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MGMJMS: Vol. 4 Issue 1: p. 35
Journal Information
Journal ID (publisher-id): MGMJMS
ISSN: 2347-7946
ISSN: 2347-7962
Publisher: Jaypee Brothers Medical Publishers (P) Ltd.
Article Information
Copyright © 2017; Jaypee Brothers Medical Publishers (P) Ltd.
open-access:
Print publication date: Season: January-March Year: 2017
Volume: 4 Issue: 1
First Page: 35 Last Page: 38
Publisher Id: mgmjms_mar17_008
DOI: 10.5005/jp-journals-10036-1134

Fetal Surgery: A Basic Overview and a Glimpse into Its Future
Sushil Kumar,1Professor and Head
Mayuri More,2Junior Resident
Sunil Sharma3Associate Professor
1-3 Department of Obstetrics and Gynecology, MGM Medical College and Hospital, Navi Mumbai, Maharashtra, India
Correspondence: Sushil Kumar, Professor and Head Department of Obstetrics and Gynecology, MGM Medical College and Hospital, Navi Mumbai, Maharashtra, India, Phone: +919168199399, e-mail: cdrsushilkumar@rediffmail.com

ABSTRACT

The routine antenatal screening for congenital disorders in the fetus has made a sea change the way we look at the fetus. With the availability of high-resolution ultrasound machines, we have technology to diagnose fetal structural defects, with high degree of certainty. Some of these babies can go through the entire pregnancy and can be operated upon after delivery without additional morbidity and mortality. Fetus with diaphragmatic hernia needs fetal surgery for better survival, while the fetus with myelomeningocele can be operated upon postnatally, but neurological outcome for the baby is better if operated upon in utero. Fetal surgery is performed in the second trimester of pregnancy either by open route or by endoscopy. Endoscopy route is still evolving and generally used to coagulate the communicating vessels in cases of twin–twin transfusion syndrome. Open fetal surgery involves hysterotomy, control of hemorrhage from edges of hysterotomy wound, aspiration of amniotic fluid, delivery of effected fetal part to the hysterotomy wound, corrective surgery, closure of uterine incision, and instillation of aspirated amniotic fluid back to uterus. Postoperatively, the patient is given tocolytics and antibiotics to avoid preterm labor and infection respectively. At appropriate date, the baby is delivered by cesarean section. Despite several benefits, fetal surgery cannot be considered safe for the mother and the fetus. It is associated with considerable maternal morbidity like hemorrhage, preterm delivery, chorioamnionitis, and so forth. It also needs coordinated team effort with a dedicated team of obstetrician, anesthetist, pediatrician, and other specialized surgeons of concerned deformity in the fetus. Currently, fetal surgery is a new frontier of fetomaternal medicine and may be labeled as evolving science, and the facility should be limited to highly specialized tertiary care centers to gain more experience. However, the future of fetal surgery as an effective tool to correct the congenital defects for the fetus is promising.

How to cite this article

Kumar S, More M, Sharma S. Fetal Surgery: A Basic Overview and a Glimpse into Its Future. MGM J Med Sci 2017;4(1):35-38.


INTRODUCTION

The unborn child has truly become a patient because of the availability of high-resolution imaging and screening procedures. Conditions like fetal malformations, genetic diseases, or in utero acquired conditions when suspected can be diagnosed and treated in utero. Certain conditions require surgical correction and in most cases, this is done after birth. Occasionally, fetal surgery is required to save the life of the fetus and to prevent permanent damage. There are around 600 fetuses requiring surgery per year, and many of them undergo fetal surgery. Fatal conditions in which the chances of survival of the baby are low like urinary tract obstruction, congenital diaphragmatic hernia (CDH), twin-to-twin transfusion syndrome (TTTS) are operated antenatally. Until the late 1990s, prenatal surgery was almost exclusively limited to life-threatening conditions. However, in 1994, the first prenatal surgery to treat myelomeningocele was performed, even though it is not a life-threatening condition.


HISTORY

Intrauterine transfusion of hydropic fetus to correct anemia in case of Rh isoimmunization was the first intrauterine procedure described in 1961. On April 26, 1981, the first successful open fetal surgery was performed for a urinary tract obstruction, under the direction of Dr Michael Harrison.1 Congenital diaphragmatic hernia was first corrected successfully in utero in 1989. The resection of a congenital cystic adenomatoid malformation (CCAM) from a fetal lung was performed in 1990 for the first time. Fetal sarcococcygeal teratoma resectioning was first done in 1992. Between 1997 and 2004, more than 200 open surgeries were performed for myelomeningocele. In the last decade of development in fetal surgery, minimally invasive procedures like fetoscopy and laser ablation have come in.


