Posterior Quadratus Lumborum Block and Its Effect on Stent-Related Urinary Symptoms Following Ureteroscopic Lithotripsy: A Randomised Controlled Trial

By Eylem Yasar¹, Ilker Akarken², Gizem Akgun³, Harun Bal², Bakiye Ugur⁴

Affiliations

1. Department of Anesthesiology and Reanimation, Mugla Training and Research Hospital, Mugla, Turkey
2. Department of Urology, Faculty of Medicine, Mugla Sitki Kocman University, Mugla, Turkiye
3. Yatagan State Hospital, Mugla, Turkiye
4. Department of Anaesthesiology and Reanimation, Faculty of Medicine, Mugla Sitki Kocman University, Mugla, Turkiye

doi: 10.29271/jcpsp.2025.10.1308

ABSTRACT
Objective: To assess the effect of a single-shot posterior quadratus lumborum block (QLB) on double-J stent-related (DJS-related) lower urinary tract symptoms (LUTS) and postoperative opioid consumption following ureteroscopic lithotripsy (URSL).
Study Design: A randomised controlled trial.
Place and Duration of the Study: Department of Urology, Mugla Sitki Kocman University, Training and Research Hospital, Mugla, Turkiye, from January to October 2024.
Methodology: A total of 154 patients undergoing unilateral URSL with double-J stent (DJS) placement under spinal anaesthesia were randomly assigned to two groups. The QLB group (n = 77) received a posterior QLB, whereas the Control group (n = 77) received standard care without regional blocking. Postoperative pain was assessed using the Numerical Rating Scale (NRS) at 1, 6, 12, 24, and 48 hours, as well as on day 7. LUTS were assessed with the Ureteral Stent Symptom Questionnaire (USSQ) on day 7 (USSQ-1, during stent indwelling) and five days after stent removal (USSQ-2). Cumulative tramadol consumption within the first 48 hours was also recorded.
Results: Compared with the Control group, the QLB group showed lower USSQ-1 scores (68.05 ± 19.08 vs. 90.22 ± 23.60; p <0.001), improved USSQ-2 scores (43.64 ± 6.04 vs. 52.58 ± 15.13; p <0.001), and reduced tramadol consumption (75.32 ± 101.51 mg vs. 229.87 ± 146.06 mg; p <0.001). Pain scores were consistently lower at all time points except the first hour. No major adverse events were observed.
Conclusion: A single posterior QLB appears to reduce DJS-related LUTS, postoperative pain, and opioid use after URSL. Its inclusion in multimodal analgesia protocols may contribute to improved perioperative care in urological surgery.

Key Words: Double-J stent, Lower urinary tract symptoms, Postoperative pain, Quadratus lumborum block, Regional anaesthesia, Ureteroscopic lithotripsy.

INTRODUCTION

The implantation of a double-J stent (DJS) is commonly employed alongside ureteroscopic lithotripsy (URSL) to avert ureteral blockage and facilitate urine outflow.¹ While clinically effective, DJS implantation is often associated with sometimes leads to lower urinary tract symptoms (LUTS), such as urgency, frequency, suprapubic discomfort, and haematuria. These symptoms may markedly undermine patient satisfaction and quality  of  life  throughout  the  postoperative  phase.²

Pharmacological interventions, such as anticholinergics and alpha-blockers, are utilised to mitigate these symptoms; however, their effectiveness is variable and often limited by systemic side effects.³ Complications related to ureteral stent placement, such as forgotten stents or spontaneous fragmen- tation, have also been documented in local studies,^4,5 further highlighting the need for exploring non-pharmacological strategies to alleviate stent-related symptoms. Recent studies have concentrated on regional anaesthesia techniques to enhance perioperative analgesia and potentially reduce stent- related morbidity.⁶

