Intuitive Surgical (NASDAQ:ISRG) is up about 11% since the company reported its third-quarter earnings last month. Better than expected financial results and rapid growth in procedures boosted investor confidence. In the aftermath of a great earnings report, it's a good time to review some of the company's key metrics.

da Vinci Xi. Image source: Intuitive Surgical.

Procedure growth
One of the key metrics Intuitive Surgical tracks is procedure growth. Increasing procedures signal more use of the company's minimally invasive da Vinci systems, which translates to greater probability of higher volume in accessory purchases, system upgrades, and additional system purchases.

On this metric, Intuitive Surgical has been performing exceptionally well in 2015.

During the company's most recent quarter, procedure growth increased 15%, year over year, helping the company achieve its third quarter in a row of accelerating year-over-year procedure growth rates.

The surgical device company has also boosted its guidance for full-year procedure growth for the last three quarters in a row.

Year-to-date procedure growth is 14%, and Intuitive Surgical expects full-year procedure growth between 13% and 14%.

Gross profit margin
Because of the significant selling, general, and administrative expenses and research and development spend required for Intuitive Surgical to develop, market, and sell its pricy da Vinci systems, it's important that gross profit margin remains high. Fortunately, the company is executing very well on this front.

Consider Intuitive Surgical's gross profit margin during its most recent quarter. At 67.1%, it's 120 basis points higher than it was a year ago. This is in line with the sort of year-over-year improvements the company has been sustaining during recent quarters.

Looking forward, Intuitive Surgical CEO Gary Guthart said that reengineering and achieving greater scale with some of its newer products could lead to further cost benefits -- and possibly higher gross profit margins. But Guthart noted these benefits probably won't be realized in Q4.

"More of the benefit will be in 2016, and even more in 2017," he said.

The challenge for the company in maintaining a high gross profit margin will be in balancing the goal to be able to sell its systems for less (in order to make its products more accessible) with its aim to drive costs lower.

da Vinci Xi surgeon console. Image source: Intuitive Surgical.

International growth
International demand for Intuitive Surgical's products is serving as a key catalyst for the company.

The increasing interest and use of Intuitive Surgical products is evident in the breakdown of the company's 15% year-over-year growth in procedures. U.S. procedures were up 12% from the year-ago quarter, and international procedures were up 28%.

If Intuitive Surgical can sustain this procedure growth in international markets over the long haul, a handful of its international markets could eventually become significant contributors to the company's business.

Investors can use all three of these key metrics, along with periodic reviews of the company's financial performance, as a means to measure its ongoing success and potential.

Daniel Sparks has no position in any stocks mentioned. The Motley Fool owns shares of and recommends Intuitive Surgical. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.