Fetal Surgery for Sacrococcygeal Teratoma 

Updated: Nov 05, 2019
Author: Eveline Shue, MD; Chief Editor: Hanmin Lee, MD 

Overview

Background

Sacrococcygeal teratoma (SCT) is the most common congenital germ cell tumor,[1] with an incidence of 1 in 35,000-40,000 live births[2] and a female predominance (3:1-4:1 ratio).[2, 3] The tumor arises from embryologically multipotent cells from the Hensen node, which is located in the coccyx.[4, 5] Most SCTs are now diagnosed antenatally because of the widespread use of routine obstetric ultrasonography (US).[6]

Patients in whom SCT is diagnosed postnatally typically do well after early surgical resection, and the main cause of mortality in these patients (though rare) is attributed to malignancy. However, mortality associated with antenatally diagnosed SCT is in the range of 30-50%[7, 8, 9] and is attributed to tumor morphology and vascularity. Whereas some fetuses are born without complications, others can develop high-output cardiac failure, nonimmune hydrops fetalis and, ultimately, fetal demise.

This wide disease spectrum has prompted several fetal treatment centers to identify US predictors of survival for fetuses with SCT to help identify high-risk fetuses who may benefit from fetal intervention. The key to optimizing survival in these fetuses is intervention before the development of high-output cardiac failure, hydrops, and maternal mirror syndrome. Identifying fetuses at risk for hydrops and fetal demise isolates those who may be salvaged by reversing the pathophysiology—the premise behind fetal intervention.[10]

Pathophysiology

The vascular supply to an SCT commonly arises from the middle sacral artery, which can enlarge to the size of the common iliac artery and cause a vascular steal syndrome.[11] These large vascular tumors can lead to high-output cardiac failure as a consequence of arteriovenous shunting through the tumor, resulting in placentomegaly, hydrops, and, ultimately, fetal demise.[11]

Polyhydramnios is commonly seen because of increased fetal cardiac output, which often leads to preterm labor and premature rupture of membranes. Conversely, oligohydramnios can also occur if an intrapelvic portion of the tumor causes significant urinary obstruction.[3]

In severe cases, maternal mirror syndrome, in which the mother develops symptoms that mimic those of the hydropic fetus, may develop. Mothers develop symptoms similar to those of severe preeclampsia, such as hypertension, emesis, peripheral edema, pulmonary edema, and proteinuria.[8]

Fetal surgery is contraindicated after maternal mirror syndrome has developed; accordingly, prognostic indicators have been characterized so as to identify patients before terminal progression of this disease. Mothers who potentially have maternal mirror syndrome need to be very closely monitored and may require delivery or pregnancy termination for maternal safety.

Classification

SCTs are categorized according to the classification developed by the American Academy of Pediatrics, Surgical Section (AAPSS), as follows[12] :

  • Type I - Primarily external or has a minimal presacral component
  • Type II - Predominantly external but has a significant intrapelvic component
  • Type III - Predominantly intrapelvic with abdominal extension, with a small external component
  • Type IV - Entirely within the pelvis and abdomen

Whereas type I tumors, being primarily external to the fetus, are easily diagnosed prenatally and are amenable to fetal resection, type IV tumors can be difficult to diagnose and are not amenable to fetal resection.[6, 13] The AAPSS classification describes surgical anatomy and identifies tumors that are amenable to fetal resection, but it does not provide prognostic information,[3] nor does it identify fetuses who would benefit from fetal intervention.

Indications

Fetuses with SCT are considered for fetal resection or fetal intervention only in extreme cases on an individual basis.

