Polarizing microscopy: A reliable and cost effective method for analysis of urinary calculi

400 calculi from 400 patients between the age group of 3-86 years were analysed by polarizing microscopy. Whewellite was found in 302 calculi. Apatite, weddelite and struvite were found in 124, 120 and 51 calculi respectively. Amongst monomineral calculi, whewellite was the most commonly found component. Whewellite was seen in its compact form in 68 calculi. In 79 calculi, it was found in its microcrystalline form. Amongst mixed calculi, whewellite + weddelite was found in 52, whewellite + apatite in 36; while whewellite + apatite + struvite was present in 31 calculi. Almost all commonly occurring components of urinary calculi were easily identified by this method of calculus analysis. The nucleus as well as peripheral layers could be studied simultaneously by thin section polarizing microscopy, rendering it an ideal method to study the structure of urinary calculi. Polarizing microscopy is not only accurate and cost effective but also is rapid and easily standardizable, thus making it one of the most useful methods of urinary calculus analysis. Minute details resolved by other methods like X-ray diffraction, Infrared Spectroscopy etc. are of little clinical value.