Rigid mini-thoracoscopy versus semirigid pleuroscopy for undiagnosed exudative pleural effusion: a randomized controlled trial

Introduction

Pleural effusion is a common manifestation of cardiopulmonary, infectious, and neoplastic disease, and its evaluation typically begins with diagnostic thoracentesis pleural fluid analysis according to Light’s criteria (1), and cyto-pathological studies. Despite the addition of closed pleural biopsy, approximately one in five exudative effusions remains undiagnosed (2). In this group, medical thoracoscopy (also known as pleuroscopy) is the recommended next investigation, with reported diagnostic yields exceeding 90% and a favorable safety profile (3-5).

Two device platforms dominate contemporary practice. The rigid thoracoscope, the original instrument developed in the early twentieth century by Jacobaeus, offers a fixed 0° optic, a wide working channel, and large rigid forceps that yield abundant tissue and allow effective adhesiolysis (6). The semirigid pleuroscope, of which the Olympus LTF-160 is the most widely used model, combines a rigid proximal shaft with a flexible distal tip, providing improved access to apical, mediastinal, and diaphragmatic regions and a higher-quality endoscopic image, but accommodates only smaller flexible biopsy forceps through a narrower (2.8 mm) working channel (4,7). Comparative studies have repeatedly shown that rigid platforms yield larger biopsy specimens than semirigid platforms, but with generally equivalent diagnostic yield and inconsistent results regarding procedure duration, sedation, and patient comfort (7-10).

To mitigate the discomfort attributed to the conventional 10-mm rigid scope, manufacturers have introduced the rigid mini-thoracoscope, which retains a 0° rigid optic and a 3.5-mm working channel within an outer diameter of 5.5 mm. The only previous randomized comparison of a rigid mini-thoracoscope with a semirigid pleuroscope, the MINT trial of Bansal and colleagues, found similar diagnostic yield and procedure duration in the two arms but greater patient-reported pain in the rigid mini arm (11). Several aspects of that trial, including operator familiarity favoring the semirigid arm, two technical crossovers from rigid mini to semirigid in patients with extensive adhesions, and a lower-than-expected overall diagnostic yield, have led to calls for confirmatory data from centers in which both devices are used routinely (4,7).

Moreover, as comprehensive molecular and genetic profiling becomes standard in the diagnosis and treatment of thoracic malignancy, the volume and quality of pleural tissue recovered at thoracoscopy—not merely whether a diagnosis is reached—has emerged as a clinically important consideration that has received little attention in prior device comparisons.

We therefore conducted a randomized controlled trial at a tertiary academic referral center where rigid mini-thoracoscopy and semirigid pleuroscopy are both utilized in routine practice, and pulmonology fellows receive training under direct supervision on both platforms. The prespecified primary endpoint was total procedure duration; biopsy specimen size, diagnostic yield, pleurodesis success at 6 weeks, sedation and analgesic requirements, patient-reported pain, operator satisfaction, chest-tube duration, and procedure-related complications were prespecified secondary endpoints. We present this article in accordance with the CONSORT reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1521/rc).

Methods

Study design and ethical statement

This was a single-center, parallel-group, open-label randomized controlled trial conducted in the Pulmonary Intervention Unit of the Division of Pulmonary and Critical Care Medicine, King Chulalongkorn Memorial Hospital, Bangkok, Thailand. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Institutional Review Board, Faculty of Medicine, Chulalongkorn University (IRB No. 231/64, approval date August 24, 2021) before enrollment commenced. Informed consent was obtained from all individual participants. The trial was registered with the Thai Clinical Trials Registry (TCTR20260508007); although registration was completed after study initiation, the protocol, including all primary and secondary endpoints, was finalized prior to enrollment and remained unmodified thereafter. Financial support for this study was provided by the Ratchadapiseksompotch Fund from the Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.

