Pacific Biosciences of California Inc. PACB is scheduled to report first-quarter 2016 results on Apr 21. Last quarter, the company reported a loss of 2 cents per share, as expected.Notably, Pacific Biosciences posted a negative earnings surprise of 3.57% on an average over the last four quarters, as shown in the below chart. Let us see how things are shaping up for this announcement.Factors Influencing This QuarterPacific Biosciences expects Sequel system shipments to fall in the first half of 2016 owing to the limited availability of Single Molecule, Real-Time (SMRT) cells. Hence, first-quarter 2016 revenues are expected to remain flat on a year-over-year basis.However, management expects revenues to grow sequentially each quarter for the rest of 2016, based on an eventual increase in shipments of the Sequel system. Pacific Biosciences expects consumable revenues to grow sequentially each quarter as well. Nevertheless, the growth rate is forecasted to be unstable owing to fluctuations in customer order patterns.Meanwhile, we believe persistent losses and cash burn are the primary headwinds in the near term.Earnings WhispersOur proven model does not conclusively show that Pacific Biosciences is likely to beat the Zacks Consensus Estimate this quarter. This is because a stock needs to have both a positive Earnings ESP and a Zacks Rank #1 (Strong Buy), #2 (Buy) or #3 (Hold) for this to happen. That is not the case here as you will see below.Zacks ESP: The Earnings ESP for Pacific Biosciences is -8.33%. This is because the Most Accurate estimate stands at loss of 26 cents, while the Zacks Consensus Estimate is pegged at a loss of 24 cents.Zacks Rank: Pacific Biosciences carries a Zacks Rank #3, which increases the predictive power of ESP; but when combined with a -8.33% ESP, it makes surprise prediction difficult.We caution against stocks with a Zacks Rank #4 and 5 (Sell-rated stocks) going into the earnings announcement, especially when the company is seeing negative estimate revision momentum.Stocks That Warrant a LookHere are some medical stocks that you may want to consider, as our model shows that these have the right combination of elements to post an earnings beat this quarter.Align Technology Inc. ALGN with earnings ESP of +12.82% and a Zacks Rank #1.PAREXEL International Corporation PRXL with earnings ESP of +2.25% and a Zacks Rank #1.Becton, Dickinson and Company BDX with earnings ESP of +2.49% and a Zacks Rank #2.Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report PACIFIC BIOSCI (PACB): Free Stock Analysis Report ALIGN TECH INC (ALGN): Free Stock Analysis Report BECTON DICKINSO (BDX): Free Stock Analysis Report PAREXEL INTL CP (PRXL): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research