Fetal meconium pseudocyst secondary to in utero perforation of colon transversum and meconium peritonitis

Fetal bowel intrauterine perforation causes sterile inflammation of the peritoneum, known as meconium peritonitis. In some cases the perforation closes spontaneously, thus forming a meconium pseudocyst between the intestinal loops and the omentum. Meconium peritonitis, complicated by pseudocyst formation, should always be considered when a fetal abdominal mass with diverse echogenicity and hyperechogenic calcifications is observed on prenatal ultrasound. Usually, this is associated with ascites and/or polyhydramnios. The differential diagnosis necessitates exclusion of all other fetal abdominal tumors. We present a case report of meconium pseudocyst diagnosed prenatally at 32 weeks of gestation which was successfully treated by surgery after birth.