Fetal Goiter (Hypothyroid/Hyperthyroid)

Step-by-step decision

Choose step by step as prompted; reaching an endpoint gives the management recommendation. You can go back a step or restart anytime.

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Full pathway

1. [Decision] Anterior neck mass + Doppler + thyroid function signs
   Anterior neck mass + Doppler flow + thyroid function signs (distinguish hypo/hyperthyroid)? (Fetal goiter = a symmetric lobulated solid anterior neck mass. The most common cause = maternal Graves (antithyroid drugs causing fetal hypothyroidism, or TRAb causing fetal hyperthyroidism). In maternal Graves/antithyroid drugs/high TRAb, screen every 4–6 weeks from 18–22 weeks. A large goiter → neck hyperextension (impeding vaginal delivery), esophageal compression (polyhydramnios), airway compression.)
   • Peripheral flow + bradycardia/delayed bone age/IUGR (suggests hypothyroid, mostly secondary to maternal antithyroid drugs) → Hypothyroid → adjust maternal ATD + intra-amniotic LT4
   • Central flow + tachycardia/cardiomegaly/advanced bone age/hydrops (suggests hyperthyroid, TRAb-mediated) → Hyperthyroid → optimize maternal ATD
   • Cannot distinguish / large goiter causing neck hyperextension or polyhydramnios → Hard to distinguish/large tumor · integrate
2. [End] Hypothyroid → adjust maternal ATD + intra-amniotic LT4
   Suggests hypothyroid (peripheral flow, bradycardia, delayed bone age, IUGR; mostly secondary to transplacental maternal antithyroid drugs): first reduce/adjust the maternal antithyroid drug dose; cordocentesis (FBS) to confirm raised TSH/low FT4; intra-amniotic levothyroxine injection (shrinks the goiter/corrects polyhydramnios); serial ultrasound follow-up.
3. [End] Hyperthyroid → optimize maternal ATD
   Suggests hyperthyroid (central flow, tachycardia >160, cardiomegaly, advanced bone age, hydrops; transplacental TRAb): optimize/increase the maternal antithyroid drug (PTU/carbimazole); cordocentesis to confirm; monitor heart failure/hydrops; maternal TRAb titer; multidisciplinary for critical cases, delivery planning (airway).
4. [End] Hard to distinguish/large tumor · integrate
   Cannot distinguish or a large goiter causing neck hyperextension/polyhydramnios: integrate maternal thyroid function + TRAb + medication history + Doppler + fetal heart rate/bone age to judge thyroid status, cordocentesis (FBS) as the gold standard if needed; plan cesarean for a large goiter + airway contingency (EXIT if the airway is compressed).

Source guidelines & references

• Fetal goiter ultrasound differentiation of hypo/hyperthyroidism and management (UOG 2009; intra-amniotic levothyroxine)

This pathway is our own synthesis of the decision logic in the guidelines above (not the guideline verbatim); thresholds and workflows change as guidelines update — in practice follow the latest guideline, your institution's protocol and the individual patient.

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