Amnioinfusion with Hartmann's solution: a safe distention medium for endoscopic fetal surgery in the ovine model

Influence of osmolarity and hydration on the tear resistance of the human amniotic membrane

The amnion is considered to be the load-bearing part of the fetal membranes. We investigated the influence of osmolarity of the testing medium and hydration on its fracture toughness. Mode I fracture tests revealed that physiological variations in the bath osmolarity do not influence the tear resistance of amnion, while larger changes, i.e. from physiological saline solution to distilled water, lead to a significant reduction of the fracture toughness. Uniaxial tensile tests on collagen hydrogels confirmed the reduction in toughness, suggesting that lower bath osmolarity triggers changes in the failure properties of single collagen fibers. Prenatal surgeries, in particular fetoscopic procedures with partial amniotic carbon dioxide insufflation, might result in dehydration of the amnion. Dehydration induced a brittle behavior; however, subsequent rehydration for 15 min resulted in a similar tear resistance as for the fresh tissue.

Amniopatch for iatrogenic rupture of the fetal membranes

With the increased use of invasive fetal procedures, the number of women facing post-procedure membrane rupture is increasing. Here we review the use of platelets and fresh frozen plasma for sealing iatrogenic fetal membrane defects by describing the mechanisms of action of the amniopatch procedure as well as published experience. In cases of iatrogenic preterm pre-labour rupture of the membranes, amniopatch effectively seals the fetal membranes in over two-thirds of cases. There is a risk of 16% of in utero fetal death, which may occur at varying intervals from the procedure and often for unknown reasons. Amniopatch has also been used as a treatment of chorionic membrane separation. In summary, current experience suggests that in cases of early onset but persistent amniotic fluid leakage following an invasive fetal procedure, amniopatch is an option.

[Amniopatch to treat iatrogenic rupture of the fetal membranes]

OBJECTIVE

With the increased use of invasive fetal procedures, the number of patients facing postprocedure membrane rupture is increasing. We aimed to describe the use of platelets and fresh frozen plasma for sealing iatrogenic fetal membrane defects.

PATIENTS AND METHODS

We describe the mechanisms of action of the amniopatch procedure as well as published experience.

RESULTS

Amniopatch effectively sealed the fetal membranes in over two thirds of published cases (n=44). There is a risk of 17% of in utero fetal death, which may occur remotely from the procedure and is often unexplained.

DISCUSSION AND CONCLUSION

In case of early onset but persistent amniotic fluid leakage following an invasive fetal procedure, amniopatch may be offered.

The pediatric surgeons' contribution to in utero treatment of twin-to-twin transfusion syndrome

OBJECTIVE

To evaluate the outcome of twin-to-twin transfusion syndrome (TTTS) treated using a combination of endoscopic fetal surgery-specific techniques and surgical restraint.

SUMMARY BACKGROUND DATA

TTTS is a condition of identical twins that, if progressive and left untreated, leads to 100% mortality. The best treatment option is obliteration of the intertwin placental anastomoses, but fetal surgery carries significant maternal and fetal risks. Even if successful, percutaneous endoscopic laser ablation of placental vessels (LASER) causes premature rupture of membranes (PROM) in 10% to 20% of pregnancies. Patient selection is particularly critical because the progression of the disease is unpredictable. This has prompted many to intervene early, yielding survival rates of >=1 twin of 75% to 80%.

METHODS

We developed a minimally invasive approach to fetal surgery, a unique membrane sealing technique and a conservative algorithm that reserves intervention for severe TTTS. Pregnancies with TTTS (stages I-IV) managed in the last 8 years were reviewed. LASER was offered in stage III/IV only.

RESULTS

Ninety-eight cases of TTTS were managed in a pediatric surgery/maternal-fetal medicine collaborative Fetal Treatment Program-39 were observed (40%) and 59 underwent LASER (60%). Survival of >= twin was seen in 82.7%, and overall survival was 69.4%. These survival rates are similar to, or better than, other comparable series with similar stage distribution (low:high stage ratio 1:1) in which all patients underwent LASER. PROM rate was 4%.

CONCLUSIONS

Reserving LASER treatment for severe TTTS results in outcomes similar to, or better than, LASER for all stages. Applying fetal surgery-specific endoscopic techniques, including port-site sealing, reduces postoperative complications.

Foetal surgery and cleft lip and palate: current status and new perspectives

Now-a-days, high-resolution ultrasound allows an accurate and relatively early diagnosis of congenital malformations. In a limited number of such conditions foetal surgery may be lifesaving. However, premature labour has been the major drawback for open foetal surgery. Recently, improvement of video-endoscopic technology has boosted the development of operative techniques for feto-endoscopic surgery, which has been demonstrated to be less invasive than the open approach. Main clinical application of fetoscopic procedures today is the treatment of feto-foetal transfusion syndrome. Although still in development, feto-endoscopic surgery seems to offer new hope for surgical foetal therapy not only in cases of life threatening conditions. Experimental intrauterine correction of cleft lip and palate (CLP) has been lately performed using the feto-endoscopic approach. This procedure offers two major advantages: first, scarless foetal wound healing and bone healing without callus formation, which would also allow a better/normal maxillary growth, and second, significant decrease of foetal and maternal morbidity. Herein, we report the current status of experimental and clinical foetal surgery and propose possible directions for continuing research to make intrauterine procedures safer. Furthermore, we discuss current knowledge and new perspectives of experimental foetal cleft lip and palate repair, which in the future may lead to such excellent results in the operative treatment of clefts, that less or no secondary corrections and therapies, such as orthodontic, dental, logopedic, etc. would be needed. Only if these conditions can be fulfilled, will we be able to improve substantially our therapy for the human foetus with a cleft lip and palate. In spite of all efforts, however, it must be considered that it may not ever be possible to find the optimal treatment method for this or other craniofacial malformations.

