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The unusual clinical presentation, importance of imaging techniques and role of low molecular weight heparin are described for an initial treatment of thrombosis in inferior vena cava agenesis associated with heterozygous factor V Leiden. The patient, a 36-year-old woman, presented to the emergency room with sudden onset of back pain, swelling of the legs and thighs, and claudication while walking. Abdominal ultrasonography was immediately ordered. Anomalies in vascular blood flow were detected. Computed tomography was performed, and initially showed a complete absence of the infrarenal segment of inferior vena cava caudally to the origin of both renal veins. Treatment with enoxaparin (1 mg/kg twice per day) was started. The patient was discharged and returned to her activities of daily living two weeks after admission. This vascular abnormality is mostly incidentally diagnosed in adults and only a few cases are described as being associated with thrombophilia.
Anomalies in the development of the inferior vena cava (IVC) appear between the sixth and eighth weeks of gestation if improper development or regression of the following three paired embryonic veins occurs: the vitelline, subcardinal and embryonic cardinal veins. Absence of the IVC has been estimated in between 0.3% to 0.5% of the general population (1). However, its prevalence in the group of patients with deep venous thrombosis may reach up to 5% (2,3). The mean adult age of clinical onset is between the second and fourth decade of life (4,5). Two main events lead to discovery of such anomalies in adults – incidental medical diagnosis and thrombosis.
A 36-year-old Caucasian woman presented to the emergency department complaining of swelling in both legs and nonradiating acute low back pain for less than 24 h. She experienced intense thigh tenderness on walking during the previous three days. The patient denied any abdominal pain, leg numbness or weakness, or standing for extended periods or physically exerting herself to exhaustion in the preceding days. She had no other systemic symptoms.
The patient had an active life, practicing climbing frequently. She smoked 20 cigarettes per day. She had no previous pregnancies. She was not taking oral contraceptives or any other medication. Her mother suffered from deep venous thrombosis.
On physical examination, she appeared healthy, and had an arterial blood pressure of 100/60 mmHg, a regular heart rate of 72 beats/min, a respiratory rate of 16 breaths/min and an axillary temperature of 35.5°C. She had no jugular venous distention. No skin lesions or enlarged lymph nodes were detected. Her chest was clear to auscultation on both sides and she had normal heart sounds. Her abdominal examination did not reveal any masses or vascular murmurs. Both legs presented tight nonfoveal edema down to her knees. The Hoffman sign was negative and her calves were pain free. The peripheral arterial pulses were symmetrical.
Abdominal duplex ultrasonography was performed in the emergency room. It showed abnormal filling of the hypogastric vessels. After this finding, contrast-enhanced computed tomography (CT) was performed. CT showed a complete absence of the infrarenal segment of IVC caudally to the origin of both renal veins. The suprarenal section was preserved. Thrombi were observed inside both common iliac veins. The ascending lumbar and venous plexus, azygos and hemiazygos veins, and anterior paravertebral collateral veins were enlarged (Figure 1).
Laboratory investigations did not reveal any abnormalities of renal and hepatic functions. The hemogram was normal. The erythrocyte sedimentation rate was 30 mm/h and the C-reactive protein reached 14.4 mg/L. Antinuclear antibodies, immunoglobulins, cryoglobulins and tumoral markers were within the normal ranges. The thrombophilia study revealed heterozygous factor V Leiden mutation.
Anticoagulation with low molecular weight heparin (LMWH) (enoxaparin) was started at a dose of 1 mg/kg twice per day. Thigh tenderness and leg swelling improved over the following week. The patient was discharged and returned to her activities of daily living two weeks after admission.
In normal adults, the IVC has four main segments – prerenal, renal, hepatic and posthepatic (6). The absence of IVC inferior segments in slices of magnetic resonance and CT angiography suggests a congenital anomaly (7,8). A multiple cavocaval anastomosis procedure has been developed, switching the IVC and superior vena cava through the azygos and hemiazygos vein system, and the iliac, lumbrosacral and vertebral vein plexus. If the collateral circulation is developed well enough, symptoms are likely to be prevented in adults, even in the presence of prothrombotic factors such as hyperhomocysteinemia (2), protein S deficiency (4) and factor V Leiden mutation (1,5). The absence of clinical symptoms in our patient may be justified by this consideration. It is hard to say how long both common iliac veins were thrombosed. A possible hypothesis is that she had been experiencing several thrombotic events due to her thrombophilia (factor V Leiden carrier). Therefore, she was asymptomatic until the collateral vein system was suddenly blocked, possibly because of a new clot formation. This point could explain the patient’s lumbar pain (8) given that possible clots were not seen on imaging, neither in the ascending collateral lumbar vein plexus nor another collateral small-sized vein.
Initial treatment with LMWH (2) is an alternative in patients who have contraindications or refuse oral administration of vitamin K inhibitors. Our patient refused initial oral anticoagulation with acenocoumarol during the first six months. The treatment with LMWH (1 mg/kg twice per day) was performed as maintenance until oral anticoagulation was finally started. After 24 months follow-up, no new symptoms were detected.
The role of the duplex ultrasonography in this pathology is not well studied. Most studies used CT angiography to show these anomalies. In our case, abdominal ultrasonography was used as a screening technique in the emergency room, helping lead us to the correct diagnosis. It is not known whether ultrasonography could be useful in the follow-up of these patients. We believe further studies should be performed to investigate this point.
Abdominal vascular pathology should be strongly considered in young women or men who complain of sudden swelling or weakness of both legs, regardless of whether it is associated with low abdominal or recent back pain (9). Other IVC malformation should be considered in young patients with idiopathic deep venous thrombosis (10–13).
The most appropriate treatment approach is long-term oral anticoagulation in those patients with thrombophilia and IVC abnormalities (9). Treatment with LMWH is a good and safe alternative for patients with any contraindication for oral anticoagulation. We also recommend avoiding additional thrombosis risk factors such as smoking, hormonal contraceptives, immobilization or unusual physical activity.
DISCLOSURE: All authors have read the manuscript and have participated in the writing and preparation of the present work. They also all had complete access to the data presented in this article. We have no potential conflict of interest arising from associations with commercial or corporate interest in connection with the work submitted.