Fetal Interventions Perfromed at Tertiary Care Centers
Editorial advice and videos courtesy: Rodrigo Ruano, M.D., Ph.D., Senior Associate Consultant, Chair, Division of Maternal-Fetal Medicine, Professor of Obstetrics and Gynecology and Physiology and Biomedical Engineering, Mayo Clinic College of Medicine.
Acknowledgements: Nasrin Benion, RDMS, Supervisor, Maternal Fetal Center Imaging. Texas Children’s Pavilion for Women, Houston.
A Video Summary on Fetal Interventions
In this review, a summary with videos is presented for the treatment of severe congenital diaphragmatic hernia (CDH) by the introduction of fetal endoscopic tracheal occlusion (FETO), the treatment of severe lower urinary tract obstruction (LUTO) by the introduction of vesico-amniotic shunt, and fetal cystoscopy, and the treatment of twin-twin transfusion syndrome (TTTS) with photocoagulation of placental vessels (Solomon technique).
These closed fetal interventions are performed in certain specialized tertiary care centers. Each procedure represents an advance in the care of the prenatal patient, and in each, preliminary data suggest increased survival and quality survival. These approaches represent innovations in maternal-fetal therapy and for a review of guidelines and suggestions, see Current Commentary by Luks, et.al.  In addition, randomized controlled trials are recommended or ongoing for these procedures.
Fetal Endoscopic Tracheal Occlusion (FETO)
Congenital Diaphragmatic Hernia
Congenital diaphragmatic hernia (CDH) is a defect in the diaphragm permitting herniation of abdominal viscera into the fetal thorax. High mortality and morbidity occur in severe cases due to pulmonary hypoplasia and pulmonary hypertension. Fetal endoscopic tracheal occlusion (FETO) is a technique whereby an inflatable balloon is passed within the fetal trachea to assist in the management of severe CDH since fetal tracheal occlusion accelerates lung growth in both animal and human models and promotes contralateral pulmonary vascularity.  FETO is feasible and safe in specialized tertiary care units and patients undergoing FETO are more likely to survive than those who do not since a subset of fetuses with severe CDH are likely to die without intervention.  In a number of studies, the most frequent procedural complication is premature rupture of the membranes (PROM).
*Lung-to-head ratio (See “Imaging Considerations” Congenital Diaphragmatic Hernia Chapter)
Above. In 2004, preliminary results were published, and a lung-to-head ratio of < 1.0 and the presence of fetal liver within the chest and no other malformations were established as the initial inclusion criteria.  Successful placement of the endotracheal balloon was possible in all initial cases. PROM occurred in 52.4% of patients and survival was 30% in the first group of 10 fetuses and 63.6% in the second group of 11 fetuses.
Above. In a follow-up study, membrane rupture occurred in 35% of patients at <32 weeks and a decrease in the occurrence of PROM was noted over time. Survival to discharge was 50% and long term survival quality was encouraging.  Retrospective analysis found the position of the liver and LHR correlates to survival. The combination of liver up in the chest and an LHR < 1.0 resulted in a survival rate of only 9%, and when the LHR was less than 0.6, there were no survivors irrespective of fetal liver position.
Ruano et al demonstrated that FETO is possible using a smaller 1 mm. fetoscope . Ruano’s group performed a randomized controlled trial of FETO with similar criteria (lung-to-head ratio <1.0) with tracheal balloon placement at 26 to 30 weeks and demonstrated increased survival in the FETO group (50%) versus (4.8%) in the non-intervention group.  Improved survival was further observed when FETO was performed at 22 to 24 weeks in CDH fetuses with an extremely severe form (LHR <0.7), liver herniation into the thoracic cavity, and no other detectable anomalies. 
These authors recommended balloon removal after 6 weeks in early FETO patients since maximal benefit and minimal risk may be achieved with that interval. Finally 4-D ultrasound may improve guidance in FETO procedures.  With respect to FETO, other randomized clinical trials in Europe and North America are ongoing but it is now acknowledged that the gestational age at birth, the pre-existing lung size, the ability to remove the balloon prior to birth, and the lung response are predictive of outcome. 
