When I am reviewing clinical treatment records, I am always surprised when the initial assessment is missing a suicide risk assessment.  
The National Alliance on Mental Illness (NAMI) reports that suicide is the second leading cause of death among people aged 10 to 14 years of age, 3rd among people aged 15 to 24 in the United States, and 12thleading cause of death among all ages. A scary 4.9% of all adults have suicidal thoughts each year, 11.3% of young adults aged 18 to 25, and 18.8% of high school aged youths do. 
And yet some behavioral health clinicians have set some basic guidelines when they begin considering whether they will assess for suicidality, which leads to some individuals never being assessed as a part of behavioral health treatment.
Being able to effectively assess suicidality is a core responsibility of the behavioral health profession and yet many clinicians have received little or no formal training in suicidal risk assessment. In one study I found, as many as 50 percent of all behavioral health clinicians have had no formal training in completing a suicide assessment. The same study indicated that proficiency through training made a substantial difference in their capacity to complete these assessments.
I would encourage any behavioral health clinician to invest some of their continuing education budget in this important topic. I would also encourage clinicians, if they have not done so yet, to take a look at the free training that comes with the Columbia Suicide Severity Rating Scale (C-SSRS). It’s one of the recognized screening tools available and the training does an effective job walking through how to administer it.
There are of course other risk assessment tools for suicidality available. One that has been receiving some attention is the Ask Suicide-Screening Questions or ASQ. Zero Suicides recommends it for individuals age 10 to 24. The Joint Commission has approved it for all ages. For adolescents, the NIMH has combined the PHQ-A (the adolescent version of the PHQ-9) and the ASQ together as one form, and its available on their website free of charge.