乌鸦传媒

"Medical Journeys" is a set of clinical resources reviewed by doctors, meant for physicians and other healthcare professionals as well as the patients they serve. Each episode of this journey through a disease state contains both a physician guide and a downloadable/printable patient resource. "Medical Journeys" chart a path each step of the way for physicians and patients and provide continual resources and support, as the caregiver team navigates the course of a disease.

This month: A noteworthy case study

When two HIV-positive patients were admitted for recurrent back pain that turned out to be caused by upper urinary tract stones, Lin Xiong, MD, of the University of Hong Kong-Shenzhen Hospital in Guangdong, China, and colleagues tried a new approach to treatment.

As they described in , instead of the standard flexible ureteroscopic lithotripsy, the team used a single-use digital flexible ureteroscope (su-fURS), which they believe is the first reported case of its use.

In one of their two patients with concomitant HIV, a male patient, presented with recurring episodes of intermittent pain and discomfort in his right lower back. He had had HIV for 3 years, and had been taking antiretroviral drugs for the past 2 years.

Blood tests showed that his CD4+ T lymphocyte count exceeded 200 cells/μl, and results of a CT exam showed multiple renal stones in the right kidney. The stones were about 10 mm in diameter, with a maximum of 1,365 Hounsfield units (HU) and a mean of 1,121 HU. Clinicians diagnosed the patient with multiple renal calculi in his right kidney, and successfully performed a right transurethral flexible lithotripsy and ureteral stenting.

The case authors explained that they typically perform urological CT or CT urography if needed prior to surgical intervention, but do not perform a retrograde pyelogram.

For the surgery, the patient was placed in a lithotomy position with routine sterilization and draping, with the following steps in the process:

• Visual placement of the ureteroscope into the ureter

• Insertion of approximately 30 cm of guidewire

• Removal of the ureteroscope, leaving about 37 cm ureteral flexible sheath in place

• Insertion of the su-fURS

• Observation of the distance between the ureteroscope and the ureteropelvic junction

• Withdrawal of the ureteroscope

• Adjustment of the ureteroscope sheath to slightly below the ureteropelvic junction

• Lumenis Holmium Laser fiber (fiber size 200 mm) with the power set to 0.2-0.6j/20-50 Hz for fragmentation and 1.0-1.5j/10-20 Hz for dusting of the calculi

The renal stones smaller than 1 cm were fragmented and removed with a tipless basket, and those larger than 1 cm were dusted to around 1 cm first, and then a lithotripsy basket was used to remove them, Xiong and co-authors noted.

They performed several operations of no longer than 1.5 hours each to manage heavy stone loads. After surgery was completed, an f5 Polaris Ultra ureteral stent tube was left in place. Infrared analysis of the stones indicated both calcium oxalate monohydrate and calcium oxalate dihydrate.

Follow-up CT scan showed that some stone residues smaller than 2 mm remained in the right lower calyx. Clinicians then removed the stent from the ureter, and the patient reported no further right lumbar pain or discomfort, and he had no postoperative complications during the 3-month follow-up.

Discussion

Use of HIV antiretroviral medications is currently the most common cause of drug-associated renal stone formation, the authors noted. And although both of their patients were taking long-term oral HIV antiretroviral drugs, analysis of stone composition in both patients identified primary stone formation.

Xiong and co-authors explained that since the number of HIV-positive patients with upper urinary tract stones is increasing, the team set out to retrospectively evaluate the clinical efficacy of a su-fURS on HIV-positive patients with upper urinary tract stones.

They described its use in two cases the group treated from July 2021 through January 2022, one of which was the subject of the case report.

Flexible ureteroscopic lithotripsy is the accepted standard of care for upper urinary tract stones smaller than 2 cm. In HIV-positive patients, however, use of percutaneous nephrolithotripsy for upper urinary tract stones smaller than 2 cm has been associated with an increased risk of complications such as bleeding, compared with use in patients who do not have HIV.

This means that both patients and healthcare workers are at risk, although the fact that flexible ureteroscopy does not involve scalpels or needles helps minimize clinicians' risk of sharp injuries.

Some researchers have reported an increased likelihood of postoperative complications in patients with CD4+ T lymphocyte counts of 200 cells/μl or higher, and while this was the case in both of the team's patients, neither of the patients had any significant postoperative complications, the group wrote.

"For flexible ureteroscopy lithotripsy, using traditional reusable flexible ureteroscopes (ru-fURS) has its pros and cons," the authors said. The device is costly to obtain and maintain, and carries the risk of incomplete sterilization. In addition, typically declines with repeated use, and the devices are easily damaged, with reported duration of durability ranging from 10 to 100 operations.

The single-use device helps reduce both overall medical and potential surgery-related infection and complications. "From 2016 to 2021, our center has been using the Storz electronic fiberoptic ru-fURS. According to our statistics, ru-fURS devices suffered degradation after 17 operations. The minimum repair cost of a ru-fURS was USD$190 per use," Xiong and colleagues wrote.

They cited several disposable electronic ureteral flexible scopes, including some developed in China reported to have "comparable clinical efficacy with scopes developed outside China."

Issues include microbial contamination, which has been reportedly identified in about 12.5% of the reusable devices. In addition, inadequate disinfection of ru-fURS between patients has been noted, with one study reporting of 100% of the sterilized ru-fURS, including microbial growth in 13%, and hemoglobin in 63%.

Use of a su-fURS for flexible ureteroscope lithotripsy can help avoid these risks, as well as transmission of HIV, and reduce the sterilization process, the team explained.

"Dusting and fragmentation with extraction approaches to ureteroscopic stone treatment have been a controversial topic," and although each is generally effective, with "relative advantages and disadvantages," more stones can be retrieved with su-fURS than ru-fURS, the case authors said.

Approaches to management of upper urinary tract stones vary, with fragmentation of upper urinary tract stones smaller than 1 cm, followed by removal by a stone retrieval basket, Xiong and co-authors said. "Renal stones larger than 1 cm should be first dusted to around 1 cm, and then fragmented into smaller pieces that can be extracted by a stone retrieval basket. We routinely apply this method in general flexible ureteroscopy lithotripsy, including in these cases with HIV-positive patients."

Conclusion

The case authors concluded that use of single-use digital flexible ureteroscopes are a clinically effective approach to managing upper urinary tract stones in HIV-positive patients, and in the team's experience with their two patients, neither had any urinary infections, bleeding, or other complications.

Read previous installments in this series:

Part 1: The Evolution of HIV

Part 2: ART Regimens: Is Less More?

Part 3: Viral Load: HIV's Most Important Disease Marker