Prenatal ultrasound (US) diagnosis and postnatal outcome are reviewed in three babies with the complex form of meconium peritonitis (MP), the cystic type. Perinatal management is discussed. Large intra-abdominal cysts with signs of calcifications were detected during the second mid-trimester. Meconium ascites and polyhydramnios appeared between 32 and 35 weeks of gestation. Signs of anaemia were assessed on median cerebral artery peak systolic velocity. Sudden appearance of hydrops and anaemia required preterm delivery, neonatal resuscitation and urgent abdominal drainage. Postnatal US imaging confirmed prenatal sonographic evidence. Abdominal X-ray showed calcifications and no free abdominal air. Intestinal diversion was performed in two patients on their first day of life and evolution was uneventful. Hospital death occurred in one baby, who was submitted to delayed surgery due to unstable hemodynamic conditions. Distal ileal perforation walled off by pseudocysts was detected in all cases. One baby was found to be affected by cystic fibrosis. Ileal intussusception was described in the non-surviving infant. The cystic type of MP may have a potentially rapid lethal course and the onset of foetal anaemia and polyhydramnios is a bad prognostic factor. Severe evolution in hydrops and foetal distress may occur at any moment suggesting the persistence of a leakage or re-rupture of the cysts with new meconium spillage into the abdomen. Prenatal detection of ascites, polyhydramnios and pseudocysts requires a strict follow-up, and timing of delivery has to be planned in a tertiary centre. Postnatal radiological imaging does not offer further information over prenatal imaging and surgical decision should not be influenced by the absence of abdominal free air. Urgent abdominal drainage at birth, followed by intestinal diversion of persistent intestinal perforation on the first day of life, may prevent bacterial colonisation and improve prognosis.