A Definitive Observation Unit (DOU) is a unit in a hospital which provides the second-highest level of care. Patients may be booked directly into the DOU when they arrive at the hospital, or they may be transferred into the DOU from the Intensive Care Unit (ICU) once they have been stabilized. A wide variety of patients may spend time in a Definitive Observation Unit, receiving attentive care from specially trained nurses and medical teams.

The highest level of care in a hospital is an ICU. ICUs are designed for extremely sick patients who require constant monitoring. Often, the nurse to patient ratio is 1:1 or sometimes even 2:1 to ensure that patients have around-the-clock care from attentive personnel. Patients who are in the ICU are often unstable, which means that they may require medical interventions to stay alive.

In a Definitive Observation Unit, patients still require a lot of attention, but their conditions are not as critical as those of ICU patients. Nurses still check on patients at least once every four hours, and they use telemetry to monitor patients. Telemetry systems take measurements at the patient's bedside and report them to a nursing station or monitoring room, allowing staff to see when a patient is in distress.

You may hear a DOU referred to as a Direct Observation or Telemetry Unit. Some hospitals call such units “step down units,” referencing the idea that the Definitive Observation Unit is a step down from the ICU. Being moved to a step down unit from the ICU is a cause for celebration, as it indicates that the patient's prognosis is improving.

Usually, a Definitive Observation Unit has restricted visiting hours, because patients are often tired and still working hard to recover. Patients work with a team of doctors to address their conditions, and they may also have access to physical therapy, psychological counseling, and other treatments which are designed to reduce the trauma and long-term effects of their stay. Typically the diet of patients in the DOU is also restricted, with a nutritionist determining what the patient should eat and when to hasten recovery.

If a friend or family member is in a Definitive Observation Unit, you should check with hospital staff about who is allowed to see the patient, and when. You should be prepared to see the patient connected to medical equipment, and if the patient appears strained or stressed, you will be asked to leave. However, patients are usually very happy to have visitors while in the hospital, especially if the visitors come bearing gifts, so the effort of making a DOU visit is usually worth it.