Shareholders of Intuitive Surgical (NASDAQ:ISRG), maker of the da Vinci Surgical System, have endured a whipsaw ride over the past two years. On four different occasions, the stock has swung more than 30%.

Source: YCharts.

This volatility is the result of a confluence of factors, including doctors questioning the efficacy of the da Vinci robotic surgical technology, tighter hospital budgets in the face of the Affordable Care Act, and the introduction of a new surgical machine.

But for current or prospective shareholders, there are three big reasons to remain bullish on the company's future.

A solid moat

While the healthcare industry is abuzz with innovative new technologies, the same can't be said for the act of performing surgery. While new tools and approaches constantly enter the scene, the option to have your surgery performed via a robot remains the only real alternative to traditional surgical procedures.

This doesn't mean that robotic procedures are always a better -- or more cost-effective -- alternative to traditional surgery. In 2013, several medical professionals questioned whether using the da Vinci for hysterectomies was worth the extra money involved.

At the same time, Intuitive isn't a static company. It regularly incorporates feedback from the medical community into the design of future machines. With each incremental improvement, the company creates a wider moat around its business.

A new machine ushering in new opportunities

Earlier this year, Intuitive introduced its latest iteration of the robotic surgery system: the da Vinci Xi.

Source: Intuitive Surgical.

The machine presents several new options for surgeons. Most important is increased mobility, as the surgical arms can rotate to cover all quadrants of the abdomen. The Xi also offers unobstructed and enhanced visual access to the patient.

With the new machine, Intuitive can attempt to differentiate the types of procedures for which the robot is used. Historically, prostatectomies and hysterectomies accounted for the vast majority of da Vinci operations. The inherent risk with such a concentrated application became painfully obvious when hysterectomy procedure growth came under pressure last year.

The company reports procedures in "general surgery" on an annual basis. This encompasses all surgical procedures outside of the core gynecological and prostate fields. Even before the Xi was introduced, general procedures were growing quickly.

Source: SEC filings

With the Xi, the growth of these types of procedures could be a major driver for Intuitive's future. In the company's second-quarter earnings release, it said that "higher procedure volume was driven by growth in U.S. general surgery procedures," and that "general surgery is now our second largest and fastest growing specialty in the U.S."

Hospitals loosening their purse strings

A reversal of business fortunes in the United States has been a major drag on Intuitive's stock. Before 2013, the company had solidly grown the number of da Vincis it sold to hospitals.

Last year, those numbers actually reversed and began to shrink. Fellow Fool Sean Williams highlighted a major reason for that reversal: the onset of the Affordable Care Act, or Obamacare.

As the effects of the legislation were largely unknown, hospitals assumed a conservative stance when it came to major capital purchases. With average selling prices of over $1 million, Intuitive's machines became far less popular.

But hospitals eventually will feel far more comfortable in forecasting their financial situation as they get more used to the legislation. And with time, I think that the benefits of the machines as noted above will be more clear.

The takeaway for investors

An investment in Intuitive isn't without its risks -- no investment is. And even if all of the possible positive events mentioned above happen, Intuitive's stock could still decline. But with a growing moat around its business, a new machine that could help perform a greater variety of procedures, and hospitals that will hopefully begin loosening their purse strings, there's a lot for investors to be excited about for this stock over the long term.