Reviews the literature to identify the gaps and trends in Machine Learning and find a clear definition and context in which the term is used. A retrospective search of the literature was conducted using online databases like Web of Science and Google Scholar. Relevant bibliographic data on review articles were selected for analysis. From the analysis it is clear that most of the studies are from western countries and conducted on different diseases. Though some are from specific diseases, but very few studies are on use of Machine Learning for general health care