(Chest. 2005;127:2015-2018.)
© 2005
American College of Chest Physicians
Transbronchial Needle Aspirates*
Comparison of Two Preparation Methods
Andreas H. Diacon, MD;
Macé M. Schuurmans, MD;
Johan Theron, MD;
Karen Brundyn, MD;
Mercia Louw, MD;
Colleen A. Wright, MD and
Chris T. Bolliger, MD, PhD
* From the Departments of Internal Medicine (Drs. Diacon, Theron, Schuurmans, and Bolliger) and Anatomical Pathology (Drs. Brundyn, Louw, and Wright), Tygerberg Academic Hospital, University of Stellenbosch, Cape Town, South Africa.
Correspondence to: Andreas H. Diacon, MD, Department of Internal Medicine, PO Box 19063, 7505 Tygerberg, South Africa; e-mail: ahd{at}sun.ac.za
 |
Abstract
|
|---|
Study objectives: Transbronchial needle aspiration has evolved as a key bronchoscopic sampling method. Specimen handling and preparation are underrated yet crucial aspects of the technique. This study was designed to identify which of two widely practiced sample preparation methods has a higher yield.
Design: Prospective comparison of two diagnostic methods.
Setting: Tertiary academic hospital.
Patients: Consecutive patients undergoing transbronchial needle aspiration.
Interventions: Transbronchial aspirates were obtained pairwise. One specimen was placed directly onto a slide and smears were prepared on site (ie, the direct technique), and the other specimen was deposited into a vial containing 95% alcohol and further prepared in the laboratory (ie, the fluid technique). In total, 282 pairs of samples were aspirated from 145 target sites (paratracheal, 10 sites; tracheobronchial, 101 sites; hilar, 17 sites; endobronchial or peripheral, 17 sites).
Measurements and results: The measured outcome was the presence of diagnostic material at the final laboratory assessment. At least one diagnostic aspirate was obtained in 66% of 86 investigated patients (small cell lung cancer, 18 patients; non-small cell lung cancer, 47 patients; other diagnoses, 21 patients). The direct technique had a better yield overall than the fluid technique (positive aspirates, 36.2% vs 12.4%, respectively; p < 0.01), as well as after stratification for tumor type and for anatomic site.
Conclusion: The direct technique is superior to the fluid technique for the preparation of transbronchial needle aspirates.
Key Words: bronchoscopy • cytodiagnosis • fine-needle biopsy • lung neoplasms
|
Introduction
|
|---|
Transbronchial needle aspiration (TBNA) via flexible bronchoscopy is an established sampling method for a variety of lung lesions.1 The most important indication for TBNA is mediastinal staging of lung cancer. The lymph node stations that are crucial for treatment and prognosis, as defined by the TNM system,2 are easily accessible with TBNA, which is cost-effective and reduces the need for exploratory surgery.3 However, the method is still underutilized.4 A possible reason for this is the failure to reproduce published success rates of TBNA.5 Investigations16 aiming to increase TBNA use and to improve overall success rates have shown that education and experience with the TBNA technique improve the yield. Much less is known about how the samples should be prepared after successful aspiration. In the original article by Wang et al,7 the specimens were flushed into a container and transported as a fluid suspension to the laboratory, where they were processed further (ie, the fluid technique).7 Alternatively, the specimen can be directly placed onto a slide, and immediately smeared and spray-fixed (ie, the direct technique).89 Based on our own experience, we hypothesized that the direct technique would be superior to the fluid technique. This study was designed to clarify whether and to what degree specimen preparation affects the diagnostic yield of TBNA in routine practice.
|
Materials and Methods
|
|---|
Transbronchial Sampling
Four experienced operators performed standard flexible bronchoscopy (models BF30 BF1T160; Olympus; Tokyo, Japan; Exera; Hamburg, Germany) and TBNA under topical anesthesia (1% lidocaine) and conscious sedation (midazolam IV). TBNA target sites were defined as (1) paratracheal (lymph nodes or lung lesions extending to the trachea), (2) tracheobronchial (American Thoracic Society [ATS] lymph node stations 1 to 410), (3) hilar (ATS lymph node stations 7 and 11), (4) bronchial (ie, parabronchial, submucosal, and endobronchial), and (5) peripheral (ie, not visible from endobronchial). We used 21-gauge or 22-gauge cytology needles (Bard; Billerica, MA) and aspirated for 10 s in the standard fashion.1 Only one needle type was used in a single patient. A paired sample consisted of two aspirate samples that were obtained in immediate succession and with identical technique, with the needle insertion points ideally 1 mm apart. This assured close proximity of the needle tips during aspiration. Preparation techniques were alternated after each pass. The direct technique was used for the first aspirate within a pair when cytologic support was available on-site. Otherwise, the fluid technique was used first. The sampling of pairs was completed without awaiting on-site results. At least four aspirates (two pairs) at each site were obtained.