Participants

Eligible adults (≥18 years) had an exudative pleural effusion that remained undiagnosed after diagnostic thoracentesis or closed pleural biopsy, or were strongly suspected of malignancy, and effusion depth at the mid-hemithorax on upright chest radiograph was required to exceed 2 cm. Exclusion criteria were pregnancy; uncorrectable bleeding diathesis (platelet count <50,000/mm³ or international normalized ratio >1.5); hemodynamic instability; acute decompensated heart failure or pulmonary edema; myocardial infarction within the preceding 6 weeks; refractory hypoxemia (oxygen saturation <90% on supplemental oxygen); ultrasonographic absence of an accessible pleural space due to dense adhesions; and patient refusal.

Randomization and masking

Block randomization with random block sizes was generated by computer in a 1:1 ratio. Allocations were sealed in sequentially numbered opaque envelopes kept in the procedure suite and opened by the assisting nurse only after the patient was on the procedure table. Because the two devices differ visibly, masking of operators and patients was not feasible. Pathologists who reported the pleural specimens and personnel who measured biopsy dimensions were unaware of group assignment.

Procedures

All procedures were performed under conscious sedation using a standardized single-port technique. After ultrasound-guided site selection, local infiltration with 1% lidocaine, and titrated sedation with intravenous fentanyl and midazolam, a transverse incision approximately 1.5–2 cm in length was made and a reusable trocar was inserted. Pleural fluid was aspirated to dryness, and the pleural space was systematically inspected, including the apex, anterior chest wall, posterior chest wall, and diaphragmatic surface. Targeted parietal pleural biopsies were obtained, and talc poudrage with 4–8 g of sterile graded talc (STERITALC^®, Novatech SA, La Ciotat, France) was performed when malignant pleural effusion was confirmed or strongly suspected. A chest tube was placed and connected to a two-bottle drainage system with low pressure suction (−10 to −20 cmH₂O). Procedures were performed by pulmonary and critical care fellows (postgraduate years 1–3) who had completed at least three previous medical thoracoscopies, including at least one with each device, under direct supervision by an interventional pulmonologist. Each operating fellow performed procedures with both devices during the study period; operators were not dedicated to a single platform. Apart from the thoracoscope itself and the corresponding biopsy forceps, the trocar set, sedation algorithm, and post-procedural care pathway were identical between groups.

Devices

The rigid mini-thoracoscope (Richard Wolf GmbH, Knittlingen, Germany) had an outer diameter of 5.5 mm, a working length of 215 mm, and a 3.5-mm working channel, and was used with rigid 3.5-mm double-spoon biopsy forceps (working length, 310 mm). The semirigid pleuroscope (Olympus LTF-160; Olympus Corporation, Tokyo, Japan) had an outer diameter of 7 mm, a working length of 270 mm, a 2.8-mm working channel, and angulation of 160° upward and 130° downward; the manufacturer’s flexible toothed biopsy forceps were used (Figure 1).

Figure 1 Instruments. (A) Semirigid pleuroscopy (Olympus, LTF-160 model). (B) Rigid mini-thoracoscopy (Richard Wolf). (C) Biopsy forceps (left: double-spoon forceps for rigid mini-thoracoscopy; right: biopsy forceps for semirigid pleuroscopy).

Outcomes

The primary outcome was total procedure duration, defined a priori as the time from skin incision to completion of the chest-tube fixation suture, recorded by the assisting nurse. Procedure duration was further partitioned into a diagnostic phase (skin incision to completion of pleural biopsy) and a therapeutic phase (initiation to completion of talc poudrage).

