A monitoring system for use with a body of a subject, the system comprising: a medical device being in fluid communication with a pressure source (32; 35), the medical device having a distal portion thereof configured to be placed inside the subject's body, said distal portion of the medical device being configured to be propelled by fluid pressure through a body lumen; first and second pressure sensors (40, 42) accommodated remotely from the subject's body at two different spaced-apart positions outside the subject's body and configured and operable to detect pressure at the two spaced-apart remote positions, respectively; said pressure sensors being in fluid communication with at least one site inside the subject's body, a relation between the pressure at said at least one site and the pressures at said two spaced-apart remote positions being thereby indicative of the fluid pressure at said at least one site; and a tubular-like member having a distal end connected to the first pressure sensor and a proximal end connected to the second pressure sensor; said tubular-like member being configured and operable as a flow resistor having a first resistance to fluid flow, a first position of one of said at least two pressure sensors being located at the proximal end of said tubular-like member, and a second position of one of said at least two pressure sensors being located at the distal end of the tubular-like member; said at least two pressure sensors measuring a pressure gradient across the resistor, said tubular-like member being provided along said fluid communication between the medical device and the pressure source, wherein a distal flow path having a second resistance to fluid flow extends between said tubular-like member and the medical device, a control unit for monitoring and regulating fluid pressure at said at least one site; said control unit being configured to generate output data indicative of the pressure level at the at least one site, utilizing a model based upon a ratio between the second resistance of the distal flow path to fluid flow and the first resistance of the tubular-like member to fluid flow. a medical device being in fluid communication with a pressure source (32; 35), the medical device having a distal portion thereof configured to be placed inside the subject's body, said distal portion of the medical device being configured to be propelled by fluid pressure through a body lumen; first and second pressure sensors (40, 42) accommodated remotely from the subject's body at two different spaced-apart positions outside the subject's body and configured and operable to detect pressure at the two spaced-apart remote positions, respectively; said pressure sensors being in fluid communication with at least one site inside the subject's body, a relation between the pressure at said at least one site and the pressures at said two spaced-apart remote positions being thereby indicative of the fluid pressure at said at least one site; and a tubular-like member having a distal end connected to the first pressure sensor and a proximal end connected to the second pressure sensor; said tubular-like member being configured and operable as a flow resistor having a first resistance to fluid flow, a first position of one of said at least two pressure sensors being located at the proximal end of said tubular-like member, and a second position of one of said at least two pressure sensors being located at the distal end of the tubular-like member; said at least two pressure sensors measuring a pressure gradient across the resistor, said tubular-like member being provided along said fluid communication between the medical device and the pressure source, wherein a distal flow path having a second resistance to fluid flow extends between said tubular-like member and the medical device, a control unit for monitoring and regulating fluid pressure at said at least one site; said control unit being configured to generate output data indicative of the pressure level at the at least one site, utilizing a model based upon a ratio between the second resistance of the distal flow path to fluid flow and the first resistance of the tubular-like member to fluid flow.