Fetal Intervention and Surgery

Fetal Therapy Ethics

With the development of advanced fetal ultrasound (US), fetal MRI, and fetal echocardiography, the ability to accurately diagnose fetal disease has improved substantially over the past 3 decades. There have also been advances in maternal anesthesia and tocolysis, reduction in maternal morbidity, development of fetal surgery–specific equipment, improved clinical expertise of the fetal care team, and construction of state–of-the-art fetal treatment centers. Fetal surgery remains controversial, however, and every discussion of fetal surgery must include a careful consideration of the ethical conflicts inherit to these procedures.

Unlike most surgical procedures, fetal surgery must consider 2 patients simultaneously, balancing the potential risks and benefits to the fetus with those to the mother during the current and future pregnancies. The International Fetal Medicine and Surgery Society (IFMSS) established a consensus statement on fetal surgery, as follows:

• 1

  A fetal surgery candidate should be a singleton with no other abnormalities observed on level II ultrasound, karyotype (by amniocentesis), α-fetoprotein (AFP) level or viral cultures.

• 2

  The disease process must not be so severe that the fetus cannot be saved and also not so mild that the infant will do well with postnatal therapy.

• 3

  The family must be fully counseled and understand the risks and benefits of fetal surgery, and they must agree to long-term follow-up to track efficacy of the fetal intervention.

• 4

  A multidisciplinary team must concur that the disease process is fatal without intervention, that the family understands the risks and benefits, and that the fetal intervention is appropriate.

Obstructive Uropathy

Obstructive uropathy is most frequently caused by posterior urethral valves (PUV) but can be caused by a variety of other defects, including urethral atresia, persistent cloaca, caudal regression, and megacystis–microcolon–intestinal hypoperistalsis syndrome (see Chapters 555 and 556 ). Obstructive uropathy usually presents on fetal US with an enlarged bladder, bilateral hydroureteronephrosis, and oligohydramnios. Mild forms of obstructive uropathy may lead to minimal short- or long-term clinical sequelae. However, the lack of fetal urine output and resulting oligohydramnios or anhydramnios in more severe forms can cause significant pulmonary hypoplasia , which is associated with death shortly after delivery in >80% of infants. Pulmonary survivors are still subject to high mortality and chronic morbidity resulting from renal dysplasia, renal failure, and the need for chronic renal replacement therapy.

The primary objective of fetal intervention in fetuses with obstructive uropathy is restoration of amniotic fluid volume to prevent pulmonary hypoplasia. Although prevention of ongoing renal injury is also desired, the efficacy of fetal intervention in achieving this goal is uncertain. Several studies have attempted to use fetal urine evaluation to predict renal outcome in these patients, but the reliability of these markers has been disappointing due to the influence of gestational age on many of these markers. Therefore, fetal intervention for obstructive uropathy is currently limited to fetuses in whom the obstruction is sufficient to cause oligohydramnios or anhydramnios.

For fetuses who still have adequate renal function and are capable of producing urine, treatment options include vesicoamniotic shunting, valve ablation via cystoscopy, and vesicostomy. Vesicoamniotic shunting is the most common and involves percutaneous, US-guided placement of a double-pigtailed shunt from the fetal bladder to the amniotic space, allowing decompression of the obstructed bladder and restoration of the amniotic fluid volume ( Fig. 116.1 ). Although simple in concept, bladder decompression may not always occur, and many catheters will become dislodged as the fetus develops; a fetus typically requires 3 catheter replacements before completion of pregnancy. Vesicoamniotic shunting may improve perinatal survival, but at the expense of poor long-term renal function.

Fetal cystoscopy is more technically challenging than vesicoamniotic shunt placement, more invasive, and requires more sedation, but this option holds some important advantages. Cystoscopy allows for direct visualization of the obstruction and does not require amnioinfusion. Moreover, when the obstruction is visualized and the diagnosis of PUV confirmed, the valves can be treated, restoring urine flow to the amniotic space and eliminating the need for repeated fetal interventions in most patients. Creation of a vesicostomy (direct opening from bladder through fetal abdominal wall) by open fetal surgery has improved perinatal survival ( Fig. 116.2 ). However, the current dataset evaluating this approach is still limited, and direct comparisons to shunting suggest no significant difference between these interventions.