DESCRIPTION

The decision to have prenatal surgery is taken when accurate diagnosis is made and associated anomalies excluded by carrying out echocardiogram, amniocentesis, and chorionic villi sampling (CVS). The cases selected are those with no possible effective postnatal therapy, and the specific surgery has a proven benefit with documented animal studies. Interventions are performed in specialized multidisciplinary centers with strict protocols. Approval of local ethics committee and informed parental consent is taken. Consultations include a neonatologist, a pediatric surgeon, a clinical nurse specialist, and a social worker. Usually only fetuses with a very poor prognosis are candidates for maternal–fetal surgery. Only about 10% of those referred for evaluation actually undergo the surgery, as additional congenital defects preclude prenatal surgery. Prenatal surgeries usually are performed between 18 and 26 weeks of gestation. Prenatal surgery usually requires a general anesthesia. The fetus receives the anesthetic via the mother’s blood. The anesthesiologist and a neonatologist monitor the heart rates of the mother and fetus respectively. Epidural anesthesia can sometimes be used instead of general anesthesia.2 Prophylactic tocolysis (preoperatively and postoperatively) is required, as the mother can go into preterm labor.

Open Fetal Surgery

Open fetal surgery is a complex procedure and should be undertaken by experienced personnel. After opening the maternal abdomen, a narrow tube is placed through a puncture in the uterine wall, through which the amniotic fluid is drained out and collected in syringes. A procedure similar to cesarean section is performed, called hysterotomy, to open the uterus. Using ultrasound as a guide, the surgeon feels for the affected fetal part. The fetus must be moved away from the placenta. The first incision is made at a point away from the placenta to prevent damaging it. Specialized reabsorbable surgical staples are applied to the cut uterine edge to prevent maternal hemorrhage. The fetus is exposed or exteriorized and monitored. The fetus is kept warm with infusion of Ringer’s lactate, at body temperature, into the uterine cavity. The specific procedure is then carried out. After the completion of the procedure, the uterus is closed. The amniotic fluid is then reinfused. An additional omental flap may be applied to cover the wound.

Amniotic fluid leakage, either from hysterotomy site or vaginally, is a common complication. Open fetal surgery has proven to be reasonably safe for the mother. All future pregnancies for the mother require cesarean delivery because of the hysterotomy. However, there are no presented data suggesting decreased fertility for the mother.3,4 For the fetus, safety and effectiveness are variable, depends on the specific procedure, the reasons for the procedure, the gestational age, and condition of the fetus. Conditions that can potentially be treated by open fetal surgery include (i) CDH (if indicated at all, it is now more likely to be treated by endoscopic fetal surgery), (ii) CCAM, (iii) congenital heart disease, (iv) pulmonary sequestration, (v) sacrococcygeal teratoma, and (vi) myelomeningocele.

Minimally Invasive Fetal Surgery

Minimally invasive fetal surgery, also called as keyhole surgery, uses specially designed fetoscopes. They are flexible fiber endoscopes with high pixelated camera for better picture quality. Current scope diameters are between 1.0 and 2.0 mm with a 0° direction of view and an opening angle of 70 to 80°.5 The intraamniotic access is facilitated by thin-walled, disposable semiflexible cannula or larger-diameter reusable rigid metal cannula to facilitate instrument change. Instrument insertion is done under local anesthesia.

Despite the minimally invasive nature of fetoscopy, it is associated with iatrogenic preterm rupture of membranes. Several initiatives have been taken toward treating and preventing this, including attempts to repair defects with tissue sealants. Use of amniopatch was first described by Quintero et al in 1996. Amniopatch is a procedure for sealing amniotic leakage after membrane rupture by using cryoprecipitate and platelets obtained after plasmapheresis.6

The first successful fetoscopic temporary tracheal occlusion for CDH7 was performed in 1996. A small surgical incision was made in the uterus, and a tiny fiberoptic fetoscope inserted to guide the surgeon. A needle-like instrument carrying a balloon was then passed through the uterus. The balloon was placed in the fetus’s trachea and inflated. This prevents lung fluid from escaping through the mouth, enabling the lungs to expand, grow, and push the abdominal organs out of the chest and back into the abdomen. The balloon is removed at birth. In a successful procedure, the lungs are developed enough for the baby to breathe on its own at birth.

For urinary tract obstructions, a needle may be used to insert a catheter through the mother’s abdomen and the uterus, into the fetal bladder. The catheter drains the urine into the amniotic fluid. The catheter may have an expandable wire mesh, which is deployed in the bladder to prevent the catheter from plugging up or dislodging.

Fetoscopic Laser Coagulation

Laser coagulation is done in TTTS. Laser coagulation of the vascular anastomoses was first reported by De Lia et al.8 They described coagulation of all vessels crossing the intertwining membrane between the twins. It became more popular when Nicolaides et al described a percutaneous approach, and since randomized trial proved this to be the most effective therapy.9,10 The fetoscopic laser coagulation is performed at around 16 weeks gestation; before that, the amniotic membrane may still be separated from the chorion, hampering amniotic access and increasing postoperative leakage.

