erections, often the snapping of the snap-gauge bands will make a loud popping noise and awaken the patient. Patients occasionally come back to the office and report that they didn't break the snap-gauge at all; however, they didn't try the test until the night before their second office visit, and they were up half the night drinking coffee and were anxious about the test and probably didn't have any REM sleep cycles at all. Either the postage stamp or the snap-gauge test has to be done over two or three nights to make sure the patient has at least one or more episodes of REM sleep to adequately test the nighttime erection. A narrow red tape is set to rupture at 15 ounces, and a clear tape, which fits the most loosely, is set to snap at about 20 ounces of pressure. A narrow blue strip, fitting rather snugly, is designed to rupture with 10 ounces of pressure. This consists of a combination of three narrow, plastic tapes designed to rupture at different forces, mounted on a Velcro fastener that snaps around the penis.