Waiting on the Urine: The Impact of Delayed Urine Collection on Length of Stay in the Emergency Department

Efficient collection of urinalyses (UAs) can be variable and is patient-dependent. Anecdotal delays in UA collection, compared with those for blood tests, can potentially lead to prolonged length of stay (LOS) and worsened throughput. Our study sought to analyze the impact of delayed urine collection on emergency department (ED) operations.

This study is a retrospective cohort analysis of 38,640 discharged encounters with a urinalysis and 67,645 discharged encounters with a complete blood count (CBC). We captured order time, collection time, and disposition time. We calculated deciles of order-to-collection times for UA and CBC groups to visualize the data. We separated the groups into patients with UA only, CBC only, and both CBC + UA. We performed adjusted and unadjusted analyses using Kruskal-Wallis tests and a quantile regression to compare median order-to-collection times as well as to compare the relationship between LOS and order-to-collection time between groups.

Median order-to-collection time in the CBC-only group was significantly shorter than the CBC + UA group (16.7 minutes [IQR, 3.7-40.6] vs 75.6 minutes [IQR, 26.9-150.5]). Median LOS was shortest in the UA-only group (259 minutes [IQR, 187-367]), followed by the CBC group (339 minutes [IQR, 255-449]) and lastly, the CBC + UA group (392 minutes [IQR, 302-507]). In the CBC + UA group, the UA order-to-collection time is a median of 37 minutes (IQR, 0-120) longer than that of the CBC. Each additional minute of order-to-collection time in the CBC-only group contributed 0.50 minutes (IQR, 0.47-0.53) to LOS, compared with 0.58 minutes (IQR, 0.56-0.60) in the CBC + UA group and 0.90 minutes (IQR, 0.83-0.97) in the UA-only group (P < 0.001).

UAs take longer to collect than CBCs. Ordering a UA in addition to a CBC significantly increased order-to-collection time and LOS. Each additional minute of collection delay contributed 16% more to LOS in this group, and with higher collection time outlier cases for UAs, this can lead to a worsening bottleneck. Understanding these effects may help EDs prioritize UA collection and target interventions in which there may be the highest impact on flow.