New Hope Without Incisions: Mercy Patient Benefits From Breakthrough Histotripsy Treatment

ST. LOUIS, June 16, 2026 When Mike Wess, 82, had a second cancerous liver tumor appear six years after a complex surgery to remove the first, he knew he would seek care with the same doctor – Mercy surgical oncologist Dr. Peter DiPasco. What came as a surprise to Wess was a new, non-invasive procedure Dr. DiPasco told him about called histotripsy. WATCH Wess tell his story.

Histotripsy uses focused, pulsed sound waves to mechanically break down and liquefy targeted tissue, avoiding the heat, needles and ionizing energy required by traditional cancer treatments.

Wess's first liver surgery in 2020 was complex, took about seven hours and required weeks of painful recovery. With histotripsy, he was home and back to normal the same evening – no pain, no incision and no recovery time.

"It was a lot easier than the first time," said Wess, the first patient in Missouri to undergo a histotripsy. "It's crazy. I was cut from my breastbone to my abdomen the first time. This time, I asked my granddaughter if she wanted to see my incision, and then said there isn't one! There's nothing to see."

Wess's wife Lillian noticed the differences between the first surgery six years ago and the more recent histotripsy procedure.

"After the first surgery, there was a large incision – and medical issues that went along with it. It was hard to see the pain he was in, and there were things I had to help him with," Lillian said. "And then with this procedure, the next day he was fine. There was nothing – he ate the same, he slept well, he functioned – it was just amazing."

Dr. DiPasco explained that while Wess's active histotripsy treatment time only took a total of about 35 minutes, the "treatment planning" leading up to it took more time. During this planning, careful and exact guidance of the system's treatment arm is programmed with extreme precision.

"It's almost like a photographer getting that perfect setup and angle," Dr. DiPasco said. "The actual click of the button is very quick, but there's a lot of work that goes into it before the snap."

In the operating room, the actual treatment head and arm never physically touch the patient – only a thin, elastic membrane filled with degassed water nicknamed a "wobble." From the treatment head, therapeutic sound waves travel through the skin and destroy the tumor.

"When you stand back and think about how it hasn't been that many years to see such a massive change in how we are performing liver surgery, that it's really been such a short amount of time, it's pretty staggering," Dr. DiPasco said.

"I was a little hesitant, not knowing what I was getting into – but I thoroughly trust Dr. DiPasco, and if he was comfortable with it, I was comfortable with it," Wess said. "I can't explain how happy I am with this decision. The other option was major surgery."

As one of the first 100 hospitals in the U.S. to use this groundbreaking technology, Mercy Hospital St. Louis continues to lead in innovative care. The integration of histotripsy into Mercy's comprehensive liver program reinforces its commitment to offering patients cutting-edge, minimally invasive therapies. Ongoing clinical trials are now assessing the Edison system's potential in treating solid renal tumors and inoperable pancreatic adenocarcinoma.

Mercy, one of the 15 largest U.S. health systems and named the top large system in the U.S. for excellent patient experience by NRC Health, serves millions annually with nationally recognized care and one of the nation's largest and highest performing Accountable Care Organizations in quality and cost. Mercy is a highly integrated, multi-state health care system including 55 acute care and specialty (heart, children's, orthopedic and rehab) hospitals, convenient and urgent care locations, imaging centers and pharmacies. Mercy has over 1,000 physician practice locations and outpatient facilities, more than 5,000 physicians and advanced practitioners and more than 50,000 caregivers serving patients and families across Arkansas, Illinois, Kansas, Missouri and Oklahoma. Mercy also has clinics, outpatient services and outreach ministries in Arkansas, Louisiana, Mississippi and Texas. In fiscal year 2025 alone, Mercy provided more than half a billion dollars of free care and other community benefits, including traditional charity care and unreimbursed Medicaid.

SOURCE Mercy