Small tumors without significant vascularity are unlikely to affect the fetus significantly.[3] These fetuses are unlikely to develop high-output cardiac failure or hydrops and can be monitored throughout gestation with serial US. Those with signs of placentomegaly and hydrops after lung maturity (usually after 32 weeks’ gestation) are delivered on an emergency basis. Only fetuses of less than 32 weeks’ gestation with signs of impending hydrops that have tumors amenable to surgical resection are considered for fetal intervention.[7, 13]

As with all invasive procedures, the risks and benefits of fetal intervention must be considered for each patient. However, consideration for the risk to and safety of the pregnant mother are unique to fetal surgery. Before fetal intervention is considered, a multidisciplinary team should counsel and evaluate each family. The evaluation should include the following[13, 14] :

  • Detailed US to confirm the diagnosis and to detect any other anatomic abnormalities
  • Fetal magnetic resonance imaging (MRI) for additional anatomic information
  • Fetal echocardiography to rule out congenital heart disease and to assess fetal cardiac function
  • Amniocentesis for fetal karyotyping

In 2009, Wilson et al proposed the following criteria for surgical resection of sacrococcygeal teratoma[15] :

  • No maternal contraindications to fetal surgery (medical or surgical issues, body mass index [BMI] < 36, anesthesia risks)
  • Fetal gestational age of 20-30 weeks
  • A favorable AAPSS stage and no additional anomalies
  • Impending hydrops (evidence of ascites, pleural effusion, and subcutaneous edema)
  • Normal fetal karyotype
  • Fetal cardiac output greater than 600-900 mL/kg/min (adjusted for gestational age)

Contraindications

Contraindications for fetal intervention for SCT include the following[15] :

  • Significant placentomegaly (placental thickness at cord insertion >35-45 mm with a gestational age < 30 weeks)
  • Maternal mirror syndrome
  • Multiple gestation
  • Chromosomal abnormality
  • Other fetal anatomic abnormalities

Outcomes

Several institutions have reported outcomes with and without fetal intervention for antenatally diagnosed SCT.[16, 17, 18, 19, 20] Among patients with antenatally diagnosed SCT, 36-41% require fetal intervention.[17, 18]

Mortality due to SCT is mainly attributed to tumor morphology; small cystic SCTs rarely cause problems in utero. Rapid growth of large vascular tumors can rupture and hemorrhage during delivery, and this is usually fatal.[13]

The overall survival rate of antenatally diagnosed SCT is 47-83%,[16, 18, 19] but the survival rate after fetal surgery is 50-75%.[16, 17, 18] It is important to note that survival after fetal intervention should be compared with survival for the subgroup of patients with hydrops and no intervention, in whom the survival rate approaches 0%.[21, 22]

About 40-50% of survivors with antenatally diagnosed SCT have long-term morbidity, which may include obstructive uropathy, bowel and bladder incontinence caused by damage to the sacral nerves due to the tumor or damage during SCT resection, and dissatisfaction with cosmetic outcomes.[16, 20]

Prognostic indicators

Placentomegaly and hydrops are harbingers of fetal demise in SCT.[8]

A retrospective review of 17 fetuses with antenatally diagnosed SCT treated at the University of California, San Francisco (UCSF), between 1986 and 1998 evaluated the factors associated with hydrops.[10] There was a significant difference in tumor morphology (solid vs cystic) and vascularity in fetuses who developed hydrops compared with those without hydrops. In addition, fetuses who developed hydrops were diagnosed at an earlier gestational age (19 vs 25 weeks) and were delivered at an earlier gestational age (28 vs 38 weeks).

In this series, 12 fetuses developed hydrops, four of whom survived.[10] Of the four survivors, three underwent fetal intervention because they developed hydrops before viability, and one patient developed hydrops at 32 weeks’ gestation and was delivered immediately. All fetuses who did not develop hydrops survived.

This study showed that fetuses with predominantly solid and highly vascular tumors were at high risk for developing hydrops. These patients should undergo close follow-up throughout gestation with serial US and echocardiography and may be considered for fetal intervention upon signs of impending hydrops.

