Keywords chorangioma - chorioangioma - coil embolization - fetal therapy
Case 1
A 27-year-old G3 P0020 was referred to our center at 256/7 weeks for a suspected placental chorangioma. Ultrasound confirmed a structurally
normal fetus with biometry consistent with 234/7 weeks, 2 weeks less than established dates. The estimated fetal weight was 622 g,
less than the fifth percentile. The amniotic fluid index was normal at 142 mm. Pleural
fluid and ascites were identified as was cardiomegaly (70% of chest circumference)
and bilateral atrioventricular valve regurgitation. A 112 × 84 × 108 mm vascular,
mixed-echogenic mass was seen with a feeding vessel, originating from the placental
cord insertion of an anterior placenta, in immediate proximity to the mass consistent
with a giant chorangioma. A multidisciplinary conference was convened, and the decision
was made to offer intervention since no other option, such as delivery or expectant
management, would likely result in a favorable outcome. Because of the location of
the anterior placenta and the tumor, the feeding vessel could not be approached fetoscopically.
Because of the diameter of the feeding vessel (9 mm), interstitial laser was felt
to be likely insufficient, could result in uncontrollable hemorrhage, and could jeopardize
adjacent structures. The possibility of percutaneous transuterine embolization was
advanced, as the risk–benefit equation favored minimizing maternal risk given the
overall poor condition of the fetus. Pathology was consulted to better understand
the angioarchitecture of the tumor. Interventional radiology was consulted regarding
embolization options. Given that chorangiomas may contain arteriovenous anastomoses,
coil embolization was chosen over liquid techniques or microspheres as appropriately
sized coils would result in complete occlusion of the feeding vessel with no risk
of migration through the tumor and back into the fetal circulation. A comprehensive
consent process was executed that included discussion of the innovative nature of
the proposed intervention. The patient expressed a desire to attempt coil embolization
in conjunction with interventional radiology followed by intrauterine transfusion
for anticipated severe fetal anemia. The single feeding vessel was catheterized with
a 21-gauge, 15-cm needle with diamond-shaped stylet (Boston Scientific, Marlborough,
MA), technically identical to intravascular access for intrauterine transfusion. A
blood specimen was collected for complete blood count (CBC) and HemoCue, the latter
returning at 3.0 mg/dL. Two 6 × 2 mm Tornado microcoils (Cook Medical, Bloomington,
IN) were deployed into the feeding vessel under direct ultrasound guidance within
seconds of intravascular access. Flow within the tumor ceased immediately by intraoperative
color Doppler interrogation. An additional 6 × 2 mm microcoil was passed as the needle
was withdrawn to occlude the needle track. Unfortunately, the fetus did not survive
the procedure. Nonetheless, the ease and effectiveness of the procedure, along with
a very favorable maternal risk profile (compared with other alternatives), were encouraging.
The case was presented at the 34th Annual Meeting of the International Fetal Medicine
and Surgery Society in 2015 as a potential alternative to fetoscopic or other thermal
ablative techniques.
Case 2
A 27-year-old G1 P0 was referred to our center at 223/7 weeks for a suspected giant placental chorangioma. Ultrasound found an appropriately
grown and structurally normal fetus but with scalp edema, pleural effusion, and ascites
consistent with nonimmune hydrops. The amniotic fluid index was 65 mm. Middle cerebral
artery Doppler was indicative of severe fetal anemia. There was a 92 × 79 × 87–mm
hypoechoic, circumscribed vascular mass with a 6-mm feeding vessel originating from
the cord insertion of an anterior placenta and traversing the surface of the tumor
before diving into the mass consistent with a giant chorangioma. A multidisciplinary
conference was convened which recommended offering intervention, and patient consent
was obtained for amnioinfusion, intrauterine transfusion, and coil embolization including
a discussion of the innovative nature of the proposed intervention. The procedure
was begun with amnioinfusion of 1,000 mL of warmed saline through a 22-gauge spinal
needle to improve ultrasound visibility and to better define intrauterine anatomy.
