A 34-year-old lady presented with acute vision changes and headaches at 33 weeks of pregnancy in the background of known physiological pituitary hypertrophy. Urgent MR pituitary scan identified diffuse enlargement of the pituitary gland (14x10x13 mm) with resultant compression of the pre-chiasmatic segments of the optic nerves and superior displacement of the chiasm. Pituitary size had increased substantially from imaging 3 years prior (10x10x10 mm).
Anterior pituitary blood tests showed findings consistent with current gestation of pregnancy, with insulin like growth factor-1 (90 ng/L) and prolactin (9480 mIU/L) concentrations elevated compared with non-pregnant reference ranges. Ophthalmological assessment identified early patchy right visual field losses. Following multidisciplinary discussion, a diagnosis of progression of pituitary hyperplasia was established. Cabergoline was offered to treat lactotroph hyperplasia, however was declined due to implications for breastfeeding. Surgery was not recommended due to pregnancy associated surgical risk and the suspicion that short term chiasmal compression would not cause persisting vision impairment following post-partum physiological shrinkage.
Fortnightly visual field monitoring showed progressive decline in visual fields over the next month. Elective caesarean section was performed at 37 weeks. Three months following delivery, there was complete resolution of visual symptoms. Repeat MR pituitary scan identified reduction in pituitary size (11x10x12 mm) with ongoing contact with the optic chiasm.
Physiological hypertrophy is characterised by a pituitary height greater than 9mm without endocrine dysfunction on serial monitoring (1). There are multiple reports of physiological hypertrophy impacting vision (2), however only limited cases during pregnancy (3, 4). In both cases, vision was preserved without surgical intervention. The predictors of vision recovery in physiological pituitary hypertrophy are unknown. This case highlights the complex decision making required for pituitary disease during pregnancy and provides evidence that cautious monitoring of short-term visual field deficits is a reasonable option for presentations in late pregnancy.