Introduction Congenital diaphragmatic hernia (CDH) is a rare anomaly (1 in 2000–3000 live births) where abdominal organs can enter the thoracic cavity. The 3 types of CDH are: posterolateral Bochdalek hernia, the anterior Morgagni hernia and the hiatus hernia. The left-sided Bochdalek hernia occurs more frequently, in approximately 85% of cases, but in the rare right-sided hernia (13% cases) the liver and a portion of the large bowel tend to herniate into the thoracic cavity.

Although CDH is usually a disorder of the newborn, as many as 10% of patients may present after the newborn stage and even during adulthood.

Method We report the case of a 3 weeks old female, born by c-section at term, with no fetal malformations diagnosed by ultrasonography during pregnancy and without any respiratory distress mentioned during the 3 days in the Neonatology unit. During the first 3 weeks she was breastfed, having a 300 g weight gain and a normal intestinal transit.

She presented in a primary Paediatrics clinic for a scheduled appointment (first visit after leaving Neonatology) with intense cyanosis, respiratory distress, very low oxygen saturation level (71%), very weak cry, hyporeactivity, tachycardia (170 bpm). She received emergency resuscitation using a bag-valve-mask (BVM), until the emergency unit arrived. She was diagnosed with right CDH in the same day at ‘Grigore Alexandrescu Children’s Hospital’, where she was intubated, admitted to the Surgery department. She underwent surgery four days later, her condition remaining critical at the moment.

Discussion and conclusion CDH is a severe malformation, usually diagnosed prenatally or immediately after birth, with less than 10% of the cases going undiagnosed beyond neonatal age. This case is remarkable by the severe clinical presentation, for a routine Paediatric examination, of a 3 weeks old infant, born from a monitored pregnancy, with no diagnostic