Thrombosis or clotting of blood in major vessels, particularly in the aorta, is very rare in neonates. We present an extremely small to date neonate who was diagnosed with descending aorta thrombosis at 72 hours of life without any identifiable risk factors for the same. This baby boy was born at Sri Ramakrishna Hospital at 35 weeks of gestation with severe intrauterine growth restriction with a birth weight of 1045 grams. The mother had previous 2 abortions with severe preeclampsia in this pregnancy for which she was on oral medications. She did not have any history of photosensitivity, rash or arthralgia. It was a nonconsanguineous marriage without family history suggestive of any premature thrombotic events. The baby vigorous at birth and was well for first 72 hours except for transient tachypnea of newborn (mild respiratory distress). No umbilical arterial or venous catheterization was done.

At 72 hours of life he was noticed to have absent lower limb pulses (including bilateral femoral pulsations) bilaterally with mottling and pallor of both lower limbs.There was no line of demarcation and no obvious cyanosis of lower limbs. Lower limb blood pressures were not recordable. The limb showed signs of viability with normal limb movements, sensory response, and a prolonged but definitely present capillary refill. The abdominal and cardiovascular examination was normal. Initially, co-arctation of aorta was considered as the clinical possibility. However, 2D ECHO was normal. 2D USG and Doppler of lower limbs showed scanty flow in B/L femoral arteries. CT angiogram clinched the diagnosis of a major thrombotic occlusion of the entire infrarenal portion of descending aorta. Biochemical parameters including renal function and hematocrit were normal. The septic screen was negative. Multidisciplinary consultations from radiology, pediatric cardiologist, cardiothoracic surgeon and hematologist were obtained. The following points were considered:

  • Though it was a major vessel thrombosis, it was neither limb threatening nor life-threatening at the time of diagnosis.
  • Risk versus benefit was not in favor of thrombolysis. The documented patency rates after thrombolysis in neonates with aortic thrombosis is as low as 39%.On the other hand, the risk of major bleeding episode secondary to thrombolysis is as high as 69%. The neonate was started on unfractionated heparin infusion (UFH). High doses of heparin were initially (up to 60 U/kg/h 

was required to achieve the desired aPTT levels (60-85sec). After 72 hours of heparin infusion, colour of lower limbs improved. On day 7 of heparin infusion, a repeat Doppler showed improved lower limb arterial flow, even in the posterior tibial arteries. Blood pressures, Spo2 were recordable after 8 days of heparin infusion. Femoral pulses returned only after 14 days. A PICC line was placed to continue heparin infusion. Later UFH was replaced by twice-daily subcutaneous (sc) doses of Low molecular weight Heparin (LMWH). On regular follow up, lower limb perfusion and BPs are normal.

Though there is no obvious aetiology for the aortic thrombosis in our case, it could be because of any of the following:
  • Antiphospholipid antibody syndrome (APLA)
  • Any of the inherited pro-coagulant states like Protein C, protein S deficiency, Factor V Leiden mutation or antithrombin III deficiency. Particularly anti-thrombin III deficiency is associated with initial heparin resistance (as was in our case).
  • Intrauterine growth restricted feti are in a pro-coagulant state through their causative role in our case is not determinable. Warfarin was not our first choice for maintenance therapy for many reasons; first, there is no data on safety and efficacy in less than three months. Second, the need for frequent monitoring and hospital visits. Third, premature neonates being already deficient in Vitamin K make them very sensitive to very low doses of Warfarin.
High points of our case:
  • No antibiotics at any stage
  • Vigilant nursing care and Multidisciplinary team approach lead to prompt diagnosis and initiation of treatment
  • Continued nutritional and developmental care leading to optimal weight gain and normal neurological status at the time of discharge Babies born to mothers with Pre-eclampsia, and babies with IUGR are at a great risk for a multitude of problems and need care in tertiary level NICUs for good outcomes.
Dr. Siddartha Buddhavarapu M.D.
Fellow In Neonatalogy
Consultant Neonatologist & HOD
Dr. Suja Mariam MD., DM
Consultant Neonatologist