However, if there are certain "red flag" symptoms present, plain radiographs (X-ray), CT scan or magnetic resonance imaging may be recommended. These red flags include:
History of cancer
Unexplained weight loss
Immunosuppression
Urinary infection
Intravenous drug use
Prolonged use of corticosteroids
Back pain not improved with conservative management
History of significant trauma
Minor fall or heavy lift in a potentially osteoporotic or elderly individual
Acute onset of urinary retention, overflow incontinence, loss of anal sphincter tone, or fecal incontinence
Saddle anesthesia
Global or progressive motor weakness in the lower limbs

Prevention
Moderate-quality evidence exists that suggests that the combination of education and exercise may reduce an individuals risk of developing an episode of low back pain. Lesser-quality evidence points to exercise alone as a possible deterrent to the risk of the condition. Management
Nonspecific pain
Patients with uncomplicated back pain should be encouraged to remain active and to return to normal activities. The management goals when treating back pain are to achieve maximal reduction in pain intensity as rapidly as possible, to restore the individuals ability to function in everyday activities, to help the patient cope with residual pain, to assess for side effects of therapy and to facilitate the patients passage through the legal and socioeconomic impediments to recovery. For many, the goal is to keep the pain at a manageable level to progress with rehabilitation, which then can lead to long-term pain relief.
Types of subclinical infections
The following pathogens (together with their symptomatic illnesses) are known to be carried asymptomatically, often in a large percentage of the potential host population:

Host tolerance
Fever and sickness behavior and other signs of infection are often taken to be due to them. However, they are evolved physiological and behavioral responses of the host to clear itself of the infection. Instead of incurring the costs of deploying these evolved responses to infections, the body opts to tolerate an infection  as an alternative to seeking to control or remove the infecting pathogen.Subclinical infections are important since they allow infections to spread from a reserve of carriers. They also can cause clinical problems unrelated to the direct issue of infection. For example, in the case of  urinary tract infections in women, this infection may cause preterm delivery if the person becomes pregnant without proper treatment. See also
References
Further reading
Endara, Pablo; Trueba, Gabriel; Solberg, Owen D.; Bates, Sarah J.; Ponce, Karina; Cevallos, William; Matthijnssens, Jelle; Eisenberg, Joseph N.S. (April 2007). "Symptomatic and Subclinical Infection with Rotavirus P[8]G9, Rural Ecuador". Emerging Infectious Diseases. 13 (4): 574–580. doi:10.3201/eid1304.061285. PMC 2391297. PMID 17553272.