postpartum hypopituitarism

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Sheehan syndrome is a rare cause of pituitary apoplexy and hypopituitarism. It only occurs in postpartum females who experience large volume hemorrhage and hypovolemic shock, either during delivery or afterward with resultant necrosis of anterior pituitary cells .

Epidemiology

Advances in obstetrical care mean Sheehan syndrome is rare in developed countries. Incidence in developing and low-income countries is as high as 5 per 100 000 births .

Clinical presentation

pituitary failure
- may be silent and present with delayed hypopituitarism
- agalactorrhoea
- amenorrhea
- oligomenorrhea
- adrenal insufficiency
- hyponatremia (diabetes insipidus) in the acute setting of extreme hypovolemia
- hypothyroidism
- growth hormone deficiency
optic chiasm compression
- visual field loss
- headache
- ophthalmoplegia

Pathology

Hyperplasia of pituitary cells, particularly lactotrophs, occurs in the weeks preceding delivery resulting in an increased metabolic demand without a concomitant increase in blood supply . The anterior pituitary bloody supply is under relatively low pressure making these cells susceptible to ischemia. Pregnancies complicated by hypovolemia secondary to postpartum hemorrhage may lead to pituitary infarction and necrosis .

The posterior pituitary has its blood supply under higher pressure and is not usually affected however diabetes insipidus may occur as a rare manifestation of Sheehan syndrome .

Radiographic features

CT

ring enhancement surrounding a low attenuation empty sella

MRI

early
- enlarged pituitary, with low T1, high T2 homogenous signal
- ring enhancement
late
- empty sella of normal size

Treatment and prognosis

The basis of treatment is lifelong replacement of deficient hormones. Anterior pituitary hormones are generally affected in the following order after necrosis; growth hormone, prolactin, follicle-stimulating hormone, luteinizing hormone, adrenocorticotropic hormone and then thyroid-stimulating hormone .