The intrahepatic portion of the umbilical vein was then cannulated with the same needle.
A pretransfusion blood specimen was collected for CBC and HemoCue, the latter returning
at 8 mg/dL; 25 mL of packed red cells were transfused for a posttransfusion Hgb value
of 15 mg/dL. The needle was withdrawn. The fetal heart rate remained stable without
evidence of deterioration.
After a period of observation, the decision was made to proceed with coil embolization
in conjunction with interventional radiology. A 21-gauge diamond-shaped stylet needle
was passed under continuous ultrasound guidance into the single feeding vessel as
it entered the tumor ([Fig. 1 ]). Two 6 mm × 2 mm Tornado microcoils were passed into the feeding vessel under direct
ultrasound guidance for immediate cessation of flow within the tumor by color Doppler
interrogation. The needle was withdrawn without evidence of extravasation of blood
into the tumor or extra-amniotic space. Ultrasound on postoperative day 1 found a
viable fetus, the coils in place without migration, and no evidence of flow within
the tumor. The patient underwent an otherwise routine prenatal course and delivered
vaginally at term after spontaneous labor for a 2,861-g healthy infant. The placenta
was fixed in formalin and transferred to our pathology department. Specimen radiograph
demonstrated two Tornado coils at the site of insertion within the feeding vessel
of the tumor ([Figs. 2a ] and [3a ]). Histology found a well circumscribed, completely necrotic tumor with minimal collateral
effect on adjacent placental parenchyma ([Figs. 2b ] and [3b ]).
Fig. 1 Ultrasound image of 21-gauge needle placed into feeder vessel of giant placental
chorioangioma. Two microcoils were then placed into the feeder vessel.
Fig. 2 (a) Specimen radiograph showing the microcoils where they were placed within the
chorangioma. (b) Macroscopic appearance of fetal surface of placenta. The chorangioma
is eccentrically located near the insertion of the umbilical cord and occupies ∼20
to 25% of the placental disc.
Fig. 3 (a) A specimen radiograph revealed and identified the position of two coils within
the feeder vessel of the chorangioma. (b) Sectioned placental parenchyma revealed
the location, color, consistency, and well-circumscribed nature of the chorangioma
postcoiling, as well as the position of the two coils.
Discussion
The optimal management of giant placental chorangioma remains undetermined. Both natural
history and pathophysiology are only partially described.[1 ]
[2 ] Maternal and fetal complications increase once the tumor exceeds 4 to 5 cm.[3 ] Maternal complications include symptomatic polyhydramnios, preterm premature rupture
of membranes, preeclampsia, and mirror syndrome. Fetal loss appears to be primarily
from shunt physiology and high-output failure, compounded by the secondary effect
of severe anemia from microangiopathic hemolysis and red cell sequestration within
the tumor.[4 ] A third mechanism may diminish oxygen and nutrient delivery to the developing fetus
due to preferential blood flow into the low-pressure vascular circuit of the tumor
and away from the intervillous space (steal phenomenon).[2 ] Finally, there is likely to be significant competitive substrate consumption by
the enlarging tumor.
