Prenatal and Postnatal Surgery for Sacrococcygeal Teratoma (SCT) - Online Course

Transcript

Alan Flake: I’m Alan Flake. I’m a pediatric surgeon and The Children’s Hospital of Philadelphia. And the topic of this presentation is prenatal and postnatal surgery for sacrococcygeal teratoma.

So this is the postnatal view of sacrococcygeal teratoma. They can be very large, very impressive tumors. Teratoma means “monstrous tumor” which is very appropriate for this entity. When they present postnatally they’re generally straight forward with respect to the treatment. We take them into the operating room immediately and resect the teratoma. And there’s usually a good outcome.

Fetal sacrococcygeal teratoma is a different entity with a much different natural history. It’s an extremely rare tumor, about 1 out of every 30,000 live births has a sacrococcygeal teratoma. They generally are not malignant at the time of birth. And large fetal sacrococcygeal teratoma have extremely high risk and potential for poor outcomes.

Years ago we looked at the natural history for prenatally diagnosed sacrococcygeal teratomas. And in this retrospective review of 42 cases, it really broke out to two groups of patients. One group had placentomegaly hydrops and in those 15 cases there was a near 100% mortality. In cases without placentomegaly hydrops there was still high risk, approximately 26% mortality, but not nearly as high with the presents of hydrops.

Fetal sacrococcygeal teratoma causes fetal mortality by different mechanisms. One mechanism is due to mass effect with or without polyhydramnios. This can lead to dystocia, pre-term labor, tumor rupture or hemorrhage at the time of delivery. Prematurity and all of that can ultimately lead to fetal demise, or neonatal death. The more important pathophysiology from a prenatal treatment prospective is the phenomenon of tumor vascular steal. This is a phenomenon of high output cardiac failure related to a low resistant vascular circuit through the tumor. This induces placentomegaly hydrops and almost, you know, formally, is associated with fetal death.

This is a cartoon diagram of that arteriovenous steal phenomenon. It’s also associated with progressive placentomegaly, which can lead to the maternal mirror syndrome, which is a syndrome where the maternal status mirrors that of the fetus with edema, and other signs of…

This is a cartoon depicting the pathophysiology of the arteriovenous steal associated with sacrococcygeal teratoma. It’s also associated with progressive placentomegaly. And this can ultimately lead to the maternal mirror syndrome which is a syndrome where the maternal status mimics that of a fetus with manifestations of preeclampsia, pulmonary edema, and other high risk complications.

This is what’s seen by echocardiography with high output physiology associated with SCT. We follow these patients with high risk tumors very closely using pre and echocardiographic monitoring and measure specific parameters associated with high output cardiac failure. These include the combined cardiac output, descending aortic velocity, IVC size, and cardiac chamber size.

With progressive high output physiology, the combined cardiac output progressively increases until the fetus de-compensates at which time then plateaus, or decreases descending aortic velocity. Also increases the IVC dilates and with the compensation you see cardiac chamber size dilatation.

These are the postnatal classifications of sacrococcygeal teratoma as put forth by the American Academy of Pediatrics surgical section. Type 1 is a tumor that’s predominantly extrinsic, Type 2 has a pelvic component with a large extrinsic component, Type 3 is predominantly intrinsic with a smaller extrinsic component and Type 4 is entirely intrinsic. This is a useful classification to anticipate the complications that can be associated with SCT. And the potential forms of treatments that are applicable.

So I’ll show you a series of images that depicted each type of SCT, and make comments related to those images. This panel shows a Type 1, actually two Type 1 fetal SCTs. The one on the left side is a mixed cystic and solid tumor. This is associated with much higher vascular blood flow than a purely cystic variety shown on the right side. And has a much higher risk tumor than a purely cystic, Type 1 fetal SCT. When they’re purely cystic, they’re usually composed of immature, neuro elements predominantly. They have minimal blood flow and minimal potential for high optic cardiac failure.

When they’re mixed solid and cystic, or predominantly solid, they have high blood flows and high potential for progressive cardiac failure, and other complications.

