Abstract
Introduction: Superior vena cava (SVC) thrombus is an exceedingly rare but potentially life-threatening condition, with an estimated prevalence ranging from 0.1% to 1% of all venous thromboembolic events. The case study presents a patient diagnosed with SVC thrombus and its possible causal factors.
Case: A 36-year-old African-American female with a history of essential hypertension, type 2 diabetes, end-stage renal disease secondary to diabetic nephropathy, anemia of chronic disease, obstructive sleep apnea, obesity, and a recent diagnosis of preeclampsia six days postpartum with sudden onset of confusion. Her husband reported that she was unable to move her right hand, had significant memory loss, and could not recall her birthday. Her symptoms resolved upon examination in the emergency room but the patient was admitted for further evaluation and treatment.
Six days prior to admission, she had undergone a scheduled C-section for a twin pregnancy at 25 weeks gestational age at which time she was treated for preeclampsia. On the day of admission, she underwent several imaging studies, including CT angiogram of the head and neck, CT brain perfusion, and CT venogram of the head, all of which were negative. The following day, an MRI of her brain was performed and an acute infarct in the left parietal lobe with no intracranial hemorrhage was discovered. Additional imaging included upper and lower extremity dopplers, both negative for DVTs, as well as a transthoracic echocardiogram, significant for trivial pericardial effusion, and a dilated IVC which was consistent with elevated central venous pressure. A follow-up transesophageal echocardiogram was then performed which revealed a large 1.3 x 1.4 cm echodensity/mass. Upon retrospective review of her previous CTA of the neck by the radiologist, a rounded filling defect within the SVC was noted which supported a diagnosis of SVC thrombus. The patient remained stable throughout her hospital stay and was treated with anticoagulants. She underwent an extensive hypercoagulability workup, which was ultimately negative.
Discussion: SVC thrombus is characterized by the formation of a thrombus within the lumen of the SVC. Complete occlusion of the SVC is usually symptomatic. The SVC thrombus present in the patient went undiagnosed for a period of five days as she was relatively asymptomatic. The thrombus remained undetected despite utilizing multiple noninvasive imaging modalities such as CT, Ultrasound, TTE, and Doppler. It was only through the utilization of a transesophageal echocardiogram that the diagnosis was finally made, with subsequent correlation to a previous CTA.
In this case, her recent pregnancy, which is a known physiological hypercoagulable state, her history of intra-dialytic hypotension which was reported by her nephrologist, and issues with catheter placement would constitute all three criteria of Virchow's Triad: hypercoagulability, hemodynamic changes, and endothelial injury. It is uncertain if the parietal lobe infarct, which undoubtedly caused her presenting neurological symptoms, was associated with the SVC thrombus or a different process. The asymptomatic presentation of the SVC thrombus posed a significant challenge for both its diagnosis and treatment, which highlights the need for clinicians to maintain a heightened level of suspicion in order to detect the thrombus and avoid potentially devastating outcomes.
