Preoperative selective embolization with vascular coiling of giant sacrococcygeal teratoma

1 Introduction

Teratomas are the most frequent neonatal tumors; their incidence is 1:14,000 to 1:40,000 live births. Almost half of these tumors are located in the sacrococcygeal region [1–3]. Altman et al., classified teratomas into four types according to their location and size [4]. Nowadays, neonatal teratomas tend to be diagnosed by prenatal screening ultrasound. While it is important to be prenatally aware of fetal hydrops, placentomegaly, obstruction of the umbilical artery flow, organ compression and associated malformations to reduce complications during delivery [1], a teratoma’s size and growth dynamics are the most important parameters for postnatal management. Placentomegaly results from high-output fetal heart failure secondary to the large, highly vascularized tumor mass functioning as an arteriovenous fistula [5]. Giant sacrococcygeal teratomas (SCT) are categorized as high-risk teratomas because of the danger of cardiac failure pre- or postnatally, or uncontrolled hemorrhage [1, 6–9].

Following delivery, when the counter pressure of surrounding amniotic fluid to tumor tissue is lost, a huge volume of blood can pool in the teratoma leading to hypovolemic shock. Next to gross hemorrhage from the main tumor artery, which is generally the middle sacral artery, persistent blood oozing from superficial vessels on the tumor’s non-epithelialized surface can endanger the newborn. Ligating the disrupted vessels is often futile, as only external compression can alleviate bleeding. Because a high-risk SCT’s mortality is significant [8], the surgical hazard may be lowered by embolizing the feeding arteries of giant SCTs [10–12]. Here we report on just such a strategy using an easy-to-handle micro-coil system that can densely pack and fully occlude feeding arteries [1, 13].

2 Patient presentation

A female newborn with a giant and highly vascularized SCT was delivered via Caesarean section at the 37th week of gestation. Birth weight including the SCT was 4050 g. The SCT had been diagnosed in the 30th week of gestation by fetal ultrasound. Subsequent examinations revealed that the SCT was growing. In the delivery room, mechanical ventilation was immediately necessary for respiratory stabilization. There were no signs of hydrops or associated malformations. Despite volume overload, myocardial performance and contractility remained normal, with no inotropic support necessary before surgery. The SCT’s surface exhibited small ulcerations and oozing blood (Fig. 1A). The placenta’s histology verified placentomegaly.

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Fig.1

A Neonate with giant SCT. B, C SCT enucleation. D Cosmetic result.

Magnetic resonance imaging (MRI) revealed an external SCT (type II) with cystic and solid compartments, significant intrapelvic extension up to the aortic bifurcation, and displaced bony structures with no pelvic-bone destruction. Our multidisciplinary clinical board recommended selective embolization of the feeding arteries as the first (pre-surgical) therapeutic step. On the second day of life, the infant underwent interventional catheterization under general anesthesia via a left-sided transscarotid access (4 Fr sheath) via sonographically-guided puncture. Three main feeding arteries were identified on selective angiography (Fig. 2A): one feeding artery arose from the arteria sacralis mediana, the second and third from the arteria iliaca interna sinistra and dextra, respectively. All three branches were successfully occluded using eight micro-coils (four Ruby Complex Soft Coils and four POD Packing Coils; Penumbra Inc., Alameda, CA, USA) (Fig. 2B, C). Final proximal occlusion was verified angiographically, achieving subtotal interruption of the SCT's perfusion, improving rather than compromising iliac and femoral artery flow on both sides (Fig. 2D). Catheterization required the use of 11.7 ml/kg iodine-containing contrast medium as well as exposure to fluoroscopy for 24 minutes; and the total intervention time for embolization was 140 minutes, respectively. Neither cardio-pulmonary nor neurological complications were noted following interventional catheterization. The day following embolization, the SCT was surgically resected in an 8-hour operation with no relevant bleeding. Despite this, however, following volume substitution of both crystalloid solutions (total 470 ml) and fresh frozen plasma (total 150 ml) during the operation, 70 ml of blood was transfused due to a drop in hemoglobin to a minimum of 9.2 g/dl due to dilution effects. The tumor was enucleated from the neighboring structures; hypotrophic pelvic muscles that had been extremely stretched were reconstructed (Fig. 1D). One of the coils was easily shortened to facilitate operability, while the other coils remained in place. We observed macroscopically an R0 resection without residual teratoma. The excised tumor weighed 1000 gr and measured 18 x 15 x 10 cm (Fig. 1B, C)

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Fig.2

A Aortogram of the SCT’s vascular supply. B/C Angiograph following selective embolization of the SCT's three main supplying vessels.^* A. abdominalis.1 A. sacralis mediana. 2 A. iliaca interior dextra. 3 A. iliaca interior sinistra. 4 A. obturatoria dextra. 5 A. obturatoria sinistra.