This panel shows a Type 2 fetal SCT. With Type 2, you’re not only worried about the high vascular flow to the solid components, but you’re also worried about pelvic outlet compression. And in this case you can see on the right side, progression to oligohydramnios with very little amniotic fluid around the fetus, a dilated bladder. And if I can show you the kidneys here, it would show hydronephrosis. So this fetus is compromised not only by the vascular requirement for the tumor, but also the pelvic outlet compression causing lower urinary tract obstruction.

These panels depict Type 3 SCT, again with a very large intrinsic component with complete pelvic outlet obstruction. You can see in those panels that there is oligohydramnios present, that they’re dilated urinary and genital urinary structures as depicted by the arrow on the left side. And hydronephrosis shown on the right panel bilaterally. This is associated with a very poor prognosis.

And then here’s another panel showing an even more severe Type 3 fetal SCT. This fetus shows placentomegaly and hydrops. You can see on the left panel the massive ascites. The skin and scalp edema, the complete absence of amniotic fluid, and a very large dumbbell shaped Type 3 SCT. On the right side you can see the markedly thickened placenta shown by the arrowheads. This fetus has no hope for survival.

This cartoon depicts a surgical resection of the fetal SCT. This is a debulking procedure, it’s not a true resection. It’s designed to very rapidly remove the pathophysiology, the high output arteriovenous steal, associated with the SCT. And no effort is made to remove the toxics or the internal components of the SCT. This procedure’s done very rarely for a very select few fetuses. That is occasionally indicated and required.

This is a case of a fetal resection SCT. This fetus presented at 22 weeks gestation with a predominantly solid, Type 1 sacrococcygeal teratoma. We only would offer fetal surgery for a Type 1 tumor, as we don’t deal with the internal component or the pelvic outlet obstruction when you do the debulking procedure by fetal surgery. So the only tumor types that we would turn the pathophysiology around is a Type 1 SCT that is evolving into myopathy cardiac failure. And that’s the only indication for fetal surgery.

In this case we can see bilateral hypogastric feeding vessels, no placentomegaly on presentation at 22 weeks. We followed this patient very closely with three times a week ultrasounds and echocardiograms. And by week 23, we’d seen a marked increase tin combined cardiac output well above the normal levels, we’d seen a marked increase in the volume of the tumor, and we’d seen evolving evidence of hydrops with pericardial effusion, [ascites] skin and scalp edema, and an early thickening of the placenta.

So with this progression, we considered this to be evolving high output cardiac failure. And resection is the only option for treatment.

This is a illustrated case of a fetal sacrococcygeal teratoma resection. This fetus presented to CHOP at 22 weeks gestation with a predominantly solid, Type 1 sacrococcygeal teratoma. That’s the only type of teratoma that we would consider fetal intervention on, that is fetal surgery. And we would only consider fetal surgery if we had…

This slide shows an illustrated case of a fetal sacrococcygeal teratoma that required fetal surgery. This fetus came to us at 22 weeks gestation with a predominantly solid, Type 1 SCT. That’s the only type of SCT that we would consider fetal surgery for because the debulking procedure really doesn’t address the internal component of the tumor, or the pelvic outlet obstruction that can be associated with Type 2 and 3 tumors.

So this case was found to have very high blood flow. It was a very large tumor on presentation, and we could detect blood flow from bilateral hypogastric feeding vessels. There was no placentomegaly presentation. As we followed the tumor very closely by ultrasound and echo, over a one week period we observed a marked, dramatic increase in the combined cardiac output, from 670 to 850. Which is well into the high output range.

The volume of the tumor increased dramatically, we saw evidence of early hydrops, including pericardial effusion, ascites and skin and scalp edema. And the placenta had thickened from 24 to 40 mm. This qualified as evolving, high output failure in our estimation, and we offered fetal surgery as the only intervention that could potentially salvage the fetus.

This is what fetal surgery for SCT actually looks like. You can see we perform a very large hysterotomy after achieving uterine relaxation. We place monitoring pulse oximetry on the fetus and start an IV in the fetus. Here are the fetal legs, here’s the very large fetal tumor. Here we’re putting a tourniquet around the base of the tumor and dividing the base of the tumor using a harmonic scalpel. We then come back and as we release the tourniquet, we control the blood vessels in the base of the tumor. And then we close the hysterotomy in our standard fashion to prevent amniotic fluid leaks and hopefully keep the fetus in for a period of time.