Preoperatively, all patients undergo ultrasound study for disease staging and to exclude discordant anomalies. The cervical length is measured, because it is a strong predictor of preterm delivery. For most cases, fetoscopic laser coagulation is performed percutaneously through 3 to 4 mm incision with local anesthesia. A neodymium–yttrium aluminum garnet laser (minimal power requirement, 60−100 W) or a diode laser (30−60 W) with fibers of 400 to 600 μm provides optimal efficacy. Three fixed landmarks are used to identify the anastomosing vessels, i.e., the recipient and donor twin’s cord insertions and the intertwining membranes. Coagulation of the anastomosing vessels is performed at a distance of 1 cm and ideally at 90° angle to the vessel, using a “no touch” technique starting at one placental border and finishing at the other end. The procedure is completed with amnioreduction in the polyhydroamniotic twin, until normal amniotic volume is measured ultrasonically.

Ex utero Intrapartum Treatment

Ex utero intrapartum treatment (EXIT) is a surgical delivery procedure done for babies who have severe respiratory disorder. It is used to permit controlled reversal of clipping of the fetal trachea, which was a treatment for CDH or disorders leading to congenital airway obstruction including laryngeal atresia (congenial high airway obstruction syndrome), large head and neck tumors, and other upper airway problems that might cause difficult intubation. The purpose of EXIT procedure is typically to establish functional and reliable fetal airway control while keeping the fetus attached to the uteroplacental circulation; EXIT is done under maximal uterine relaxation, typically provided by deep inhalational general anesthesia. Therefore, the maternal risks of this procedure are mainly hemorrhagic.11

The largest single center with 43 EXIT procedures is reported by Children’s Hospital of Philadelphia. The most common indications were neck masses and reversal of tracheal clipping. Maternal complications included placental abruption, intraoperative blood transfusion, and chorioamnionitis. There were no cases of uterine atony or maternal death. One intraoperative fetal death occurred in a fetus with a large cervical lymphangioma who could not be intubated and whose parents had declined a tracheostomy. The maternal anesthetic protocol typically involves rapid sequence induction, followed by intubation and maintenance of anesthesia. To support adequate uteroplacental perfusion, effective maternal arterial pressure is maintained. Fetal umbilical artery and venous catheters ensure adequate vascular access for perinatal resuscitation. After EXIT, the fetal delivery is completed and the umbilical cord divided.

Extracorporeal membrane oxygenation (ECMO) is used for fetuses with severe cardiopulmonary pathology, where the fetal heart is unable to pump. The ECMO is similar to cardiopulmonary bypass machine, but the patient can be hooked up for longer duration. In severe disorders of the fetal airway, techniques have been developed to provide oxygenated blood to the fetus by maintaining fetoplacental circulation through ECMO, until the infant’s airway is secured.12 At times, EXIT is done along with ECMO for certain cardiac defects, for conjoined twins, or in surgery for CCAM of the lung.


THE FUTURE

Stem cell therapy was used to treat genetic diseases, metabolic disorders, hemoglobinopathies, and immunodeficiency.13,14 In a newer study of myelomeningocele, spina bifida is combined with stem cell transplantation. Human placenta-derived mesenchymal stromal cells (PMSCs) are used. This combination has shown a significant improvement in motor function at birth. The intrauterine period is considered as the ideal time for stem cell therapy, because the fetal environment has poorly developed immunological system and more receptive to stem cells. The fetal MSCs have pluripotent stem cell markers and have greater expansion capacity than adult stem cells. The PMSCs have been shown to be immunomodulatory, neuroprotective and to improve wound healing, and are readily available from the placenta throughout pregnancy. Placenta is an autologous source of these cells.15 There is a report of in utero transplantation of paternal bone marrow with hematopoietic cell progenitors to fetus having X-linked severe combined immunodeficiency, confirmed by CVS at 12 weeks gestation.16


CONCLUSION

Fetal surgery is one of the latest developments in the field of obstetrics and neonatology. From the first open fetal surgery conducted in 1981 to the minimally invasive techniques developed over the last four decades, fetal surgery has come a long way. During the past few years, the research and development has revolved around prevention of the complications of open fetal surgery like amniotic fluid leakage, preterm premature rupture of membranes, and preterm labor. This has been achieved with the use of minimally invasive procedures. With newer imaging modalities and procedures like fetoscopy and laser ablation, the need for open surgery has decreased tremendously. The use of fetal stem cell transplantation promises to extend the horizon of fetal surgery.17 Although experimental currently, fetal surgery is a field with unending possibilities.


Notes

Source of support: MGMIHS

Conflict of interest: None

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Article Categories:
Keywords: Fetal surgery, Minimally invasive fetal surgery, Open fetal surgery.
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