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Differential Diagnosis (S. haematobium)

The differential diagnosis of calcification of the bladder is not difficult in most patients because each cause has a very different appearance. Calcification can be due to amyloidosis, in which it is very spotty. Some chemicals and drugs, such as cyclophosphan may cause quite heavy calcification, but the bladder will be small and does not expand. Tuberculosis can cause localized calcification in one, or perhaps, two areas of the bladder, usually a small flat area. Carcinoma which has been treated by radiotherapy may also calcify when it heals, associated with scarring and distortion of the bladder outline and localized to one area. There is nearly always residual local thickening. In schistosomiasis the bladder calcification follows the shape of the bladder, is seldom associated with distortion except in the final stages, and does not usually affect bladder distention or contraction. It is by far the commonest cause of bladder calcification and is very characteristic. It is the only cause of bladder calcification in which there is likely to be calcification of the ureters as well.

In those who have acquired the infection recently (such as travelers) as opposed to those who have lived with it for many years, it is important to recognize the early signs of prolonged ureteric filling during contrast urography. This may be the only evidence of the infection. Later the irregularity and beading of the ureter, the stenosis and dilatation can be recognized by ultrasound or radiography at a time when the bladder may still be normal. Following treatment, particularly in those who have not been previously infected, follow-up ultrasound and intravenous urography after six months will ensure that there has been no ureteric stenosis or dilatation.

The finding of calcified eggs in the gallbladder, in any part of the bowel, in the seminal vesicles, or in the female genital tract is also a strong indication of schistosomiasis, as is the presence of hepatic periportal fibrosis on ultrasonography.

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