A system comprising a probe (1, 101,201, 301) for monitoring stents comprising: - a first coupling port (2, 102, 302) on a supporting base configured to launch an electromagnetic field onto a stent, such that a guided electromagnetic wave is propagated through at least a portion of the stent; - a second coupling port (3, 103, 303) on the supporting base configured to collect the electromagnetic field from the guided electromagnetic wave of the stent; - the supporting base configured to position at least the first coupling port and the second coupling port, such that at least one connecting axis is defined between the first coupling port (2, 102, 302) and the second coupling port (3, 103, 303); the system further comprising a measuring device, in electrical communication with the first coupling port (2, 102, 302) and the second coupling port (3, 103, 303), the measuring device comprising a memory and a processor, embodying instructions stored in the memory and executable by the processor, the instructions comprising functionality to execute a method comprising: - sensing an input signal the first coupling port and an output signal of the second coupling port, the input signal being related to the electromagnetic field launched onto the stent and the output signal being related to the electromagnetic field collected from the guided electromagnetic wave of the stent; - obtaining a transmission coefficient between the first coupling port and the second coupling port by comparing the input signal with the output signal; - performing a frequency response of the transmission coefficient; and - comparing the frequency response of the transmission coefficient with a reference frequency response of the stent, the reference frequency response comprising expected values for the stent, the expected values comprising local maxima and/or local minima or expected transmission coefficients for a range of frequencies; characterised in that the probe further comprises: a ground element (6, 106, 306) disposed in a region of the probe in between both coupling ports so as to propagate an image of the guided electromagnetic wave of the stent. - a first coupling port (2, 102, 302) on a supporting base configured to launch an electromagnetic field onto a stent, such that a guided electromagnetic wave is propagated through at least a portion of the stent; - a second coupling port (3, 103, 303) on the supporting base configured to collect the electromagnetic field from the guided electromagnetic wave of the stent; - the supporting base configured to position at least the first coupling port and the second coupling port, such that at least one connecting axis is defined between the first coupling port (2, 102, 302) and the second coupling port (3, 103, 303); - sensing an input signal the first coupling port and an output signal of the second coupling port, the input signal being related to the electromagnetic field launched onto the stent and the output signal being related to the electromagnetic field collected from the guided electromagnetic wave of the stent; - obtaining a transmission coefficient between the first coupling port and the second coupling port by comparing the input signal with the output signal; - performing a frequency response of the transmission coefficient; and - comparing the frequency response of the transmission coefficient with a reference frequency response of the stent, the reference frequency response comprising expected values for the stent, the expected values comprising local maxima and/or local minima or expected transmission coefficients for a range of frequencies;