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Role of abdominal ultrasound in the context of the HIV/AIDS epidemic.

To the Editor: I read the article in the June 2009 edition of the SAJR entitled 'Trans-abdominal ultrasonic findings correlated with a CD4+ counts in adult HIV-infected patients in Benin, Nigeria', (1) with interest.

I totally agree that the use of ultrasound (US) is invaluable in the assessment of HIV-positive patients and in the monitoring of treatment in these patients. I must, however, disagree with the statement that it should be used in all HIV-infected patients as a baseline investigation. The authors themselves clearly state that 'few of the ultrasound findings correlated statistically with the CD4+ counts.' This is unsurprising, given the unfocused use of US in terms of the patients' symptomatology in their study. The manpower needs to perform a baseline US study of the abdomen in every patient diagnosed with HIV, regardless of their clinical state, are also probably not realistically achievable, given the workload and staffing ratios of our hospitals.

In the appropriate clinical setting, however, US can be a vital tool in the assessment of patients with abdominal symptoms and in patients with an unexplained pyrexia in whom the chest X-ray is normal and sputum examination for acid-fast bacilli is negative. In this setting, US of the abdomen has the potential to detect many conditions, but in particular to demonstrate evidence of disseminated TB (which is a relatively common condition in our immuno-compromised population).

In 2002, Dr Mike Hunter and I published our experience with the use of abdominal sonar in HIV-infected patients with a fever of undetermined origin in a letter to the South African Medical Journal. (2) Three findings were of particular note. The first was that pericardial effusion (which is easily demonstrated via the infra-sternal approach on abdominal US, and should be a routine component of every abdominal US) was a not uncommon, and often unexpected, finding, even in patients where the cardiac density was not enlarged on chest X-ray. Because small pericardial effusions are common in HIV-infected patients, we used a threshold of 5 mm for the diagnosis of a pathological collection. As tuberculous pericarditis is by far the most common cause of an effusion in this setting, patients with a pericardial effusion >5 mm in width were started on treatment for TB and closely monitored.

Secondly: in our experience, the most common cause by far of abdominal lymphadenopathy in HIV-infected patients with pyrexia is tuberculous lymphadenitis. The distribution typically involves the porta hepatus, peripancreatic region, and occasionally the splenic hilum. The differential diagnosis includes lymphoma and persistent generalised lymphadenopathy (a component of the AIDS-related complex). Both these latter conditions appear to be very uncommon in our population. We therefore regard abdominal lymphadenopathy (in the appropriate clinical setting) as diagnostic of tuberculous lymphadenitis in the first instance, and therefore an indication for TB treatment. Should the patient fail to respond to antituberculous treatment (a very rare occurrence in our series), further investigation of the lymphadenopathy is indicated.

The third important finding in our series, in the diagnosis of disseminated TB, is that of splenic micro-abscesses. We found the demonstration of micro-abscesses within the spleen to be highly correlated with a diagnosis of disseminated TB. Although a number of other causes of splenic micro-abscesses (including salmonella, candida, lymphoma and histoplasmosis) have been described, disseminated TB is by far the most common cause in our population, and is regarded as an indication for commencing TB treatment. As with the other findings (as described above), these patients are closely monitored on both clinical and sonographic follow-up. Only patients who fail to respond to TB treatment (again, very rare in our series) are subjected to further investigation.

When used in this way, US of the abdomen results in substantial savings in terms of rendering more expensive and invasive investigations and their substantial costs unnecessary. This is of particular relevance in a resource-constrained setting, where access to sophisticated diagnostic modalities is limited. US, with its immediate results, also has the potential to save days (sometimes even weeks) in the time interval between performing the diagnostic examination and commencing treatment (compared with, for example, awaiting the results of tissue biopsy or bone marrow aspiration).

Although I do not dispute that the article is valuable in furthering our knowledge of HIV/AIDS via the medium of US imaging, I believe that there are very limited indications for US in asymptomatic patients, even those who are HIV-positive. However, in our hospital (and in several other institutions that I am aware of), abdominal US is not only being successfully used on a daily basis not only for the evaluation of patients with abdominal symptoms but also, according to the above criteria, in the diagnosis or exclusion of disseminated TB.

D J Emby

AngloGold Ashanti Health, Western Deep Levels Hospital, Carletonville

demby@anglogoldashanti.com

(1.) Igbinedion B O-E, Marchie T T, Ogbeide E. Trans-abdominal ultrasonic findings correlated with CD4+ counts in adult HIV-infected patients in Benin, Nigeria. S Afr J Radiol 2009; 13(2): 34-40.

(2.) Emby D J, Hunter M. The value of ultrasound in the HIV-infected patient with a fever of undetermined origin. S Afr Med J 2002; 92(8): 566.

Dr Igbinedion and co-authors reply: We thank Dr Emby for his interest in our article. During the course of the study, the recruiting physicians noted its usefulness, especially in renal scans, where we detected several asymptomatic nephropathies; consequently, these patients benefitted from improved follow-up laboratory reports after medical intervention. We are therefore of the opinion that radiologists should, if at all possible, not shy away from their responsibilities, even in the context of unbalanced staff ratios. This is one of the reasons why unqualified individuals offering ultrasonography in several Nigerian communities have led to increased frequencies of quackery and missed diagnosis, which is a major and potentially disastrous non-biological hazard of ultrasound.

Our study was rather an abridged version of a broader perspective. In the study, fever, cough, skin rash and diarrhoea were the most common presenting complaints (45.3%, 25%, 20% and 14.7% respectively) while uncommon complaints constituted only 8.6%. Unfortunately, apart from skin rash, these symptoms did not correlate significantly with abnormal sonographic findings on univariate analysis. But, as would be expected, patients with abdominal symptoms had more abnormal sonographic findings compared with those with other complaint or no presenting complaint at all. However, since we are currently undertaking a follow-up study, there may be further interesting findings in the offing.

B O-E Igbinedion

Department of Radiology, College of Medical Sciences, University of Benin

and University of Benin Teaching Hospital, Benin, Edo, Nigeria

igbins2@yahoo.com
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Title Annotation:LETTERS
Author:Emby, D.J.
Publication:South African Journal of Radiology
Geographic Code:6NIGR
Date:Dec 1, 2009
Words:1091
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