{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,15]],"date-time":"2026-08-15T11:26:38Z","timestamp":1786793198977,"version":"build-2736575974"},"reference-count":21,"publisher":"Wiley","license":[{"start":{"date-parts":[[2026,8,15]],"date-time":"2026-08-15T00:00:00Z","timestamp":1786752000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2026,8,15]],"date-time":"2026-08-15T00:00:00Z","timestamp":1786752000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Intl J Gynecology &amp;amp; Obste"],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Retroperitoneal ectopic pregnancy (RPEP) is an exceedingly rare form of trophoblastic implantation within the retroperitoneal compartment, posterior to the parietal peritoneum and anatomically separate from the uterus, fallopian tubes, and ovaries. Proximity to major retroperitoneal vessels, including the abdominal aorta and inferior vena cava, creates potential for severe hemorrhage and complex operative management. Three mechanisms compound this risk by delaying diagnosis: transvaginal ultrasonography is physically limited to the true pelvis and cannot visualize supra\u2010pelvic retroperitoneal implantations; persistent classification as pregnancy of unknown location defers extended imaging; and Zone I implantations may mimic acute pancreatitis, renal colic, or gastrointestinal illness, redirecting assessment away from obstetric consideration. This focused narrative review synthesizes published clinical experience of RPEP to identify recurring diagnostic pitfalls, anatomical patterns, and management themes, and to propose a practical framework for institutional use. The literature search encompassed PubMed\/MEDLINE, Embase, Scopus, Google Scholar, and reference lists of relevant publications, from database inception to June 2026, using a structured set of RPEP\u2010specific search terms. No meta\u2010analysis was attempted because the evidence consists of case reports and small case series with heterogeneous reporting. Zone I para\u2010aortic and interaortocaval implantation appears to be the most frequently reported anatomical pattern. Systemic methotrexate alone appears unsuitable as routine definitive therapy for high\u2010risk phenotypes \u2014 characterized by elevated beta\u2010hCG, embryonic cardiac activity, or major\u2010vessel proximity. Multidisciplinary operative planning is essential in confirmed or probable cases. Based on this synthesis, we propose diagnostic categories for definite, probable, and possible RPEP; a five\u2010zone surgical anatomical classification intended to support operative planning; and a seven\u2010step institutional escalation framework. These proposals are derived exclusively from very low\u2010certainty evidence consisting predominantly of case reports, small case series, and expert anatomical interpretation. They should be regarded as hypothesis\u2010generating frameworks rather than evidence\u2010based recommendations or validated clinical guidance and require prospective evaluation before clinical adoption.<\/jats:p>","DOI":"10.1002\/ijgo.71314","type":"journal-article","created":{"date-parts":[[2026,8,15]],"date-time":"2026-08-15T11:01:26Z","timestamp":1786791686000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Retroperitoneal ectopic pregnancy: A narrative review proposing diagnostic criteria, surgical anatomical classification and an institutional management algorithm"],"prefix":"10.1002","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9826-1775","authenticated-orcid":false,"given":"Rana","family":"Mondal","sequence":"first","affiliation":[{"name":"Department of Obstetrics and Gynecology Luton and Dunstable University Hospital, Bedfordshire Hospitals NHS Foundation Trust  Luton UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-8694-3233","authenticated-orcid":false,"given":"Mouli","family":"Nandi","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology Luton and Dunstable University Hospital, Bedfordshire Hospitals NHS Foundation Trust  Luton UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,8,15]]},"reference":[{"key":"e_1_2_15_2_1","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMcp0810384"},{"issue":"2","key":"e_1_2_15_3_1","first-page":"1","article-title":"Pregnancy\u2010related mortality surveillance \u2014 United States, 1991\u20101999","volume":"52","author":"Chang J","year":"2003","journal-title":"MMWR Surveill Summ"},{"key":"e_1_2_15_4_1","doi-asserted-by":"publisher","DOI":"10.1093\/humrep\/17.12.3224"},{"key":"e_1_2_15_5_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejogrb.2021.02.014"},{"key":"e_1_2_15_6_1","doi-asserted-by":"publisher","DOI":"10.1177\/10926429261422135"},{"key":"e_1_2_15_7_1","doi-asserted-by":"publisher","DOI":"10.1093\/humupd\/dmt047"},{"key":"e_1_2_15_8_1","doi-asserted-by":"publisher","DOI":"10.1097\/AOG.0000000000002965"},{"key":"e_1_2_15_9_1","doi-asserted-by":"crossref","first-page":"487","DOI":"10.1016\/S0002-9378(42)90488-5","article-title":"Primary peritoneal pregnancy","volume":"44","author":"Studdiford WE","year":"1942","journal-title":"Am J Obstet Gynecol"},{"key":"e_1_2_15_10_1","doi-asserted-by":"publisher","DOI":"10.1002\/ijgo.16139"},{"key":"e_1_2_15_11_1","doi-asserted-by":"publisher","DOI":"10.1186\/s12884-023-05909-7"},{"key":"e_1_2_15_12_1","doi-asserted-by":"publisher","DOI":"10.1155\/2017\/9871865"},{"key":"e_1_2_15_13_1","doi-asserted-by":"publisher","DOI":"10.1186\/s12884-022-04799-5"},{"key":"e_1_2_15_14_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jmig.2022.03.009"},{"key":"e_1_2_15_15_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.fertnstert.2022.05.034"},{"key":"e_1_2_15_16_1","doi-asserted-by":"publisher","DOI":"10.1093\/jscr\/rjaf413"},{"key":"e_1_2_15_17_1","doi-asserted-by":"publisher","DOI":"10.29271\/jcpsp.2022.03.415"},{"key":"e_1_2_15_18_1","doi-asserted-by":"publisher","DOI":"10.1111\/1471-0528.14189"},{"key":"e_1_2_15_19_1","doi-asserted-by":"publisher","DOI":"10.1080\/01443615.2024.2361456"},{"key":"e_1_2_15_20_1","doi-asserted-by":"publisher","DOI":"10.2147\/IJWH.S486185"},{"key":"e_1_2_15_21_1","doi-asserted-by":"publisher","DOI":"10.1055\/s-2007-1004829"},{"key":"e_1_2_15_22_1","doi-asserted-by":"publisher","DOI":"10.2147\/IJWH.S408319"}],"container-title":["International Journal of Gynecology &amp; 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