The low surface brightness usually associated with nebulae mixing with the ISM has long been a substantial obstacle in the observation and statistical study of these interactions. Thanks to the detection capability of the INT Photometric H-alpha Survey (IPHAS), in terms of sensitivity and imaging resolution, we were able to detect and select tens of examples of candidate Planetary Nebulae apparently at different stages of interaction with the interstellar medium (PNe-ISM hereafter) following the Wareing et al. (2007) classification. A spectroscopic investigation was conducted with the San Pedro Martir 2.1m telescope (SPM) in Mexico and we present the first results involving a proper classification and analysis of our candidates. The main difficulty is visually separating PNe-ISM from other faint asymmetric nebulosities such as old HII regions, SNRs and general diffuse H-alpha structures. This investigation is a first step in a more comprehensive study of PNe-ISM as more candidates are uncovered by the IPHAS team.