What are the causes of unilateral pleural effusion in pregnancy?

From the Guidelines

Unilateral pleural effusion in pregnancy should be promptly evaluated with a thorough history, physical examination, and imaging studies such as chest X-ray with abdominal shielding or ultrasound, as it can result from various causes including pulmonary embolism, pneumonia, heart failure, or malignancy. The management of unilateral pleural effusion in pregnancy is crucial to prevent morbidity, mortality, and to improve the quality of life for both the mother and the fetus. According to the British Thoracic Society guideline for pleural disease 1, a systematic approach to investigation is necessary to establish a diagnosis swiftly, while minimizing unnecessary invasive investigations.

The initial evaluation should include a careful history and physical examination of the patient, as the likely cause can often be elucidated by careful history taking, which will then allow directed further investigations. Thoracic ultrasound (TUS) is now an essential diagnostic tool and should be performed on every patient at their initial presentation and again whenever a pleural procedure is being performed 1. If it is not safe to proceed with a pleural aspiration, a CT scan should be obtained as the next step.

The European Respiratory Journal also suggests that several blood biomarkers, such as natriuretic peptides, have been assessed to diagnose heart failure and pleural effusion of cardiac origin 1. However, the role of natriuretic peptides in patients with known heart failure and a unilateral pleural effusion is still being studied.

In terms of treatment, antibiotics, anticoagulation, or diuretics may be used depending on the underlying cause, and malignant effusions may require thoracentesis for symptom relief and oncology consultation. Throughout management, fetal monitoring is essential, particularly during procedures, and supplemental oxygen should be provided to maintain maternal oxygen saturation above 95% to ensure adequate fetal oxygenation. A multidisciplinary approach involving obstetricians, pulmonologists, and radiologists is necessary to optimize outcomes for both mother and fetus.

Some key points to consider in the management of unilateral pleural effusion in pregnancy include:

• Prompt evaluation with a thorough history, physical examination, and imaging studies
• Use of thoracic ultrasound as a diagnostic tool
• Consideration of several blood biomarkers to diagnose heart failure and pleural effusion of cardiac origin
• Treatment depending on the underlying cause, such as antibiotics, anticoagulation, or diuretics
• Fetal monitoring and supplemental oxygen to ensure adequate fetal oxygenation
• A multidisciplinary approach involving obstetricians, pulmonologists, and radiologists to optimize outcomes for both mother and fetus.

From the Research

Unilateral Pleural Effusion in Pregnancy

• Unilateral pleural effusion in pregnancy can be a serious complication, with potential for misdiagnosis during labor and delivery 2.
• The etiology of pleural effusion remains unclear in nearly 20% of cases, making diagnosis and treatment challenging 3.
• In cases of fetal pleural effusion, close sonographic surveillance is necessary to monitor the progression of the effusion and potential development of fetal hydrops 4, 5.
• Thoracoamniotic shunt placement may be an effective treatment option for fetal pleural effusion, resulting in resolution of fetal hydrops and prevention of intrauterine fetal death 4.
• The management of pleural effusion in adults, including those who are pregnant, depends on the underlying cause, with treatment options ranging from pleurodesis to thoracoscopy and video-assisted thoracoscopy 3, 6.

Diagnosis and Treatment

• Thoracocentesis should be performed for new and unexplained pleural effusions to determine the etiology and guide treatment 3, 6.
• Laboratory testing, including chemical and microbiological studies, as well as cytological analysis, can help distinguish pleural fluid transudate from an exudate and provide further information about the etiology of the disease process 3, 6.
• Immunohistochemistry can provide increased diagnostic accuracy in cases of pleural effusion 3.
• Transudative effusions are usually managed by treating the underlying medical disorder, while exudative effusions require treatment of the underlying etiology 3, 6.

Fetal Pleural Effusion

• Fetal pleural effusions can be classified as resolved, stable, or progressive, with progressive effusions requiring close monitoring and potential intervention 5.
• In utero therapy, including thoracoamniotic shunt placement, may be necessary to prevent intrauterine fetal death and ensure a favorable postnatal outcome 4, 5.
• The natural history and outcomes of fetal primary pleural effusions can vary, with some cases resolving spontaneously and others requiring intervention 5.