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Compression and Doppler ultrasound of deep vein thrombosis in patients on tuberculosis treatment
Background. Ultrasound has until recently been regarded as a sophisticated examination reserved for tertiary health care. In reality it is well suited to the district or primary health-care situation. A DVT (deep vein thrombosis) is an important complication of the treatment of TB and this can lead to more devastating sequelae such as a pulmonary embolus. Many DVTs are clinically silent, making the diagnosis difficult. Method. This study was a prospective, longitudinal observational study. The study documented the incidence of DVTs and their onset, assessed certain aspects in an attempt to identify some risk factors, and noted the most common position of the DVT in a TB population. The feasibility of a sonographer-led ultrasound clinic for the diagnosis of DVTs was also assessed. This was achieved by screening the in-patient population at a district TB hospital. The participants received up to four routine duplex Doppler compression ultrasound examinations of the venous system of the lower extremities on week 0, week 4, week 8 and week 14. In addition a single abdominal ultrasound was performed at week 0. Results The incidence of DVTs in this TB population was 15.3%. A median of day 10 from commencing TB treatment was identified as the most common day to develop a DVT. The popliteal vein was the most frequent position for a DVT. Several statistically significant factors were identified, including a decreased ambulatory status, TB regimen and the use of anticoagulants. Only 52% of the DVTs were clinically symptomatic. The clinical evaluation for a DVT diagnosis in this study population had a sensitivity of 52.4% and a specificity of 65.3%. The positive predictive value (PPV) was 21.7%. Of the abdominal ultrasound reports there were 75.5% (281) abnormal reports, 22.5% (n = 90) normal reports and 4.5% (n = 18) with no report. Conclusion This body of work has shown how an effective ultrasound service can be provided at a district level TB hospital successfully administered by a trained ultrasonographer. This also facilitated a screening service to diagnose both symptomatic and asymptomatic deep vein thromboses in newly diagnosed tuberculosis patients. This study confirmed a higher rate of DVT in newly diagnosed TB patients than has been previously seen. It also provided detail on additional risk factors. The study illustrates the poor performance of clinical signs and symptoms as a trigger for further investigation for the confirmation of a DVT. Given the frequency and impact of the embolic complications of DVT, this study provides a strong justification for further research into routine serial ultrasonic screening and/or prophylactic antithrombolytics in newly diagnosed TB patients. As well as the DVT ultrasound scans there was the ancillary service offered by the research sonographers. This included an abdominal scan that detected abdominal pathology in 75% of the scans performed. An ultrasound scan is not pathognomonic but it does provide significant insight into the extent of some of the abdominal pathologies seen in TB patients. The information provided from this study gives a good indication of the problem that DVTs present in this population and the complexities of the disease TB. It is hoped that the results from this study will better equip the medical team in the non-tertiary situation to be vigilant for the presence of a DVT and educate them on the usefulness of the ultrasound scan.