In this particular case, the fetus did stay in and the pathophysiology reversed itself. The hydrops resolved, and the fetus was delivered 11 weeks later by cesarean section at 34 weeks gestation. She delivered a non-hydropic, stable newborn who had an O2 requirement, but did not require mechanical ventilation. And had a small open sacral wound with visible tumor. On the third day of life we went back and resected the residual SCT and did a coccygeal resection. And discharged the patient three weeks later.

And now the patient’s actually a normal child at 3 weeks of age with the exception of the scar on her bottom, and the pathology showed immature teratoma with no [unclear] tumor and no malignant potential.

So this was a successful case of fetal resection of SCT. In reality they are not all, by any means, successful. At CHOP we’ve done seven cases of fetal SCT resection, there were two deaths related to advanced hydrops and fetal decompensation. There are five survivors. One patient had recurrent malignant endodermal sinus tumor that was subsequently resected, and there’s currently no evidence of disease in that patient during teenage years. One had multiple bowel atresia due to tumor embolization and had a poor neurological outcome as well as other complications. One had severe neurological injury related to a low blood flow state in utero.

Therefore we really only had two quality of life survivors out of seven attempts. This is not a surgery that we recommend lightly to patients with candidates for this surgery. And it requires a great deal of counseling and discussion prior to consideration of proceeding with open fetal surgery.

So what’s the future for fetal surgery for sacrococcygeal teratoma? I think we need better physiologic and metabolic assessment so that we can predict those patients that will evolve into high output failure, and those that will remain stable, which many do for many weeks.

In addition we would love to develop a minimally invasive ablated technology. There’ve been a number of attempts at other centers using RFA and other ablative techniques. These have generally resulted in a high level of collateral injury and some disastrous results. So the technology is not yet ready for human application. But we’re hopeful in the future that at some point there will be an appropriate minimally invasive ablated technology to apply to these tumors.

And finally the future is now with respect to the last option, with is early delivery and in a select few cases, the exit procedure for delivery of fetal SCT. And I’ll talk about that next.

So we published a paper in 2011 reviewing our series of sacrococcygeal teratomas that were followed at CHOP and delivered at CHOP. And we noticed that we had a very high morbidity and mortality in a select group of patients that were delivered between 27-32 weeks gestation. Have nine patients in that group, only four were survivors.

So this is a gestational window, a very uncomfortable window, when traditionally it’s been considered a little late for fetal intervention. And too early for delivery for treatment outside the womb. The overall mortality of this series was 42%.

When we really broke the series down, we looked at the patients that delivered between 27-32 weeks, it was clear that our policy of watchful waiting was quite hazardous. And that very few patients actually followed a step-wise progression to hydrops which would provide us the opportunity for fetal intervention. What we noticed was that there were really two forms of decompensation. One was a maternal decompensation with pre-term labor, polyhydramnios, those sorts of problems. Maternal mirror syndrome, and the other was a fetal decompensation with rapidly evolving hydrops, hemorrhage into the tumor, and utero tumor rupture, those kinds of events.

The reason that in many of these cases we simply reacted too slowly. And that we hadn’t preemptively delivered the patient at the first sign of trouble after achieving a gestation of 26 weeks or beyond. So we’ve decided, from that point forward, to take a preemptive approach to delivery of these patients at the first sign of fetal, or maternal decompensation. That’s based on the observation that the minority of high-risk, fetal SCTs, or candidates for fetal surgery, that is bad things happen at the worse time. And in general these patients remained compensated till rapid decompensation occurs.

The other reasons that we can’t offer fetal surgery…

So the rational for preemptive, preterm delivery, or the exit procedure, for sacrococcygeal teratomas is that the minority of high-risk fetal SCTs are candidates for fetal surgery. And these patients remain compensated until rapid decompensation occurs. Which is often after 27 weeks. Outside the window of fetal surgery. They often develop the placentamegaly relative early. Which is a counter indication for fetal surgery. They can hemorrhage acutely into the tumor with fetal demise. Or they can develop maternal preterm labor, or mirror syndrome.

