The frequency of posterior urethral valves in Oman

To ascertain the frequency of posterior urethral valves (PUV) in Oman, using hospital records.

The resident population of Oman is 1.5 million and all complex paediatric surgical cases are referred to a single unit in the capital city of Muscat. A register of patients has been kept in that unit since 1988. Hospital case-records were reviewed to determine associated abnormalities, date and place of birth, tribal origin and, from further interviews, the family pedigree and degree of consanguinity.

This retrospective survey identified 56 Omani children born between 1989 and 1994 who were treated in the Paediatric Surgery Department at the Royal Hospital, Muscat for congenital PUV. The calculated incidence was 1 in 2375 newborn males, which is 2-4 times higher than that previously reported in other populations. There was no relation to the estimated month of conception and therefore environmental hyperthermia due to the extreme ambient temperature does not seems not to be a causative factor. There was consanguinity in 40 of 46 cases (87%) where a complete family history was available. Parents were first cousins in 54% of cases, compared with the background rate of 24% in over 6000 families interviewed in the antenatal clinics at six hospitals in Oman. There was also a concentration of PUV within specific tribes. About one-third of the cases also had associated congenital abnormalities, the most frequent of which were genitourinary (17%), but gastrointestinal (9%) and spinal (7%) defects were also observed.

The frequency of PUV in newborn Omani males was 1 in 2375, which is considerably higher than any previously reported series. This was associated with an increased rate of consanguinity, but there was no clear pattern of inheritance.