Karen L. Stern, MD

Karen L. Stern, MD

Mayo Clinic

Phoenix, AZ


Karen L. Stern MD is an Associate Professor in the Department of Urology at the Mayo Clinic Arizona in Phoenix, Arizona. Dr. Stern received her MD from the University of Arizona, where she received the Alpha Omega Alpha distinction. She completed Urology residency at the Mayo Clinic College of Medicine in Phoenix, Arizona and was a Mayo Clinic Scholar. During her Endourology fellowship at the Glickman Urological & Kidney Institute at the Cleveland Clinic, she was awarded the Urology Fellow Teacher of the Year in 2019.

Dr. Stern specializes in the medical and surgical management of complex stone disease. At the Mayo Clinic, Dr. Stern oversees the multi-disciplinary stone clinic which incorporates urology, nephrology, and dietetics in the management of recurrent stone formers. Dr. Stern’s surgical practice includes complex ureteroscopy, percutaneous nephrolithotomy (PCNL), mini-PCNL, and ultrasound-guided percutaneous access for PCNL. Dr. Stern is involved in multiple ongoing clinical trials and is part of the Endourology Disease Group for Excellence (EDGE) and Collaborative for Research in Endourology (CoRE) research consortiums.

Dr. Stern is the Program Director for the Endourology Fellowship at Mayo Clinic Arizona and takes an active role in medical student, resident, and fellow education. She is active within the American Urological Association and serves on the Legislative Affairs Committee and Public Policy Committee.

Talks by Karen L. Stern, MD

Point-Counterpoint: HoLEP vs. GreenLightTM PVP – HoLEP

Karen L. Stern, MD, discusses holmium laser enucleation of the prostate’s (HoLEP’s) greater efficiency, safety, and durability compared to GreenLightTM photosensitive vaporization of the prostate (PVP). Dr. Stern references a 2020 study that found improved outcomes with HOLEP over PVP regarding operative time, tissue removal, International Prostate Symptom Score (IPSS) at one year, Qmax, post-void residual volume (PVR), and post-operative prostate-specific antigen (PSA). Dr. Stern then discusses small-volume prostates, emphasizing HoLEP’s effectiveness.

However, she acknowledges that PVP and transurethral resection of the prostate (TURP) are acceptable modalities in treating small-volume prostates, contrary to the treatment of large-volume prostates. Dr. Stern then reviews American Urological Association (AUA) guidelines. These note that HoLEP may serve to treat BPH and lower urinary tract symptoms (LUTS) regardless of prostate size. The AUA further notes that PVP may be less effective for large-volume prostates.

In a review of other factors, the AUA cites a 2020 study showing that PVP had a bladder outlet obstruction retreatment rate of about 27% compared to HoLEP at 5%. Dr. Stern also explains that the majority of HoLEP patients experience same-day catheter removal and discharge from hospital stays. She then evaluates the safety profile of HoLEP and PVP, finding a low rate of perioperative complications with HoLEP and high rates of urgency with PVP. Dr. Stern highlights the increased quality of life produced by HoLEP and its increased durability, boasting a reoperative rate of less than 1% per lifetime. Dr. Stern completes her discussion by reiterating HoLEP’s status as the gold standard in the surgical treatment of BPH.

This lecture is part of a Point-Counterpoint debate. Its opposing lecture is “Point-Counterpoint: HoLEP vs. GreenLightTM PVP– GreenLightTM PVP.”

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Point-Counterpoint: Holmium vs. Thulium Laser – Thulium

Karen L. Stern, MD, discusses the advantages of the thulium fiber laser (TFL) compared to the holmium laser. She highlights the increased irrigation, visibility, and flexibility of the technology, emphasizing its ablation capabilities and citing studies from the American Urological Association and the European Association of Urology.

Dr. Stern addresses TFL concerns and notes the increased convenience, hearing safety, and cost-effectiveness of TFL. She also encourages utilizing thulium fiber laser enucleation of the prostate (ThuFLEP) rather than holmium laser enucleation of the prostate (HoLEP), noting ThuFLEP’s increased water absorption ability and hemostatic approach.

