Approach Considerations
Fetal surgery for sacrococcygeal teratoma (SCT) remains challenging; it should be considered only in select fetuses with impending hydrops and performed only at experienced centers. [57, 58] The purpose of fetal intervention is to debulk the tumor, with the understanding that formal oncologic resection will be performed postnatally. [59] The key to successful fetal intervention is identifying fetuses before the onset of hydrops, as well as identifying fetuses who may best be served by early delivery rather than fetal intervention.
Open Fetal Surgery
Fetal exposure for SCT resection is similar to what has been reported for other open fetal surgical procedures. [20]
The uterus is exposed through a Pfannenstiel incision. If the placenta is located posteriorly, the superior and anterior skin and subcutaneous tissue flaps are created, and a midline fascial incision is then created to expose the uterus (see the image below).
Gravid uterus is exposed through Pfannenstiel incision. Media file courtesy of Dr Douglas Miniati and Dr Payam Saadai, Division of Pediatric Surgery, University of California, San Francisco, School of Medicine.
An anterior hysterotomy is performed while the uterus remains in the abdomen. However, if the placenta is located anteriorly, the rectus muscles will have to be divided in order to prevent uterine vascular compromise as the uterus is lifted out of the abdomen to perform a posterior hysterotomy.
A large ring retractor is used to maintain exposure. [20]
Intraoperative sterile ultrasonography (US) is used to delineate the position of the fetus and the placenta (see the image below), and continuous echocardiography is used to monitor fetal well-being throughout the operative procedure.
Intraoperative ultrasonography is used to mark extent of placenta and position of fetus prior to hysterotomy. Media file courtesy of Dr Douglas Miniati and Dr Payam Saadai, Division of Pediatric Surgery, University of California, San Francisco, School of Medicine.
If the pregnancy is complicated by polyhydramnios and placentomegaly, the true edge of the placenta is not always appreciated on US, and the hysterotomy should be planned even farther away from this edge.
Stay sutures are placed on the uterus, and a small hysterotomy is made, which is then extended with a stapler designed especially to be used on the uterus (see the image below). [60] In view of the use of anesthetic agents that cause uterine relaxation, the uterine stapler is crucial for limiting blood loss. This hemostatic stapler is also important for securing the membranes to the uterine wall to prevent separation of membranes. Once the hysterotomy is performed, the fetus is positioned so that the tumor is exposed through the hysterotomy.
Specially designed uterine stapler provides hemostasis and prevents separation of membranes during hysterotomy. Media file courtesy of Dr Douglas Miniati and Dr Payam Saadai, Division of Pediatric Surgery, University of California, San Francisco, School of Medicine.
A "fetal cocktail,” which consists of a paralytic agent (either pancuronium or rocuronium) and fentanyl, is administered to the fetus via an intramuscular (IM) injection. A pulse oximeter is placed on the fetus to monitor fetal well-being (see the first image below). Intravenous (IV) access is obtained for administration of fluids, blood, or medication (see the second image below). Use of this strategy of fetal monitoring during open fetal surgery allows administration of fluids in response to changes in preload during the resection and may improve fetal survival. [61]
Pulse oximeter is placed on foot of fetus to ensure fetal well-being. Media file courtesy of Dr Douglas Miniati and Dr Payam Saadai, Division of Pediatric Surgery, University of California, San Francisco, School of Medicine.
Intravenous access is established in saphenous vein of fetus before debulking of sacrococcygeal teratoma. Media file courtesy of Dr Douglas Miniati and Dr Payam Saadai, Division of Pediatric Surgery, University of California, San Francisco, School of Medicine.
The fetus is kept buoyant and warm in the uterus with continuous infusion of warmed lactated Ringer solution (LRS) into the uterus.
After the SCT is resected, a two-layer uterine closure is performed. Before the uterus is completely closed, however, LRS is instilled into the uterus until US shows that normal amniotic fluid volume has been restored.
An omental flap can be secured over the hysterotomy, and the fascia, subcutaneous tissue, and skin are closed.