Prespecified secondary outcomes were: (I) pleural biopsy specimen size, measured immediately after the procedure on a calibrated grid in millimeters as the longest and shortest dimensions, with surface area calculated as the product of these dimensions; (II) diagnostic yield, defined as a definitive histopathological diagnosis or a histopathological pattern consistent with the patient’s clinical course and treatment response; (III) pleurodesis success at 6 weeks, classified as complete (no recurrent effusion and no dyspnea), partial (recurrent effusion <50% of baseline volume, no need for repeat drainage, and no dyspnea), or failure (12); (IV) total intraoperative dose of 1% lidocaine, fentanyl, and midazolam; (V) intraoperative pain, scored by the patient on a 0–10 visual analog scale (VAS) 2–4 hours after the procedure once procedural sedation had cleared; (VI) operator satisfaction (0–10); (VII) chest-tube duration; and (VIII) procedure-related complications during the index admission and at 1-, 6-, and 12-week follow-up visits. For procedures that yielded non-specific chronic pleuritis or otherwise non-diagnostic histology, the final diagnosis was adjudicated by an assessor blinded to device allocation who reviewed the treating physicians’ subsequent medical records over a follow-up period of up to 12 months; malignancy was assigned on the basis of repeat pleural fluid cytology or of follow-up demonstrating progression of the pleural effusion in conjunction with malignancy at other sites, and a benign diagnosis was assigned only when neither malignancy nor progression was observed over this period.

Sample size and statistical analysis

Sample size was based on the primary endpoint and the difference in procedure duration reported by Rozman and colleagues (7). Assuming a prespecified, operationally meaningful difference of 10 minutes [approximating the time required to perform an additional diagnostic thoracentesis in our suite, and consistent in magnitude with the ~9-minute difference reported by Rozman and colleagues (7)] and a pooled standard deviation of approximately 8 minutes, with α=0.05 and power =0.95, 18 patients per arm were required. Power was deliberately set at 0.95, rather than the conventional 0.80–0.90, because comparative data for the rigid mini-thoracoscope were limited and we sought to minimize the risk of a false-negative result for the primary endpoint in this single-center trial. Allowing for up to 20% loss to follow-up for the secondary endpoints, the planned enrollment was 22 patients per arm (44 total).

All analyses were performed according to the intention-to-treat principle, with patients analyzed by allocated device, unless otherwise specified. Diagnostic yield was assessed in the evaluable population, defined as procedures in which adequate pleural tissue was obtained for histopathological assessment; specimens deemed inadequate by the pathologist were excluded from the diagnostic-yield denominator but retained in all other analyses. Pleurodesis success was analyzed per protocol, restricted to patients in whom pleurodesis was attempted and a 6-week assessment was feasible. Continuous variables are reported as mean ± standard deviation when approximately normally distributed and as median [interquartile range (IQR)] otherwise; between-group comparisons used Welch’s t-test or the Mann-Whitney U test as appropriate. Categorical variables are presented as counts (percentages) and compared with Fisher’s exact test. Univariable exploratory analyses examined the influence of fellow seniority and effusion size on procedure duration. A two-sided P value <0.05 was considered statistically significant. Analyses were performed in SPSS version 22 (IBM Corp., Armonk, NY, USA).

Results

Participants and baseline characteristics

Between 1^st October 2021 and 30^th June 2022, total of 54 patients with undiagnosed pleural effusion or suspected malignant pleural effusion were screened for eligibility. Ten patients were excluded: eight declined to participate, and two were excluded due to transudative effusion; 44 patients were randomized: 22 to medical thoracoscopy with the rigid mini-thoracoscope and 22 to medical thoracoscopy with the semirigid pleuroscope (Figure 2). All 44 patients underwent the assigned procedure and were included in the intention-to-treat analysis. Three patients (two assigned to rigid mini and one assigned to semirigid) required intra-procedural device crossover for technical reasons; results were directionally identical when these crossovers were excluded in a per-protocol analysis.

Figure 2 Study flow diagram of the 44 randomized patients; all completed the assigned procedure and were included in the intention-to-treat analysis. Three patients (two rigid mini, one semirigid) required intra-procedural device crossover for technical reasons.

