We read the article “Factors Influencing the Diagnostic Yield of Endobronchial Ultrasound-guided Transbronchial Needle Aspiration” by Kennedy et al1 with considerable interest and respect. The authors eloquently state, “It is imperative that all novel diagnostic and therapeutic modalities undergo widespread and systematic evaluation such that informed decisions regarding the adoption of new technology can be made. The influence of user expertise, patient selection, and ancillary support in the larger tertiary referral centers that often conduct the initial clinical trials of a new technology is difficult to quantify, but must be taken into consideration.”
The author's data, data from other experts from multiple centers, and the results from a meta-analysis all unequivocally confirm the utility of endobronchial ultrasound (EBUS) transbronchial needle aspiration (TBNA) with high sensitivity, specificity, and accuracy.2 The authors went on to ask, “Does our data support the role of EBUS-TBNA as a first-line modality for tissue confirmation of mediastinum involvement in primary lung cancer mediastinum staging?” Is comparing the good results obtained from the use of EBUS-TBNA by a few experts with the average data obtained for standard TBNA the basis for reaching such a recommendation? This is a an article that all TBNA specialists must read. Figure 1 is excellent, and illustrates that EBUS-TBNA allows access to more mediastinal and hilar lymph nodes in comparison with mediastinoscopy and endoscopic ultrasound with fine needle aspiration. In their analysis of the factors that might affect the diagnostic yield, they show that a lower yield is obtained in smaller lymph nodes and paratracheal lymph nodes. Other factors include airway distortions and calcifications. These limitations are exactly the same as those of standard TBNA. Everything accomplished by EBUS-TBNA has been accomplished by standard TBNA. EBUS-TBNA is a highly effective and less-invasive method than surgical staging procedures. However, in comparison with standard TBNA, is it more effective? If so, why and when should it be used? Guidelines for recommendations not only are dependent on how well the procedure performs but should also take many other factors into consideration, such as the invasiveness of the procedure, the availability of equipment and expert personnel, the risk, and cost. Most importantly, what is the comparative alternative procedure?
The difference between standard TBNA and EBUS-TBNA is as follows. EBUS-TBNA identifies the lesion to be biopsied by ultrasound and the lesion is punctured and biopsied also under direct ultrasound visualization. On the contrary, in standard TBNA the lesion is identified by a computed tomographic scan and puncture of the lesion and biopsy are carried out according to a lymph node map without confirming the presence of the needle in the lesion.
Over the years many attempts have been made to increase the yield of standard TBNA, of which EBUS-TBNA and rapid on-site cytologic evaluation (ROSE) are the most prominent. Both provide an endpoint for the procedure. ROSE confirms whether the lesion or lymph node has been reached by the pathologic examination, forcing more attempts to increase the diagnostic yield. It does not help to determine the location of the puncture nor does it help in determining the manner of puncturing. In contrast, the endpoint with EBUS-TBNA is confirmation that the needle is in the lesion by ultrasound visualization. It guides in determining the location of the puncture, although it does not help in determining the manner by which the needle is to puncture through the bronchial wall into the lesion. The principle and technique of TBNA, puncturing the needle into the lesion through the bronchial wall, are exactly the same with or without ultrasound. This technique is the most difficult and important in the success of TBNA. While training in standard TBNA, the most common mistake committed by beginners is not ensuring that the needle has punctured through the bronchial wall completely and the operator is not aware of it because of the distance of the catheter from the tip of the bronchoscope. The second mistake is using the needle to puncture into the bronchial wall without adequate angulations, resulting in the needle not having adequate depth to reach the lesion. The third mistake is missing the lesion even with adequate angulation and depth. All these shortfalls can be avoided by ultrasound guidance in EBUS-TBNA. If one possesses the skill of conducting TBNA and is able to select the correct puncture site under guidance of bronchoscopy, direct visualization by ultrasound may or may not play an important role.
The value of EBUS-TBNA goes beyond its diagnostic yield. It has validated the utility of TBNA and confirmed the accuracy of the lymph node puncture map that we have been using for standard TBNA. Its value in education is easily appreciated. Given the equal effort and intensity of training in TBNA with or without ultrasound guidance, the procedure that will be quicker to learn and easier to carry out for beginners performing TBNA remains to be defined. EBUS-TBNA seems to be more attractive and dependable. Initiating a TBNA program with EBUS, ROSE, and general anesthesia in the operating room is a good start. It will likely accelerate the learning curve for recognition of anatomy and for skill of performing TBNA.
We should set a new endpoint for TBNA, which is to be able to perform TBNA in the absence of EBUS, ROSE, and general anesthesia in the operating room. With proper training by a TBNA expert, this is an accomplishable goal. Continuous dependency and use of EBUS may be a passion and personal preference because of a lack of confidence and interest in conducting standard TBNA. Using general anesthesia can compensate for the inadequate skill of the bronchoscopist by improving the patient's comfort and allowing more time for the procedure. ROSE in addition to EBUS is the icing on the cake. A recommendation to use it in all abnormal lymph nodes regardless of size is counterproductive.
In every report of EBUS-TBNA, the standard bronchoscope is used before the EBUS scope. Why not perform a few punctures with standard TBNA followed by EBUS-TBNA if ROSE is not available? If ROSE is available when standard TBNA is positive, EBUS-TBNA is not necessary. If it is negative, one can then upgrade to EBUS-TBNA. This will be the most credible comparative study and help determine whether EBUS should ultimately be the standard or be reserved as a rescue modality for a nondiagnostic standard TBNA. The same stations of lymph nodes are sampled by both techniques with the same number of punctures by the same gauge of needle and by the same operator on the same patients. Experts in standard TBNA are encouraged to explore EBUS-TBNA for its style and challenge. The operator performing an EBUS-TBNA has to be proficient in 4 separate skills: interpreting ultrasound images, being able to use a convex probe bronchoscope, knowing how to use all the knobs and buttons on the ultrasound equipment, and using the complex EBUS needle. One should improve one's proficiency in performing EBUS-TBNA, not only for the necessity but also for the fact that it will fine-tune the knowledge and skill of conducting standard TBNA. Skill with both techniques can better evaluate the added benefit of EBUS-TBNA.
In the future, we will likely be required to justify the cost of TBNA and provide the best value to the patient and healthcare system for our diagnostic procedures. The vision for the future should include applying technological advances to revolutionize our instruments and techniques with ultrasound capability, by focusing on accuracy and safety and developing a simpler instrument and easier methodology for TBNA to minimize patient discomfort and cost so that it can be widely applied for the diagnosing and staging of lung cancer.3
1. Kennedy MP, Jimenez CA, Morice RC, et al. Factors influencing the diagnostic yield of endobronchial ultrasound-guided transbronchial needle aspiration J Bronchol Intervent Pulmonol.. 2010;17:202–208
2. Gu, P, Zhao YZ, Jiang LY, et al. Endobronchial-ultrasound guided transbronchial needle aspiration for the staging of lung cancer: a systematic review and meta-analysis. Eur J Cancer.
3. Wang KP, Browning R. Transbronchial needle aspiration with or without endobronchial ultrasound. Thoracic Cancer.