A retrospective review of 23 patients evaluated at the Children’s Hospital of Philadelphia (CHOP) between 2003 and 2006 with antenatally diagnosed SCT showed that SCTs with a growth rate exceeding 150 cm3/week are associated with increased perinatal mortality.[15]

In a study from UCSF that retrospectively reviewed 28 fetuses with antenatally diagnosed SCT between 1991 and 2005, solid tumor volume–to–head volume ratio (STV/HV) on US was identified as a predictor of poor outcomes.[23] All patients with an STV/HV lower than 1 survived, whereas 61% of fetuses with an STV/HV higher than 1 died.

In addition, the study determined that 97.3% of fetuses with an STV/HV higher than 1 were associated with one or more abnormal US findings, such as polyhydramnios, hepatomegaly, placentomegaly, cardiomegaly, ascites, pericardial effusion, or integumentary edema.[23] With serial US , increases in the STV/HV ratio can guide management in fetal SCT so that fetal intervention or early delivery[24] can be performed before hydrops develops.

In a study from the Fetal Center at Texas Children’s Hospital, tumor volume–to–fetal weight ratio (TFR) was a marker of poor outcome in 12 fetuses with SCT between 2004 and 2009.[21] With MRI or US, tumor volume was determined by the prolate ellipsoid formula and fetal weight by the Hadlock formula. A TFR higher than 0.12 before 24 weeks’ gestation predicted poor outcomes (fetal hydrops, demise, or neonatal death) with 100% sensitivity, 83% specificity, a negative predictive value of 100%, and a positive predictive value of 80%.

Of the 12 fetuses with SCT in this series, 33% (4/12) developed hydrops.[21] All fetuses who developed hydrops had a TFR higher than 0.12 by 24 weeks’ gestation, and three fetuses died. One patient underwent fetal intervention after hydrops developed and survived. Thus, TFR may be used to identify fetuses with SCT who are at risk for poor outcomes before 24 weeks’ gestation and who may benefit from fetal intervention.

TFR higher than 0.12 in combination with tumor morphology was further validated as a sonographic predictor of poor prognosis in a subsequent retrospective study from UCSF.[25]

In a review of 79 fetuses with antenatally diagnosed SCT at three fetal centers from 1986 to 2011, receiver operating characteristic (ROC) analysis revealed that a TFR higher than 0.12 before 24 weeks' gestation was predictive of a poor prognosis, as was solid tumor morphology and the presence of hydrops.[26] However, none of these factors were found to be independent predictors of a poor prognosis on multivariate analysis.

In a retrospective review of 28 pathology-confirmed isolated SCT patients evaluated with at least two documented US scans and followed through hospital discharge between 2005 and 2012, a faster SCT growth rate—calculated as the difference between tumor volumes on a late-gestation sonogram and an early-gestation sonogram divided by the difference in time—was associated with adverse outcomes (death, high-output cardiac failure, hydrops, and preterm delivery).[27]

SCT can create a low-resistance large arteriovenous shunt, which can progressively increase preload and afterload on the fetal heart, leading to volume overload, ventricular dilation, ventricular hypertrophy, and high-output cardiac failure.[28] A 10-year retrospective review of seven fetuses showed that the most important prognostic criteria for maternal and fetal complications due to antenatally diagnosed SCT included cardiomegaly, hydrops, and increased preload indexes of the fetal venous system.[29]

Studies on fetuses with SCT show that combined cardiac output increases dramatically before the development of hydrops.[30, 31] Fetuses with combined cardiac output that exceeded 700-800 mL/kg/min died in utero.[28] Rychik et al analyzed the acute cardiovascular effects of fetal surgery in four patients with SCT and saw a significant decrease in combined cardiac output (690 ± 181 mL/kg/min vs 252 ± 82 mL/kg/min) after fetal resection of SCT.[32]

In a retrospective review of 11 fetuses with SCT, those with poor outcomes (ie hydrops, fetal demise, neonatal death) had a cardiothoracic ratio higher than 0.5, a combined ventricular output exceeding 550 mL/kg/min, tricuspid or mitral valve regurgitation, or a mitral valve Z-score higher than 2.[33] Identifying these cardiovascular indicators of poor outcome helps identify patients at high risk for fetal demise and can prompt fetal surgical intervention before the development of hydrops.

