Congenital cystic adenomatoid malformation: accuracy of prenatal diagnosis, prevalence and outcome in a general population

OBJECTIVES: Most available data regarding accuracy of prenatal diagnosis, prevalence and outcome of congenital cystic adenomatoid malformation (CCAM) are derived largely from tertiary referral centres and may not reflect general population rates. We aimed to describe the accuracy of prenatal diagnosis, ascertain the population prevalence and post-natal outcome for cases of suspected CCAM. METHODS: Retrospective collection of prenatal and paediatric data for cases of suspected CCAM notified to the Trent Congenital Anomalies Register 1997 to 2001. RESULTS: Thirty-seven cases of CCAM were suspected prenatally. Twenty-one cases were confirmed post-natally as having a CCAM (positive predictive value 57%). Eighteen of the 21 cases were delivered at term as live births, 15 of which have undergone successful surgery to date. Thirteen of the 37 cases had apparently resolved by delivery. Three further cases were subsequently found to be cases of lung sequestration or lobar emphysema. Five cases of CCAM were detected after delivery (sensitivity of prenatal detection 81%). The population prevalence at delivery was 9.0 per 1,00,000 total births. Five confirmed cases of CCAM developed hydrops, three required in utero intervention and delivered as live births at term, one was terminated and one died in utero. The overall mortality in the confirmed cases of CCAM was 23% of which the majority were terminations of pregnancy. CONCLUSIONS: Problems of diagnostic accuracy and apparent resolution of CCAM render counselling difficult, although our data suggest that the prognosis is better than others have reported. Confirmation of the diagnosis in the neonatal period is vital in order to obtain the true population prevalence figures and to interpret outcome data.