Many diseases may actually share both medical and surgical manifestations. An infection, for example, might involve antibiotics (a medical approach). An infected abscess, however, would require a surgical approach to drain it and reduce the infectious load on the body. A dislocated shoulder typically requires an intervention (not necessarily surgical but at least some form of manual manipulation) as it is highly unlikely that taking a pill will do the trick. Cancer is another example that is treated either surgically or medically (or both). Earlier (or more localized) tumors are often excised surgically, whereas chemotherapy is generally indicated for more advanced diseases. Also, in many cases, the increasing realization that even localized disease can often harbor cancer stem cells throughout the body means that surgery is not uncommonly combined with more generalized medical therapies.
Some conditions, such as back pain, can have either surgical or medical treatment options in which it is not definitively clear which approach is necessarily superior. Also, there are some diseases that have been historically surgical that are now medical and vice versa. Some may be surprised to learn that tuberculosis (TB) was once treated by surgically excising diseased lung tissue. TB is now, of course, mostly a medical disease. Diseases have also made the opposite switch from the medical to the surgical size. Before the advent of heart transplantation and other such circulatory support (such as left-ventricular assist devices), heart failure was largely a medically treated disease.
So what factors make a disease surgical vs medical? In general, a surgical disease has the following characteristics:
(1) is local in extent,
(2) requires rapid treatment, and
(3) has a surgical intervention with a sufficiently favorable risk–benefit balance
These are not hard-and-fast rules as there are certainly medical diseases such as asthma that are local (e.g., affecting bronchi in the lungs) and in which medicine (such as an inhaled β2 agonist) is rapidly effective. Nonetheless, these basic criteria help explain how doctors make that all-important decision on whether to send a patient to the operating room or to manage the disease medically.