So the majority of patients that present as high-risk fetal SCTs never really are candidates for fetal intervention in the traditional sense. In the absence of fetal hydrops, maternal indications, in other words, early delivery can be associated with good outcomes. And the exit procedure and debulking avoids adverse events that can occur between delivery and tumor resection. So we identified a number of patients in which, for instance, there was extensive hemorrhage into the tumor before we could even make the transition from the delivery by cesarean section, to the adjacent operating room for definitive resection of the tumor.

We also noticed that attempts of definitive resection were associated with excessive blood loss, ultimately hypothermia, DIC, those sorts of complications. So the concept of preemptive delivery with a quick debulking procedure followed by stabilization in the NICU, allowing for physiological normalization and elective tumor resection at a later date. That makes a great deal of sense in this population.

So this is our current CHOP algorithm for fetal SCT. It’s somewhat complicated, I’ll try to walk you through it. We still would recommend fetal surgery for a few select patients that have progressive evolution of hypoxic cardiac failure prior to really 27 weeks or so. And these would be considered candidates for fetal surgery. Again, this is an unusual scenario of the high-risk SCT, that is the large tumor which is predominantly solid with high vascular blood flow. Will be screened by frequent echocardiography and ultrasound. Types 1 and 2 are…

So this is our current algorithm at CHOP for managing prenatally diagnosed patients with SCT. This starts with an extensive prenatal evaluation obviously, with ultrasound and fetal echocardiography, as well as MRI and amniocentesis for [care]. We then can classify these patients into either a high-risk SCT category, which are large, predominantly solid tumors with high blood supply, or a low risk SCT. The low risk patients can be followed at relatively infrequent intervals, and undergo an elective cesarean delivery after 36 weeks. And assuming that the tumor is large enough to warrant a cesarean.

The high-risk SCTs are another story. We follow them very frequently by serial ultrasounds and echocardiography as often as two to three times per week. And they fall into a number of categories. There’s the rare fetus, as I mentioned, that is shown on the left here where you have a progressive evolution in a TYPE 1 SCT of high output cardiac failure early in gestation. And these patients are still offered, under qualified circumstances, open fetal surgery.

The large group in the middle are patients that do not follow that progressive evolution, but rather either develop hydrops later in their course, after 27-28 weeks gestation. Or have either fetal or maternal decompensations of the types described on the figure. When this happens we now preemptively perform early delivery. And this can be either by an emergency cesarean section, particularly if it’s a maternal decompensation, or occasionally by the exist procedure if it’s a fetal decompensation and we’re concerned that the patient could have adverse events, even between the delivery from the cord, to an adjacent operating room for the debulking procedure.

We now treat these patients by an initial debulking procedure rather than attempt a complete tumor resection. And then take them to the NICU for resuscitation and general care until their pathophysiology reverses itself and they reach an adequate gestational age to perform the definitive resection. And this can be weeks or even months after the delivery.

Moving on to postnatal care of sacrococcygeal teratomas that are non-hydropic and delivered by cesarean section at a more mature gestational ages. Here’s an example, for instance, of a massive sacrococcygeal teratoma that did not evolve hydrops or have fetal or maternal decompensation prior to 32 weeks. And was delivered at 33 weeks by cesarean section after following the fetus very closely for ten weeks in utero. She did develop polyhydramnios with the placentamegaly, which was the cause of the premature delivery. She also had evidence of skin breakdown and some moderate hemorrhaging in utero with anemia at birth.

Despite the massive size of this tumor, it was very amiable to postnatal resection. And you can see here the tumor on it’s pedicle of blood supply hypoxic after dissection out of the pelvic outlet. And then the reconstructive procedure giving a good cosmetic, functional outcome.

The principle of resection of these tumors are important. You can have a very deforming, dysfunctional result if you don’t do this correctly. I treat it as a midline dissection, preserving all of the non-tumor elements as possible. And dissecting from the midline outward. Approximate control is extremely important for tight pelvic outlet tumors, Type 2 and Type 3. And this is achieved through an abdominal approach either laparoscopically or open surgery, depending on your skill and capability.

