A girl weighing 3.59 kg was born via cesarean section at 38 weeks of gestation, with a large sacrococcygeal mass measuring 15 × 15 cm. Magnetic resonance imaging (MRI) obtained on the third day of life revealed a huge type I SCT with heterogenous signal intensity and minimal enhancement in post-gadolinium images (Fig. 1). The MRI also identified at least three feeding arteries supplying the mass. A few episodes of bleeding from the external surface of the mass were observed and subsequently sutured. In addition, the hemoglobin level dropped from 11.0 to 9.7 g/dL.

a Large sacrococcygeal mass causing abduction of both legs. b Unenhanced MRI of the pelvis in coronal T1W view shows large exophytic sacrococcygeal mass with heterogenous signal intensity. c Post-gadolinium MRI of the pelvis in coronal T1W view shows minimal enhancement of the exophytic mass

As a result, the patient was referred for pre-operative embolization on the seventh day of life, weighing 2.88 kg, indicating a reduction of 20% in weight. The pre-procedural measurement of the left femoral artery was 1.2 mm. While evaluating various vascular access options, the decision was made to proceed with the left femoral artery due to associated higher risk of thrombus formation or stroke with the use of the common carotid artery. The left femoral artery was then punctured using 24G branula under ultrasound guidance. Following this, a 4-Fr Micropuncture introducer was inserted as a sheath, and a 2.7-Fr Progreat microcatheter was used for selective cannulation (Fig. 2). A heparin bolus of 40 U/kg was administered following sheath insertion.

Left femoral artery access using 24G branula, microwire, and Micropuncture introducer (black arrow) as a sheath

Angiography confirmed a high-vascular tumor supplied by the middle sacral artery, which was embolized using Contour polyvinyl alcohol (PVA) 150–250 μm and 3 mm × 3 cm coils. The distal branches of bilateral internal iliac arteries were also embolized using Contour PVA 45–150 μm and Gelfoam slurry (Fig. 3a). Post-embolization angiography demonstrated complete occlusion of the feeding vessels (Fig. 3b). A total of 8 ml of non-ionic contrast media was used.

a Pre-embolization angiogram shows feeding arteries to the mass. b Post-embolization angiogram shows complete occlusion of the feeding vessels. Note coil within the middle sacral artery (white arrow). IIA: internal iliac artery; MSA: middle sacral artery

Three hours post-procedure, the patient’s left lower limb exhibited a bluish color, and there was a discrepancy in pulse oximetry reading compared to the contralateral side. Ultrasound assessment revealed a smaller caliber of the left common femoral artery than on the contralateral side. No evidence of thrombus was found; therefore, the patient was treated for post-procedural femoral artery spasm. A glyceryl trinitrate (GTN) patch was applied to the puncture site, and the spasm resolved after 3 days of treatment.

Resection of the tumor was performed 24 h post-embolization, with a total blood loss of 20 ml. Histopathological examination of the excised tumor confirmed it as a sacrococcygeal mature teratoma. The patient was discharged well on the eighth day after surgery, with routine outpatient follow-up.

In this case, we encountered challenges particularly due to the acute anatomical angulation of the femoral artery and feeder arteries. The semi-abduction position of the lower limbs further complicates the femoral artery approach. However, by employing a Micropuncture introducer as a sheath, combined with manipulation of microwire and reshaping of the microcatheter, we managed to achieve adequate catheterization support before proceeding to deliver the embolic materials. For the internal iliac arteries, we opted to use small Contour PVA particles, followed by Gelfoam slurry, to occlude the arteries. Subsequently, the middle sacral artery was embolized using larger Contour PVA particles and a pushable coil.

The small size of the femoral artery further compounded the difficulty, especially with the occurrence of femoral artery spasm following catheterization. However, this was successfully treated with a GTN patch, and no significant disability was observed. Such minor complication could potentially be mitigated by administering a heparin bolus following catheterization or through continuous infusion throughout the procedure.