Blood Specimen Collection

Try searching for blood sample in the thesaurus of your favourite database. What comes up?

EBSCO Medline: stuff about blood e.g. Fetal Blood, Blood Cell Count, etc...)
CINAHL: nothing relevant - mostly stats stuff e.g. Convenience Sample
However, if you do a search for Blood Specimen Collection, it is a CINAHL Heading

Ovid Medline: Blood Specimen Collection
EMBASE: blood sampling
PubMed: Blood Specimen Collection is the second result

Now try searching for blood scalp sampling:

EBSCO Medline: same results as when searching for blood sample
PubMed: no items found

CINAHL: Fetal Monitoring
Ovid Medline: Fetal Monitoring, Scalp, Fetal Distress
EMBASE: fetus blood sampling, fetus monitoring, scalp, fetus distress, fetus hypoxia

The following MeSH and Cinahl Headings exist but were not found by this search:

MeSH: Fetal Hypoxia
CINAHL: Fetal Distress, Fetal Anoxia, Scalp