Accuracy of pleural puncture sites: a prospective comparison of clinical examination with ultrasound.

STUDY OBJECTIVE: To assess the value of chest ultrasonography vs clinical examination for planning of diagnostic pleurocentesis (DPC).

DESIGN: Prospective comparative study.

SETTING: Pulmonary unit of a tertiary teaching hospital.

PATIENTS AND PARTICIPANTS: Sixty-seven consecutive patients referred to 30 physicians of varying degrees of experience for DPC.

INTERVENTIONS: Based on clinical data and examination, physicians determined whether and where a DPC should be performed. Selected puncture sites were evaluated with ultrasound and considered accurate when > or = 10 mm fluid perpendicular to the skin were present.

MEASUREMENTS AND RESULTS: In 172 of 255 cases (67%), a puncture site was proposed. Twenty-five sites (15%) were found to be inaccurate on ultrasound examination, and a different, accurate site was established in 20 of these cases. Physicians were unable to locate a puncture site in 83 cases (33%). Among these, ultrasound demonstrated an accurate site in 45 cases (54%), while a safe tap was truly impossible in 38 cases (46%). Overall, ultrasound prevented possible accidental organ puncture in 10% of all cases and increased the rate of accurate sites by 26%. The sensitivity and specificity for identifying a proper puncture site with clinical examination compared to ultrasound as the "gold standard" were 76.6% and 60.3% (positive and negative predictive values, 85.5% and 45.8%, respectively). Risk factors associated with inaccurate clinical site selection were as follows: small effusion (p < 0.001), evidence of fluid loculation on chest radiography (p = 0.01; relative risk, 7.8; 95% confidence interval, 1.9 to 32.9), and sharp costodiaphragmatic angle on chest radiography (p < 0.001; relative risk, 7.0; 95% confidence interval, 2.3 to 15.2). Experienced physicians did not perform better than physicians in training.

CONCLUSIONS: Puncture site selection with bedside ultrasonography increases the yield of and potentially reduces complication rate in DPC. Physician experience does not predict the accuracy of selected puncture sites.