What causes unilateral pleural effusion in pregnancy?

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Last updated: May 2, 2025View editorial policy

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From the Guidelines

Unilateral pleural effusion in pregnancy is most commonly caused by pulmonary embolism, pneumonia, malignancy, tuberculosis, and heart failure, with pulmonary embolism being particularly concerning due to the hypercoagulable state of pregnancy. According to the British Thoracic Society guideline for pleural disease 1, the investigation and management of pleural disease, including undiagnosed unilateral pleural effusion, have shifted towards more patient-centered outcomes and ambulatory treatments.

Key Causes

  • Pulmonary embolism: a significant concern in pregnancy due to the hypercoagulable state
  • Pneumonia: may lead to parapneumonic effusions
  • Malignancy: a possible cause, although less common in pregnancy
  • Tuberculosis: should be considered, especially in endemic areas
  • Heart failure: pre-existing cardiac conditions can worsen during pregnancy

Evaluation and Management

Evaluation should include:

  • Thoracentesis for fluid analysis
  • Chest imaging, preferably ultrasound to minimize radiation
  • Appropriate laboratory tests Management depends on the underlying cause, with treatment tailored to address the specific etiology while considering the safety of both mother and fetus, as emphasized in the guideline 1.

From the Research

Unilateral Pleural Effusion in Pregnancy

Causes

  • The exact cause of unilateral pleural effusion in pregnancy can be due to various factors, including obstetric and gynecologic conditions 2
  • Some possible causes include catamenial hemothorax, ovarian hyperstimulation syndrome, and benign peripartum pleural effusion 2
  • In some cases, the etiology of pleural effusion remains unclear, and further diagnostic evaluation is necessary to determine the underlying cause 3, 4

Diagnostic Evaluation

  • Diagnostic evaluation of pleural effusion includes chemical and microbiological studies, as well as cytological analysis of the pleural fluid 3
  • Thoracocentesis should be performed for new and unexplained pleural effusions to determine the etiology and guide treatment 3
  • Fetal echocardiography and other imaging studies may be used to evaluate the fetus and guide management in cases of fetal pleural effusion 5, 6

Treatment and Management

  • Treatment of pleural effusion depends on the underlying etiology and may involve drainage of the effusion, treatment of the underlying medical disorder, or other interventions 3, 4
  • In cases of fetal pleural effusion, management may involve close surveillance, thoracoamniotic shunt placement, or other interventions to prevent complications and improve outcomes 5, 6

References

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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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