Intuitive Surgical reported higher-than-expected fourth-quarter profit on Tuesday on increased sales of its da Vinci surgical robots and a rise in gynecologic procedures using the pricy machines.

Intuitive shares rose more than 8 percent after the company announced its quarterly results.

Intuitive issued its first forecasts for 2013, saying it expects procedure growth of 20 to 23 percent and revenue growth of 16 to 19 percent over 2012 levels, with the second half of the year likely to be stronger than the first.

"The guidance leaves room for upside, so I think we're going to see another year of good earnings and see them continue to beat estimates in 2013," said Mizuho Securities analyst Michael Matson.

The Sunnyvale company reported a net profit of $175 million, or $4.25 per share, compared with $151 million, or $3.75 per share, a year ago, topping analysts' average expectations by 21 cents, according to Thomson Reuters.

Revenue rose 23 percent to $609 million, topping Wall Street's estimate of $584.4 million, driven by the sale of 175 da Vinci systems in the quarter at a price of about $1.5 million each and procedure growth of 25 percent.

The 175 da Vincis sold was up from 152 in the year-ago quarter and 155 in the previous quarter. The company said 114 of the da Vincis went to repeat customers and that it sold 24 in Europe, up from 13 in the previous quarter.

Still, the company cautioned that challenging economic conditions in Europe were likely to persist for the next several quarters.

Intuitive now has a total of 2,584 da Vinci systems placed worldwide.

Instruments and accessories sales rose 29 percent to $254 million, with instrument and accessory revenue at about $2,050 per procedure.

Growth in da Vinci procedures was led by increased gynecology and general surgeries in the United States and was partially offset by continued declines in prostatectomies, the company said.

The 25 percent growth was a touch better than Intuitive had signaled in October, when it lowered its 2012 forecast to 24 percent growth.

General surgeries, such as colon and kidney surgeries, with da Vincis rose to 42,000 in 2012 from 15,000 a year earlier, while 176,000 da Vinci hysterectomies were performed in 2012, the company said.

"They've go a lot of momentum in the general surgery area," said Matson. The number performed was "way ahead of what I had modeled. They're doing really well there and that's important because it's a huge opportunity for them."

U.S. prostatectomies, long the company's bread and butter, fell 17 percent from the fourth quarter of 2011. They were up 2 percent from the prior quarter, but Intuitive management on a conference call with investors and analysts said it was "not in position to declare an end point to its decline."

Prostate surgeries have been down in part due to a decline in prostate cancer screening in the United States and due to a strategy known as watchful waiting in which treatment is delayed while the cancer is observed.

Japan remains a potential bright spot for the company going forward. It sold 10 da Vinci system in Japan in the quarter and said positive reimbursement decisions in Japan contributed to an early increase in procedures there.

The company is still seeking approvals for instruments and advanced da Vinci systems in Japan as well as reimbursement for additional procedures.

"We expect progress in Japan to proceed in steps," CEO Gary Guthart said.

Intuitive Surgical shares, which were already up nearly 6 percent this year, rose to $562 in after hours trading from their Nasdaq close at $518.49.