Interventional procedure overview of balloon disimpaction of the baby's head at emergency caesarean during the second stage of labour
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Appendix A: Methods and literature search strategy
Methods and literature search strategy
NICE has identified studies and reviews relevant to balloon disimpaction of the baby's head at emergency caesarean during the second stage of labour from the medical literature. Relevant published studies identified during consultation or resolution that are published after this date may also be considered for inclusion.
Search strategy design and peer review
This search report is informed by the Preferred Reporting Items for Systematic reviews and Meta-Analyses literature search extension (PRISMA-S).
A NICE information specialist ran the literature searches on 24/06/2024. See the search strategy history for the full search strategy for each database.
The principal search strategy was developed in MEDLINE ALL (Ovid interface). It was adapted for use in each of the databases listed in table 4a, taking into account the database's size, search functionality and subject coverage. The MEDLINE ALL strategy was quality assured by a NICE senior information specialist. All translated search strategies were peer reviewed to ensure their accuracy. The quality assurance and peer review procedures were adapted from the Peer Review of Electronic Search Strategies (PRESS) 2015 evidence-based checklist.
Review management
The search results were managed in EPPI‑Reviewer version 5 (EPPI‑R5). Duplicates were removed in EPPI‑R5 using a 2‑step process. First, automated deduplication was done using a high-value algorithm. Second, manual deduplication was used to assess low-probability matches. All decisions about inclusion, exclusion and deduplication were recorded and stored.
Limits and restrictions
The CENTRAL database search removed trial registry records and conference material. The Embase search excluded conference material.
English language limits were applied to the search when possible in the database. This is standard NICE practice for review topics.
The search wasn't limited by date. Any records already identified by previous searches for this topic were found and removed through the de-duplication process in EPPI-R5.
The limit to remove animal studies in the searches is standard NICE practice, which has been adapted from Dickersin K, Scherer R, Lefebvre C (1994) Systematic Reviews: Identifying relevant studies for systematic reviews. BMJ 309(6964): 1286.
Main search
Database | Date searched | Database platform | Database segment or version | Number of results downloaded |
Cochrane Central Register of Controlled Trials (CENTRAL) | 24/06/2024 | Wiley | Issue 5 of 12, May 2024 | 57 |
Cochrane Database of Systematic Reviews (CDSR) | 24/06/2024 | Wiley | Issue 6 of 12, June 2024 | 1 |
Embase | 24/06/2024 | Ovid | 1974 to 2024 June 21 | 365 |
INAHTA International HTA Database | 24/06/2024 | https://database.inahta.org/ | n/a | 5 |
MEDLINE ALL | 24/06/2024 | Ovid | 1946 to 2024 June 21 | 238 |
MEDLINE ALL search strategy
(balloon* adj4 (dilat* or expand* or inflat* or device*)).tw. 20797
(cephalic adj4 elevat*).tw. 37
((elevat* or (disimpact* or dis-impact*)) adj4 (foetal or fetal or fetus or foetus)).tw. 1249
((foetal or fetal or fetus or foetus) adj4 (pillow* or balloon* or cushion*)).tw. 125
or/1-4 22175
cesarean section/ 54154
(caesarian or cesarian or caesarean or cesarean).tw. 76659
c-section.tw. 1872
(reverse breech adj4 (method* or technique* or extract* or deliver*)).tw. 30
or/6-9 90732
cephalopelvic disproportion/ or dystocia/ 4070
((cephalopelvi* adj4 disproport*) or dystocia).tw. 5152
(cord adj4 prolapse).tw. 576
Fetal Distress/ 3546
Labor Presentation/ 4547
((foetal or fetal or fetus or foetus) adj4 (distress* or non-reassuring or malpresentation*)).tw. 6387
or/11-16 19076
Labor Stage, Second/ 1649
((engage* or impact* or fix*) adj4 (foetal or fetal or fetus or foetus) adj4 head*).tw. 175
((obstruct* or second-stage or advanced) adj4 labo?r).tw. 4146
(full* adj4 dilat*).tw. 763
or/18-21 5508
