Funny how Rule Breakers recommendation Intuitive Surgical (NASDAQ:ISRG) posted another great quarter of growth and actually raised revenue growth guidance . yet the stock is down about 11% in early trading. Sure, go ahead and sell Intuitive Surgical -- I'm sure you'll find loads of stocks with virtually no competition, better than 50% revenue growth and nearly 30% operating margins, and sizable markets left to exploit.

Revenue jumped another 65% this quarter as the company sold an incremental 13 systems (39 systems sold this quarter versus 26 a year ago) and saw instrument/accessory revenue rise 61%. Although the comparisons move around a bit from quarter to quarter, I find it interesting that system revenue growth (69% this quarter) is still often able to surpass recurrent revenue -- suggesting to me that we're not close yet to the saturation point for these surgical robots.

As I've discussed here in prior quarters, there are numerous surgical procedures that could benefit from robotic assistance, which is already pretty popular in prostate surgeries. The next major growth arena appears to be an even larger one -- hysterectomies. After that, there are still applications like acid reflux surgery, artery takedowns for bypass surgery, gastric bypasses, spinal surgery, and so on. And don't take that to mean that it's a one-at-a-time proposition; I see no reason that usage can't expand in several directions at once -- other than the constraints of hospital budgets and a limit to the number of available hours per machine per day.

Perhaps it's an amusing comparison given the discrepancies in size, but I'm wondering whether Intuitive Surgical will soon begin to face a problem that Medtronic (NYSE:MDT) has had from time to time -- namely, that it's so successful at generating cash, it all piles up on the balance sheet. I used to jokingly refer to Medtronic as the "First National Bank of Minneapolis" back in my analyst days, but it can be an actual problem -- cash is part of the asset base that managers have to employ efficiently. And in the case of Intuitive, since a stock buyback seems silly and a dividend unlikely, maybe it has some tool or instrument companies in its sights.

If you invest in growing med-tech companies like Intuitive or Aspect Medical (NASDAQ:ASPM), you have to make your peace with volatility. Of course, even relative giants like St. Jude (NYSE:STJ) and Boston Scientific (NYSE:BSX) aren't immune to some hair-raising dips. So just remember, growth has its price -- not only in valuations but often in volatility as well.

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).