Open spina bifida is the most common congenital anomaly of the central nervous system compatible with life. Prenatal repair of open spina bifida via open maternal-fetal surgery has been shown to improve postnatal neurologic outcomes, including reducing the need for ventriculoperitoneal shunting and improving lower neuromotor function. Fetoscopic repair of open spina bifida minimizes the maternal risks while providing similar neurosurgical outcomes to the fetus. The following 2 fetoscopic techniques are currently in use: (1) the laparotomy-assisted approach, and (2) the percutaneous approach. The laparotomy-assisted fetoscopic technique appears to be associated with a lesser risk of preterm birth than the percutaneous approach. However, the percutaneous approach avoids laparotomy and uterine exteriorization and is associated with lesser anesthesia risk and improved maternal postsurgical recovery. The purpose of this article was to describe our experience with a modified surgical approach, which we call percutaneous/mini-laparotomy fetoscopy, in which access to the uterus for one of the ports is done via a mini-laparotomy, whereas the other ports are inserted percutaneously. This technique draws on the benefits of both the laparotomy-assisted and the percutaneous techniques while minimizing their drawbacks. This surgical approach may prove invaluable in the prenatal repair of open spina bifida and other complex fetal surgical procedures.
Introduction
Open spina bifida (OSB) is the most common congenital central nervous system abnormality that is compatible with life, with an incidence of approximately 3 per 10,000 births in the United States. Surgical closure of OSB has traditionally been completed postnatally within 24 to 48 hours after birth. The goals of the postnatal surgery are to protect the exposed neural elements (neural placode), reconstruct the thecal sac, and halt cerebrospinal fluid leak. Although the neural placode is believed to contain functional nervous tissue, postnatal closure has not been shown to restore neurologic function. ,
Techniques related to fetal surgery for OSB were extensively explored in animal and human models since the 1980s, culminating with the randomized clinical trial known as Management of Myelomeningocele Study (MOMS). The goal of this trial was to compare the safety and efficacy of prenatal repair via open maternal-fetal surgery (maternal laparotomy and hysterotomy) vs postnatal repair of myelomeningocele (MMC). The trial was stopped early on the basis of the efficacy of prenatal surgery for the infant. The rate of cerebrospinal fluid shunt placement at 12 months was lower in the prenatal group (40%) than the postnatal group (82%). At 30 months, there was improvement in motor function in the prenatal group. Although the benefits for the infant were apparent, the pregnancy and maternal risks of open maternal-fetal surgery were also significant. Chorioamniotic membrane separation, oligohydramnios, placental abruption, preterm premature rupture of membranes (PPROM), preterm labor, blood transfusions, pulmonary edema, and days spent in the intensive care unit were all substantially higher in mothers that underwent prenatal surgery. Furthermore, the risk of uterine dehiscence and rupture after open maternal-fetal surgery was not insignificant, , and mothers enrolled in the trial were recommended to undergo preterm cesarean delivery for the index and all future pregnancies.
While the MOMs trial was ongoing, our group and others embarked on developing a minimally-invasive surgical approach for the antenatal correction of OSB. The ultimate goal of the fetoscopic repair of OSB is to provide similar or better outcomes for the child as those obtained with open maternal-fetal surgery while minimizing maternal risks. Currently, there are 2 surgical approaches for the fetoscopic repair of OSB as follows: (1) laparotomy-assisted ( Figure 1 ), , , and (2) percutaneous ( Figures 2 and 3 ). , , , Each approach has its own set of advantages and disadvantages as detailed in Table 1 . The percutaneous fetoscopic technique is associated with the least maternal morbidity, but preterm birth remains a concern. Laparotomy-assisted fetoscopic repair may be associated with a decreased risk of preterm premature ruptured membranes and preterm birth but is also associated with relatively increased maternal morbidity owing to maternal laparotomy and uterine exteriorization.