Because of capillary leak syndrome after surgery, the neonate was given dopamine for 4 hours for hypotension, and another blood transfusion of 50 ml was administered because of anemia (Hb 12.6 g/dl) without signs of active bleeding. Forced diuresis therapy was carried out for 3 days. Complications such as postoperative hyperkalemia or arrhythmias were not observed. Mechanical ventilation support was required until day 2 after surgery. Analgesia with fentanyl was given for 2 days, and enteral feeding was started on day 3. Despite the delicate proximity to the anus, wound healing of the sutures proceeded without complications, and the patient was discharged with intact stool and bladder function on day 11 following surgery.

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Fig.3

Radiograph of the pelvis, overview before (A) and after (B) surgery with all platinum coils.

Histology revealed an immature teratoma (Grad II-III by Norris et al. [14]) with a yolk sac tumor component (<5%). Because of a questionable small residual tumor above the bladder on MRI and borderline serum concentrations of alpha-fetoprotein, the infant underwent a re-resection three months after her initial surgery. Histologically, the tissue removed was free of teratoma; a small ovarian cyst was removed. As of the time of writing, at age 8 months, the infant reveals no evidence of residual tumor.

The teratoma presented here was classified as a “giant SCT” according to the Altman classification, defining a tumor size exceeding 10 cm [4]. The complication rate of giant SCTs is high because of possible arteriovenous shunting with consecutive high-output cardiac failure and hemorrhage [1, 8–11]: mortality ranges from 15% to 18% [2, 9].

Fetal therapy may improve perinatal outcomes for hydropic fetuses with a solid SCT, but is often complicated by intrauterine death or preterm birth. In fact, a number of antenatal procedures to treat giant SCT have been reported [16, 17]. They include open fetal surgery, minimally invasive procedures like fetoscopic laser ablation, radiofrequency ablation, thermocoagulation and thrombogenic coiling of the main vessel. Procedure-related rate of complications is generally high, with 35 – 70% mortality [8, 16].

In contrast, recent reports indicate that preoperative embolization of the feeding arteries of SCT is safe and can effectively lower the rate of hemorrhage before and during surgery. Furthermore, laparotomy to clamp feeding arteries becomes unnecessary [10, 12]. Meticulous angiographic identification of the number and origin of all feeding vessels is mandatory prior to embolization. Different embolization techniques have been described including radiofrequency ablation, gelatin sponges, or platinum coils [10, 12]. New is our use of the Penumbra microcoil system (off-label) for neonatal SCT treatment. Firstly, their high platinum content makes these coils extremely visible. Secondly, a very high packing density is achievable, which immediately leads to the desired stop of perfusion even in high-flow areas. Its delivery system is relatively long (designed for adult patients), so it must be employed with great care, especially considering the limited patient length and limited table space (access from the neck). Therefore, in young patients it is best to have 2 examiners (4 well-coordinated hands) at the table.

The left-sided carotid approach we selected is not a standard access route, even in neonatal patients. However, it enables direct probing of the descending aorta and an optimal angle to the iliac and SCT arteries, both of which facilitate closely-controlled advancement of the guide and microcatheter system, and the correct positioning of each coil in use. Others have chosen a transsubclavian [12] or transfemoral [10] access with similar success. The transfemoral approach, however, seems to be significantly more anatomically demanding, and access-site complications are more likely when transbrachial/-subclavian access is chosen. Thus transcarotid access may be considered first choice in this setting. Meticulous tumor enucleation was only possible because we had minimized bleeding during surgery thanks to successful embolization. The need for transfusion in our case can be explained by the context of dilution due to increased volume substitution, as there was no active bleeding at any time. Because the interruption of perfusion is rarely complete, tissue damage appears limited, and successful recovery is generally achievable. Common complications, such as gluteal skin necrosis, may be limited and even absent if highly selective embolization of the tumor-supplying vascular branches succeeds, as in our case.

Because this neonate’s postnatal condition was stable, we benefited from being able to carefully plan all procedures with our multidisciplinary team without undue haste. In neonates at risk of imminent cardiac failure, initial angiography and embolization may be necessary immediately following birth, even in the delivery room [1, 12]. However, in most cases the newborn can be stabilized first via invasive ventilation, inotropic support, and blood transfusions.

4 Conclusions

Selective pre-operative embolization is potentially an important component in the successful treatment of neonates with giant SCTs. It greatly facilitates subsequent tumor resection with little bleeding. With good visibility in situ, delicate pelvic-floor structures can be identified more precisely, thus rendering the surgery gentler and improving the patient’s long-term outcome.