Real and apparent mortality from congenital diaphragmatic hernia

Some 50 cases of congenital diaphragmatic hernia (CDH) born in the authors' regional referral area over the 14 years from 1980 to 1993 were reviewed, contrasting 7 years when management included preoperative ventilatory stabilization with the preceding 7 when urgent surgery was performed. Six children experienced no respiratory distress and suffered no mortality. For infants with respiratory distress in the first 6 h of life, ventilatory stabilization improved survival rates of those who reached the surgical centre from 45 per cent between 1980 and 1986 to 59 per cent between 1987 and 1993. A larger proportion of the total number of patients, however, continued to die without reaching the surgical centre. The improvement in survival rate based on the true incidence of CDH was from 28 per cent in the first period to 38 per cent in the second. The apparent poor survival rate of patients born in central obstetric units compared with those born in peripheral units (37 versus 75 per cent) can be attributed to patient selection; a larger number of children born in central units were transferred for surgery (70 versus 57 per cent). There is no evidence that paediatricians have altered their referral practice to include prolonged ventilation outside the surgical unit since delayed surgery was advocated. Assessment of the impact of altering the management of CDH cannot be made without knowing the number of patients who die before transfer to a neonatal surgical unit. Any serious attempt to reduce the mortality rate of CDH must be directed to neonates who are not presently referred to the surgical service.