Inferior vena cava agenesis revealed by neonatal hypertension

Introduction

Most often, interruption of the inferior vena cava results from insufficient development of the anastomosis between the subcardinal vein and the vitelline vein.

Method

Clinical case: A young male infant, aged 49 days, with a gestational age of 35 weeks and 4 days. Birth weight: 3 kg. The infant presents with moderate respiratory distress due to a well-evolved early neonatal infection, under antibiotic treatment. On day 13 of life (corrected age: 37 weeks), the infant develops edema of the lower limbs and hypertension (120/50 mmHg). Clinical examination: Respiratory rate: 40 cycles/min, SaO2: 94%, heart rate: 120 bpm, regular rhythm, heart sounds well audible, and all pulses palpable. No lumbar tenderness or abdominal mass. Neurological examination is normal.

Results

Abdominal echo-Doppler showed a thrombus measuring 22 × 6 mm in the IVC, which was confirmed by an angioscanner revealing a thrombus in the IVC and the right renal vein, along with dilation of the compensatory azygos vein and the presence of a collateral network, without impact on the right kidney. Cardiac echodoppler: normal. Echodoppler of both lower limbs: absence of signs of deep vein thrombosis.

Blood tests: Renal function normal (no proteinuria, no hematuria, urea: 0.05 g/l and creatinine: 3 mg/l). Hemostasis assessment: normal, Antithrombin III: 51% (N: 41 to 93%), Protein C: 24% (N: 20 to 64%) and Protein S: 76% (N: 22 to 78%).

Mangement: anticoagulant treatment (Lovenox) 150 UI/kg/12 h, extended for 6 months (anti-Xa activity: 0.54 UI/l) + antihypertensive medication with an ACE inhibitor (captopril) 0.5 mg/kg/day in 2 doses (the blood pressure normalized within a few days).

Six months later: Abdominal echodoppler shows the inferior vena cava below the liver at the limit of visibility, non-vascularized in Doppler mode. Thoraco-abdominal angioscanner reveals the absence of opacification of the inferior vena cava. Renal and sub-renal venous drainage occurs at the level of the right hemi-azygos vein, which drains into the superior vena cava and then into the right atrium (RA). The hepatic veins drain directly into the RA.

Conclusion

Inferior vena cava agenesis is an extremely rare pathological entity. This case highlights the importance of considering this malformation in a newborn presenting with lower limb edema and hypertension due to thrombosis of the inferior vena cava and the right renal vein. Consequently, further radiological investigations should be conducted to detect it.