Chapter 2 : Collection, Preservation, and Shipment of Fecal Specimens

Figure 2.1

Stool collection vial; “clean vial” contains no fixatives. doi:10.1128/9781555819002.ch2.f2.1

Figure 2.2

Increased detection of Entamoeba histolytica by using various diagnostic techniques and serial stool specimens. (Adapted by Markell EK, Voge M, John DT, 1992, Medical Parasitology, 7th ed., The W. B. Saunders Co., Philadelphia, PA, from references 17 and 31 , with permission.) doi:10.1128/9781555819002.ch2.f2.2

Figure 2.3

Flow diagram for preservation and processing of stool specimens. As mentioned in the text, the examination of fecal specimens using the ova and parasite examination is not considered complete unless a concentration and a permanent stained smear are examined for every specimen submitted to the laboratory. For a fresh specimen, a direct wet mount should be performed if the specimen is very soft to liquid; the complete ova and parasite examination would include the direct wet mount, the concentration, and the permanent stained smear. If the specimen is submitted in preservative, the direct wet mount should be eliminated (no motility is possible); the complete ova and parasite examination would include the concentration and the permanent stained smear ( 1 , 2 ). doi:10.1128/9781555819002.ch2.f2.3

Figure 2.4

Stool collection vial containing 10% formalin; note the “FILL LINE” and the poison signs at each side of the label.

When the stool specimen is added to the vial, the final ratio of stool to preservative is about 1:3. doi:10.1128/9781555819002.ch2.f2.4

Figure 2.5

Stool collection vials, one containing SAF fixative and the other containing Z-PVA, one of the non-mercury-based fixatives. This combination of collection vials is an excellent option; concentrations and fecal immunoassays can be performed from the SAF vial, while the permanent stained smear can be performed from the Z-PVA vial. doi:10.1128/9781555819002.ch2.f2.5

Figure 2.6

Albumin used to precoat the slide prior to the application of SAF-fixed stool concentration sediment. Once the smear is dry, it is ready for permanent staining. doi:10.1128/9781555819002.ch2.f2.6

Figure 2.7

ECOFIX is an example of a fixative that represents the single-vial collection system. This fixative has been coupled with its own stain, the ECOSTAIN ( 11 ). Remember to inquire about the compatibility of all single-vial systems with the immunoassay procedures; not all single-vial preservatives are compatible with all fecal immunoassays. doi:10.1128/9781555819002.ch2.f2.7

Figure 2.8

ProtoFix is a single-vial collection option. It is always important to review peer-reviewed literature regarding the results of new products compared with those previously in use. doi:10.1128/9781555819002.ch2.f2.8

Figure 2.9

UNIFIX is a single-vial collection system; information on this product can be found at the company website (www.med-chem.com). This fixative works well with trichrome stain. doi:10.1128/9781555819002.ch2.f2.9

Figure 2.10

TOTAL-FIX is a single-vial collection system; the fixative contains no mercury, no formalin, and no PVA. It is considered a Universal Fixative and can be used for concentrations, permanent stained smears, fecal immunoassays, special stains, and some molecular methods. doi:10.1128/9781555819002.ch2.f2.10