In this module, we will provide a comprehensive review of the evaluation of a neonate with constipation and some of its causes that you cannot afford to miss. Critical questions to ask in history, including age and developmental stage of the baby, prenatal and birth history, and feeding history will be reviewed, as will physical findings and investigations, which include complete abdominal examination and barium enema studies and rectal biopsy. You will learn a comprehensive diagnostic approach to and management of neonatal constipation and how to recognize and manage acute intestinal obstruction. Lastly, you will learn to recognize clinical conditions that require immediate evaluation and management to prevent permanent complications, such as Hirschsprung’s disease, meconium ileus, and imperforate anus.