Background Congenital chylothorax (CCT) is a rare disease of unknown aetiology. Treatment approaches vary; none has been evaluated prospectively.

Objective To prospectively determine incidence, treatment and outcome of infants with CCT born in Germany in 2012.

Design CCT was defined as non-traumatic chylous pleural effusion within 28 days after birth. As part of the Surveillance Unit for Rare Pediatric Conditions in Germany (Erhebungseinheit für seltene pädiatrische Erkrankungen in Deutschland), all paediatric departments (n=432) received monthly reporting cards to notify the study centre of CCT cases, which were analysed based on anonymised questionnaires and discharge summaries. Data are shown as median (range) or n/N.

Results Of 37 cases reported, 28 met inclusion criteria. Questionnaires and/or discharge summaries were available for 27/28. Assuming complete reporting, the incidence of CCT was 1:24 000.

Nine infants suffered from proven or suspected syndromal anomalies, most frequently Noonan syndrome (5/9). Postnatally, 23 required mechanical ventilation, 3 continuous positive airway pressure; only 1 had no respiratory support. 17 infants were treated with inotropes/vasopressors, 25 required pleural drainage for 11 (1–36) days. In 13 infants, enteral feeds were withheld initially; 25 received medium-chain triglyceride diet at some time, 9 were treated with octreotide or somatostatin. 18 infants survived without, 6 with sequelae attributable to the underlying disorder; 3 infants died (median age at death 37 (2–144) days). Duration of hospital stay in survivors was 51 (20–127) days. Infants treated with octreotide or somatostatin had similar outcomes compared with those not treated.

Conclusions Based on this small observational study, CCT seems to have a favourable prognosis if not associated with genetic disorders.