Aims There is limited information on how many patients are undiagnosed. The aim was to evaluate the proportion of paediatric inpatients without a diagnosis on Undiagnosed Day in a specialist hospital serving both the general local population, and tertiary referrals in 34 specialties.

Methods On ‘Undiagnosed Day 2016’ (29/04/16), all inpatient notes were reviewed to establish whether an overarching diagnosis existed. Demographics, specialty and reason for admission were collected, as well as how diagnosis was made (if at all). The data was analysed to show the proportion of patients with no definitive diagnosis per specialty.

Results There were 270 inpatients and data was collected for 269. The male to female ratio was 56%: 44%, ages ranged from 0–17 years. 49 out of the 269 patients (18.2%) had no overarching diagnosis, with the highest proportion by age being 8 years. This varied in each specialty including 15.2% in general paediatrics, 31% in neurology and 36% in respiratory and hepatology.

Figure 1

67% of admissions were acute, 28% elective and 5% tertiary transfers. The proportion of undiagnosed patients was 31% in tertiary transfers, 22% in acute admissions and 15% in elective cases. Of all undiagnosed cases, 50% had multiple problems, affecting two or more systems. These patients may have a rare syndrome, multiple diagnoses, an uncommon presentation of a common condition or there may not be a diagnosis.

Conclusion In this snapshot review of inpatients in a major specialist UK hospital, 18.2% do not have an overarching diagnosis. Effective treatment is more challenging. For families, not having a prognosis and knowing whether other family members are affected is distressing. SWAN UK, the UK charity supporting undiagnosed families, reports the struggle of having their child’s needs taken seriously and in accessing services. In the UK, the 100K Genome Project is enrolling patients without an underlying genetic diagnosis.