Pituitary Tumors and Pregnancy

Abstract

As dopamine agonists are usually stopped as soon as a pregnancy is confirmed, prolactinomas increase in size during pregnancy (Fig. 8.1). The prolactinoma volume roughly doubles when measured during the last trimester of pregnancy, and the volume of normal pituitary tissue also increases (Fig. 8.2). Increase in volume involves the intrasellar tumoral component as well as the intracavernous one, if any (Fig. 8.3). According to the size of the tumor, the risk of complications is well defined: very rare with microprolactinomas, and rare and depending on the original size with macroprolactinomas. This means that the size of a prolactinoma has to be precisely known before any dopamine agonist treatment is instituted: dopamine agonists given blind, even for a few weeks, can change a macroprolactinoma into a microadenoma. The rule “MRI first” must never be broken. Moreover, apart from the size, the T2 signal of the prolactinoma can also have some interest: it seems that the unusual T2-hypointense prolactinomas have the propensity to increase their size in larger proportion than the hyperintense ones during pregnancy (Fig. 8.4). Practically, if MRI follow-up has no place during pregnancy for the usual T2 hyperintense microadenomas, such a place may be discussed at the onset of the third trimester for the rare T2-hypointense prolactinomas, mainly if their maximal diameter is at the upper limit of microadenomas (i.e., 10 mm). If necessary, MRI—without gadolinium injection—can be obtained. In the rare cases where medical treatment appears mandatory to avoid further enlargement of the adenoma during pregnancy, the oldest molecule, bromocriptine, is classically preferred to cabergoline.