Evaluating factors associated with the risk of hydrothorax following standard supracostal percutaneous nephrolithotomy

OBJECTIVE: To report our experience with supracostal percutaneous nephrolithotomy (SC-PNL) and evaluate factors which could predict the risk of hydrothorax following SC-PNL. METHODS: We reviewed 347 patients who underwent SC-PNL from January 2011 to December 2019. Patients were assessed for demographic characteristics, indication for the supracostal access, level of supracostal access, anatomy of the kidney (normal or malrotated), site of the puncture in relation to the mid-scapular line (medial or lateral), and whether another subcostal tract for stone clearance was required or not. Patients were assessed for the incidence of hydrothorax and requirement of intercostal drain depending on the level of percutaneous access. In addition, a multivariable logistic regression analysis model was developed to identify factors which could predict the occurrence of hydrothorax following SC-PNL. RESULTS: Of the 347 patients with SC-PNL, 248 (71.5%) underwent a supra-12th rib approach, while the rest needed a supra-11th (n=85; 24.5%) or a supra-10th (n=14; 4.0%) rib tract. Overall, 17 (4.9%) patients developed a hydrothorax, while an intercostal-drain was required in seven of these 17 patients for 48 h. None of the patients with a supra-12th rib puncture required an intercostal-drain. More than a third of the patients with a supra-10th puncture developed a hydrothorax (35.7%) and all of them required an intercostal drain. Factors such as anteriorly malrotated kidney (odds ratio [OR]=2.722; 95% confidence interval [CI]=1.042–5.617, p=0.03), puncture medial to the mid-scapular line (OR=1.669; CI=0.542–1.578, p=0.03), and an access higher than the supra-12th level (OR=5.265; CI=1.292–9.342, p<0.001) proved to be independent predictors of hydrothorax following a SC-PCNL on multivariable analysis. CONCLUSION: Incidence of clinically significant hydrothorax requiring an intercostal-drain after SC-PNL is very low. Knowledge of the predicting factors will help to anticipate the risk of hydrothorax in a particular patient and take necessary peri-operative measures.