Ex-Utero Intrapartum Treatment Procedure
In some cases, early delivery of the fetus without SCT resection has led to adverse events between delivery and neonatal resection (eg, tumor hemorrhage and fetal exsanguination). In cases where delivery and tumor resection may lead to hemodynamic instability, the ex-utero intrapartum treatment (EXIT) procedure may be considered. EXIT-to-resection of fetal SCT is used in fetuses after 32 weeks' gestation (and may be considered for a fetus of 27-32 weeks' gestation) with a large vascular type I or II tumor necessitating early delivery in the absence of maternal contraindications. [43, 23]
The EXIT procedure, originally developed to establish an airway in a fetus with airway compromise while the fetus is still connected to placental circulation for oxygenation, has been adapted for intervention in fetuses with other anomalies who may experience instability during birth. [62] For fetuses with SCT, the EXIT procedure allows tumor debulking to interrupt the vascular steal phenomenon, which minimizes preoperative manipulation and trauma to the tumor. [43] The infant can be safely delivered and stabilized before definitive oncologic resection.
The EXIT procedure is performed with the mother under general anesthesia to maximize uterine relaxation and uteroplacental blood flow. [63] The hysterotomy, fetal monitoring, and fetal IV access are performed as described for open fetal surgery.
After debulking of the tumor, the fetus is intubated and given surfactant before the umbilical cord is clamped. The hysterotomy, fascial, and skin closures are performed in the same fashion as in open fetal SCT resection.
Roybal et al reported one survivor with this technique, who had neurologic complications due to tumor invasion into the spinal canal. [43] Surgeons at the University of California, San Francisco (UCSF), treated two fetuses with EXIT-to-resection of SCT, one of whom survived [14] ; the toher died of necrotizing enterocolitis and sepsis. One additional case was reported by surgeons at Zhejiang University (China), with favorable outcomes for both the fetus and the mother at 18-month follow-up. [64]
Benefits of the EXIT procedure include the following [64] :
-
Direct ligation of the tumoral blood supply
-
Absence of need to obtain or secure a fetal airway before resection
-
Ability of the placenta can compensate for fetal blood loss during resection
Risks of the EXIT procedure include the following [64] :
-
Potential for increased maternal blood loss due to relaxation of the uterus (decreased with the use of uterine staplers for hysterotomy)
-
Risk of maternal infection
-
Prolonged postpartum recovery time
Radiofrequency Ablation
Several centers have described salvage of hydropic fetuses with SCT with open fetal resection. However, preterm labor remains the Achilles heel of fetal surgery. To circumvent preterm labor and to decrease maternal morbidity associated with fetal intervention for SCT, minimally invasive techniques such as percutaneous cyst aspiration for cystic SCTs and radiofrequency (RF) ablation (RFA) for solid SCTs, have been developed. [65, 66]
The RFA technique employs US guidance to target the vessels feeding the SCT and thereby reduce tumor vascularity. An eight-prong LeVeen RF probe is deployed through a 15-gauge needle into an umbrellalike configuration to a diameter of 20-35 mm. [65] The probe delivers energy in a spherical volume to cause tissue and tumor necrosis.
RFA for SCT has been controversial. The potential risks of this procedure include gas embolization due to microbubbles, hyperkalemia caused by tissue necrosis, perineal damage, hemorrhage, preterm labor, and fetal demise. [66]
In a report of four fetuses with SCT, RFA successfully reduced tumor vascularity in all cases [65] ; however, intrauterine fetal demise due to hemorrhage into the tumor occurred in one case, and another fetus underwent termination after postoperative magnetic resonance imaging (MRI) showed fetal brain damage. The two remaining fetuses survived but had evidence of perineal damage at birth.
Lam et al reported using RFA to treat an SCT in an 18-week-old fetus, but the fetus died 2 days after the procedure. [67] Ibrahim et al reported a fetus born with sciatic nerve injury and malformation of the acetabulum and femoral head after RFA treatment for SCT. [68] A study from Korea reported six cases of fetal SCT treated with RFA; five of the six patients survived, and one patient had a left-leg palsy and fecal and urinary incontinence. [29]
In summary, although RFA has been used as salvage therapy in fetuses who would have otherwise died, many of these patients were born with complications. The keys to successful treatment with RFA may be (1) limiting the extent of coagulation in any single attempt to prevent massive hemorrhage or perineal necrosis and (2) performing a series of limited ablations. [65, 67] RFA as a treatment modality for fetal SCT remains limited and problematic, and more studies are necessary to determine whether and how this technique should be used.
Laser Ablation
Laser ablation for SCT was first described in 1996 at 20 weeks' gestation. [69] The pregnancy was complicated by polyhydramnios but not by placentomegaly or hydrops. Two unsuccessful attempts were made at 20 and 26 weeks' gestation to ablate the main vessels feeding the SCT, but the infant survived.
