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Definition: Goiter
represents an enlargement of the thyroid gland.
Prevalence: Rare.
Etiology: Fetal goiter can be associated with hyperthyroidism, hypothyroidism
or an euthyroid state. Goiter associated with hyperthyroidism
can be the result of iodine excess or deficiency, intrauterine exposure to
antithyroid drugs or congenital metabolic disorders
of thyroid synthesis.
Ultrasound features: The goiter is manifested as a solid, anteriorly
located symmetric
mass, that may result hyperextension of the fetal
head. Polyhydramnios is common due to mechanical obstruction of the
esophagus.
Prognosis: Goiter may cause dystocia
by extension of the fetal head during the
process of labor. It can also cause upper airway obstruction,
leading to acute respiratory failure. The prognosis depends on the basic
cause of the goiter. Most cases of fetal goiters occur in women with a history
of thyroid disease. Fetal blood sampling can
aid in determining fetal thyroid status, especially in women
suffering from Grave’s disease where a transplacental transfer of drugs
or thyroid-stimulating antibodies may result in fetal goiter.
Maternal therapy usually corrects fetal hyperthyroidism. Direct
fetal therapy in cases of fetal hypothyroidism is available either by
amniocentesis or by cordocentesis. Cases of disappearance
of goiters after direct fetal therapy have been reported (18).
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fig. 5 |
| 18. | Abuhamad, A.Z., Fisher, D.A., Warsof, S.L., Slotnick, P.G, Pyle, S.-Y. Wu, Evans, A.T. Antenatal diagnosis and treatment of fetal goiterous hypothyroidism: case report and review of the literature. Ultrasound Obstet Gynecol 1995; 6:368-371. |
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