 

Periprocedural Care

Patient Education and Consent

After evaluation at a fetal treatment center, families should undergo extensive multidisciplinary counseling. Specialists should include fetal/pediatric surgeons, obstetricians, perinatologists, and anesthesiologists, as well as a social worker and nurse coordinator to discuss the risks and benefits of fetal intervention. Potential risks of fetal intervention include the following[13] :

  • Uterine disruption
  • Rupture of membranes
  • Side effects of tocolytics (to prevent preterm labor)
  • Maternal pulmonary edema
  • Fetal demise

Additional risks of fetal surgery include bleeding, need for blood transfusion, and wound infection.

Preprocedural Planning

An experienced operative team is essential and usually includes the following[13] :

  • Two pediatric surgeons
  • Perinatologist
  • Ultrasonographer/echocardiographer
  • Experienced operating room personnel
  • Pediatric/obstetric anesthesiologist

The team should also have blood products prepared for potential intraoperative transfusion. Patients needing fetal intervention usually have vascular, solid tumors, which were shown to have increased transfusion requirements in a retrospective study that evaluated 112 cases of operative management of sacrococcygeal teratoma (SCT), including six in-utero repairs.[34]

Equipment

Open fetal surgery and ex-utero intrapartum treatment procedure

The following are used for maternal perioperative monitoring:

  • Blood pressure cuff
  • Large-bore intravenous (IV) catheters
  • Bladder catheter
  • Electrocardiographic (ECG) leads
  • Sequential compression devices
  • Pulse oximeter

Also necessary for open fetal procedures are the following:

  • Intraoperative ultrasound device
  • Uterine stapler
  • Large ring retractor
  • Sterile neonatal pulse oximeter and IV catheter for the fetus
  • Fluid warmer
  • Sterile neonatal laryngoscope and endotracheal tube (for ex-utero intrapartum treatment [EXIT] procedure)

Minimally invasive techniques

Equipment for minimally invasive techniques includes the following:

  • Intraoperative ultrasound device
  • LeVeen radiofrequency probe (8 prong) for radiofrequency ablation (RFA)
  • Fetoscope (1.9 mm, 60°) for laser ablation)
  • Neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser fiber (0.4 mm) for laser ablation

Patient Preparation

Patients are usually admitted to the obstetric ward the evening before fetal surgery. Preoperatively, indomethacin is given to prevent uterine contraction during the procedure, and antibiotics are given prophylactically to prevent infection.

Anesthesia

Anesthesia for open fetal surgery includes maternal epidural and general anesthesia. This provides anesthesia to both the mother and the fetus and ensures uterine relaxation during the procedure.[13, 35] The epidural anesthesia also decreases uterine contractions during the postoperative recovery period.

Anesthesia options for minimally invasive techniques can range from spinal anesthesia with local anesthetic to general anesthesia, depending on the patient and circumstances for fetal intervention.

During the procedure, intramuscular injection of pain medication and a paralytic agent can be administered under ultrasonographic (US) guidance.[36]

Positioning

The mother is placed in a supine position on the operating room table, with the right side elevated to decrease the pressure of the uterus on the inferior vena cava.[13]

Monitoring & Follow-up

Depending on the postoperative course, patients can be discharged within a week of fetal surgery, although they will need to stay at a facility near the fetal treatment center. Activity is gradually modified if there is minimal uterine irritability. US is performed twice a week to assess fetal development and resolution of hydrops. Because of the location of the hysterotomy, the mother will require cesarean delivery for all future deliveries.

