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

Using broader term may result in loss of narrower terms

The other day I came across the MeSH term: Trauma, Nervous System. Looking at the MeSH tree, I saw that this term fell under two broader terms:

• Nervous System Diseases
• Wounds and Injuries

However, when I looked at the narrower terms, I discovered that in the tree where Trauma, Nervous System fell under Nervous System Diseases, it had a narrower term, Spinal Cord Injuries, which was not listed in the tree where Trauma, Nervous System fell under Wounds and Injuries.

Here's a picture that hopefully will explain it better:

Note that Spinal Cord Injuries is listed on the left but not the right.

I wondered, if I searched Wounds and Injuries (autoexploded in PubMed), would it search Spinal Cord Injuries, or not?

I tried a search for "Spinal Cord Injuries"[Mesh] NOT "Wounds and Injuries"[Mesh], and there were 73 results. These results had one MeSH term in common: "Autonomic Dysreflexia"[Mesh]

Checking the MeSH tree for Spinal Cord Injuries shows that Autonomic Dysreflexia is a narrower term of Spinal Cord Injuries only when Spinal Cord Injuries is a narrower term of Nervous System Diseases, not Wounds and Injuries.

This means that if a searcher decides to use a MeSH's broader term to search, they risk losing some of the narrower terms of the original MeSH. I didn't know this before, but will be sure to check the tree for this phenomenon in future searches.

BTW, if you're thinking of trying it yourself, you'll notice that Spinal Cord Injuries is also listed immediately under Wounds and Injuries in the tree, which fooled me for a little while. However, this does not change the phenomenon explained above.

Neuromuscular blockade

If you are searching for drugs causing neuromuscular blockade, there are two MeSH to try:

Neuromuscular Blockade
Neuromuscular Blocking Agents

And if you are searching in PubMed, the second one is searchable as a Pharm. Action:

"Neuromuscular Blocking Agents"[Pharmacological Action] OR "Neuromuscular Blockade"[Mesh]