Table 1 Leading causes of EDs crowding

Patient-related factors [18, 20, 23,24,25]

• Being a critically ill

• Age (being child and aging)

• Male gender

• Lifestyle such alcoholism

Emergency service delivery related causes

a) Emergency patient flow and emergency care related [3, 8, 17, 19, 22, 26,27,28,29,30]

• Delay in discharging admitted patients

• Severe emergency condition

• A high proportion of emergency patients

• Long waiting of emergency patients for diagnostic test results

b) Emergency department staff related causes [22, 25, 27, 28, 31,32,33,34]

• Wrong diagnosis

• Delay of consultants

• Delay of staff to provide emergency services

• Delay in transferring patients to inpatient ward

• Shortage of emergency care providers

c) Premises and materials of ED-related factors [9, 27]

• Shortage of beds for admitting emergency patients

Other hospital services delivery related causes [3, 19, 22, 27, 29, 31]

• Delay in laboratory and imaging investigations

• Delay in diagnostic test results/reports

• The high number of patients in the waiting room of a hospital

• The reluctance of hospital staff to admit patients from ED