Optum – the parent of major ambulatory surgery center (ASC) chain SCA Health – continues to play an important role at health care giant UnitedHealth Group (NYSE: UNH).

Not too long ago, Optum played a complementary role under the broader UnitedHealth Group umbrella. Now, however, Optum is taking center stage, with the health care services arm serving as UnitedHealth Group’s leading revenue generator.

“In the first half of the year, revenues grew by nearly $14 billion, with strong contributions from across the enterprise, led by double-digit growth at Optum,” UnitedHealth Group CEO Andrew Witty said during a Tuesday morning conference call discussing the company’s Q2 2024 financial results.

Specifically, Optum brought in $62.9 billion in Q2 2024 revenue, a nearly 12% year-over-year increase compared to $56.3 billion during the same period in 2023.

Overall, UnitedHealth Group’s second quarter revenue totaled $98.8 billion, a 6.5% year-over-year increase compared to $92.9 billion in Q2 2023.

“The second quarter results we reported today reflect diversified and durable growth and a commitment to ensuring high-quality care is available to every person we’re privileged to serve,” Witty said.

Collectively, UnitedHealth Group and Optum are fairly guarded on what information they disclose about their specific health care services assets. Not only is Optum the parent of SCA Health, but it’s also the owner of home health powerhouse LHC Group and outpatient mental health business Refresh.

Neither Witty nor CFO John Rex offered any color on those particular health care subsidiaries during Tuesday’s call.

UnitedHealth Group acquired Surgical Care Affiliates for $2.3 billion in 2017.

“Combining SCA and OptumCare will enable us to continue the transition to high-quality, high-value ambulatory surgical care, partnering with the full range of health systems, medical groups and health plans,” former UnitedHealth Group and Optum executive Larry C. Renfro said at the time of the deal. “We have an incredibly high regard for SCA’s leadership and people, so we look forward to working with them and our payer partners to implement care models that reward independent surgeons and specialists for quality and care efficiency.”

SCA, according to its website, has more than 320 surgical facilities across its footprint. The ASC chain and its roughly 9,200 physicians serve about 1.43 million patients annually.

Another health care tool in UnitedHealth Group’s chest: Its house calls asset. While it often flies under the radar, this capability can potentially serve as a feeder to the company’s surgery centers by creating more direct touch points with patients.

Witty praised the house calls service at length toward the beginning of Tuesday’s call.

“Last year, our medical professionals made more than 2.5 million home visits,” Witty explained. “As a direct result, our clinicians identified 300,000 seniors with emergent health needs that may otherwise have gone undiagnosed.”

Within 90 days of one of those home visits, 75% of the patients seen received follow-up services in a clinical setting, the CEO continued.

“The bottom line, our home visit programs help patients live healthier lives and save taxpayers money,” Witty said.