| Open maternal- fetal | Laparotomy-assisted fetoscopic | Completely percutaneous fetoscopic | Percutaneous/mini-laparotomy fetoscopic | |
|---|---|---|---|---|
| Intraoperative technical considerations | ||||
| Uterine exteriorization and manipulation | Î Î Î | Î Î Î | 0 | 0 |
| Uterine access for port closure and membrane fixation | Î Î Î | Î Î Î | 0 | Î Î |
| Surgical access limited by placental location | Î | Î | Î Î | Î Î |
| Risk of loss of uterine access a | Î | Î | Î Î | Î |
| Magnitude of torque at uterine port site b | Î | Î | Î Î | Î |
| Ultrasound quality | Î Î | Î Î | Î Î | Î |
| Intraoperative maternal considerations | ||||
| Inhalational anesthetic need | Î Î Î | Î Î | Î | Î |
| Intraoperative tocolysis | Î Î Î | Î Î Î | Î | Î |
| Insensible losses | Î Î Î | Î Î Î | Î | Î |
| Postoperative maternal considerations | ||||
| Maternal morbidity risk c | Î Î Î | Î Î | Î | Î |
| Postoperative tocolysis | Î Î Î | Î Î | Î | Î |
| Postoperative pain | Î Î Î | Î Î | Î | Î |
| Postoperative hospital days | Î Î Î | Î Î | Î | Î |
| Obstetrical risks and considerations | ||||
| Prematurity risk | Î Î | Î | Î Î | Î |
| Obligate cesarean delivery | Î Î Î | 0 | 0 | 0 |
| Future pregnancy risk | Î Î Î | 0 | 0 | 0 |
a Loss of uterine access owing to pneumoperitoneum, uterine contractions, abruption, etc.
b The magnitude of torque is directly proportional to the distance from the fulcrum (the uterine port site). Therefore, torque at the uterus and membranes increases as distance from the fulcrum point increases. For the percutaneous approach, torque increases as the abdominal wall thickness (distance from fulcrum point) increases
c Maternal morbidity: pulmonary edema, ileus, wound infection, dehiscence, and blood transfusion.
In this report, we describe a modified surgical approach—the percutaneous/mini-laparotomy (PML) fetoscopic technique ( Figure 4 )—which draws on the benefits and decreases the risks of each of the currently used fetoscopic techniques.
Detailed description of percutaneous/mini-laparotomy fetoscopic spina bifida repair
A video depicting procedural steps is available ( Video ).
- 1.
Preoperative optimization
Surgical candidacy on the basis of predefined inclusion and exclusion criteria is confirmed. , , The risks, benefits, indications, and alternatives of each management option are reviewed. Informed consent is obtained for the PML fetoscopic spina bifida repair with possible emergent cesarean delivery if necessary for fetal indications. Consultations are obtained with fetal surgery or maternal-fetal medicine, pediatric neurosurgery, a pediatrician specializing in the care of children with spina bifida, neonatology, and social work.
The patient is admitted to the hospital in the evening before the scheduled surgery. Indomethacin 100 mg per rectum is given on admission for the promotion of uterine relaxation. Antibiotic prophylaxis with intravenous cefazolin 2 grams and gentamicin 80 mg is given on call to the operating room.
- 2.
Preparation of patient in the operating room and maternal anesthesia
The patient is taken to the operating room and positioned on the operating room table. A bump is placed beneath the maternal right side for uterine displacement. As many steps as possible are performed while the patient is awake but sedated to decrease the exposure time to general anesthesia. The operating room temperature remains at standard settings, as the uterus will remain in situ (not exteriorized) throughout the case.
The Foley catheter, arterial and central lines, and transversus abdominis plane blocks are placed while the patient is awake. Positioning of the patient depends on the expected site of surgical access. The abdomen is prepped with 2% chlorhexidine gluconate or 70% isopropyl alcohol solution, and the patient is draped in the usual sterile fashion.
General endotracheal anesthesia, primarily with intravenous anesthesia, is provided, keeping in mind the goal of minimal inhaled anesthetics. As the uterus remains in situ with minimal manipulation, the use of inhalation anesthetics is relatively low. , Although each case is unique, in general, the minimal alveolar concentration (MAC) ranges between 0.3 and 0.6, with the rare case requiring up to 1.0 MAC, for the purpose of uterine relaxation. No tocolytic agent such as magnesium sulfate or indomethacin is given during the surgery.
The fetal heart rate and/or umbilical artery Doppler waveforms are periodically (at least every 10 minutes) assessed throughout the procedure via transabdominal ultrasound, with the probe directed at an umbilical cord loop submerged in a rim of amniotic fluid or a fetal vessel on the placental surface.
- 3.
Fetal positioning, fetal anesthesia, and amnioinfusion for surgical access
The fetal position is assessed by ultrasound. If the fetus is in a breech presentation, an external cephalic version is performed to place the fetus in the cephalic presentation. Mapping of the placental location is performed. Using a marking pen, the expected locations of the trocar insertion sites are planned ( Figure 5 , A ). In general, the trocars are positioned at least 3 cm apart, , , optimally in a triangular configuration with the camera port in the middle.
