Clinical laboratory tests have relatively less utility in resource-poor settings, but lives can be saved if a few simple tests are available, such as those for urine pregnancy and, in endemic/high-prevalence areas, for human immunodeficiency virus (HIV), malaria, and tuberculosis (TB) screening. This chapter discusses how to improvise various materials, equipment, and tests when clinicians need laboratory tests and the normal procedure for doing them is unavailable.
Table 20-1 lists essential laboratory tests worldwide, which differ depending on the facility’s capabilities (described in Table 5-1).
TABLE 20-1Laboratory Testing Essentials |Favorite Table|Download (.pdf) TABLE 20-1 Laboratory Testing Essentials
| ||Facility Level |
|Resources/Capabilities ||Basic ||GP ||Specialist ||Tertiary |
|HIVa ||E ||E ||E ||E |
|Urine pregnancy ||E ||E ||E ||E |
|Hemoglobin/hematocrit ||D ||E ||E ||E |
|Malariaa ||D ||E ||E ||E |
|Urinalysis ||D ||E ||E ||E |
|Glucose ||I ||E ||E ||E |
|Gram stain ||I ||D ||E ||E |
|Tuberculosisa ||I ||D ||E ||E |
|Sickle cell prep ||I ||D ||E ||E |
|Bacterial cultures ||I ||D ||D ||D |
|Electrolytes (Na, K, Cl, CO2, BUN, creatinine) ||I ||D ||D ||D |
|Arterial blood gas measurements ||I ||D ||D ||D |
|Serum lactate ||I ||I ||D ||D |
Use filtered rainwater rather than distilled water to make laboratory reagents, such as stains. Collect uncontaminated rainwater in rooftop tanks.1 Distilled water is best for use in autoclaves and in pressure cookers used as sterilizers. If available, also use distilled water to produce intravenous (IV) fluids.
Distillation involves boiling clean water and collecting the steam, which then condenses back to water. The water from condensed vapor does not contain salt and other impurities. In austere situations, improvising distillation systems saves many lives, as is seen in the following story from a World War II prison camp2:
Some six weeks before the outbreak [dysentary] I had constructed, as a precaution, a small plant for distilling water for intravenous saline. It was a very primitive affair, the condenser being a coiled rubber tube inside a hollow bamboo in which cold water was circulated. The boiler was a 4-gallon kerosene can. Within 24 hours of the outbreak we were able to give intravenous saline. The plant was producing 40 pints daily, and eventually double that figure. The giving IV bottle was a jam-jar connected to a needle by a rubber tube.
Obtain small amounts of distilled water by heating water in a kettle and running rubber tubing from the spout through a hole in the lid of a collecting jar (Fig. 20-1). Use another small tube as a vent in the jar’s lid. ...