Interpretation of bronchoalveolar lavage fluid cytology - ILD care

Interpretation of BALF cytology
Introduction: Importance of standardization of handling BAL
fluid samples
Prof. Robert P. Baughman, MD
University of Cincinnati Medical Center
Holmes, Room 1001
Eden Avenue and Albert Sabin Way
Cincinnati, Ohio 45267-0565
e-mail: baughmrp@ucmail.uc.edu
The concept of bronchoalveolar lavage (BAL) is not new. Bronchial lavage was a technique performed during rigid
bronchoscopy, especially for obtaining samples in patients with tuberculosis. To sample the alveolar space,
FINLEY described the use of the Matras catheter (used to perform bronchograms without a bronchoscope) to instill
and immediately aspirate fluid [1]. However, the use of a flexible bronchoscope to obtain BAL fluid (BALF) samples
was popularized by Dr. HERBERT REYNOLDS [2]. The technique has been widely used for both research and
diagnostic indications.
Technical aspects
The technical aspects of the lavage procedure can not be ignored. Some of the controversy about interpreting
lavage results can be traced to different centers having different results because of variations in the technique. As
in any test, the details are important. This work deals with the cellular aspects of BAL.. In order to interpret the
cellular information, one should be sure that the information has been obtained in a reliable manner. I will review
some of the difficulties which have been described with various aspects of lavage.
One of the difficulties inherent with BAL is the variability of the sampling [3]. The lavage process provides a
washing of the alveolar space. In the process of washing the space, the amount of cells and fluid returned will vary.
This variability may be on the basis of the underlying disease. Other factors also affect the variability: the amount of
fluid instilled [4,5], the amount of pressure used to aspirate the fluid, the method of collecting the aspirated fluid [6],
and the handling of the aspirated fluid. In addition, different parts of the lung may have different BALF findings [7,8].
For Pneumocystic carinii, lavage in the upper lobe may contain far more organism than lavage from the middle or
lower lobe [9]. Some of the differences are due to operator differences, some are due to the conditions when the
procedure is done.
To deal with the variability of lavage, several groups have proposed using markers [10]. These include external
markers, such as methylene blue [11], or internal markers, such as urea [12]. Unfortunately, none of these markers
is perfect. This is because the alveolar space is not a water tight vessel. During the process of lavage, fluid and
proteins are crossing from the lung fluid into the cells and blood stream. Also, internal proteins efflux into the lung
fluid [3]. Because of this variability of lavage, a recent recommendations of an European Respiratory Society Task
Force was to report acellular content of BALF per ml of aspirated fluid [13].
Standardization of other aspects of BAL have been attempted. In the United States, KING et al. demonstrated that
BAL interpretation could be improved by using a standard approach across several centers [14]. However, those
recommendations have not been widely followed. The European Respiratory Society (ERS) had made a series of
recommendations on performing BAL [15,16]. In a recent report, the ERS has also included recommendations
regarding the reporting of BALF analysis results. These recommendations are summarized in Table 1 [13].
Introduction. R.P. Baughman. 2001. 1