There is a broad agreement regarding the necessity of building usable and functional tools for specification of machine-interpretable clinical guidelines, to provide guideline-based medical care. There is much less of a consensus of how to go about it and whether the whole process is feasible in a real clinical domain. In this study, we have applied a new architecture, the Gesher graphical tool, to the specification of an important Obstetric guideline (diagnosis and management of PreEclampsia / Eclampsia toxemia). We have assessed the feasibility (functionality and usability) of (1) representing a clinical consensus customized for a particular medical center and (2) structuring the full content of the guideline. In addition, we have assessed in a preliminary fashion, the potential of using a less experienced clinician as a markup editor, by asking both a senior Obstetrics and Gynecology clinician, and a general intern, to represent the same guideline using the Gesher system. The results demonstrated the functionality and usability of the Gesher system, at least for these two editors; the intern's performance was at least as good as that of the senior physician with respect to the specific task of structuring the guideline according to the Hybrid Asbru ontology, using our tools.