Karleen Oberton
Chief Financial Officer at Hologic
Thank you, Steve, and good afternoon, everyone, and congratulations again to our diagnostics team. In my statements today, I will provide an overview of our divisional revenue results and walk down our income statement that highlights the broad-based strong performance across our business. I will also touch on a few additional key financial metrics and finish with our guidance for the second quarter of fiscal '24 and the full year.
Jumping right in, we are pleased to share that our first quarter financial performance was strong. We exceeded our expectations on both the top and bottom line. Total revenue came in at $1.013 billion, beating the midpoint of our guidance by about $40 million. As Steve mentioned, despite four fewer selling days in the quarter, we delivered organic revenue growth of 5.2%, excluding the impact of COVID in line with our long-term revenue growth target of 5% to 7%. In addition, non-GAAP earnings per share, was $0.98, exceeding the high end of our guidance. Overall, we continue to deliver robust performance on both the top and bottom lines.
Before moving to our divisional results, we again want to emphasize that our balance sheet and willingness to deploy capital remain a core strength of our business in a macro environment that remains dynamic. As an example, in our first quarter, we initiated a $500 million accelerated share repurchase program. We purchased an additional $150 million of our stock and also paid down $250 million of floating rate debt. With a cash balance of $1.9 billion, a leverage ratio well below our target range, and roughly $350 million remaining on our current share repurchase authorization, we have significant firepower and flexibility to deploy further capital, should the opportunity arise.
Turning to our divisional results. In Diagnostics, first quarter revenue of $447.8 million declined 20.6%. Excluding COVID assay and related ancillary revenue, Diagnostics revenue declined 0.9%. Yet adjusted for selling days, we estimate we grew mid-single digits compared to the prior year.
As a reminder, Q1 '23 was a very strong quarter for Diagnostics, posting 15.8% growth ex-COVID and Molecular Diagnostics 24.5% growth ex-COVID. And without a doubt, our Q1 '24 results was impacted by four fewer selling days compared to the prior year. Within Diagnostics, our Molecular business continues to drive the division's results, delivering growth of 1.9% ex-COVID or mid- to high single digits when adjusted for the impact of fewer selling days.
We continue to see underlying strength in BV/CV/TV, which grew more than 20% in the quarter and is still in its early innings of adoption by our customers. More than 95% of our BV/CV/TV revenue is derived in the US, representing incredible longer-term opportunity internationally.
In addition, non-COVID respiratory revenue delivered ahead of our expectations, as we experienced stronger-than-anticipated demand for our flu, RSV and [Indecipherable] assays. Our responding with published CDC data on respiratory virus positivity, sales ramped up in the final weeks of the quarter. Finally, Biotheranostics remains a positive driver of growth for our molecular business and delivered accretive revenue performance in the period.
Now moving to Breast Health. Total first quarter revenue of $377.7 million increased 12.2%, showcasing solid double-digit growth. Demand for our gantries remains robust, and our interventional business also delivered a strong quarter. In our gantry business, we continue to benefit from a strong cadence of orders in our elevated backlog continues to give us high confidence in the performance of this business going forward. Finally, as a reminder, Q1 2023 results were impacted by constrained supply.
In Interventional, we continue to see strong performance from our Brevera needle as well as from our two markers used for marking biopsy sites in suspicious lesions in breast tissue. Leveraging strong performance in the quarter, we believe our Breast Health franchise remains well positioned to deliver on its financial targets in fiscal 2024.
Continuing next to Surgical. Our first quarter revenue of $162.2 million increased 4.6% or high single-digits when adjusted for selling days. The division's growth continues to be fueled by MyoSure in the related fluid system with an increasing contribution from our laparoscopic portfolio. As anticipated, NovaSure declined in Q1 as we lapped the selling price contribution from the product's V5 extension introduced just before fiscal 2023. And finally, in our Skeletal business, first quarter revenue of $25.4 million declined 5.6% from lower capital placement and upgrades.
Now let's move on to the rest of the non-GAAP P&L for the first quarter. Gross margin of 60.8% was driven primarily by strong performance in our base business and higher-than-expected COVID revenues, which carries a favorable impact to our margins. However, as anticipated, our gross margin results remains temporarily depressed due to the ongoing amortization of semiconductor chips purchased at higher costs during the chip supply headwind. As we continue to deploy gantries, we are moving farther away from this high-priced inventory. And as a result, we expect margins to continue to benefit from this inventory cycling as we progress through the year.
Shifting to operating expenses. Total operating expenses of $327.3 million in the first quarter decreased by 3.6%. This decrease in the period was driven by lower marketing spend, lower costs from fewer days and less expense due to the recently divested SSI business. For Q1 2023, this translates to a 28.5% operating margin, in line with our expectations. While we continue to deliver peer group-leading operating margins, we continue to exercise operational discipline and continuously seek to improve where it makes sense for our business.
