Updated from 3:19 p.m. EDT

Shares of

Synovis Life Technologies

(SYNO)

were among the worst-performing health and pharmaceutical stocks Wednesday after the company posted weaker-than-expected third-quarter earnings and sales, and withdrew its earnings guidance for the fourth quarter.

Excluding items, the medical device company earned 3 cents a share during the third quarter on sales of $15.1 million. Analysts surveyed by Thomson First Call were expecting earnings of 8 cents a share on sales of $17.7 million. Citing complexities in the gastric bypass market and the unpredictability of customers' buying decisions, the company withdrew its fourth-quarter earnings guidance. If the market stabilizes during 2005, the company will consider offering earnings guidance again. Shares of Synovis Life Technologies traded down 61 cents, or 6.9%, to $8.26.

Despite its auditor resigning because of a disagreement over the way it recognized certain sales during 2001 through 2003, shares of

Impac Medical Systems

(IMPC)

rose Wednesday. As a result of its disagreement with Deloitte & Touche, Impac said it would not be able to release its third-quarter results on time. Impac said that it would quickly hire another auditor so that it can file its quarterly results with the

Securities and Exchange Commission

before Aug. 23. If the filing is not completed by Aug. 23 its shares could be delisted from the

Nasdaq

stock market. On a preliminary basis, Impac said third-quarter sales were $18.7 million, which would be above analysts' expectations. Shares of Impac Medical Systems traded up $1.04, or 8.8%, to $12.92.

Shares of

Sontra Medical

(SONT)

rose after the company received Food and Drug Administration marketing clearance for its SonoPrep ultrasonic skin permeation device for use with topical lidocaine. Previously, SonoPrep received marketing clearance for use in electrophysiology applications in Feb. 2004. The company expects to launch the product in Sept. 2004. Shares of Sontra Medical traded up 73 cents, or 51.4%, to $2.15.

Shares of

Xoma

(XOMA) - Get Report

fell for a second straight day Wednesday. Late Monday the company said its acne gel showed inconclusive results. Xoma said the phase II trial showed no discernable dose response and said the vehicle response was higher than anticipated. It also said the drug appeared to be safe and well-tolerated. The company will analyze the data and review the results with dermatology experts, but it does not plan to initiate additional trials with the drug. After falling more than 35% on Tuesday, shares of Xoma traded down an additional 20 cents, or 8.8%, to $2.07.

Other health care volume movers included

Pfizer

(PFE) - Get Report

, up 47 cents to $31.85;

Elan

(ELN)

, up $1.39 to $21.96;

Amgen

(AMGN) - Get Report

, up $1.28 to $57.26;

Teva Pharmaceutical

(TEVA) - Get Report

, up 51 cents to $28.01;

Johnson & Johnson

(JNJ) - Get Report

, up 49 cents to $57.03; and

Schering-Plough

(SGP)

, up 35 cents to $18.38.