- Results from intrauterine GI perforation.
- Initially, it is a sterile chemical peritonitis, but if perforation of the GI tract persists after birth, complicating bacterial infection may supervene.
- Perforation and subsequent meconium peritonitis can occur from many causes
- In some cases, fluid and meconium can pass into the chest, presumably through congenital communications, resulting in meconium thorax.
 Imaging Findings
 Plain film
- Amorphous and irregular or curvilinear abdominal calcifications, with the latter suggesting cystic loculation or coating of the peritoneum (i.e. pseudocyst)
- Negative is mecomium does not calcify.
- Eventually, most of the calcification in meconium peritonitis slowly disappears
Patient #1: Abdominal calcifications seen on prenatal ultrasound