Impedance systems and methods of using the same to obtain luminal organ measurements. Such impedance systems include a device for insertion into a mammalian luminal organ and one or more external electrodes that are independent of the device. The device of the system comprises at least two electrodes positioned thereon—at least one of which comprises an excitation electrode and at least one of which comprises a detection electrode. The one or more external electrodes may comprise excitation electrodes, detection electrodes, or a combination of both. The methods hereof generate an electric field using the excitation electrodes of the impedance system, obtain one or more conductance values from a mammalian luminal organ within the electric field using the detection electrode(s), and calculate a parameter of the luminal organ based at least in part on the measured one or more conductance values.