Baseline characteristics were balanced between groups (Table 1). Mean age was approximately 63–67 years and the gender distribution was approximately equal. The two arms were comparable with respect to symptom duration, baseline dyspnea VAS, distribution of radiographic effusion size, computed tomography findings, and pleural fluid biochemistry. Twenty-seven patients (14 in the rigid mini-thoracoscopy, and 13 in the semirigid pleuroscopy group) had a previous history of malignancy and 21 patients (10 and 11, respectively) had stage IV disease. Indications, laterality, intercostal access level, attending supervisor distribution, and the seniority of operating fellows were also balanced.

Primary outcome: procedure duration

The total procedure duration was significantly shorter in the rigid mini-thoracoscopy arm (median 27.5 minutes, IQR, 24.0–30.0 minutes) than in the semirigid pleuroscopy arm (median 38.0 minutes, IQR, 30.3–41.8 minutes), an absolute median difference of 10.5 minutes (P=0.001) (Table 2, Figure 3). The therapeutic (pleurodesis) phase contributed most of this difference (median 12.0 vs. 16.0 minutes; P=0.01); the diagnostic phase was numerically shorter with the rigid mini-thoracoscope (15.5 vs. 21.5 minutes; P=0.051). In a prespecified per-protocol analysis (after exclusion of the three crossovers), all three time intervals were significantly shorter in the rigid mini-thoracoscope arm, including the diagnostic phase, which had not reached significance in the intention-to-treat analysis.

Figure 3 Procedure duration by phase (diagnostic, therapeutic and total procedure) and group (rigid mini-thoracoscopy and semirigid pleuroscopy).

Pleural biopsy specimen size

The number of biopsies per procedure was similar between the rigid mini and semirigid arms (median 7 vs. 8; P=0.29), but specimens obtained with the rigid mini-thoracoscope were substantially larger in every dimension. The largest specimen dimension had a median of 6.0 mm (IQR, 4.9–9.3 mm) in the rigid mini arm vs. 4.0 mm (IQR, 3.4–6.0 mm) in the semirigid arm (P=0.005). The calculated specimen surface area was 50.5 (IQR, 35.9–99.7) vs. 27.3 (IQR, 18.0–37.9) mm², corresponding to specimens nearly twice as large with the rigid mini-thoracoscope (P=0.001).

Diagnostic yield

A definitive histopathological diagnosis was obtained in 17 of 21 rigid mini-thoracoscopy procedures (81.0%) and 20 of 23 semirigid pleuroscopy procedures (87.0%) (P=0.69) (Table 3). The seven procedures yielding only non-specific chronic pleuritis (four rigid mini, three semirigid) were resolved on extended clinical–pathological follow-up: six were ultimately attributed to malignant pleural effusion and one to a benign cause. Overall, thoracoscopy correctly identified malignancy in 33 of 39 patients with a final malignant diagnosis (84.6%) and in 5 of 5 patients with non-malignant disease (predominantly tuberculous pleurisy). The most common final diagnoses were metastatic pleural malignancy of pulmonary, breast, and miscellaneous primary origin.

Sedation, analgesia, and patient-reported pain

Intraoperative doses of 1% lidocaine (median 9 vs. 10 mL), fentanyl (50 vs. 75 µg), and midazolam (1 vs. 2 mg) did not differ significantly between groups, although fentanyl and midazolam each trended numerically lower in the rigid mini-thoracoscopy arm (Table 2). Patient-reported intraoperative pain on a 0–10 VAS, recorded 2–4 hours after the procedure, was equivalent in the two groups (median 3.0). Pain VAS could not be reliably ascertained in 13 of 44 patients (29.5%) because of transient anterograde amnesia.

Operator satisfaction

Operators rated their satisfaction higher with the rigid mini-thoracoscope (median 8, IQR, 7.5–9.0) than with the semirigid pleuroscope (median 7, IQR, 7.0–8.0; P=0.02), reflecting the easier handling of rigid forceps through a wider working channel and the steadier optical platform afforded by a 0° rigid telescope.

