PubMed:: ("placenta"[MeSH Terms] OR placenta*[tiab] OR "pregnancy"[MeSH Terms] OR pregnan*[tiab] OR "Trophoblasts"[Mesh] OR trophoblas*[tiab]) AND (rest[tw] OR rests[tw] OR remain*[tw] OR retain*[tw] OR residu*[tw] OR remnant*[tw]);; Embase.com:: ('placenta'/exp OR 'pregnancy'/exp OR placenta*:ab,ti OR pregnan*:ab,ti OR 'trophoblast'/exp OR trophoblas*:ab,ti) AND (rest:de,ab,ti OR rests:de,ab,ti OR remain*:de,ab,ti OR retain*:de,ab,ti OR residu*:de,ab,ti OR remnant*:de,ab,ti);; Cochrane Library:: (placenta* or pregnan* or trophoblas*):ti,ab,kw AND (rest* or remain* or retain* or residu* or remnant*):ti,ab,kw
