A new era in invasive fetal therapy began in the early 1980s when several independent groups introduced shunting procedures for hydrocephalus.

These first few cases represented an extension of invasive fetal therapy from simple intrauterine blood transfusion for a medical illness to the first attempts at in utero treatment of structural anomalies.

During this period, hydrocephalus was recognized more frequently with ultrasound examination. The prenatal natural history of this lesion was established by serial sonographic observation of untreated cases.

In obstructive hydrocephalus, it was known that shunting in the newborn period improved neurologic outcome, and it was reasoned that decompression in utero might avert progressive brain damage.

At the time, the understanding of the natural history, pathophysiology, and patient selection criteria was rudimentary and incomplete at best. However, experimental work by numerous investigators, in appropriate animal models, helped to define the pathophysiology of these lesions and establish the theoretical basis for intervention.