Microscopic identification of eggs in stool or urine is the most practical method for diagnosis. Stool examination should be performed when infection with "S. mansoni" or "S. japonicum" is suspected, and urine examination should be performed if "S. haematobium" is suspected. Eggs can be present in the stool in infections with all "Schistosoma" species. The examination can be performed on a simple smear (1 to 2 mg of fecal material). Because eggs may be passed intermittently or in small numbers, their detection is enhanced by repeated examinations or concentration procedures, or both. In addition, for field surveys and investigational purposes, the egg output can be quantified by using the Kato-Katz technique (20 to 50 mg of fecal material) or the Ritchie technique. Eggs can be found in the urine in infections with "S. haematobium" (recommended time for collection: between noon and 3 PM) and with "S. japonicum". Quantification is possible by using filtration through a nucleopore filter membrane of a standard volume of urine followed by egg counts on the membrane. Tissue biopsy (rectal biopsy for all species and biopsy of the bladder for "S. haematobium") may demonstrate eggs when stool or urine examinations are negative.