DOI: 10.5811/westjem.2014.7.22896
Riddell J, Case A, Wopat R, et al.
Sensitivity of Emergency Bedside Ultrasound to Detect Hydronephrosis
in Patients with Computed Tomography-proven Stones.
West J Emerg Med. 2014;15(1):96-100.

To the Editor:

We read with great interest the article by Riddell et al.¹ and we believe the study addresses a very important clinical question; however; we have some remarks and questions below.

In Tables 2 and 3, we noticed there were 103 patients with ultrasound (US) evidence of hydronephrosis or stone; but in Table 4, total number of patients with bedside US evidence adds up to 99. Besides that, in Table 1 the number of patients with bedside US evidence of Stone is given to be 98. We could not find information about the missing patients and discrepancy in the number of total patients neither in the results nor discussion, and we feel further clarification is needed.

We also had some questions about the methodology of the study. It is stated that two investigators reviewing charts were blinded to the study hypothesis; however, there is no information regarding whether the emergency physicians performing the ultrasound examination were blinded to computed tomography (CT) results. Similarly, inter-rater reliability was stated to be 100% based on screening of a random sample of study records. We think interrater reliability of the chart reviews is important; however, this is a bit confusing since there is no information given about interobserver variability of the ultrasound examination. We feel including data from the literature about interobserver variability of ultrasound, or evaluating the variability of the performers in another set of patients, would help to give a better sense of real inter-observer variability.

From the perspective of a radiologist, technical details of devices, probes used for ultrasound and protocols used for CT are crucial for external validity, thus including this information would be beneficial.

A result of the study was that, for stones of size >=6 mm, a sensitivity of 100% was reported. Since this is expected to be an SnNout study, we believe this result is very valuable. Also, a sensitivity of 100% was reported for cases with 3 or more stones. However, we think some clarification could be very beneficial regarding how many cases with stones >=6 mm had 3 or more stones, or vice versa.

We think the clarification to our questions above would contribute to the literature in the clinical usefulness of the issue addressed in the study.

Footnotes

Address for Correspondence: Özgür Kızılca, MD, Akdeniz University School of Medicine Department of Radiology 07050 Antalya, Turkey Email: ozgurkizilca82@hotmail.com.

Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. The authors disclosed none.

REFERENCES

1. Riddell J, Case A, Wopat R, et al. Sensitivity of emergency bedside ultrasound to detect hydronephrosis in patients with computed tomography-proven stones. West J Emerg Med. 2014;15(1):96-100. [PubMed]