Sample Preparation and Analysis
For the direct technique, the aspirate was immediately placed onto a glass slide, covered with a second slide, and, while exerting gentle continuous pressure, the slides were drawn apart. One of the smears was spray-fixed using commercial cytology fixative (Sangene; Cape Town, South Africa), and the other one was air-dried. For the fluid technique, the aspirate was deposited into 2 mL 95% alcohol and was processed further in the cytology laboratory in routine fashion. The fluid was centrifuged at 1,500 revolutions per minute for 10 min, and the resulting sediment was placed onto two slides, one spray-fixed and the other one air-dried. All slides were stained using standard Giemsa and rapid or standard Papanicolau methods.11 Histochemical or immunohistochemical examination was performed when necessary on the destained Papanicolau slides.11 For the study, the test results for an aspirate were considered to be positive when it contained diagnostic material (ie, adequate numbers of malignant cells or distinct features of granulomatous disease with or without necrosis). This was determined by two independent cytopathologists, who were unaware of the preparation method used and of any provisional diagnoses issued before the final assessment.
Statistical Aspects and Study Progress
The sample size was calculated for the detection of a 10% difference between the preparation methods assuming a 50% yield for the better method and an average of four sampled pairs per patient. A two-tailed test of proportions would show significance with 48 patients (power, 0.8; significance level, 95%). The first analysis showed a surprisingly low yield for the fluid method. This was thought to probably be due to insufficient material being expelled into the vials. Subsequently, the fluid method was modified by using a 50-mL syringe instead of a 20-mL syringe for aspiration and by expelling the sample with 1 mL of normal saline solution instead of air. This procedure might lead to better clearance of aspirated material out of the needle and cannot be performed with the smear method, because the fluid would wash the material off the slide. Consequently, separate needles for each technique were used, which also eliminated the problem of possible needle contamination with material retained from the previous pass. The target sample size was doubled in order to allow for the modifications to show an effect. Counts were compared with contingency tables and 
2 tests (p < 0.05 [a significant difference]) using a statistical software package (StatView, version 4.0 for Macintosh; SAS Institute; Cary, NC). All patients gave written informed consent. The institutional ethics review board approved the study.
|
Results
|
|---|
Patients and Diagnosis
We prospectively included 90 consecutive patients (56 men) with a mean (± SD) age of 57 ± 15 years (age range, 16 to 88 years). Of these patients, four had to be excluded post hoc because faded slide labels did not allow the identification of the preparation method that had been used. In the remaining 86 patients, 282 pairs were aspirated from 145 target sites (paratracheal, 10 sites; tracheobronchial, 101 sites; hilar, 17 sites; bronchial or peripheral, 17 sites). Two thirds of patients had at least one positive finding from TBNA. A definitive cytologic diagnosis with TBNA was possible in more neoplastic than nonneoplastic lesions (Table 1
). Among the neoplastic lesions, small cell lung cancer was more often identified than non-small cell lung cancer. Among the nonneoplastic lesions, only one case of sarcoidosis and one case of tuberculosis could be identified with TBNA. The direct method (49 patients; 57%) was used first more often than the fluid method (37 patients; 43%).
Yield of TBNA and Preparation Methods
The results of at least one TBNA was positive in 112 of 282 pairs of samples (39.7%) collected (Table 2
). Only one of the techniques provided a positive aspirate in 30.8% of pairs (direct technique exclusively positive, 27.3%; fluid technique exclusively positive, 3.5%). Overall, the direct technique was significantly superior to the fluid technique (positive aspirates, 36.2% vs 12.4%, respectively; p < 0.01) [Table 2]. Although differences varied, stratification for tumor type and for anatomic target site did not identify a single constellation in which the fluid technique was superior. The modification of the fluid technique after 45 patients did not change the difference between the techniques (before modification, 34.8% vs 13%, respectively [p = 0.01]; after modification, 38% vs 11.6%, respectively [p = 0.03]).
|
Discussion
|
|---|
This prospective comparative study showed that directly prepared and smeared TBNA specimens provide better results than those expelled into alcohol for use in the laboratory. This finding might contribute to further improve TBNA results and to promote TBNA as a key technique in bronchoscopic sampling.