In this technique, local anesthesia is infiltrated into the skin and subcutaneous tissues. [31] Cordocentesis is performed to deliver fetal anesthesia with fentanyl (15 µg/kg) and pancuronium (2 mg/kg). [31] This can also be delivered to the fetus IM. Under US guidance, a 1.9-mm 60° fetoscope is introduced into the amniotic cavity percutaneously through a sheath, and a 0.4 mm neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser fiber is used to coagulate the vessels. [69]
In a retrospective study of 12 patients undergoing fetal intervention for SCT, four patients underwent laser ablation, but only one survived. [30] In a case report, a 24-week-old hydropic fetus underwent percutaneous laser ablation for SCT but died 2 days after fetal intervention. [31] In another study, a 22-week-old fetus underwent percutaneous laser ablation of tumor vessels and survived.
Another retrospective multicenter study identified five fetuses who underwent minimally invasive fetal intervention for hydrops or cardiac insufficiency as a result of SCT. [55] Four of these five fetuses underwent laser ablation, and three of them were targeted vascular ablations. Survival for the fetuses who underwent fetal intervention was 40%, but many patients required multiple procedures because of the recurrence of hydrops, cardiac insufficiency, or both.
Systematic review of laser ablation for SCT showed that ablation caused cessation of tumoral blood flow in 36.4% of cases but led to preterm premature rupture of membranes (PROM) in 18.2% of cases and preterm labor in 87.5% of cases. [70]
In contrast to laser ablation of the vascular inflow to the tumor, a retrospective single-center study out of Poland described percutaneous intratumor laser ablation in seven fetuses with large solid SCTs. [71] Three patients survived to delivery and underwent surgical excision, three survived to delivery but died before undergoing surgical resection, and one died in utero. [71]
Laser ablation for SCT, like RFA for SCT, represents the movement in fetal surgery toward minimally invasive techniques. However, the outcomes vary, and current experience is too limited to determine whether laser ablation will be effective in reducing mortality in fetuses with SCT.
Alternative minimally invasive techniques for ligating the tumoral vascular supply are currently being developed, such as the smart shape-memory polymeric string, [72] but outcomes from preclinical studies have not yet been reported.
Postoperative Care
After the operative procedure, 6 g of magnesium sulfate is given IV as a loading dose, and a continuous infusion is maintained for tocolysis. An epidural infusion also prevents uterine irritability, and indomethacin rectal suppositories are given every 6 hours for tocolysis. Approximately 18-24 hours after the procedure, the mother is transitioned from a magnesium drip to oral nifedipine for tocolysis. A single dose of maternal betamethasone is given in anticipation of preterm delivery. [28]
Postoperatively, the fetus undergoes daily echocardiography and US to assess for ductal constriction, fetal movement, amniotic separation, and volume of amniotic fluid.
-
Gravid uterus is exposed through Pfannenstiel incision. Media file courtesy of Dr Douglas Miniati and Dr Payam Saadai, Division of Pediatric Surgery, University of California, San Francisco, School of Medicine.
-
Intraoperative ultrasonography is used to mark extent of placenta and position of fetus prior to hysterotomy. Media file courtesy of Dr Douglas Miniati and Dr Payam Saadai, Division of Pediatric Surgery, University of California, San Francisco, School of Medicine.
-
Specially designed uterine stapler provides hemostasis and prevents separation of membranes during hysterotomy. Media file courtesy of Dr Douglas Miniati and Dr Payam Saadai, Division of Pediatric Surgery, University of California, San Francisco, School of Medicine.
-
Pulse oximeter is placed on foot of fetus to ensure fetal well-being. Media file courtesy of Dr Douglas Miniati and Dr Payam Saadai, Division of Pediatric Surgery, University of California, San Francisco, School of Medicine.
-
Intravenous access is established in saphenous vein of fetus before debulking of sacrococcygeal teratoma. Media file courtesy of Dr Douglas Miniati and Dr Payam Saadai, Division of Pediatric Surgery, University of California, San Francisco, School of Medicine.
-
Sacrococcygeal teratoma is exteriorized and is intimately involved with anus. Red rubber catheter can be inserted into anus to help identify rectum and prevent or identify iatrogenic injury. Media file courtesy of Dr Douglas Miniati and Dr Payam Saadai, Division of Pediatric Surgery, University of California, San Francisco, School of Medicine.
