A15.0

Tuberculosis of lung, confirmed by sputum microscopy with or without culture

A15.0 is a specific clinical classification for pulmonary tuberculosis where the diagnosis is definitively established through the detection of acid-fast bacilli (AFB) in a sputum specimen via microscopic examination (smear-positive), regardless of whether a subsequent culture was performed or returned positive results. This represents the most infectious form of pulmonary tuberculosis, as the high bacterial load required for detection via microscopy indicates significant bacterial shedding. The infection is caused by Mycobacterium tuberculosis, which primarily affects the pulmonary parenchyma. The 'smear-positive' status is a critical indicator in public health for contact tracing and assessing the risk of community transmission. Pathologically, the disease is characterized by the formation of granulomas, caseous necrosis, and potentially cavitary lesions within the lung tissue. Patients with A15.0 require immediate respiratory isolation and initiation of a standardized multi-drug antitubercular regimen (typically RIPE: Rifampin, Isoniazid, Pyrazinamide, and Ethambutol).

Clinical Symptoms

  • Chronic productive cough (lasting 3 weeks or longer)
  • Hemoptysis (coughing up blood or blood-streaked sputum)
  • Dull or pleuritic chest pain
  • Unexplained weight loss (consumption)
  • Drenching night sweats
  • Low-grade evening fever
  • Persistent fatigue and malaise
  • Anorexia (loss of appetite)
  • Dyspnea (shortness of breath) in advanced stages

Common Causes

  • Infection with Mycobacterium tuberculosis (obligate aerobic bacterium)
  • Transmission via aerosolized droplets (coughing, sneezing, speaking)
  • Immunocompromised state (particularly HIV/AIDS)
  • Prolonged exposure to individuals with active pulmonary TB
  • Malnutrition and protein deficiency
  • Socioeconomic factors including overcrowding and poor ventilation
  • Chronic corticosteroid use or TNF-alpha inhibitor therapy
  • Substance abuse (tobacco and alcohol use)
  • Underlying conditions such as diabetes mellitus or silicosis

Documentation & Coding Tips

Explicitly state the method of confirmation specifically as sputum microscopy to justify the use of A15.0.

Example: Patient presents with persistent cough and weight loss. Sputum microscopy confirmed acid-fast bacilli (AFB) 3+ density. This microbiological confirmation identifies the condition as pulmonary tuberculosis, rather than clinically diagnosed without laboratory evidence. Billing focuses on the exact laboratory confirmation method, while risk adjustment is driven by the acute infectious status of the pathogen.

Billing Focus: Confirmation by sputum microscopy (AFB smear) must be documented in the medical record to support A15.0 versus A16.0.

Document the presence and location of pulmonary cavitary lesions on imaging to reflect disease severity.

Example: Chest CT reveals a 3cm thick-walled cavitary lesion in the right upper lobe, consistent with active tuberculosis of the lung confirmed by positive sputum microscopy. Patient is starting intensive phase RIPE therapy. Documentation of cavitation supports higher clinical complexity and resource utilization for disease monitoring.

Billing Focus: Site-specific lung involvement (right upper lobe) and radiological findings support the anatomical specificity of the diagnosis.

Specify the presence or absence of drug resistance to secondary agents to ensure comprehensive coding.

Example: Tuberculosis of the lung confirmed by microscopy. Molecular testing confirms susceptibility to isoniazid and rifampin. No multidrug resistance (MDR) detected. By documenting drug susceptibility, we support accurate selection of Z-codes if resistance were present and justify the standard four-drug regimen.

Billing Focus: Linking the infectious agent to drug susceptibility results prevents under-coding of complex resistant cases.

Always document the relationship between Tuberculosis and HIV status as it significantly alters the treatment plan.

Example: Patient with known HIV (B20) presents with pulmonary TB confirmed by sputum microscopy. Current CD4 count is 250. Initiating TB therapy prior to restarting ART to minimize IRIS risk. Clear documentation of the co-morbidity ensures both conditions are captured in the risk profile.

Billing Focus: Sequential coding of B20 and A15.0 is required when both are present and being managed.

Detail the initiation of Directly Observed Therapy (DOTS) and the specific phase of treatment.

Example: Patient is in the initial 2-month intensive phase of treatment for pulmonary TB (A15.0). All doses are administered via Directly Observed Therapy (DOTS) through the county health department to ensure adherence. This documentation supports the complexity of managing a public health threat.

Billing Focus: Documentation of treatment phase and delivery method (DOTS) supports the medical necessity of frequent follow-up visits.

Relevant CPT Codes

Related Diagnoses

Hierarchy