Below operating income, other income net, represented a gain in our fiscal first quarter. As expected, we benefited from elevated cash balance and high interest rates, even though we deployed significant cash in the quarter. Finally, our tax rate in Q1 was 19.75% as expected.
Moving on from the P&L. Cash flow from operations was $220 million in the first quarter. In addition, as previously mentioned, during Q1, we repurchased 2.2 million shares for $150 million. This activity was above and beyond initiating a $500 million ASR, showcasing our high confidence in our business and willingness to bet on ourselves, as well as our ongoing strategy to deploy capital.
Now, let's move on to our non-GAAP financial guidance for the second quarter and full year fiscal '24. For our fiscal Q2 '24, we are expecting total revenue in the range of $990 million to $1.01 billion and EPS of $0.95 to $1. For the full year '24, our guidance assumes revenue of $3.99 billion to $4.065 billion and EPS of $3.97 to $4.12.
With respect to foreign exchange, we are assuming an FX tailwind of $2 million for Q2 and $12 million for fiscal '24. Much of this tailwind was realized in Q1. And therefore, we estimate that foreign exchange will remain neutral to marginally favorable throughout the remainder of the year.
Turning to our divisions. We want to reiterate that we expect each business to grow at least 5% to 7% for the full fiscal '24, excluding the impact of COVID. Starting with Diagnostics. We expect the business to grow within our 5% to 7% long-term framework for the remainder of fiscal '24. While performance was below this level in Q1, primarily due to the impact of fewer selling days compared to the prior year period, we expect the division to return to more normal growth in Q2 and for the remainder of our fiscal year.
We expect improving utilization and menu expansion on the Panther, coupled with ongoing contributions from Biotheranostics to continue to drive molecular growth. Closing out on non-COVID diagnostics, we expect blood [Phonetic] revenue of approximately $7 million in Q2 and $30 million for the year. In terms of COVID revenue, we expect COVID assay sales to be approximately $20 million in the second quarter of '24 and $60 million for the full year. COVID related items are expected to be slightly less than $30 million in the second quarter and approximately $105 million for the full year fiscal '24.
Moving to Breast Health. We continue to expect fiscal '24 to showcase strong demand for our portfolio of products and services. While moving on, it's important to understand the comp dynamics that will impact the breast business through fiscal '24. As previously noted, Q1 '23 was a softer comp due to shipped supply constraints. As a reminder, in Q2 '23, we delivered a strong quarter of gantry placements to meet pent-up customer demand during these earlier days of chip supply recovery. And deliveries in Q3 and Q4 of '23 were both lower than Q2. We expect this dynamic to result in a lower breast health year-over-year growth rate in Q2 that will improve in the back half of fiscal '24.
For the full year, we continue to expect to deliver more gantries in fiscal '24 than in '23 as we move further from the chip supply headwinds while maintaining excellent demand visibility. Finally, in Surgical, we anticipate our full year fiscal 2024 revenue growth to be at the high end of our 5% to 7% long-term target. Although impacted by fewer selling days, Q1 started the year strong, and we expect the business to perform well in Q2 and the remainder of the fiscal year.
Moving next to margins. Our guidance assumes a cadence of improvement throughout fiscal 2024 for both gross margin and operating margin. For gross margin, we anticipate Q2 levels similar to Q1, exiting the fiscal year in the low 60s. As well, our guidance assumes Q2 operating margins approaching 30% with the Q4 2024 exit rate around 31%.
Continuing down the P&L. We expect Q2 operating expenses to step down from Q1. As a reminder, Q1 is typically our highest spend quarter seasonally as we kick off the fiscal year with our internal global sales meetings and major trade show events such as RSNA. For the balance of the year, we anticipate quarterly operating expenses to be about $300 million to $310 million.
Below operating income, we estimate fiscal 2024 other income net to be in an expense of approximately $10 million in Q2 and an expense between $30 million to $50 million for the full year. Our current guidance assumes an increase in interest income relative to our previous guide as we expect to have a higher cash balance throughout the remainder of the fiscal year. Our guidance is based on an annual effective tax rate of approximately 19.75% and diluted shares outstanding are expected to be approximately $239 million for the full year.
To conclude, Q1 was a strong quarter across each of our businesses and sets us up nicely for the rest of the year. As we closed Q1, we moved forward to Q2 in fiscal 2024 with good momentum. And as always, we remain focused on advancing women's health around the world while delivering on our promises and commitments to our shareholders, employees, customers and patients around the world.
With that, we ask the operator to open the call for questions.