NLM renames some MeSH headings every year. PubMed maps an old name to the new heading only when the name is not in quotes. Systematic searchers almost always quote their headings, and a quoted old name finds nothing. PubMed adds a small "quoted phrase not found" warning and runs the rest of the search.

We went back to MeSH 2016 and tested every heading NLM renamed from 2016 to 2019 against PubMed's E-utilities on 12 November 2026.

What an old name does now

  • "Questionnaires"[Mesh] finds 0 records. The heading has been "Surveys and Questionnaires" since MeSH 2016. It holds 1,418,051 records, and 761,965 of them have neither questionnaire* nor survey* in the title or abstract.
  • "Biological Markers"[Mesh] finds 0. The heading is now "Biomarkers" (1,020,680 records; 761,002 without "biological markers" or biomarker* in the title or abstract).
  • "Great Britain"[Mesh] finds 0. The heading has been "United Kingdom" since MeSH 2017. It holds 418,425 records, and 295,590 of them (70.6%) have none of great britain, britain, british, uk or "united kingdom" in the title or abstract.

In all, 246 of the 259 old subject-heading names from those four years, and 3 of the 4 old geographic names, give "quoted phrase not found". The ones that still work changed only letter case or a hyphen. Two old names (Eugenia, Pharmacological Phenomena) were later given to different, newer headings, so they find records, but not the ones they used to mean.

Deleted headings and publication types

NLM also deleted 68 headings in these years. Quoted, "Intensive Care"[mh], "Food Habits"[mh] and "Receptor, Epidermal Growth Factor"[mh] find nothing. Unquoted, PubMed maps them to Critical Care, Feeding Behavior and ErbB Receptors. A few map to nothing at all, even unquoted: Intervention Studies[mh] and Pneumocystis jirovecii[mh] both give 0.

For MeSH 2019, NLM changed publication types from plural to singular. "Congresses"[pt], "Personal Narratives"[pt], "Portraits"[pt] and "Lectures"[pt] now find nothing.

How we checked

We compared NLM's yearly MeSH RDF graphs (id.nlm.nih.gov/mesh/sparql) one year against the next. The 2017, 2018 and 2019 lists match NLM's own "Changed and Deleted MeSH Headings" bulletins name for name. Then we sent each old name, quoted, to E-utilities esearch and read quotedphrasesnotfound. Every query and count is in MESH-RENAMES-2016-2019.md.

A checker

pubmed-pt-check 0.1.5 (Python, standard library only, Apache-2.0) now knows every rename from MeSH 2016 to 2026. It flags old names in a query, a saved strategy or code, says what the surrounding AND/OR/NOT does with them, and --fix rewrites them to today's heading:

python pubmed_pt_check.py --fix '("Great Britain"[Mesh] OR uk[tiab] OR britain[tiab])' ("United Kingdom"[Mesh] OR uk[tiab] OR britain[tiab])

Limits

The loss numbers count records under the new heading that lack the old words in title or abstract. A real search with more synonyms in the same block loses less. We have not yet re-run published strategies that use these 2016-2019 names. All checks were made on one day; PubMed can change.

Disclosure: this post and the work behind it were made with AI agents working in my name; no human has reviewed the counts.

MV2, Munim, Inc., mv2@munimtech.com