Although temporizing interventions such as amnioreduction for symptomatic polyhydramnios
and intrauterine transfusion for severe fetal anemia may have a role in management,
the primary goal of treatment is to address the underlying pathophysiology by disrupting
the tumor's blood supply, thereby arresting shunt physiology, hemolysis, sequestration,
steal, and substrate consumption. Tumor devascularization has been attempted using
various forms of thermal energy such as bipolar cautery, interstitial laser, radiofrequency
ablation, and fetoscopic laser photocoagulation, alone or in combination, each with
their advantages and disadvantages.[4 ]
[5 ]
[6 ]
[7 ] Vascular clips have been placed under fetoscopic guidance.[7 ] Embolization has been performed with liquid agents such as ethanol, cyanoacrylate,
and enbucrilate.[8 ]
[9 ]
[10 ] Chorangiomas, however, may contain arteriovenous anastomoses, which can allow for
passage of liquid or small particulate embolic agents through the tumor and back to
the fetus. Voon et al recently reported a case of portal vein thrombosis in a newborn
after use of the liquid embolic agent enbucrilate and advised caution with this material.[10 ] This risk is overcome by the use of microcoils, which cause vascular occlusion at
the point of insertion and cannot pass through the capillary bed of the tumor.[11 ]
Advantages of embolization are the ease and familiarity of the technique (technically
similar to vascular access for percutaneous umbilical blood sampling/intrauterine
transfusion [PUBS/IUT]), its minimally invasive nature (percutaneous, ultrasound guidance,
21-gauge needle, intravenous sedation and local anesthetic, and extra-amniotic instrumentation
in the case of an anterior placenta), and lack of collateral damage that can occur
with thermal energy.
Lau et al describe the use of microcoils in the management of a 10-cm giant chorangioma
with a 7.4-mm feeding vessel using multiple (10) coils ranging in size from 2 to 6 mm
injected into secondary branches of the feeding vessel that did not cause complete
occlusion. Another nine were inserted 1 week later under general anesthesia, again
with incomplete occlusion. In contrast, we inserted two 6 × 2 mm Tornado microcoils
within the 6-mm lumen of primary feeding vessel which resulted in rapid and complete
occlusion. Location, size, and number of coils were left to the discretion of the
interventional radiologist who placed the coils after intravascular access was achieved
by the fetal interventionalist. We suspect that preoperative and intraoperative interdisciplinary
collaborations were instrumental in our clinical success.
Due to the rare nature of giant placental chorangioma, a rigorous evaluation of natural
history and response to treatment will likely require a multicenter registry, which
could be accomplished through the North American Fetal Therapy Network. If coil embolization
appears to be easier and safer than other techniques, the risk–benefit assessment
may shift toward earlier intervention before the fetus demonstrates evidence of frank
decompensation (cardiomegaly, growth restriction, oligohydramnios, severe anemia,
and hydrops fetalis), which may improve clinical outcomes. In retrospect, we believe
our first case was technically successful, but that the fetus was too ill to survive
the hemodynamic changes that would occur with any occlusive procedure. An alternative
approach could have been temporizing intrauterine transfusion as a form of intrauterine
resuscitation followed by definitive embolization therapy. Maternal risks from embolization,
the other half of the risk–benefit equation, were no greater than with intrauterine
transfusion, which is probably the safest procedure performed in fetal intervention.
Finally, with an anterior, lateral, or fundal placenta, this technique has the potential
of being entirely extra-amniotic, thereby eliminating the risk of iatrogenic amniorrhexis
and its deleterious consequences, chiefly preterm birth.
We applied what we had learned from our first case to the second, namely, preoperative
and intraoperative interdisciplinary collaborations; amnioinfusion to better elucidate
the anatomical relationships among the tumor, placenta, and feeding vessel; and intrauterine
transfusion to restore intravascular volume and oxygen carrying capacity before proceeding
with embolization. Also, the fetus in the second case was likely not as chronically
ill as the first and was, therefore, better able to tolerate the intervention, supporting
the argument that earlier intervention may result in improved pregnancy outcomes.
Although it is true that our second case was not entirely extra-amniotic in that membranes
were punctured for amnioinfusion and intrauterine transfusion, earlier intervention
may eliminate the need for these adjuncts, and the membranes were punctured with a
22-gauge needle.
In summary, we describe a technically simple, minimally invasive, percutaneous, ultrasound-guided,
extra-amniotic technique of coil embolization of a giant placental chorangioma that
safely and completely occluded the feeding vessel, did not migrate back into the fetal
circulation, did not cause collateral thermal damage, and exposed the mother to minimal
risk. We hope that, through collaborative multicenter research, we can optimize pregnancy
outcomes complicated by giant chorangioma in a scientifically rigorous and ethically
sound manner.[12 ]
