Untreated Subsegmental Pulmonary Embolism (SSPE) in High Risk Women: Incidence and Outcome

Abstract

PURPOSE: 1) Determine incidence of SSPE using 1.25mm collimation in at risk obstetric and gynecologic patients suspected of PE; 2)Assess the rate of clinically significant venous thromboembolism (VTE) in patients with untreated SSPE compared to controls. METHODS: Women with clinical suspicion of PE who underwent imaging using a 16 multidetector CT scanner were recruited. Images were reconstructed to 1.25 and 2.5mm collimation and reviewed on the PACS Cerner work station. Standard imaging protocol was modified for pregnant patients. 2.5mm collimation images were reviewed for clinical purposes at the time of study and management based on those results. At the end of the predetermined follow up period, both 2.5mm and 1.25mm collimation images were independently and randomly reviewed by 2 radiologists, blinded to each other's reading and patients' outcomes. Follow up period for VTE outcomes were 3 months (non-pregnant), and 3 months/6 weeks postpartum, whichever is longer (pregnant). Neonatal outcomes were recorded for all pregnant patients. RESULTS: A total of 100 women at risk for VTE (56 obstetric and 44 women with gynecologic surgery / malignancy) were recruited. So far, 70 patients have completed follow up. Mean age is 43 + 17.5 and mean BMI is 31 + 9.4. Incidence of PE restricted to the subsegmental level among patients suspected of PE was 10%. 1.25mm MDCT has detected 7 cases of SSPE that were not identified on 2.5 mm collimation; none of these cases were treated and all were available for follow up. There were no VTE outcomes in the treated SSPE group, untreated SSPE group or the group without thromboembolism. There was a trend toward higher gestational age at delivery in the obstetric group without VTE, but no difference in birth weight. Death occurred in 4 treated patients and was due to extensive metastatic disease. CONCLUSIONS: Incidence of SSPE in women at risk for VTE and clinically suspected of having PE is significant and is higher with 1.25 mm compared to 2.5mm collimation. No VTE outcomes were noted in the group with untreated SSPE. CLINICAL IMPLICATIONS: Clinical significance of SSPE remains unclear. Outcomes studies in untreated patients are sorely needed to help with the management of this controversial entity. This study adds to the limited data.