Chest-tube duration, length of stay, and complications

Chest-tube duration was 1 day longer in the rigid mini-thoracoscopy arm (median 4 vs. 3 days; P=0.04), but length of hospital stay did not differ significantly (median 6 vs. 4 days; P=0.17). Procedure-related complications occurred in 5 of 22 patients in each arm (P>0.99; Table 4). The most frequent procedure-related events were transient air leak or pneumothorax, subcutaneous emphysema, and post-pleurodesis fever; pleural infection complicated two semirigid procedures and surgical-site infection one rigid procedure. There were no procedure-related deaths.

Pleurodesis

Among the 36 patients in whom pleurodesis was attempted and a 6-week assessment was feasible, successful pleurodesis (complete or partial) was achieved in 14 of 17 patients in the rigid mini arm (82.4%) and 14 of 19 patients in the semirigid arm (73.7%) (P=0.70) (Table 3). Five pleurodesis failures occurred in the semirigid arm, and three in the rigid mini arm. Five patients (three rigid mini, two semirigid) could not be evaluated at 6 weeks because of intercurrent death from advanced malignancy.

Exploratory subgroup analyses

In univariable exploratory analyses of factors influencing procedure duration, total procedure time was inversely related to fellow seniority (median total time 35, 29, and 25 minutes for postgraduate-year 1, 2, and 3 fellows, respectively; P=0.01) and radiographic effusion size (median total time 27, 28.5, and 41 minutes for small, moderate, and large effusions; P=0.001). These observations are consistent with a learning effect and with the additional time required to evacuate larger effusions before pleural inspection and biopsy.

Discussion

In this single-center randomized controlled trial, medical thoracoscopy with a 5.5-mm rigid mini-thoracoscope yielded pleural specimens roughly twice as large by surface area as a 7-mm semirigid pleuroscope and was approximately 10 minutes shorter, while preserving diagnostic yield, safety, and patient comfort. Operators rated the rigid mini-thoracoscope as easier to use; chest-tube duration was modestly longer in the rigid arm but did not translate into a longer hospital stay. To our knowledge, this is the second randomized controlled trial to compare these specific contemporary device generations, and the first to demonstrate an operationally meaningful procedure-time advantage for the rigid mini-thoracoscope when both platforms are used by trainees of comparable experience.

Our procedure-time results align directionally with the pilot trial of Rozman and colleagues, in which conventional rigid thoracoscopy was 9 minutes faster than semirigid pleuroscopy (27 vs. 36 minutes) (7). They contrast with the trials of Dhooria et al. (8) and Bansal et al. (the MINT trial) (11), which reported equivalent procedure duration. Several factors may explain this divergence. First, our institutional workflow standardizes a fixed procedural sequence—single-port entry, complete fluid evacuation, systematic parietal sweep, targeted biopsy, and (when indicated) talc poudrage—which favors the wider working channel and greater torque control of a rigid platform during both biopsy acquisition and aerosolized talc delivery. Second, the 2.8-mm working channel of the Olympus semirigid pleuroscope constrains both the rate at which fluid can be aspirated through the scope and the size of the talc cannula, which probably accounts for the 4-minute therapeutic-phase difference we observed. Third, our trainee operators rotated through both devices in approximately equal numbers, minimizing the device-familiarity asymmetry that may have biased earlier studies toward the semirigid platform (4,11). Fourth, the optical and ergonomic characteristics of the two devices differ in ways that bear directly on procedural efficiency. The 0° rigid optic of the mini-thoracoscope offers a fixed field of view that, in our experience, simplifies orientation and instrument control during both parietal sweep and biopsy acquisition. The semirigid pleuroscope provides a more dynamic field that depends on continuous operator articulation of the distal tip, which can prolong both navigation and target acquisition; this disadvantage in operating-time efficiency is offset by the genuine advantage of being able to advance the flexible tip closer to apical, mediastinal, or diaphragmatic lesions that are otherwise difficult to reach with a 0° rigid optic.

