Patient Report Congenital absence of the infrahepatic segment of the inferior vena cava with deep venous thrombosis in an 8.5-year-old boy Essam A. Ismail, 1 Asmaa F. Azab, 1 Sateesh Jayappa 2 and Hanan Al-Qattan 1 Departments of 1 Paediatrics and 2 Radiology, Farwaniya Hospital, Kuwait Key words deep vein thrombosis, inferior vena cava malformation, thrombophilia. In a recent study, the prevalence of interruption or congenital stenosis of the inferior vena cava (IVC) was found to be 0.15%. 1 Embryological formation of IVC occurs between the fourth and eighth weeks of gestation; this period coincides with the devel- opment of most organs (spleen, liver, heart, and lungs). Thus, it is not surprising to have asplenia, polysplenia, situs inversus, con- genital heart disease, lung and kidney malformation associated with IVC anomalies. 2 The IVC is formed of four segments (in a caudal direction: hepatic, suprarenal, renal and infrarenal). These segments are formed by complex embryological processes involving the formation, fusion and regression of three main paired primitive veins called cardinal veins. Failure of proper development of one or all of these events leads to several con- genital anomalies; one of these is the congenital absence of IVC (AIVC). It may be the entire IVC or one of its segments. 2 It is also suggested that absence of the infrarenal segment of the IVC is not embryonic in origin, rather the result of intrauterine or perinatal thrombosis. 3,4 The prevalence of AIVC in deep venous thrombosis (DVT) is about 5%. 5,6 Approximately 90% of previously reported cases involved the absence of the suprarenal segment and 6% involved the renal or infrarenal segment. The combined absence of the suprarenal and infrarenal segments (infrahepatic) is so rare that only 10 cases were reported in the English-language literature prior to 2002. 3 We present a patient who developed right iliofemoral throm- bosis at the age of 8.5 years and was found to have this rare infrahepatic AIVC on computed tomography (CT) of the abdomen and magnetic resonance venography. There was no recurrence 16 months after discontinuing the anticoagulant treat- ment. To the best of our knowledge, this patient is one of the young- est patients reported to develop unprovoked DVT in association with infrahepatic AIVC. Case report The patient is currently 10.5 years old. He was seen at the age of 8.5 years because of painful swelling involving the whole right lower limb over a few hours before admission. The skin looked bluish-red and slightly tender. The popliteal arteries and dorsalis pedis arteries felt well in both lower limbs. There was no history of preceding trauma, strenuous exercise, high fever, severe vom- iting or diarrhea. There was no family history of venous throm- bosis or suggestive of a hypercoagulable state. The patient is the product of in vitro fertilization because of primary infertility for 11 years. It was a twin pregnancy. Delivery was by cesarean section at 36 weeks of gestation because of maternal gestational diabetes. Our patient weighed 1.3 kg at birth, while his co-twin weighed 2.5 kg. Our patient was admitted to the neonatal ward for extreme low birthweight with Apgar scores of 6 and 9 at 1 and 5 min, respectively. Reviewing his chart, he did very well in the neonatal ward and did not develop sepsis, respiratory distress, dehydration or any other medical problems. He was discharged after 4 weeks when his weight was 1.940 kg. Color Doppler sonography at the age of 8.5 years revealed thrombosed right popliteal, femoral and external iliac veins (Fig. 1). Thrombophilia markers were unremarkable including protein S and C, factor V Leiden mutation, prothrombin 20 210 mutation, antithrombin III, activated protein C resistance, factor VIII and factor IX. Other normal or unremarkable blood studies included methionine and homocysteine level, lupus anticoagu- lant, complement 3 and 4, anticardiolipin antibodies, antinuclear antibodies and sickling test. The vascular surgeon was immedi- ately consulted and reported limited experience in pediatric vas- cular thrombolytic therapy or catheter-directed thrombolysis and advised to continue medical therapy. The patient was commenced on low-molecular-weight heparin, which continued for 10 days. Warfarin was introduced on day 5 and continued for 8 months. The swelling of the right lower limb gradually improved, and some dilated veins appeared on the lateral aspect of the thigh. Complete recanalization of the thrombosed vessels was seen on Doppler ultrasound after 6 months. Contrast-enhanced CT scan (Figs 2,3) showed that the entire infrahepatic segment of the inferior vena cava was missing as well as the right common iliac vein with multiple paravertebral Correspondence: Essam A Ismail, MRCP, Department of Paediatrics, Farwaniya Hospital, BO Box 936, Salmiya, 22010, Kuwait. Email: rsessam@hotmail.com, rsessam@yahoo.co.uk Received 17 August 2008; revised 16 February 2009; accepted 8 April 2009. Pediatrics International (2010) 52, e117–e120 doi: 10.1111/j.1442-200X.2010.03081.x © 2010 Japan Pediatric Society