1	'general surgery' OR 'abdominal surgery' OR 'pelvic surgery' OR 'gynecologic surgery'
2	'abdominal surgery'/exp
3	'general surgery'/exp
4	'pelvis surgery'/exp
5	'gynecologic surgery'/exp
6	#1 OR #2 OR #3 OR #4 OR #5
7	thrombo* OR thromboem* OR embol*
8	'thrombosis'/exp OR 'thrombosis prevention'/exp
9	'thromboembolism'/exp
10	'embolism'/exp
11	#7 OR #8 OR #9 OR #10
12	'prophylaxis' OR 'prophylactic' OR 'prevention' OR 'preventative' OR 'chemoprophylaxis' OR 'antithrombotic prophylaxis' OR 'reduction' OR anticoag* OR 'heparin' OR 'thromboprophylaxis'
13	'prevention'/exp OR 'thrombosis prevention'/exp
14	'heparin'/exp
15	'anticoagulant agent'/exp
16	#12 OR #13 OR #14 OR #15
17	'prolonged' OR 'long term' OR 'duration' OR 'late' OR 'extended' OR 'discharge'
18	#6 AND #11 AND #16 AND #17
19	'crossover procedure':de OR 'double blind procedure':de OR 'randomized controlled trial':de OR 'single blind procedure':de OR random*:de,ab,ti OR factorial*:de,ab,ti OR crossover*:de,ab,ti OR ((cross NEXT/1 over*):de,ab,ti) OR placebo*:de,ab,ti OR ((doubl* NEAR/1 blind*):de,ab,ti) OR ((singl* NEAR/1 blind*):de,ab,ti) OR assign*:de,ab,ti OR allocat*:de,ab,ti OR volunteer*:de,ab,ti
20	#18 AND #19