Fetal upper tract urinary system dilation is one of the most common findings on prenatal ultrasonography. Rarely, this may represent fetal lower urinary tract obstruction (LUTO), of which posterior urethral valves are the predominant etiology. LUTO is the most dire fetal urologic diagnosis, as it affects not only the baby’s management after birth but sometimes the course of the pregnancy itself. A variety of treatment options are available prenatally; these include observation, vesicoamniotic shunt placement, amnioinfusion, and attempts at direct treatment of the valves themselves. All fetal interventions carry substantial risks; caution should attend every discussion of treatment.