Sputum cytology
Sputum cytology is a diagnostic procedure used to detect abnormal cells in sputum, which is mucus that is coughed up from the respiratory tract. This technique is primarily employed in the screening for lung cancer, particularly when tumors are located centrally and may have infiltrated the airways. The procedure is generally risk-free and cost-effective, making it accessible for patients. Sputum samples can be collected through simple coughing or via bronchoscopy, the latter of which may require fasting and anesthesia.
The process typically involves collecting multiple samples over several days for accurate analysis. Recent advancements in sputum cytology, such as liquid-based cytology preparation and automated analysis, have improved diagnostic accuracy. Despite its utility, the U.S. National Cancer Institute notes that routine lung cancer screening using sputum cytology or chest X-rays has not been shown to reduce mortality and can lead to false positives and unnecessary procedures. Therefore, these tests are recommended primarily for patients exhibiting symptoms rather than healthy individuals.
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Sputum cytology
DEFINITION: Sputum cytology is a screening for the presence of abnormal cells in sputum (saliva).
Cancers diagnosed:Lung cancer
Why performed: If a tumor is centrally located and has invaded the airways, this procedure may allow visualization of tumor cells for diagnosis. It is risk-free and inexpensive.
Patient preparation: A sputum sample may be collected from coughed-up mucus (sometimes induced by an inhaled saline mist) or by bronchoscopy, which uses a bronchoscope to examine the throat and airways.
No special preparation is required if the sputum sample is to be collected by coughing with or without a saline mist at home or in the doctor’s office. If a sputum sample is to be obtained by bronchoscopy, then the patient may not eat or drink for eight to ten hours before the procedure. The patient may be given medications to dry the secretions in the mouth and airways. A chest X-ray may also be done before bronchoscopy.
Steps of the procedure: For simple coughing procedures, three sputum samples are usually collected over three days in a container with a fixative to preserve the sample.
Bronchoscopy is performed with a flexible or a rigid bronchoscope. Rigid requires general anesthesia. In either case, the patient must sign a consent form.
After the procedure: There are no requirements following sputum collection by coughing. A second chest X-ray is taken after bronchoscopy, and the patient should be driven home. Patients should call immediately if they cough up more than two tablespoons of blood, have difficulty breathing, or have a fever for more than twenty-four hours.
Advances in sputum cytology have increased diagnostic accuracy in the twenty-first century. Novel sample collection techniques have enhanced the sensitivity of sputum cytology. Using a liquid-based cytology preparation has allowed for greater cell preservation and, therefore, more accurate diagnosis of abnormal cells. Flow cytometry and the automated analysis of samples are also technological advances that have been made in sputum cytology. Immunohistochemistry is also used alongside sputum cytology. Due to the COVID-19 pandemic, enhanced safety procedures were implemented when sputum cytology was employed to shield healthcare workers from possible infections while preserving the quality of the sample.
Risks: There is no risk in collecting sputum samples by coughing procedures. Bronchoscopy is usually a safe procedure, and complications are rare. Complications that may occur include spasms of the bronchial tubes, irregular heart rhythms, infections, hoarseness, and bubbles under the skin.
Results: The most common screening tests for lung cancer are chest X-ray and sputum cytology. According to the United States National Cancer Institute, the results of many studies have shown no evidence that screening for lung cancer using sputum cytology or chest X-ray reduces lung cancer mortality. The institute also concludes that screening could lead to false positive tests and unnecessary, invasive diagnostic procedures and treatments. Hence, these tests are not used for routine screening of healthy individuals, but only when symptoms indicate their use.
Bibliography
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“Lung Cancer Screening (PDQ®).” National Cancer Institute, 28 Mar. 2024, www.cancer.gov/types/lung/hp/lung-screening-pdq. Accessed 29 June 2024.
Panakkal, Neeraja, et al. "Effective Lung Cancer Control: An Unaccomplished Challenge in Cancer Research." CytoJournal, vol. 20, 2023, doi.org/10.25259/Cytojournal‗36‗2022. Accessed 29 June 2024.
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