Our biopsy size results extend, with greater magnitude, the consistent literature observation that rigid platforms yield larger pleural specimens (7-11). Beyond the near-doubling of surface area, the larger forceps cup of the rigid mini-thoracoscope also produces a thicker tissue bite, which translates into a greater absolute number of viable tumor cells per specimen—the substrate on which immunohistochemistry, in situ hybridization, and next-generation sequencing all depend. This matters increasingly in pleural malignancy, where comprehensive molecular characterization is now standard of care for non-small cell lung cancer and where the contemporary mesothelioma workup relies on a multi-marker immunopanel (BAP1, MTAP, with or without Merlin and p53) supplemented by panel next-generation sequencing (13,14); each additional assay consumes tissue, and small specimens are a recognized source of diagnostic uncertainty in distinguishing mesothelioma from reactive mesothelial proliferations. Despite a similar number of biopsies per procedure between groups (median 7 vs. 8; P=0.29), the total recovered tissue area was markedly larger with the rigid mini-thoracoscope, reflecting the greater specimen size per bite rather than a greater number of samples. Notably, four of the seven non-diagnostic procedures occurred in the rigid mini arm despite its larger specimens, suggesting that accuracy of targeting, rather than tissue volume, governed diagnostic failures in our serie.

In contrast to the MINT trial (11), we found no significant difference in patient-reported pain between groups, and a numerical trend toward lower fentanyl and midazolam requirements in the rigid mini arm. Two factors may be relevant. We used the same reusable trocar (and therefore the same skin incision size) for both devices, whereas the MINT trial used a smaller dedicated cannula in the semirigid arm; differences in chest-wall trauma, rather than the scope itself, may account for previously reported differences in patient comfort. Additionally, nearly 30% of our patients experienced transient anterograde amnesia, rendering the VAS assessment unreliable during the 2- to 4-hour post-procedural period. This limitation likely attenuated our ability to detect modest differences in pain levels between the two groups during the immediate recovery phase. Future trials should consider standardized assessment of intraoperative breakthrough pain by the operator, complemented by post-procedure recall whenever feasible (15).

Diagnostic yield (81–87%) and pleurodesis success rates (74–82%) in our trial match the upper range of values reported for medical thoracoscopy in undiagnosed exudative and malignant pleural effusion (3,16-18). Although pleurodesis success was numerically higher in the rigid mini arm (82.4% vs. 73.7%), the difference did not reach statistical significance, and failures occurred in both arms (3 of 17 rigid mini, 5 of 19 semirigid); this finding warrants confirmation in a larger trial powered for pleurodesis as a primary endpoint. The procedure-related complication profile was modest in both arms and consistent with prior reports (19,20).

In high-volume thoracoscopy programs operating under resource constraints—particularly in Asia and Latin America, where pleural disease burden is high and dedicated procedure suites are scarce, reduction in procedure time translates directly into additional throughput. Combined with the larger tissue volume available for molecular characterization, our findings suggest a potential role for use of the rigid mini-thoracoscope when its features are well matched to the case (extensive parietal disease, suspected mesothelioma, or expected adhesiolysis), while preserving the semirigid pleuroscope for situations in which its tip flexibility is advantageous (apical, mediastinal, or diaphragmatic targets that are otherwise inaccessible with a 0° rigid optic).

