A diverticulum is an abnormal sac or pouch that develops at a weak point in the intestines. Various types of diverticula can develop as you age. When you’re born with a diverticulum in your intestines, it’s referred to as Meckel’s diverticulum. Meckel’s diverticulum usually develops between the fifth and seventh weeks of fetal development. Because the condition is present at birth, it’s classified as a congenital health issue.