Complimentary support for the effects of FETO is suggested by intrapulmonary arterial Doppler, which predicts increased survival among treated patients , and MRI demonstration of increased lung volume in FETO patients compared to controls. 
Ongoing clinical trials can be followed at ClinicalTrials.gov Inentifier: NCT00881660
Management Options: CDH
Above. Summary of Management Options. For more details see “Management Options” under chapter “Congenital Diaphragmatic Hernia”
Above. This fetal video demonstrates placement of a small fetoscope within the trachea and placement of a detachable balloon to complete the fetal endoscopic tracheal occlusion.
Lower Urinary Tract Obstruction (LUTO)
Above. Lower urinary tract obstruction (LUTO) is a potentially lethal fetal abnormality, which can result in ureteral dilation, hydronephrosis, anhydramnios and neonatal death due to pulmonary hypoplasia or renal failure. Prognosis is difficult to define among fetuses with lower urinary tract obstruction but the best predictors of poor outcome are oligohydramnios and the presence of renal cortical cysts.  However, until recently, the prognosis for the severe variety of this disorder was dismal and few intervention techniques were successful.
Major etiologies include posterior urethral valves (PUV) [63%], urethral atresia (absence of the urethra) [9.9%], urethral stenosis [7.0%], Prune Belly Syndrome [2.5%], unspecified 17.6%, while 77.8% of LUTO cases were isolated. 
The “keyhole” sign, which is considered recognizable on 2-D ultrasound, is not specific for PUV but is commonly seen in a number of other non-PUV conditions such as vesicoureteral reflux, bilateral junction stenosis and others.  However, the etiology cannot always be determined by ultrasound or MRI, while fetal cystoscopy is sometimes necessary to define the obstructive lesion. 
Above. Options for fetal surgery include vesico-amniotic shunting and fetal cystoscopy. Literature surveys indicate that survival and normal renal function occur in 40% to 50% after vesico-amniotic shunting and 65% to 75% after fetal cystoscopy.  Vesico-amniotic shunt placement using a double basket catheter is successful in a limited number of patients.  Fetal cystoscopy allows views of the upper urethra and may be successful, allowing guide wire passage or hydro-oblation.  In a study comparing fetal cystoscopy, vesicoamniotic shunting and no intervention, cystoscopy and vesicoamniotic shunting improve the 6-month survival rate in cases of severe LUTO, and in fetuses with posterior urethral valves, fetal cystoscopy may prevent impairment of renal function.
Further trials are ongoing, ClinicalTrials.gov Identifier: NCT02315521.
Above. This video demonstrates a bladder to amniotic cavity shunt by the placement of a stent within the fetal bladder to decompress a lower urinary tract obstruction.
Vesico-amniotic Shunt Video
Above. This video demonstrates an obstructed fetal bladder due to posterior urethral valves (PUV) and fetoscopic fulguration of PUV to decompress this lower urinary tract obstruction.
Fetal Cystoscopy Video
The neonatal mortality for PUV has improved due to antenatal diagnosis and early neonatal decompression of the urinary tract.  Renal functional impairment correlates with poor bladder compliance, detrusor over-activity, vesicoureteral reflux, and renal dysplasia. 
Placental laser photocoagulation for twin-twin transfusion syndrome (TTTS)
Twin to twin transfusion syndrome is covered in detail elsewhere with information, imaging considerations, images and video. The purpose of this update is to demonstrate video photocoagulation of the placental vessels using the Solomon technique.
Survival rates are greater with laser coagulation of connecting vessels in TTTS compared with other treatment options such as septostomy and amnioreduction. Coagulation of the entire vascular equator (Solomon technique) may confer certain benefits compared to standard laser therapy, and may reduce postoperative fetal morbidity in severe twin-to-twin transfusion syndrome. , 
Above. This video demonstrates fetoscopic laser photocoagulation of placental vessels in twin-twin transfusion syndrome utilizing the Solomon technique.
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