{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T03:31:40Z","timestamp":1784691100081,"version":"3.55.0"},"reference-count":28,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2025,9,7]],"date-time":"2025-09-07T00:00:00Z","timestamp":1757203200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Background\/Objectives: Grey zone serologic results in blood donor screening pose challenges for transfusion safety, donor management, and blood supply sustainability. In Saudi Arabia, standardized national protocols for managing grey zone outcomes remain lacking. This study aimed to evaluate the prevalence and follow-up outcomes of grey zone serologic results among blood donors at a Saudi hospital over a five-year period. Methods: Serological screening results of six transfusion-transmissible infections (TTIs) markers were extracted alongside nucleic acid testing (NAT) results for HBV, HCV, and HIV. The grey zone was defined as a signal-to-cutoff (S\/CO) of 0.90\u20130.99. Repeat and follow-up results, including subsequent donations, were assessed for seroconversion. Results: A total of 48,241 donations from 38,524 donors were analyzed. Anti-HBc showed the highest reactivity (n = 2312; 4.8%), followed by HbsAg (n = 2292; 0.31%) and syphilis (n = 218; 0.5%). Grey zone results were rare, and most frequent in anti-HBc (n = 76; 0.16%), HCV (n = 39; 0.08%), and HBsAg (n = 28; 0.06%). Grey zone-to-reactive conversion upon subsequent donation was rare. Three donors who initially tested in the grey zone for anti-HBc later tested reactive in subsequent donations, but their HBV NAT remained negative. Conclusions: While grey zone outcomes were infrequent, a subset involving HBV markers showed low-level reactivity on repeat testing. For other TTIs markers, grey zone results likely reflected assay variability rather than true infection. We propose a six-month temporary deferral with follow-up serologic and NAT testing, allowing conditional re-entry for donors with consistently non-reactive results, supporting both transfusion safety and a more sustainable donor pool.<\/jats:p>","DOI":"10.3390\/diagnostics15172261","type":"journal-article","created":{"date-parts":[[2025,9,8]],"date-time":"2025-09-08T08:06:32Z","timestamp":1757318792000},"page":"2261","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["The \u201cGrey Zone\u201d in Blood Donor Screening: A Retrospective Study and Proposal for Donor Re-Entry"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8536-6989","authenticated-orcid":false,"given":"Wajnat A.","family":"Tounsi","sequence":"first","affiliation":[{"name":"Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4956-0132","authenticated-orcid":false,"given":"Nora Y.","family":"Hakami","sequence":"additional","affiliation":[{"name":"Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-7317-2607","authenticated-orcid":false,"given":"Seraj O.","family":"Alamoudi","sequence":"additional","affiliation":[{"name":"Laboratory Department, King Abdulaziz University Hospital, Jeddah 21589, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wejdan A.","family":"Altayeb","sequence":"additional","affiliation":[{"name":"Blood Transfusion Services Unit, King Abdulaziz University Hospital, Jeddah 21589, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shahad H.","family":"Aljuhani","sequence":"additional","affiliation":[{"name":"Blood Transfusion Services Unit, King Abdulaziz University Hospital, Jeddah 21589, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Afnan J.","family":"Al-Sulami","sequence":"additional","affiliation":[{"name":"Blood Transfusion Services Unit, King Abdulaziz University Hospital, Jeddah 21589, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-7510-3106","authenticated-orcid":false,"given":"Osama A.","family":"Alzahrani","sequence":"additional","affiliation":[{"name":"Laboratory Department, King Fahad Armed Forces Hospital, Jeddah 23311, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0006-3787-5590","authenticated-orcid":false,"given":"Raed M.","family":"Garout","sequence":"additional","affiliation":[{"name":"Molecular Diagnostic Laboratory, King Abdulaziz University Hospital, Jeddah 21589, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5653-3533","authenticated-orcid":false,"given":"Taghreed S.","family":"Almansouri","sequence":"additional","affiliation":[{"name":"Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9393-1538","authenticated-orcid":false,"given":"Waleed M.","family":"Bawazir","sequence":"additional","affiliation":[{"name":"Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aisha","family":"Qattan","sequence":"additional","affiliation":[{"name":"Laboratory Department, King Fahad Armed Forces Hospital, Jeddah 23311, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3272-2393","authenticated-orcid":false,"given":"Maha A.","family":"Badawi","sequence":"additional","affiliation":[{"name":"Hematology Department, Faculty of Medicine, King Abdulaziz University, Jeddah 21589, Saudi Arabia"},{"name":"Hematology Research Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah 22254, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"71","DOI":"10.4103\/0973-6247.164272","article-title":"Impact of grey zone sample testing by enzyme-linked immunosorbent assay in enhancing blood safety: Experience at a tertiary care hospital in north India","volume":"10","author":"Solanki","year":"2016","journal-title":"Asian J. 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