Strengths of this study include its randomized design, balanced trainee operator distribution between arms, and prospective collection of procedural and follow-up outcomes. Limitations include modest sample size, single-center design, and the predominance of malignant pleural effusion (most participants had stage IV disease, limiting follow-up duration and 6-week pleurodesis ascertainment). The inability to mask operators and patients is intrinsic to comparisons of visibly distinct devices. The high rate of unrecordable pain VAS due to transient anterograde amnesia may have attenuated our ability to detect modest between-group differences in pain. We did not measure baseline pleural pressure, which influences pleurodesis success in trapped-lung physiology (21). Our biopsy specimen size measurement also has methodological constraints worth acknowledging. Specimens were measured on a calibrated grid as longest and shortest in-plane dimensions and surface area was calculated as their product, which approximates the specimen as a rectangle and ignores tissue thickness; this 2-D proxy is the standard adopted by previous comparative trials (7,11) but may both overestimate true specimen surface and underestimate total recovered tissue volume, particularly when forceps caliber differs between devices. The 2.8-mm working channel of the semirigid pleuroscope necessarily constrains forceps cup size relative to the rigid mini-thoracoscope, so part of the observed between-group difference reflects the physical limit of the instrument rather than operator technique; volumetric or weighed-tissue assessment, and direct measurement of viable tumor content suitable for molecular testing, would strengthen future trials. Finally, our results may not generalize to operators with markedly asymmetric experience between the two platforms; multicenter confirmation is warranted. Operators were also at a relatively early point on the learning curve (≥3 prior thoracoscopies, ≥1 with each device); the procedure-time advantage observed here may narrow with greater operator experience, particularly with the articulating tip of the semirigid pleuroscope.

A multicenter randomized trial powered for diagnostic yield, pleurodesis success, and patient-reported outcomes, ideally with intraoperative breakthrough-pain assessment, comparative measurement of recovered tissue suitable for next-generation sequencing, and a formal cost-effectiveness analysis incorporating institutional throughput gains, would substantially strengthen the evidence base. Given the global increase in malignant pleural effusion and the central role of pleural tissue in molecular characterization of underlying malignancy, such a trial should be a priority for the interventional pulmonology community. Future trials should also consider adopting the adequacy of recovered tissue for molecular and next-generation-sequencing–based characterization as a primary endpoint, since this—rather than procedure time—is likely to be the outcome of greatest clinical consequence as molecular profiling becomes standard in thoracic oncology.

Conclusions

Among trainee operators at a comparable, early point on the learning curve, medical thoracoscopy with a 5.5-mm rigid mini-thoracoscope yielded pleural specimens roughly twice as large by surface area as a 7-mm semirigid pleuroscope, while also shortening total procedure time by approximately 10 minutes, without evidence of a significant difference in diagnostic yield, pleurodesis success at 6 weeks, sedation requirements, or safety. The principal implication is not the time saving itself—an operational benefit offset in part by a modestly longer chest-tube duration in the rigid mini arm—but the substantially greater tissue yield, which may prove advantageous as molecular and genetic characterization of pleural malignancy becomes routine. These findings warrant confirmation in larger multicenter trials, designed with tissue adequacy for molecular testing as a primary endpoint.

Acknowledgments

The authors express their gratitude to the nursing staff and pulmonary fellows of the Pulmonary Intervention Unit, Division of Pulmonary and Critical Care Medicine, King Chulalongkorn Memorial Hospital, for their invaluable assistance with data collection.

Footnote

Reporting Checklist: The authors have completed the CONSORT reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1521/rc

Trial Protocol: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1521/tp

Data Sharing Statement: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1521/dss

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1521/prf

Funding: This work was supported by the Ratchadapiseksompotch Fund, Faculty of Medicine, Chulalongkorn University. The funder had no role in the study design, data collection, patient enrollment, clinical procedures, data analysis, or the decision to submit the manuscript for publication.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1521/coif). All authors report that this work was supported by the Ratchadapiseksompotch Fund, Faculty of Medicine, Chulalongkorn University. The funder had no role in the study design, data collection, patient enrollment, clinical procedures, data analysis, or the decision to submit the manuscript for publication. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Institutional Review Board, Faculty of Medicine, Chulalongkorn University (IRB No. 231/64, approval date 24/8/21) before enrollment commenced. Informed consent was obtained from all individual participants.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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