In the year since I last reviewed United Surgical Partners (NASDAQ:USPI), the company has continued to expand, and the basic environment for ambulatory surgical centers has remained healthy. But even though it's operating in excess of 20% more facilities, United Surgical posted fourth-quarter results that seem to be a mix of good and bad news.

Revenue rose 8% but missed the average estimate, and same-facility revenue climbed by about 7%, better in the unconsolidated facilities and worse in the consolidated facilities. Somewhat more concerning to me was that total facility cases were up just a little more than 1% on a same-facility basis (and down in the consolidated facilities), and that's not an especially robust number.

The better news was on the profits side. The company controlled operating expense growth fairly well, and the operating margin expanded more than 2 full points while operating income rose about 17%. That, in turn, ultimately led to nearly 32% growth in income from continuing operations and allowed the company to meet its EPS estimate despite the lower revenue base.

As is the case with many similar companies like Pediatrix (NYSE:PDX), VCA Antech (NASDAQ:WOOF), PainCare (AMEX:PRZ), and Psychiatric Solutions (NASDAQ:PSYS), a lot of the business model revolves around ongoing acquisitions. To that end, the company recently acquired facilities in St. Louis and announced a $200 million deal to acquire privately held Surgis and its 31 facilities, including 24 locations in service and seven under development. Of course, these acquisitions come at a price, and USPI does carry a fair bit of debt.

While the sluggish case growth has me a little concerned, I still believe that large market trends favor this sort of business model. What's more, United Surgical may have a leg up on some of its competitors in that it pursues joint ventures with hospitals. That makes would-be competitors more like partners, which can be good for referrals. Current prices don't suggest a whole lot of upside here, but this might be a reasonable candidate for the watch list.

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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).