The type of sampling where the individual himself introduces the other subjects of surgery is called as:
Snowball sampling is a technique for developing a research sample, where existing study subjects recruit future subjects from among their acquaintances.
It is a type of non-probability sampling.
This sampling technique is often used in hidden populations which are difficult for researchers to access; example, drug users or commercial sex workers.
Thus, the sample group appears to grow like a rolling snowball.
Because sample members are not selected from a sampling frame, snowball samples are subjected to numerous biases.
Systemic sampling
Snowball sampling
Introductory sampling
Successive sampling