High-growth stocks often capitalize on emerging trends and new technologies. But with a world of fast-evolving tech out there, it can sometimes be tricky to identify likely growth stocks. One way to do it, though, is to look at emerging trends and see what companies are likely to benefit. 

We asked three of our Motley Fool contributors what companies they think are poised for rapid growth based on emerging trends. They came back with iRobot (NASDAQ:IRBT)Twilio (NYSE:TWLO), and Guardant Health (NASDAQ:GH). Here's why they think these companies are worth considering as part of a growth-focused portfolio. 

Short-term setback, long-term opportunity

John Bromels (iRobot): It's impossible to know with certainty what the "next big thing" is going to be, but the trends are looking pretty good right now for smart-home devices. According to the International Data Corporation, the market for smart-home devices is expected to grow 26.9% year over year in 2019, with 16.9% compounded annual growth over the next five years.

True, robotic vacuum manufacturer iRobot doesn't make smart-home devices in the traditional sense (usually voice-activated or smartphone-controlled speakers, thermostats, or lighting). That being said, its robotic vacuums, mops, and lawn mowers -- including the iconic Roomba -- are autonomous and "smart" in many ways. Better yet, the company's newest models are already set up to integrate with smart-home devices including Amazon Echo speakers. Today, if you have the right Roomba and speaker combo, you can sit down on your couch to watch the game, say "Alexa, vacuum the living room" to your smart speaker, and check that chore off your list. Soon, you may be able to mow your lawn the same way. 

iRobot is clearly interested in pursuing this trend. CEO Colin Angle says the company is not only furthering its partnership with Amazon, but also working with Alphabet's Google to develop "new, innovative smart-home experiences that leverage a broader understanding of the home's space, enabled through Roomba's spatial awareness of the home."

iRobot's stock has taken a beating so far this year, as tariffs have caused the company to revise its 2019 growth projections downward. That said, the company is still looking at double-digit growth this year, and once the trade issues are settled, it should resume even faster growth. Although tariffs may keep the stock volatile in the short term, now is a great time to pick up shares for the long term at a discount. 

A high-growth mobile cloud play

Leo Sun (Twilio): Twilio's cloud platform processes messages, voice calls, videos, and other content for mobile apps. In the past, developers built those features from scratch, which was often buggy, time-consuming, and tough to scale.

Twilio lets companies outsource those features to its cloud platform by embedding a few lines of code. That solution is also easier to scale, since Twilio's platform does all the heavy lifting as an app's user base grows.

Its first-mover's advantage in this space gives it a major advantage over rivals like Vonage's (NYSE: VG) Nexmo and Bandwidth (NASDAQ: BAND), and demand for its services is surging. Its revenue rose 63% to $650 million last year, and accelerated to 81% growth in the first quarter and 86% in the second quarter.

Furthermore, Twilio's dollar-based net expansion rate, which measures increasing business from existing active customers, jumped 140% annually last quarter. This indicates that its expanding ecosystem -- which includes new email, analytics, and security services -- is locking in customers. Analysts expect its revenue to surge 72% for the full year.

The company's growth looks promising, but there are a few flaws. It isn't profitable under generally accepted accounting principles (GAAP), and its losses are widening as it develops and launches new services. The stock rallied more than 70% over the past 12 months, and it isn't cheap at 16 times this year's sales. There's also a chance that some customers will develop their own in-house alternatives to Twilio -- as Uber did two years ago.

Therefore, it will likely remain a volatile stock, but I think its strong core business, sticky ecosystem, and wide moat should propel it to fresh highs over the next decade.

Liquid gold

Keith Speights (Guardant Health): One major problem with fighting cancer is that the disease is often detected too late to effectively treat it. But there's a potential solution at hand: liquid biopsies that can detect the presence of DNA fragments that have broken off from tumor cells in the blood. All that's required is a blood sample and the technology to analyze the blood. Guardant Health is pioneering liquid biopsy technology.

The company currently markets four liquid biopsy products. Guardant360 matches patients with advanced-stage cancer with the appropriate therapy. GuardantOmni helps biotechs and pharmaceutical companies screen patients for participation in clinical studies evaluating cancer drugs. The company's Lunar-1 and Lunar-2 DNA assays detect early stage cancer as well as recurrence of cancer.

Revenue is skyrocketing thanks to heavy demand for Guardant360 and GuardantOmni. But all of the company's products are still only in their early stages of adoption. CEO Helmy Eltoukhy said in the company's recent Q2 conference call that "clinical adoption of Guardant360 is still only in the mid single digits." The Lunar DNA assays are currently only available for use by researchers.

The potential market for the company's liquid biopsies is massive. It estimates an addressable market of $6 billion for Guardant360 and GuardantOmni, $15 billion for Lunar-1, and $18 billion for Lunar-2. And that's just in the U.S.

Guardant Health will have competition, but it's in a great position to capture much of the potential market. My view is that the liquid biopsy market should make this stock the equivalent of liquid gold over the next decade.