The quadratus lumborum block (QLB), a fascial plane block targeting the thoracolumbar nerves, has been shown to be effective in abdominal and pelvic surgeries by providing both somatic and visceral analgesia.⁷ The posterior QLB variant is particularly advantageous owing to its capacity to deliver more consistent cranial spread and prolonged analgesic effect via the thoracolumbar fascia pathway. Despite the growing interest in regional anaesthesia for urological interventions, the potential effectiveness of QLB in mitigating double-J stent-related (DJS- related) LUTS has not been comprehensively evaluated.^8,9 The QLB is distinguished among regional anaesthesia techniques in urological surgery by due to extensive dermatomal coverage (T10–L1) and prolonged analgesia, potentially providing improved haemodynamic stability relative to neuraxial blocks such as caudal or spinal anaesthesia.^7,9 Literature suggests that alternative fascial plane blocks employed in abdominal procedures typically offer more superficial and restricted analgesia, whereas the QLB provides deeper and visceral analgesia.¹⁰

This randomised controlled trial sought to assess the hypothesis that a single injection of posterior QLB at the end of URSL surgery would significantly reduce DJS-related LUTS and decrease postoperative opioid use by day 7 compared to standard analgesic regimens.

METHODOLOGY

This randomised controlled study was conducted in the Department of Urology, Mugla Sitki Kocman University Training and Research Hospital, Mugla, Turkiye, from January to October 2024. Ethical approval was obtained from the Ethics Committee of the Mugla Sitki Kocman University, Mugla, Turkiye (Approval date: 11/05/2022, 9/VIII). This study was conducted in accordance with the Declaration of Helsinki. Before enroling any patients, the study protocol was registered by the principal investigator (EY) on ClinicalTrials.gov (NCT 06290323; Protocol ID: 11/05/2022-9/VIII). All participants provided formal informed consent before entering the trial. This study adhered to the 2010 Consolidated Standards of Reporting Trials (CONSORT) guidelines.

The study included patients aged 18 to 70 years who had unilateral ureteral stones measuring between 5 and 15 mm, were scheduled for unilateral URSL with DJS placement, and were classified as American Society of Anaesthesiologists (ASA) physical status I to III. The exclusion criteria included ASA physical status IV, bilateral ureteral stones, stone size greater than 15 mm or less than 5 mm, known allergies to paracetamol or local anaesthetics, contraindications to regional anaesthesia (such as coagulopathy or infection at the injection site), chronic use of opioids or analgesics, inability to communicate, or BMI exceeding 35 kg/m².

Upon entering the operating room, standard monitoring was commenced, including three-lead electrocardiography, non- invasive blood pressure assessment, and pulse oximetry, while peripheral intravenous access was established. All patients received spinal anaesthesia while seated. A 25-gauge Quincke spinal needle was employed to penetrate the interspinous space at the L3–L4 or L4–L5 level. A sensory block extending to the T10 dermatome was attained with the administration of 10 mg of 0.5% hyperbaric bupivacaine (Marcain Heavy^®; Aspen Pharma, Germany) in conjunction with 20 mcg of fentanyl (Fentanyl Citrate^®, Johnson & Johnson, Belgium).

Patients were randomly allocated to the QLB group or the Control group in a 1:1 ratio via a computer-generated randomisation list. The allocation sequence was created before patient enrolment using a web-based random number generator, with assignments concealed in sequentially numbered, opaque, sealed envelopes prepared by an independent investigator who was not engaged in patient care or data collection. On the day of the procedure, following verifying patient eligibility and obtaining informed consent, an envelope was unsealed to ascertain group assignment. The anaesthesiologist administering the block (EY) was informed of the allocation, whereas the patient and outcome assessor remained blinded to group assignment.

After group allocation, patients were administered care in accordance with their designated procedure. In the Control group, patients were positioned in the lithotomy position, and the surgical process commenced without any regional anaesthesia. In the QLB group, patients were placed in the lateral decubitus position with the operative side oriented upward to facilitate the administration of the posterior QLB before surgery.

After sterilising the skin, a convex ultrasound probe (SonoSite M-Turbo; FUJIFILM SonoSite, Bothell, WA) was placed perpendicular to the spine and advanced laterally to visualise the quadratus lumborum and psoas muscles. Using the in-plane technique, 1–2 mL of saline (Polifarma^®, Turkiye) was injected at the L4 vertebral level to confirm the correct positioning between the quadratus lumborum muscle and the anterior layer of the thoracolumbar fascia. Subsequently, 20 mL of 0.375% bupivacaine (Marcaine^®, AstraZeneca, UK) was injected. The patient was then positioned in the lithotomy position for the surgical procedure.

