3.1 Impact of COVID-19 on urolithiasis practice
Urolithiasis practice pattern has markedly changed during COVID-19. According to the EULIS Collaborative Research Group, a large survey that included 60 physicians whose main area of expertise is urinary stones was conducted to evaluate urolithiasis practice patterns following the COVID-19 pandemic. The survey showed that 49% of experts experienced > 90% change in their routine clinical practice. Among them, 72.3% used telemedicine during the crisis. 89.4% of the responders tended to change the treatment strategy of emergency COVID-19 patients by planning temporary collection system drainage followed by an elective intervention afterward. Nevertheless, 10.6% of them continued to perform definitive stone surgical treatment. It is worth noting that 55.3% and 39.8% of the experts changed their elective surgical treatment approaches by a rate of 90–100% and 75–89%, respectively. On the other hand, 6.4% of them continued as before the pandemic .
Antonucci and colleagues studied the impact of COVID-19 outbreak on urolithiasis emergency department (ED) admissions, hospitalizations, and clinical management in three high-volume Italian centers. Among 304 patients included in the analysis, there was a significant reduction (48.4%) in the global number of patients admitted to ED for treatment of urolithiasis between March and April 2020 compared to the same period of the last year. Moreover, patients admitted to ED during COVID-19 had more complications (20.4% vs. 10.9%, p = 0.025), more frequently need hospitalization (38.8% vs. 20.9%, p = 0.001), and regarding clinical stone management a statistically significant increase in early stone removal procedures over urinary drainage only was reported (p = 0.015) . Likewise, in Dallas, USA, Steinberg and colleagues observed a 38% and 44% reduction in the number of ED visits for stone disease at both their private academic and county hospitals, respectively .
In several hospitals, it took about 21 days to adopt changes related to COVID-19 and intervention for urinary stones. There was a significant increase in the rate of conservative approaches such as nephrostomy tube (NPT) insertion, double JJ stent placement or extraction from 38.2 to 81%, while definitive treatment options such as ureteroscopy (URS), retrograde intrarenal surgery (RIRS), and percutaneous nephrolithotomy (PCNL) dropped from 60.8 to 19% (p < 0.001) .
In another study that compared the diagnostic and therapeutic procedures for management of urinary stone emergencies during COVID-19 pandemic (i.e., March–April 2020) with the management performed in the same hospital in a non-COVID-19 period (i.e., March–April 2019), the number of urinary stone emergencies, complication rates, urinary stone diameter, grade of hydronephrosis, and the use of NPT or ureteral stent for the first aid did not significantly change during COVID-19 pandemic . However, patients had higher serum creatinine levels and stone position significantly changed with increase rate of middle and lower third ureteric stones during COVID-19 time due to delay of patient presentation to the hospital, related to the pandemic . Similarly, Gul and colleagues found that serum creatinine levels and the white blood cell counts at hospital admission were significantly higher in the COVID period and the rate of grade 3 and 4 hydronephrosis was higher. These findings reflect the increased rate of complicated ureteral stone disease during the COVID-19 restrictions period .
3.2 Recommendations, triage systems, and clinical pathways
Recently, several researchers have published recommendations to prioritize the treatment of urinary stones during the COVID-19 pandemic [10,11,12,13,14,15,16,17,18,19,20]. Ribal and colleagues divided the priority of urological diseases into: low priority (if treatment delayed by 6 months, it is unlikely to cause clinical harm); intermediate priority (if treatment delayed by 3–4 months, it may cause clinical harm, but it is unlikely); high priority (if treatment delayed more than 6 weeks, it is likely to cause clinical harm); and emergency (a life or organ-threatening situation) . Others have developed triage tier classification systems [11, 13] and clinical pathways  to facilitate decisions on surgical care of patients with urinary stones. Tier systems ranged from “tier 0 to tier 4” based on the urgency to intervene. Tier 0 was classified as top emergency cases that require intervention within 24 h, whereas tier 4 can be postponed >12 weeks.
3.3 Factors affecting urolithiasis treatment decision
With regard to strategies for the prevention and treatment of urinary stones during this COVID-19 pandemic, patients can be divided into two groups. First group includes those who do not need urological intervention including non-struvite, non-cystine renal stones < 7 mm, with no anatomic abnormalities. In this group of patients, general dietary recommendations and lifestyle modifications are helpful, and it is preferred to perform follow-up ultrasonography after cessation of the COVID-19 pandemic. The second group comprises those patients in whom urological intervention either emergent or nonemergent is indicated . There are multiple parameters used to assess the urgency of surgical intervention for treatment of urolithiasis including stone size and site, severity of symptoms, control of symptoms, presence of hydronephrosis or infection, degree of obstruction, presence of indwelling JJ stent or nephrostomy tube (NPT), and if the patient has a solitary functioning kidney and/or renal function impairment [11,12,13,14,15,16,17,18,19].
Of note, the treatment decision of urinary stones treatment depends not only on the patient and calculus-related factors, but also on other disciplines and healthcare resources, including the number of surgical staff and anesthesiologists, availability of hospital beds, operating rooms, and mechanical ventilators, as well as the burden of COVID-19 in the country.
3.4 Preoperative evaluation and anesthesia applied for urinary stones
Medical staff are at risk of contracting COVID-19 infection from positive diagnosed COVID-19 patients, asymptomatic or patients in the incubation period. Anesthesiologists have more risk of contracting infection during intervention from exposure to the patient’s airway . Regional anesthesia may provide patients with a successful anesthesia method and help protect the anesthesia team . Nevertheless, recent report showed that COVID-19 virus may also spread the virus during regional anesthesia as it can affect the central nervous system . Thus, it is necessary to determine the principle of the best preoperative evaluation during a pandemic to protect healthcare workers.
Recently, Gökce et al. studied the preoperative evaluation and methods of anesthesia applied for stone disease treatment during COVID-19 pandemic. They included 473 patients from 11 centers in 5 countries, and they found CT chest scan and PCR from the nasopharyngeal swab increased by 59.6% and 56.7%, respectively. In addition, there was significant alteration in anesthesia methods by 9.5%. General anesthesia, spinal/epidural anesthesia, and topical/local anesthesia were applied in 71.2%, 16.1%, and 11% of patients, respectively .