Effects on the maternofetal unit of the rabbit model after substitution of the amniotic fluid with perfluorocarbons

OBJECTIVES

Exchanging amniotic fluid (AF) with perfluorocarbon (PFC) may serve as a medium for fetoscopic surgery. This study evaluates the distribution and physiologic effects of intraamniotic PFC as a medium for fetoscopy.

METHODS

Fetuses of 17 pregnant rabbits underwent either exchange of the AF with PFC, electrolyte solution (ES), or control. The quality of vision during fetoscopy was assessed in AF and PFC. After 6 h, we determined the distribution of PFC in the maternofetal unit.

RESULTS

Quality of vision during fetoscopy was better in PFC than with AF. There was no difference in fetal survival between the study groups. PFC was demonstrated on X-ray in the pharynx of 4 fetuses, and the esophagus in 1.

CONCLUSIONS

PFC provided an ideal medium for fetoscopy without fetal compromise.

What--and why--the pediatric surgeon should know about twin-to-twin transfusion syndrome

Abstract Endoscopic laser ablation of placental vessels is the most commonly performed fetal operation today. Herein, we review the pathophysiology of twin-to-twin transfusion syndrome and the challenges of its treatment. Pediatric surgeons, with their knowledge of fetal and congenital pathology, and their technical expertise with minimally invasive surgery, can be of great benefit to the patient and the medical team.

Ex vivo testing of a temperature- and pressure-controlled amnio-irrigator for fetoscopic surgery

BACKGROUND

Currently, amnioinfusion fluids used in operative fetoscopy usually are preheated to body temperature. As the complexity of procedures increases, purposed designed devices should be designed that allow control of pressure and temperature during amnioinfusion or amnioexchange. In the current study, a prototype amnio-irrigator and fluid heater were evaluated.

METHODS

The medical fluid heater heats fluid by conduction up to 37 degrees C. The maximum irrigation pressure and flow rates can be preset. Actual irrigation pressure (0 to 30 mm Hg) and flow rate (0 to 300 mL/min) can be read on the front panel. A series of ex vivo experiments were set up to determine the relationship between the flow rate (FR) and lumen of the instruments as well as the maximum flow rate (MFR) with and without the pressure control. Further, the relationship between FR and the irrigation pressure (IP) was determined. In an artificial pseudoamniotic sac the relationship between FR and change in temperature was measured, with and without the use of the medical fluid heater.

RESULTS

When the IP was limited to 24 mm Hg, FR and pressure were correlated (r = 0.34; P <.001). The larger the functional lumen of the fetoscopic instrumentation, the higher the flow (r = 0.43; P <.001) and the lower the increase in IP (r = -0.47; P <.001). A quadratic relation between flow and temperature was observed both for preheated fluid as when using the fluid heater (r(2) = 0.71 and r(2) = 0.88; P <.001). However, at low flow rates, a thermal decrease of over 3 degrees C was observed when the fluid heater was not used.

CONCLUSIONS

The current study quantifies an expected relationship between the diameter of the irrigation channel and achievable flow rates. It also shows that a medical fluid heater is needed when strict control of temperature would be desired.

The combined method: a novel access technique for fetal endoscopic surgery

BACKGROUND/PURPOSE

To develop practical and less invasive techniques for fetal endoscopic surgery, new methods of lifting the uterine wall to allow fetal surgery without maternal laparotomy were developed and assessed.

METHODS

Fetal endoscopic surgical procedures, including tracheostomy and umbilical vascular cannulation, were performed using one of the three methods to enter the uterus without maternal laparotomy in pregnant goats (n = 6; 105 to 115 days' gestation): (1) direct uterine lifting with an air-cushion device; (2) indirect uterine lifting, in which the uterine wall was fixed to the maternal abdominal wall using balloon tip ports inserted percutaneously by Seldinger's method, then the maternal abdomen was lifted mechanically; and (3) combined method, in which low pressure CO2 (5 mm Hg for initial inflation and 2 mm Hg for maintenance) was insufflated into the uterus in addition to the indirect uterine lifting cited above.

RESULTS

The direct uterine lifting caused massive injury of myometrium and uterine membranes. The creation of intrauterine space and the protection of the membranes were not accomplished effectively by the indirect uterine lifting only. The combined method provided the adequate intrauterine space and excellent endoscopic visibility for completion of the endoscopic procedures with minimal uterine injury.

CONCLUSION

The fetal endoscopic surgery may be accomplished simply and safely by the combined method, a novel technique of uterine lifting to allow fetal surgery without maternal laparotomy.