What six steps are involved in evaluating a mass in the fetal abdomen?

1. Identify the organ of origin if possible. Masses that touch the spine are usually renal in origin.
2. Characterize the abnormality (i.e., cystic, solid, mixed).
3. Check the contralateral kidney (more than 50% of anomalies are bilateral).
4. Check the fetal bladder.
5. Assess the amniotic fluid volume.
6. Check for posterior urethral valves, especially in male fetuses.