The role of ultrasound in evaluation of radiographically suspected pleural effusions among in patients at mulago hospital.

Abstract

INTRODUCTION: The annual incidence of pleural effusion (PEs) is estimated at 320 per 100,000 persons in the industrialised countries. Its distribution and incidence are dependent on the population studied. Morbidity and mortality of PEs are directly related to the causes, stage of the disease and biochemistry. Early establishment of its presence, relief of symptoms and finding the cause are key factors to management. Despite the advances in chest imaging and other diagnostic modalities, the discrimination between anechoic and echogenic PEs and establishing other characteristics of PEs on U/S may become an Important first step in evaluating patients with PEs. Echogenic PEs usually indicate pleura or lung parenchyma tissue diseases or both. These are usually exudates. Anechoic effusions are usually due to cardiac, renal, hepatic diseases and hypoprotenemic states. They are usually transudates. Ultrasound can assist in finding other pathologies associated with PEs, guide biopsy and aspiration.

OBJECTIVES: The study aimed at finding the sonographic appearances, nature of PEs and the lesions associated with them, among in-patients with radiographically suspected PEs at Mulago hospital. METHODOLOGY: A Descriptive cross-sectional study was done on ward 4C pulmonology unit mulago university teaching and national referral hospital from the month of February to April 2009. Three hundred and five patients whose chest X-rays where suscipicious of presence of PEs were recruited. A sonoace 8000 ultrasound machine manufactured by Medison (2001) with low (7-10MHZ) and high (3-5 MHZ) frequency probes was used. The patients’ chest radiographs, clinical, sonographic and laboratory findings were recorded in a precoded questionnaire. The data was entered into the computer using Epidata and analysed by SPSS version 8 software. RESULTS: A Total of 305 patients with suspected pleural effusions (PEs) on chest radiography were recruited. Their ages were 18-90 years. The male to female sex ratio was about 1:1. Approximately 48% patients lived in the rural and 52% lived in urban areas. Two hundred twenty nine (75.1%) had sonographic features of PEs and 76(24.9%) did not have. Of the 299 patients, 6(2.6%) (p=0.014) also had lung parenchyma masses. Of the 76 patients without PEs, 69 had pleura thickening only had 7(9.2%) had pleural thickening and lung parenchyma masses. One hundred ninety one 191(62.2%) patients had exudative or transudative PEs of known underlying aetiology and 6(3.1%) of them also had parenchyma masses. Of the 229 patients with PEs, 38(16.6%) patients did not have definitive diagnosis and none of these had masses. Class one PE (54.05%) was the most common and class four (6.7%) was the least common.

CONCLUSION AND RECOMMENDATIONS: Ultrasound is a useful imaging modality used in studying chest X-ray opacities suspected to be due to PEs. It can differentiate between PEs and masses. Class one PEs may be exudates or transudates but classes 2 and above are almost always exudates. The physicians should employ U/S for further investigation of the patients suspected to have PEs after plain radiography.