A urologist, blinded to group allocation, visited each patient in the ward at 1, 6, 12, 24, and 48 hours postoperatively to assess pain intensity using the Numerical Rating Scale (NRS). Patients were monitored for 48 hours postoperatively in accordance with the study protocol to standardise pain and opioid assessment and to enable early detection of possible complications. Starting 1 hour after spinal anaesthesia, all patients received 1,000 mg of intravenous paracetamol (Perfalgan^®, Bristol-Myers Squibb, France) every 8 hours for baseline analgesia. If the NRS score remained ≥3 for more than 30 minutes, a rescue dose of 100 mg tramadol (Contramal^®, Grunenthal, Germany) was administered. The cumulative tramadol consumption during the first 48 postoperative hours was recorded. On postoperative day 7, when DJS remained in situ, LUTS were assessed with the Ureteral Stent Symptom Questionnaire (USSQ) by the same blinded urologist (HB) through a telephone interview. It was recorded as USSQ-1 for each patient.

According to the study clinical protocol, approximately one month after URSL, a routine cystoscopic evaluation and stent removal were performed. On day 5 following DJS removal, the blinded urologist contacted patients again by phone to reassess LUTS using the post-stent removal version of the USSQ. It was recorded as USSQ-2 for each patient.

Table I: Baseline demographic and clinical characteristics.

Variables	Control Group (n = 77)	QLB Group (n = 77)	p-values
Age (years)	48.43 ± 12.50	49.68 ± 12.35	0.685
BMI (kg/m2)	24.94 ± 3.27	25.37 ± 3.01	0.513
Stone size (mm)	9.92 ± 2.96	9.97 ± 3.34	0.313
Values are expressed as mean ± SD. p-values were determined using Student’s t-test. BMI: Body mass index.

Table II: Comparison of ureteral stent symptom (USSQ) scores.

Domains	Control Group (n = 77)	QLB Groups (n = 77)	p-values
USSQ-1 (day 7)	90.22 ± 23.60	68.05 ± 19.08	0.149
USSQ-2 (5 days after removal)	52.58 ± 15.13	43.64 ± 6.04	<0.001
Values are expressed as mean ± SD; Student’s t-test was used for determining p-values.

Table III: Postoperative pain scores and tramadol use.

Variables	Control Group (n = 77)	QLB Group (n = 77)	p-values
NRS – 1 hour	1.00 ± 1.05	1.26 ± 1.78	0.272
NRS – 6 hours	4.01 ± 1.94	1.38 ± 1.66	<0.001
NRS – 12 hours	3.55 ± 1.68	1.43 ± 1.57	<0.001
NRS – 24 hours	2.96 ± 1.64	1.10 ± 1.22	<0.001
NRS – 48 hours	2.08 ± 1.32	0.91 ± 1.03	<0.001
NRS – 7 days	2.03 ± 1.11	0.94 ± 0.96	<0.001
Tramadol (mg, 48 hours)	229.87 ± 146.06	75.32 ± 101.51	<0.001
Values are expressed as mean ± SD; p-values were determined using Student’s t-test. NRS: Numerical rating scale.

During hospitalisation, patients were monitored for sequelae, including local anaesthetic systemic toxicity (LAST), allergic reactions, visceral injury, postoperative nausea and vomiting (PONV), and surgical site bleeding. Adverse reactions and complications were documented.

Since no prior studies have specifically evaluated the effect of posterior QLB on DJS-related symptoms using the USSQ, a moderate effect size (Cohen’s d = 0.5) was assumed for the sample size estimation. Based on this assumption, a minimum of 64 patients per group was required, with a two- tailed α of 0.05 and 80% power (1−β). To account for a potential 20% dropout rate, 77 patients were enrolled in each group.

