Fetal Adrenal/Retroperitoneal Mass Differentiation

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] Cystic-solid/flow/side/evolution
   Cystic-solid / flow / side / evolution over time? (Adrenal mass differentiation. Fetal MRI helps characterize (especially early, check metastases). Key differentiators: feeding artery, Doppler flow, side, evolution over time.)
   • Mostly right, cystic/solid/mixed ± calcification, separate from the kidney, no single feeding artery, peripheral/no flow (third trimester) → Neuroblastoma
   • Mostly left, echogenic, single aortic feeding artery (second trimester) → Pulmonary sequestration (SEPS)
   • Evolves over time (solid → cystic → shrinks ± calcification), no flow, may be bilateral → Adrenal hemorrhage
2. [End] Neuroblastoma
   Neuroblastoma (mostly right, cystic/solid/mixed ± calcification, separate from the kidney, no single feeding artery, peripheral or no flow, mostly third trimester): the most common non-hematologic infant malignancy; cystic has a better prognosis; fetal MRI characterization + check metastases (liver/placenta) + assess the contralateral adrenal; most small ones observed/may regress, postnatal urine catecholamines/MIBG + oncology.
3. [End] Pulmonary sequestration (SEPS)
   Pulmonary sequestration (extralobar SEPS, mostly left, homogeneous echogenic, a single feeding artery from the aorta = key differentiator, mostly second trimester): mostly benign, can regress; serial ultrasound follow-up, postnatal contrast CT to confirm the feeding artery, resect if symptomatic.
4. [End] Adrenal hemorrhage
   Adrenal hemorrhage (right 75%, evolves over time: solid → cystic → shrinks → calcification, no flow, bilateral favors hemorrhage): mostly benign self-limited; serial ultrasound showing shrinkage is diagnostic (key differentiation from neuroblastoma: hemorrhage has no flow and shrinks); check renal vein thrombosis/BWS/birth trauma; postnatal ultrasound follow-up.

Source guidelines & references

• Fetal adrenal mass differentiation (neuroblastoma/sequestration/hemorrhage; AJOG SMFM 2021)

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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