 

Technique

Approach Considerations

Fetal surgery for sacrococcygeal teratoma (SCT) remains challenging; it should be considered only in select fetuses with impending hydrops and performed only in experienced centers.[37, 38] The purpose of fetal intervention is to debulk the tumor, with the understanding that formal oncologic resection would be performed postnatally.[39] The key to successful fetal intervention is to identify fetuses before the onset of hydrops, as well as to identify 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.[13]

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 inci 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.[13]

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 ext 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).[40] This hemostatic stapler is used to secure the membranes to the uterine wall to prevent separation of membranes. The fetus is positioned so that the tumor is exposed through the hysterotomy.

Specially designed uterine stapler provides hemost 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 with an intramuscular 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.[41]

Pulse oximeter is placed on foot of fetus to ensur 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 vei 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. However, before the uterus is completely closed, 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 may be considered for a fetus of 27-32 weeks’ gestation with a large vascular type I or II tumor requiring early delivery but in the absence of maternal contraindications.[24]

The EXIT procedure, originally developed to establish an airway in a fetus with airway compromise while the fetus was still connected to placental circulation for oxygenation, has been adapted to resuscitate fetuses with other anomalies who may experience instability during birth.[42] 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.[24] The infant can be stabilized before definitive oncologic resection.

The EXIT procedure is performed with the mother under general anesthesia[43] to maximize uterine relaxation and uteroplacental blood flow. The hysterotomy, fetal monitoring, and 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 closure are performed in the same fashion as the open fetal SCT resection.

Roybal et al[24] reported one survivor using this technique, with neurologic complications due to tumor invasion into the spinal canal. Surgeons at the University of California, San Francisco (UCSF), have treated two fetuses with EXIT to SCT resection, with a survival of 50%[25] ; one patient died of necrotizing enterocolitis and sepsis.

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 radiofrequency ablation (RFA), have been described.[44]

This technique employs US guidance to target the vessels feeding the SCT to reduce tumor vascularity. An eight-prong LeVeen radiofrequency probe is deployed through a 15-gauge needle into an umbrellalike configuration to a diameter of 20-35 mm.[44] It 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, and hemorrhage.

In a report of four fetuses with SCT, RFA successfully reduced tumor vascularity in all cases.[44] However, intrauterine fetal demise due to hemorrhage into the tumor occurred in one case, and another fetus underwent termination after postoperative 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 SCT in an 18-week-old fetus, but the fetus died 2 days postoperatively.[45] Ibrahim et al reported a fetus born with sciatic nerve injury and malformation of the acetabulum and femoral head after RFA for SCT.[46] A study from Korea[17] reported six cases of fetal SCT treated with RFA; five of the six patients survived, and one patient had left-leg palsy and fecal and urinary incontinence.

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.[45, 44] 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.[47] The pregnancy was complicated by polyhydramnios but not by placentomegaly or hydrops. Two unsuccessful attempts were made at 20 weeks’ 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.[19] Cordocentesis is performed to deliver fetal anesthesia with fentanyl (15 µg/kg) and pancuronium (2 mg/kg).[19] This can also be delivered intramuscularly to the fetus. 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.[47]

In a retrospective study of 12 patients undergoing fetal intervention for SCT, four patients underwent laser ablation, but only one patient survived.[18] In a case report, a 24-week-old hydropic fetus underwent percutaneous laser ablation for SCT but died 2 days after fetal intervention.[19] In another study, a 22-week-old fetus underwent percutaneous laser ablation of tumor vessels and survived.

An additional retrospective multicenter study identified five fetuses that underwent minimally invasive fetal intervetion for hydrops or cardiac insufficiency as a result of SCT.[36] Four of these five fetuses underwent laser ablation, and three of them were targeted vascular ablations. Survival for the fetuses that underwent fetal intervention was 40%, but many patients required multiple procedures because of the recurrence of hydrops, cardiac insufficiency, or both. 

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.

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.[16]

Postoperatively, the fetus undergoes daily echocardiography and US to assess for ductal constriction, fetal movement, amniotic separation, and volume of amniotic fluid.