Statistical analyses were performed using IBM SPSS Statistics for Windows, version 20.0 (IBM Corp., Armonk, NY, USA). Continuous variables were assessed for normality using the Shapiro-Wilk test. Continuous data were summarised as mean ± standard deviation (SD) and compared using the Student’s t-test. A two-tailed p-value <0.05 was considered statistically significant.

RESULTS

A total of 161 patients were screened for eligibility between January and October 2024. Of these, four patients declined to participate, and three were lost to follow-up. Thus, 154 patients met the inclusion criteria and were randomised into two equal groups: seventy-seven patients in the Control group and 77 patients in the QLB group.

Table I summarises the baseline demographic and clinical characteristics of the two groups. There were no statistically significant differences between groups regarding the mean age (Control group: 48.43 ± 12.50 vs. QLB group: 49.68 ± 12.35; p = 0.685), body mass index (BMI) (Control group: 24.94 ± 3.27 vs. QLB group: 25.37 ± 3.01; p = 0.513), or stone size (Control: 9.92 ± 2.96 mm vs. QLB group: 9.97 ± 3.34 mm; p = 0.313), indicating appropriate randomisation and baseline comparability. Moreover, the distribution of ASA physical status scores was similar in both groups, supporting cohort homogeneity.

Patients in the QLB group had lower USSQ-1 scores than those in the Control group (68.05 ± 19.08 vs. 90.22 ± 23.60; p = 0.149). However, this difference did not reach statistical significance (Table II). In contrast, the USSQ-2 scores were significantly lower in the Control group (43.64 ± 6.04 vs. 52.58 ± 15.13; p <0.000), indicating fewer stent-related symptoms after stent removal (Table II).

Postoperative pain was assessed with the NRS at 1, 6, 12, 24, and 48 hours, as well as on day 7. At 1 hour, no significant difference was found between the groups (p = 0.272). At all later time points, the mean NRS scores were lower in the QLB group (Table III). At the 1-hour mark, no statistically significant difference in NRS scores was observed between the QLB and Control groups (p = 0.272). In contrast, the QLB group demonstrated significantly lower NRS scores at all subsequent time points—6, 12, 24, and 48 hours, as well as on postoperative day 7—when compared to the Control group (Table III). In addition, cumulative tramadol consumption over the first 48 hours postoperatively was significantly reduced in the QLB group (QLB group: 75.32 ± 101.51 mg vs. Control group: 229.87 ± 146.06 mg, p <0.001), confirming the opioid-sparing effect of the block.

No major adverse events associated with the block or surgery were observed during the study period.

DISCUSSION

This randomised controlled trial indicates that posterior QLB, when performed after URSL, may help reduce DJS-related LUTS and postoperative pain compared with standard care regimens.

Patients in the QLB group had lower USSQ scores during stent placement, a finding that aligns with earlier reports describing the burden of DJS-related urinary symptoms, such as dysuria and pollakiuria.¹ Beyond the physical discomfort, qualitative work has shown that these symptoms are often accompanied by psychological distress and heightened anxiety,¹¹ while prospective survey data further highlight their negative effect on overall quality of life and convalescence after ureteroscopy and stent placement.¹²

The mechanism behind this benefit is likely linked to the modulation of visceral nociceptive input from the ureter and bladder. The ureter receives sympathetic fibres from T11–L2 via the aorticorenal, superior hypogastric, and pelvic plexuses, while the bladder is innervated by sympathetic fibres (T11–L2) and parasympathetic fibres (S2–S4).¹³ Posterior QLB permits spread of local anaesthetic within the thoracolumbar fascia, with potential extension to paravertebral and subcostal spaces, thereby covering the T10–L2 dermatomes.¹⁴ This spread provides abdominal wall analgesia along with visceral modulation. In contrast to more superficial fascial plane blocks, posterior QLB appears to offer more consistent visceral coverage, which may explain the reduction in stent-related discomfort.^15,16

Neuroanatomical data also suggest that QLB can dampen sympathetic outflow, potentially reducing ureteric spasm and referred pain.¹⁷ Such an effect may ease irritation from the indwelling stent and improve urinary comfort. Comparable mechanisms have been proposed in studies of catheter-related bladder discomfort, where peripheral blocks were able to reduce afferent signalling.¹⁸ These observations support the role of posterior QLB as a non-pharmacological adjunct for stent-related morbidity.

