- Sheehan Syndrome refers to ischemic necrosis of the pituitary gland following a catastrophically hemorrhagic delivery of a newborn. Given improved obstetric medical care, Sheehan Syndrome is now relatively rare.
- The anterior pituitary typically undergoes hypertrophy during pregnancy as lactotrophs, the cells which secrete prolactin enlarge and proliferate. Recall from hypothalamic-pituitary anatomy that the anterior pituitary is perfused only by a portal vessel system which first goes through the hypothalamus. Therefore, the anterior pituitary receives fairly oxygen-poor blood at baseline. In the context of hypovolemic shock resulting from a catastrophically hemorrhagic delivery, the perfusion of the anterior pituitary drops to a level where ischemic necrosis of the hypertrophied pituitary can occur. The loss of pituitary tissue does not manifest immediately but
- This manifests as post-partum pan-Hypopituitarism
- The loss of functional pituitary tissue does not manifest immediately but becomes apparent over the course of days to weeks after the delivery. Any and all of the clinical consequences of hypopituitarism may result, depending on the extent and distribution of pituitary loss.
- Some patients may present due to a failure of lactation from insufficient prolactin secretion whereas others may develop acute or chronic adrenocortical insufficiency due to reduced ACTH secretion.