Manual of basic techniques for a health laboratory - libdoc.who.int

250 Manual of basic techniques for a health laboratorySedimentation method1. Shake the urine specimen well and pour into the conical flask.2. Allow the urine to sediment for 1 hour. Remove thesupernatant and transfer the sediment into a centrifuge tube.Centrifuge at 2000g for 2 minutes.3. Examine the deposit under the microscope for the presenceof ova.Do not increase the centrifugation time and do not exceed 2000gas this may disrupt the ova and release miracidia.Important:— process the specimen as soon as possible;— shake the container before pouring the urine specimen intothe conical flask;— label slides and tubes carefully.Fig. 7.37 Drawing urine into the syringeFiltration method1. Place a filter in the filter holder.2. Agitate the urine sample gently and draw 10ml into the syringe(Fig. 7.37). Attach the syringe to the filter holder.3. Expel the urine from the syringe through the filter over a bucketor sink (Fig. 7.38).4. Disconnect the syringe from the filter holder. Draw air intothe syringe (Fig. 7.39), reattach the syringe to the filter holderand expel the air through the filter (Fig. 7.40).Fig. 7.38 Expelling the urine throughthe filterFig. 7.39 Drawing air into the syringe5. Disconnect the syringe from the filter holder. Using forceps, carefully removethe membrane filter or filter-paper and place it on a microscope slide. The nylonmembrane and filter-paper should be placed face-up, while the polycarbonatemembrane should be placed face-down.6. Add one drop of Lugol iodine solution to improve the visibility of the eggs.7. Examine the entire filter under the microscope at ¥ 10 or ¥ 40. Record the resultsas the number of eggs per 10ml of urine.