Clinical evidence also points to a broader utility of QLB in urological surgery. A meta-analysis of 13 randomised trials with 751 patients reported lower pain scores and reduced opioid requirements in those receiving QLB.¹⁹ The present findings are consistent with these results, with reduced pain at multiple postoperative time points (6, 12, 24, 48 hours, and day 7) and less tramadol use. The prolonged analgesic effect is probably due to cranial spread of local anaesthetic along the thoracolumbar fascia, providing both somatic and visceral blockade. Prior comparative studies in abdominal and pelvic procedures have similarly demonstrated visceral analgesic properties of QLB.²⁰

Close collaboration between anaesthesiologists and urologists is therefore valuable in optimising management of patients with indwelling ureteral stents, addressing both surgical and symptom-related aspects of care.

However, certain results should be interpreted with caution. The minimal clinically important difference (MCID) for the USSQ domains has not been defined, and it remains uncertain whether the observed 22-point reduction in urinary symptoms at day 7 translates into a meaningful clinical improvement. Consistent reductions in pain intensity and opioid use suggest the benefits were real and relevant for patients. Also, it also cannot be excluded that the apparent improvement in urinary symptoms mainly reflected more effective overall pain control rather than a direct action on bladder afferents. In accordance with the present study protocol and institutional practice, DJS were routinely removed after one month to enable ureteral healing and consistent symptom assessment, although stent dwell times may differ across centres.

This study has additional limitations. Because patient blinding was not possible, reporting bias cannot be ruled out, although outcome assessors were blinded. The USSQ was only measured at two time points, preventing a more detailed analysis of symptom progression. The trial was conducted at a single centre with relatively uniform surgical and anaesthetic practice and included only ASA I–III patients undergoing elective unilateral procedures, thereby limiting external validity. Finally, the lack of an established MCID for the USSQ complicates the distinction between statistical significance and clinical relevance.

Nonetheless, the study has important strengths. To the best of the authors’ knowledge, it is the first randomised trial to evaluate the effect of posterior QLB on DJS-related LUTS using the validated USSQ. Blinded outcome assessment, adherence to standardised perioperative care, and the use of objective analgesic consumption data increase the robustness of the findings. Repeated postoperative assessments and follow-up after stent removal further add to the clinical value of the results.

Future studies should compare posterior QLB with other regional blocks, such as erector spinae plane or TAP blocks, and consider imaging or neurophysiological tools to clarify mechanisms. Longer follow-up may also help determine whether symptom relief persists beyond the early postoperative period.

CONCLUSION

This randomised controlled trial demonstrated that a single posterior QLB reduced postoperative pain and alleviated DJS-related LUTS in patients undergoing URSL. The use of QLB was linked to reduced analgesic needs, suggesting a potential role in multimodal perioperative management. This technique may help ease postoperative recovery by lowering opioid use and improving symptom control. Further studies with larger samples and extended follow-up are needed to confirm these findings.

ETHICAL APPROVAL: 
The study was approved by the Ethics Committee of Mugla Sitki Kocman University, Mugla, Turkiye (Approval No. 11/05/ 2022–9/VIII). This study was also prospectively registered on ClinicalTrials.gov (Identifier: NCT06290323).

PATIENTS’ CONSENT: 
Written informed consent was obtained from all the patients prior to their enrolment for the publication of anonymised data derived from their clinical information.

COMPETING INTEREST: 
The authors declared no conflict of interest.

AUTHORS’ CONTRIBUTION:
EY, IA: Conception and design of the study; data collection, analysis, and interpretation; drafting and critical revision of the manuscript.
GA: Data collection, data analysis, and interpretation of results.
HB: Data collection, patient management, contribution to data analysis and interpretation.
BU: Critical revision of the manuscript for important intellectual content and supervision of the study.
All authors approved the final version of the manuscript to be published.

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