Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Volcano (NASDAQ:VOLC), a medical device maker of products used to diagnose and treat vascular and structural heart diseases, gushed lower by as much as 16% after reporting its fourth-quarter earnings results.

So what: For the quarter, Volcano reported revenue growth of 10% to $102.5 million and a GAAP profit of $0.04, down considerably from the $0.54 in GAAP EPS reported in the year-ago period. Wall Street expectations had been calling for a profit of $0.09 on revenue of $102.1 million. More damaging, however, was Volcano's 2013 guidance, which calls for a profit of $0.08-$0.11 on $406 million to $412 million in revenue. This is considerably lower than the $0.29 in EPS and $423.5 million that the Street had been projecting.

Now what: What's even more bizarre about Volcano's guidance is that the company had to issue a second press release essentially updating its 2013 guidance, because the forecast in its initial earnings release was given on a "constant currency basis." Talk about all the different ways you could anger investors and analysts in a 24-hour period! I'm pretty sure investors have some major questions as to why Volcano's EPS is nowhere near expectations, and I personally have concerns about the potential for product delays if the figures are this far off. I'm perfectly fine adding Volcano to my watchlist, but I'd suggest steering clear until management gets its act together.

Craving more input? Start by adding Volcano to your free and personalized watchlist so you can keep up on the latest news with the company.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

Motley Fool newsletter services have recommended buying shares of Volcano. Try any of our Foolish newsletter services free for 30 days. We Fools don't 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.