Thank you, Leon. Good afternoon. I am Carl Iberger, Precipio's Chief Financial Officer. Yesterday Precipio issued a press release that provided a synopsis of our 2020 topline results. This press release followed the filing of our 10K on Monday, March 29. In his opening remarks, Ilan covered a number of items. I'd like to take this opportunity to add some additional comments regarding our sales growth in pathology services the headway we are making developing a distribution market for IV-Cell and finally the impressive reception HemeScreen is receiving with office-based oncologists and larger oncology commercial labs.
First pathology diagnostic services, just prior to the interruption in business shutdown from COVID, we reconstituted and reorganized our sales force at the tail end of February and into early March 2020. This action by the company proved to be extremely timely.
Our initiatives actually enabled Precipio to address the many disruptions of normal business of operations resulting from the economic shutdown.
First on that list of issues, with just basic access to physician accounts by our sales reps.
During Q2 2020 with COVID shutdown ramping up, we seamlessly executed the onboarding of accounts from the non-cash, non-equity acquisition of our Poplar Healthcare's OncoMetrix business and as we move through Q3 and Q4 of 2020, the decisions and preparation affected in February and early March in our sales organization our lab operations and lab logistics allowed the sales force to actually grow account volumes and add new business as our customers experience minimal changes from normal business routines. Stepping back and reviewing 2020, case volume grew throughout the year, issuing our 10K, we reported a year over year volume growth of billable cases of 120%.
While we are just completing Q1 '21, our initial unaudited results are as impressive.
Given the impact of the variety of storms in Southeast and Midwest, we project revenues to approximate Q4 of 2020.
Second IV-Cell, as Ilan stated IV-Cell is a sophisticated, highly complex cytogenetic product being introduced in the commercial lab setting.
Our path of building market revenues has been elongated reflecting the complexity and change this advanced technology has and will have on the cytogenetic lab process.
So where are we today? The bottom line on IV-Cell is that it delivers what is clinically advertised, simultaneous cultures and speed and processing.
Additionally, the financial value proposition to the customer is very real and very meaningful. Therefore, we are extremely confident in the product and our ability to sell through our partnership with ADS and its international customers.
Third HemeScreen, having a product that offers a turnkey solution, both including diagnostic equipment as well as reagent, a product that offers extremely low entry cost for the customer, a product that is able to build new revenues for oncology practices and a product that eliminates the need for the practice to reference out tests that are not only expensive but have a long lead time 10 days to two weeks reducing that to one day, that product defines HemeScreen. We project HemeScreen to produce very meaningful revenues for Precipio in 2021 and for HemeScreen to be a material driver for the company. Taking the growth in HemeScreen and past services together, we anticipate accelerating the company's timeline for cash flow breakeven.
Now moving to financial results, our 10K provides extensive information and financial results of our operations. The press release provided highlights of 2020. Diving into the financial performance, I'd like to address sales and gross profit, operating expenses and our balance sheet. Sales and gross profit both rose in 2020. Sales for 2020 of $6.1 million increased 95% over 2019 driven by pathology services.
Our increases in past services enabled our lab operations to leverage text expenses to maximize our batch processing and to a large extent consolidate purchase expenses, all reducing our purchase costs. 2020 gross profit of $1.2 million increased by 4X in comparison to 2019.
For 2020, gross margin increased to 19% from 7%.
Looking at Q4 of 2020, our margin increased to 24% and on an incremental revenue basis in 2020, on a $3 million increase in sales year-over-year, gross profit grew 900K and incremental gross margin was 31%. We anticipate the continual pace volume increases in pathology will show a significant and meaningful improvement in gross profit and gross margin percentage in 2021. Continuing our discussion of gross profit, we're very encouraged about the impact HemeScreen will have on our 2021 future gross profits.
As HemeScreen revenues are beginning to build and our upfront investment costs are behind us, we see HemeScreen being a material factor in accelerating total reported revenues, gross profit and the timeline to cash flow breakeven.
Moving towards operating expenses, in 2020, operating expenses were $9.8 million an increase less than $0.2 million or less than 2% when compared to 2019, while revenues during same period almost doubled.
During 2020, we focused on reducing G&A expenses. We took those savings and reinvested in selling and R&D initiatives. Within R&D in 2021, we were actively working on the development of a suite of HemeScreen panels and as we build HemeScreen accounts, we look to expand the HemeScreen offering to those oncology practices.
Moving on to the balance sheet, growth [ph] has provided the company definitely more financial flexibility. With growth to a degree, we've been able to shore up our balance sheet, reduce cash burn, increase cash on hand, reduce accounts receivable and made gains stabilizing the total liabilities to provide the accounts payable and accrued expenses. Ending 12-31-2020, accounts receivable was $0.9 million an increase of only $0.3 million on a sales increase of $3.0 million. DSO at the end of 2020 was 52 days, a decrease of 15 days from 2019.
As the majority of our revenue is patient billing, I'm very pleased with the results turned in by the company's reimbursement team. Accounts payable and accrued expenses remain essentially level year-over-year on a much larger book of business and with the investments in R&D. The improvement in DSO -- improvement in revenue collected per case and accelerating the collections have assisted the company's cash needs and our operations.
Moving on to CapEx, in Q4 of 2020, seeing the monthly case volume continually increase in pathology services, the finance group and operations reassessed the company's CapEx needs for the future. The assessment ended with initiatives by lab operations and renegotiating existing contracts with major equipment and reagent suppliers and additionally operations revisited equipment rental programs and upgraded lab diagnostic competencies, expanding our molecular testing capabilities. This change allows Precipio to bring in-house previously reference out testing that was very expensive and had lengthy reporting times that would impact our services to our customers. We're encouraged that growth in volume will be met by our continual emphasis on diagnostic quality and will provide lower case costs. Financing for the company in 2020, we utilized our equity line to fuel the company's growth in operation. Entering 2021, with anticipated revenues on the rise, we project a reduction in the cash burn rate each and every quarter. Key to this equation will be building HemeScreen revenues.
As Ilan stated earlier regarding COVID, while we are actively moving forward, our endeavor in COVID antibody testing and the resulting revenue performance is as of yet very uncertain.
As such, we do not have a material impact of COVID revenue in our projections.
As we move forward, the company will provide additional shareholder information on this product as material data becomes available. In summary, 2020 was a unique year and a very challenging period for the company.
Going forward, we are truly excited about 2021 and our growth opportunities. Operationally, we anticipate continual improvement through volume growth in pathology services and as HemeScreen revenues build. Financially, we continue to gain strength, but we remain focused on leveraging our assets and driving the company to breakeven. At this time, I done with my portion of the presentation and I will return the meeting over to the Ilan. Thank you. Ilan?