Qualitative urine toxicology testing has not been shown to improve the routine management of psychiatric patients in emergency rooms because of the potential for false positives, false negatives, true positives which are unrelated or minimally relevant to the clinical presentation, and finally the delay in psychiatric assessment and management as a result of testing.
Sources:
Korn CS, et al. “Medical clearance” of psychiatric patients without medical complaints in the emergency department. J Emerg Med. 2000 Feb;18(2):173-176. PMID: 10699517.
Olshaker JS, et al. Medical clearance and screening of psychiatric patients in the emergency department. Acad Emerg Med. 1997 Feb;4(2):124-128. PMID: 9043539.
Schiller MJ, et al. Utility of routine drug screening in a psychiatric emergency setting. Psychiatr Serv. 2000 Apr;51(4):474-78. PMID: 10737822.
Tenenbein M. Do you really need that emergency drug screen? Clin Toxicol. 2009 Apr;47(4):286-91. PMID: 19514875.