Being situated in the "gray zone" of competence between bronchoscopist and cytopathologist, the issues of preservation, transport, and preparation of samples have received very little attention in the past. The direct smear method was described as an alternative to the original fluid method soon after the introduction of TBNA into clinical practice.789 To our knowledge, however, no sufficiently powered comparative study has compared the methods against each other, and several review articles135 have not recommended a specific method for TBNA specimen preparation. The present study highlights the importance of the preparation method and its significant impact on the diagnostic yield of TBNA. We can only speculate as to the reason for the superiority of the direct method. Our study used the patients as their own control subjects, which virtually eliminated all variables other than the preparation method. Therefore, the most likely explanation lies with the loss of cellular material with the fluid method, which includes initial dilution, centrifugation, aspiration, and transfer of material onto the final slides. It seems logical to assume that both the quality and quantity of a sample may deteriorate with this multistep approach, even when performed by trained personnel. In contrast, the direct method allows the immediate transfer of cellular material onto slides and results in adequate, well-fixed slides for cytologic evaluation. A further advantage of directly smeared slides is their availability for rapid on-site examination.12
No unequivocal data exist on the absolute yield of the fluid method. However, its performance in this study might seem lower than expected in the eyes of those who routinely use it. One must remember that in standard clinical practice several successive aspirates are usually flushed into one single vial. This results in an additive yield of these specimens, while in the present study single samples were analyzed. Some shortcomings of the present study must also be mentioned. First, we employed no objective quantitative and qualitative measures for determining the slide contents. This means that we cannot prove our subjective impression that the number of cells available for analysis is reduced with the fluid method, while the quality of the cells is well-preserved. Second, we did not exploit all available variations of aspiration needle sizes and methods for the preparation of the fluid specimen. For example, a histologic sample obtained with a larger caliber needle prepared with the cellblock technique might provide even better results.13 Third, it might be criticized that we did not randomize the sequence of preparation techniques used in a paired sample. It is plausible that the second sample could have greater chances of containing diagnostic material, since some might have been retained in the needle after the first pass. However, this would not have changed the study outcome since second samples were more often prepared with the fluid method than with the smear method. Moreover, the use of separate needles for each technique eliminated this possible bias in the second half of the study.
TBNA via flexible bronchoscopy is a technically advanced, minimally invasive, cost-effective, and elegant sampling procedure. To achieve a regular high yield with TBNA, however, careful attention to technical detail is essential. Smear preparation of a TBNA sample can be easily learned and will increase the diagnostic yield of TBNA at very low cost.
|
Footnotes
|
|---|
Abbreviations: ATS = American Thoracic Society; TBNA = transbronchial needle aspiration
Dr. Diacon was supported by a research fellowship grant of the University of Stellenbosch, South Africa.
Received for publication September 2, 2004.
Accepted for publication October 27, 2004.
|
References
|
|---|
- Minai, OA, Dasgupta, A, Mehta, AC (2000) Transbronchial needle aspiration of central and peripheral lesions. Bolliger, CT Mathur, PN eds. Interventional bronchoscopy ,66-79 Karger. Basel, Switzerland:
- Clifton, F, Mountain, MD Revisions in the international system for staging lung cancer. Chest 1997;111,1711-1717
- Mazzone, P, Jain, P, Arroliga, AC, et al Bronchoscopy and needle biopsy techniques for diagnosis and staging of lung cancer. Clin Chest Med 2002;23,137-158[CrossRef][ISI][Medline]
- Dasgupta, A, Jain, P, Minai, OA, et al Utility of transbronchial needle aspiration in the diagnosis of endobronchial lesions. Chest 1999;115,1237-1241[Abstract/Free Full Text]
- Dasgupta, A, Mehta, AC Transbronchial needle aspiration: an underused diagnostic technique. Clin Chest Med 1999;20,39-51[CrossRef][ISI][Medline]
- Hsu, LH, Liu, CC, Ko, JS Education and experience improve the performance of transbronchial needle aspiration: a learning curve at a cancer center. Chest 2004;125,532-540[Abstract/Free Full Text]
- Wang, KP, Brower, R, Haponik, EF, et al Flexible transbronchial needle aspiration for staging of bronchogenic carcinoma. Chest 1983;84,571-576[Abstract/Free Full Text]
- Wang, KP, Selcuk, ZT, Erozan, Y Transbronchial needle aspiration for cytology specimens. Monaldi Arch Chest Dis 1994;49,265-267[Medline]
- Rosenthal, DL, Wallace, JM Fine needle aspiration of pulmonary lesions via fiberoptic bronchoscope. Acta Cytol 1982;28,203-210
- Wang, KP Staging of bronchogenic carcinoma by bronchoscopy. Wang, KP Metha, AC eds. Flexible bronchoscopy 1995,6-17 Blackwell Science. Cambridge, UK:
- Keebler, KM Cytopathology techniques. Bibbo, M eds. Comprehensive cytopathology 2nd ed. 1997,881-906 WB Saunders. Philadelphia PA:
- Diacon, AH, Schuurmans, MM, Theron, J, et al Utility of rapid on-site evaluation of transbronchial needle aspirates. Respiration 2005;72,182-188[CrossRef][ISI][Medline]
- Mehta, AC, Kavuru, MS, Meeker, DP, et al Transbronchial needle aspiration for histology specimens. Chest 1989;96,1228-1232[Abstract/Free Full Text]
TOP
Abstract
Introduction
