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Introduction: Point-of-care ultrasound (POCUS) has been suggested as an initial investigation in the management of renal colic. Our objectives were: 1) to determine the accuracy of POCUS for the diagnosis of nephrolithiasis, and 2) to assess its prognostic value in the management of renal colic (PROSPERO: 42016035331). Methods: An electronic database search of MEDLINE, EMBASE, and PubMed was conducted utilizing subject headings, keywords, and synonyms that address our research question. Bibliographies of included studies and narrative reviews were manually examined. Studies of adult emergency department patients with renal colic symptoms were included. Any degree of hydronephrosis was considered a positive POCUS finding. Accepted criterion standards were CT evidence of renal stone or hydronephrosis, direct stone visualization, or surgical findings. Screening of abstracts, quality assessment with the QUADAS-2 instrument, and data extraction were performed by two reviewers, with discrepancies resolved by conference with a third reviewer.Test performance was assessed by pooled sensitivity and specificity, calculated likelihood ratios, and a summary receiver operator curve (SROC). The secondary outcome of prognostic value was reported as a narrative summary. Results: The electronic search yielded 627 unique titles. After relevance screening, 25 papers underwent full-text review, and 8 articles met all inclusion criteria. Of these, 5 high-quality studies (N=1773) were included in the meta-analysis for diagnostic accuracy, and three yielded data on prognostic value. The pooled results for sensitivity and specificity were 70.2% (95% CI=67.1% to 73.2%) and 75.4% (95% CI=72.5% to 78.2%), respectively. The calculated positive and negative likelihood ratios were 2.85 and 0.39. The SROC generated did not show evidence of a threshold effect.Three studies examining prognostic value noted a higher likelihood of a large stone or surgical intervention with positive POCUS findings. The largest randomized trial showed lower cumulative radiation exposure and no increase in adverse events in those who received POCUS investigation as the initial renal colic investigation. Conclusion: Point-of-care ultrasound is of modest accuracy for the diagnosis of nephrolithiasis. While positive POCUS findings are associated with larger stones and greater likelihood for intervention, the clinical importance of this is unclear.
