It would appear to be correct -
"A subspecialty or subspeciality (British English) is a narrow field of professional knowledge/skills within a specialty of trade, and is most commonly used to describe the increasingly more diverse medical specialties. A subspecialist is a specialist of a subspecialty.
In medicine, subspecialization is particularly common in internal medicine, cardiology, neurology and pathology, and has grown as medical practice has:
1. become more complex, and
2. it has become clear that a physician's case volume is negatively associated with their complication rate; that is, complications tend to decrease as the volume of cases per physician goes up."
However, it sounds like US nomenclature and there is also a warning -
"Subspecialty Hospitals Pose a Dilemma for Health Care"
https://www.creators.com/read/david-lip ... ealth-care
To find a for(u)m that accommodates the mess, that is the task of the artist now. (Samuel Beckett)