It is critical, however, to have distil aortic control as these tumors receive their blood supply from both from hypogastrics and often the middle sacral. You need to stay on the true tumor capsule and preserve the sutto capsule. So there’s often a thick sutto capsule around the tumors, and this actually contains the [untenanted] reminisce of the gluteal musculature and pelvic floor musculature. So if you take the sutto capsule with the tumor, you leave the child with muscular deficit and ultimately, often an unfunctional deficit. You need to preserve all non-tumor tissue except the coccyx for the same reasons. Stay well outside the anal rectal sphincter complex, and to a midline pelvic floor reconstruction. Avoiding hitching the rectum to the sacrum, which is the older approach for reconstruction, which left many functional and cosmetic deficiency.

There are dangers in resections of these tumors predominantly related to their blood supply and your ability to control that blood supply. So any larger tumor with associated hydrops is inherently a high risk, high blood flow, tumor with deranged physiology in the fetus. And these are best handled by debulking rather than resection initially, if that’s possible, that’s not always possible with Type 2 and 3 tumor.

Highly vascular Type 2 tumor with cystic external components are dangerous because they can actually bleed into the cystic component while you’re operating with them. And patients can lose a blood volume into the tumor itself which is not easily appreciated by you or the anesthesiologist; with secondary decomposition and lose of the patient.

Then you can have extensions of these tumors into the spinal canal occasionally. The panel of figures below shows that extension in a patient that had a poor, very poor neurologic result because of actual destruction by the tumor of spinal elements prior to resection. And then the dumbbell tumor is particularly hazardous. It’s difficult to approach from above, it’s difficult to approach from below. And once again, controlling the blood supply is critical. And this has to be done from the abdomen in a very tight pelvic output. So these are the tumors that I find most difficult to deal with and they require some careful planning and strategy prior to surgery.

So the long term outcome of sacrococcygeal teratoma, one concern is tumor recurrence, or metastasis. This can result from incomplete resection really. You can have material malignant histology of the entire resection in 1-3% of sacrococcygeal teratomas. And these patients need to be aggressively treated, as they are very high-risk for a subsequent teratoma related tumors. And also the age of diagnosis was with stage 4 tumors is critical with respect to their malignant potential. And because stage 4 tumors are entirely…

The long term outcome of sacrococcygeal teratomas that are in the postnatal period is generally very good. There are exceptions related to tumor recurrence, or metastasis. This can be due to incomplete resection of the tumor really in inexperienced hands. You can have immature, malignant histology that ultimately leads to endodermal sinus tumor, and other teratoma related malignancies. And this, if it’s present, are found in the original histology after resection. Should be very aggressively treated and followed because there’s a very high rate of subsequent malignance.

The age of diagnosis in Type 4 tumors is the probable reason for the high rate of malignance in these tumors. Type 4 tumors can be completely internal and not appreciated at the time of delivery if they’re not prenatally diagnosed. And can evolve into a malignant tumor prior to their appreciation or resection.

Urinary and rectal dysfunction have been reported with various instances after resection of sacrococcygeal teratomas. Some of this is surgically related. However we recently reviewed our series on SCTs for long term urinary and rectal dysfunction. The reference is shown here. And all of our urinary and rectal dysfunction could be anticipated after prenatal imagining and evaluation. And was related to Type 2 and Type 3 SCTs that had components of pelvic outlet obstruction. So in the circumstance of the prenatally diagnosed Type 2 and Type 3 SCT, with pelvic outlet obstruction, the parents should be counselled that there is the future possibility of having various types of urinary and rectal dysfunction.

Lower extremity dysfunction is extremely rare in circumstances related to the tumor. And is confined primarily to spinal cord involvement by the tumor. Other lower extremities dysfunction is usually related to surgical mishap. And should be a very, very rare occurrence.

And finally, there’re cosmetic issues related to resection of the SCT that can be major if the reconstruction is done particularly with the hitch technique. Overall, however, the survival and morbidity outcomes on postnatally treated SCT are very good.

And that concludes our CME presentation on fetal and postnatal sacrococcygeal teratoma treatment.