What are the findings of a right infrahilar (below the hilum) region on a chest X-ray (X-ray)

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Last updated: May 21, 2025View editorial policy

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From the Guidelines

The right infrahilar region on a chest X-ray is a critical area to evaluate for signs of pulmonary hypertension (PH), including enlargement of the central pulmonary arteries and right heart chamber enlargement, as these findings can be suggestive of PH, especially in patients with persistent unexplained symptoms such as dyspnea or risk factors for PH 1. When examining the right infrahilar region on a chest X-ray, it is essential to look for any abnormal opacities, masses, consolidations, or enlarged lymph nodes that might indicate pathology.

  • Common findings in this region can include pneumonia, lung masses, enlarged lymph nodes due to infection or malignancy, or vascular abnormalities.
  • The right infrahilar region is particularly important to assess because abnormalities here can sometimes be subtle yet clinically significant.
  • According to the study by Miniati et al, cited in 1, CXR has high sensitivity (96.9%) and specificity (99.1%) for detection of PH, but it is known to be insensitive in the detection of mild PH.
  • Findings of PH on CXR include enlargement of the central pulmonary arteries, with or without rapid tapering (pruning), and right heart chamber enlargement, as well as a measurement of the right interlobar artery >15 mm in women (>16 mm in men) at the hilum, which is suggestive of PH 1.
  • When interpreting findings in the right infrahilar region, it's essential to compare with previous imaging if available and correlate with clinical symptoms, and additional imaging such as CT scans may be recommended if there are concerning or unclear findings on the initial chest X-ray.

From the Research

Right Infrahilar Region on Chest X-ray

There are no research papers to assist in answering this question, as the provided studies do not mention the right infrahilar region on chest X-ray.

  • The studies focus on the treatment of tuberculosis, including the pharmacokinetics of antituberculosis drugs 2, treatment regimens for isoniazid-resistant tuberculosis 3, and updates in the treatment of active and latent tuberculosis 4, 5.
  • One study discusses the efficacy and safety of a combined isoniazid-rifampicin-pyrazinamide-levofloxacin dry powder inhaler in the treatment of pulmonary tuberculosis, but does not mention the right infrahilar region on chest X-ray 6.
  • None of the studies provide information on the diagnosis or interpretation of chest X-rays, including the right infrahilar region.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Treatment of isoniazid-resistant tuberculosis with isoniazid, rifampin, ethambutol, and pyrazinamide for 6 months.

The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease, 2002

Research

Drugs for tuberculosis.

Treatment guidelines from the Medical Letter, 2012

Research

Updates in the Treatment of Active and Latent Tuberculosis.

Seminars in respiratory and critical care medicine, 2018

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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