Sampling methodology | Fish on Farms

As promised, I wrote about the “5Ws” of our blood collection: who, what, when, where, and why. I even threw in the “how”. Today’s post focuses on what happened in the field.

One of the most important (and expensive!) components of FoF is the blood collection and subsequent analysis. This process provides us with concrete evidence that there are more (or less) nutrients in a person’s body by looking at biochemical indicators of nutritional status. Obtaining this information is what sets FoF apart from previous homestead food production interventions.

During baseline blood was collected from 450 women. We will collect samples from the same 450 women during endline for a paired analysis. While we considered collecting blood from children as well, it was decided this would be too traumatic. Plus, we had other less-invasive methods available to assess whether or not children were anemic (finger-pricking to measure hemoglobin).

When we arrived in each village, a random lottery was held. Each house was assigned a number (1-10) and slips of paper with those numbers were randomly selected. In the end, we selected 5 women from each village. Women were given an ID number and asked to report to their local Health Center the day after our visit to their village.

The morning of collection, the local Village Health Volunteer (VHV) came with the women and their children to the Health Center. The VHV was responsible for making sure everyone who agreed to provide samples was present. Most mornings everyone was at the Health Center by 7:30 am, as they had to fast for a minimum of 3 hours before providing samples. When all the women assembled, they were briefed by Mr. Tee from HKI.

One at a time, the women entered a room where a technician was working. The technician drew 3 vials of blood. After, the women were given a sarong as a thank you for their participation.

Two of the vials collected were 4.5 mL test tubes containing Ethylenediaminetetraacetic acid(EDTA), which is an anticoagulant, that prevents blood from clotting. They were then packed on ice and transported via a car we dubbed the “Blood Taxi” to the National Institute of Public Health Laboratories (NIPHL) in Phnom Penh for further processing.

The third tube collected was a 7 mL trace element free tube. It was centrifuged in the field. This separated the blood into 3 components: the serum plasma, the buffy coat (most of the white blood cells and platelets), and the erythrocytes (red blood cells). The serum was packed on ice and sent to the NIPHL, where samples were stored at -70 degrees Celcius until the end of baseline.

Some pictures: