Horrendous! That's how some health-care stocks performed during the market week ending on Oct. 12. Which ones stand out as real stinkers this week? Let's take a look at three of the worst.

An appropriate ticker
The ticker for Edwards Lifesciences (NYSE:EW) seemed to fit for this week. Maybe a few more w's would have been in order, though. Ewwww. (That's what kids say when they hold their noses after smelling something rotten.)

The stock began the week around $110, and ended barely over $87. Why the 20% drop? The company missed sales forecasts for the third quarter, resulting in the worst one-day stock plunge in 12 years.

Reasons for the miss included European woes, and a delayed reimbursement decision in the U.S. Also, too many doctors took vacations, which resulted in fewer procedures being performed with the company's heart valves.

Low threshold for pain
Next on our horrendous health-care list is Threshold Pharmaceuticals (NASDAQ:THLD). The problems for Threshold actually started back in September when the company announced disappointing results from a phase 2b study involving its TH-302 pancreatic cancer drug.

Shares were down 18% for the week. That's on top of a 25% drop since mid-September. That's definitely painful for Threshold investors.

Threshold faces something of a battle for affection with rival Celgene (NASDAQ:CELG). Even when the company attempted to provide more data that bolstered its case for TH-302 at a conference a few weeks ago, the buzz centered on Celgene's forthcoming phase 3 study results for use of Abraxane in treating pancreatic cancer.

A week of weakness
Last but not least (barely) is MannKind (NASDAQ:56400P706). Shares fell over 15% for the week. As was the case with Threshold, there weren't any new announcements that caused the stock to decline.

Actually, MannKind reported a little bit of good news this week. The company wrapped up the patient recruiting process for phase 3 trials for Afrezza, its long-awaited insulin inhalant. Mr. Market yawned, and simply watched as shares continued their three-week skid.

The last great hope for MannKind is to find a good partner with plenty of cash. More horrendous weeks could be in store until it does. On the other hand, with a share price only a little above $2, there's a lot more room to move up than down at this point.

Movers and shakers
Other candidates for our list abound. Healthcare typically sees more than its fair  share of rapid gainers and decliners. A good example from this week is Repros Therapeutics (NASDAQ:RPRX). The stock jumped 11% on Oct. 5, but slipped over 15% over the last few days.

Of our stinkers this week, I pick Edwards Lifesciences as the one most likely to smell good over the long run. The company has its challenges for sure, but my prediction is that its performance should improve going forward. Time will tell if Edwards ultimately proves to be a hero or a horror. 

Keith Speights has no positions in the stocks mentioned above. The Motley Fool has no positions in the stocks mentioned above. Motley Fool newsletter services recommend MannKind. 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.