This lecture is part of a Point-Counterpoint debate. Its opposing lecture is “Point-Counterpoint: Holmium vs. Thulium Laser – Holmium.”

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Point-Counterpoint: Mini-PCNL vs. Standard PCNL– Mini-PCNL

Karen L. Stern, MD, explores the improved postoperative outcomes and increased cost-effectiveness of mini percutaneous nephrolithotomy (PCNL) compared to standard PCNL. Dr. Stern continues by pinpointing the specific advantages of mini PCNL, citing that blood loss, blood transfusion, and hospitalization rates all favor mini PCNL according to recent 2022 studies.

Dr. Stern notes that, while stone-free rates and fever rates are equivalent between mini and standard PCNL, meta-analyses comparing the outcomes of mini and standard PCNL tend to favor mini PCNL, even with larger kidney stones. Dr. Stern closes by exploring the capabilities of plastic vacuum sheaths and lower lithotripsy times of mini PCNL, emphasizing efficient stone removal and lower fever rates over that of standard.

This lecture is part of a Point-Counterpoint debate. Its opposing lecture is “Point-Counterpoint: Mini PCNL vs. Standard PCNL – Standard PCNL.”

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Point-Counterpoint: Next Generation Sequencing vs. Standard Culture – Standard Culture

Karen L. Stern, MD, reviews Next Generation Sequencing (NGS) concerns, places for NGS in urology, and benefits of standard urine cultures. Dr. Stern analyzes a 2017 study of 44 patients, explaining that NGS can lead to overtreatment. Using statistics from the CDC, she also illustrates the potential for NGS to contribute to antibiotic resistance.

Dr. Stern notes that NGS is generally expensive since it is labor intensive, and the technology may not be cost-effective in high-risk patients. She also reviews the potential for increased false positives with NGS, comparing the sensitivity and specificity rates of NGS and standard urine cultures. She highlights the lack of research on NGS and calls for additional analysis into its capabilities.

However, Dr. Stern reviews data from the World Congress and concedes that NGS may have some specific uses in urology. Dr. Stern continues by comparing stone cultures and renal pelvis urine cultures to preoperative midstream urine cultures, highlighting the utility of these cultures while acknowledging the lack of research comparing them to NGS.

She transitions to a 2018 study and evaluates the listed NGS successes, expressing doubts about the usefulness and nature of these successes. Dr. Stern completes her discussion by emphasizing the need to research NGS further and reserve NGS for specific areas in urology, urging urologists to turn to standard cultures for detection.

This lecture is part of a Point-Counterpoint debate. Its opposing lecture is “Point-Counterpoint: Next Generation Sequencing vs. Standard Culture–NGS.”

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Point-Counterpoint: 24-Hour Urine Tests vs. Empiric Therapy – 24-Hour Urine Tests

Karen L. Stern, MD, discusses the benefits of 24-Hour urine tests over Empiric Therapy alone in the diagnosis and treatment of kidney stones. Dr. Stern cites American Urological Association (AUA) guidelines urging “additional metabolic testing in high-risk or interested first-time stone formers and recurrent stone formers.” Dr. Stern explains that metabolic urine testing, such as the 24-Hour test, is effective in screening for other relevant health issues, in addition to providing treatment guidance.

She cites data that show that kidney stones lead to renal dysfunction, and emphasizes that kidney stones often need more than dietary recommendations to treat. Medical therapy can help reduce stone recurrence.

Dr. Stern points out that 24-hour urine tests track patient compliance. She then discusses adverse effects of medication and asserts that 24-hour urine testing helps focus the therapy to the patient’s individual needs rather than taking a one-size-fits-all approach. Dr. Stern summarizes her points that 24-hour urine testing for kidney stones is guideline-supported, provides a workup of a chronic disease, provides effective screening, tracks compliance, and avoids unnecessary side effects and costs for patients.

This lecture is part of a Point-Counterpoint debate. Its opposing lecture is “Point-Counterpoint: 24-Hour Urines vs. Empiric Therapy–Empiric Therapy.”

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