10 or 17 or 22 105876
5 and 23 270
Fetal Pillow.tw. 18
Fetal Disimpacting System.tw. 0
25 or 26 18
24 or 27 271
animals/ not humans/ 5199241
28 not 29 255
limit 30 to English language 238
Embase search strategy
balloon dilatation/ 24552
(balloon* adj4 (dilat* or expand* or inflat* or device*)).tw. 36065
(cephalic adj4 elevat*).tw. 39
Fetal head elevator/ 35
((elevat* or (disimpact* or dis-impact*)) adj4 (foetal or fetal or fetus or foetus)).tw. 1797
((foetal or fetal or fetus or foetus) adj4 (pillow* or balloon* or cushion*)).tw. 224
or/1-6 49535
cesarean section/ 131355
(caesarian or cesarian or caesarean or cesarean).tw. 112027
c-section.tw. 5008
(reverse breech adj4 (method* or technique* or extract* or deliver*)).tw. 48
or/8-11 154807
cephalopelvic disproportion/ or dystocia/ 6482
((cephalopelvi* adj4 disproport*) or dystocia).tw. 6828
umbilical cord prolapse/ 517
(cord adj4 prolapse).tw. 730
Fetus Distress/ 10356
malpresentation/ 1592
((foetal or fetal or fetus or foetus) adj4 (distress* or non-reassuring or malpresentation*)).tw. 9351
or/13-19 25008
((engage* or impact* or fix*) adj4 (foetal or fetal or fetus or foetus) adj4 head*).tw. 258
Obstructed labor/ or Labor stage 2/ 3307
((obstruct* or second-stage or advanced) adj4 labo?r).tw. 5579
(full* adj4 dilat*).tw. 1294
or/21-24 7933
12 or 20 or 25 171382
7 and 26 694
Fetal Pillow.tw. 52
Fetal Disimpacting System.tw. 2
28 or 29 54
27 or 30 695
Nonhuman/ not Human/ 5467922
31 not 32 678
(conference abstract or conference paper or conference proceeding or "conference review").pt. 5976910
33 not 34 410
limit 35 to English language 364
Cochrane Library (CDSR and CENTRAL) search strategy
(balloon* near/4 (dilat* or expand* or inflat* or device*)):ti,ab,kw 2613
(cephalic near/4 elevat*):ti,ab,kw 3
((elevat* or (disimpact* or dis-impact*)) near/4 (foetal or fetal or fetus or foetus)):ti,ab,kw 38
((foetal or fetal or fetus or foetus) near/4 (pillow* or balloon* or cushion*)):ti,ab,kw 52
#1 or #2 or #3 or #4 2693
MeSH descriptor: [Cesarean Section] this term only 4504
(caesarian or cesarian or caesarean or cesarean):ti,ab,kw 17871
(c-section):ti,ab,kw 433
(reverse breech near/4 (method* or technique* or extract* or deliver*)):ti,ab,kw 11
#6 or #7 or #8 or #9 18014
MeSH descriptor: [Cephalopelvic Disproportion] this term only 1
MeSH descriptor: [Dystocia] this term only 148
(cephalopelvi* near/4 disproport* or dystocia):ti,ab,kw 673
(cord near/4 prolapse):ti,ab,kw 80
MeSH descriptor: [Fetal Distress] this term only 199
MeSH descriptor: [Labor Presentation] this term only 105
((foetal or fetal or fetus or foetus) near/4 (distress* or non-reassuring or malpresentation*)):ti,ab,kw 1132
#11 or #12 or #13 or #14 or #15 or #16 or #17 1864
MeSH descriptor: [Labor Stage, Second] explode all trees 255
((engage* or impact* or fix*) near/4 (foetal or fetal or fetus or foetus) near/4 head):ti,ab,kw 35
((obstruct* or second-stage or advanced) near/4 labo?r):ti,ab,kw 1191
(full* near/4 dilat*):ti,ab,kw 272
#19 or #20 or #21 or #22 1434
#10 or #18 or #23 19652
#5 and #24 123
(Fetal Pillow):ti,ab,kw 22
(Fetal Disimpacting System):ti,ab,kw 0
#26 or #27 22
#25 or #28 136
"conference":pt or (clinicaltrials or trialsearch):so 750874
#29 not #30 58
INAHTA HTA Database search strategy
(balloon* AND (dilat* or expand* or inflat* or device*)
(cephalic elevat*)
(foetal or fetal or fetus or foetus) AND (elevat* or disimpact* or dis-impact)
(foetal or fetal or fetus or foetus) AND (balloon or pillow or cushion)
#1 OR #2 OR #3 OR #4
"Cesarean Section"[mh]
(caesarian or cesarian or caesarean or cesarean)
(c-section)
(reverse breech AND (method* or technique* or extract* or deliver*))
"Cephalopelvic Disproportion"[mh]
"Dystocia"[mh]
((cephalopelvi* AND disproport*) or dystocia)
(cord AND prolapse)
"Fetal Distress"[mh]
"Labor Presentation"[mh]
((foetal or fetal or fetus or foetus) AND (distress* or non-reassuring or malpresentation*))
"Labor Stage, Second"[mh]
((engage* or impact* or fix*) AND (foetal or fetal or fetus or foetus) adj4 head*)
((obstruct* or second-stage or advanced) AND (labor or labour)
(full* AND dilat*)
#6 OR #7 OR #8 OR #9 OR #10 OR #11 OR #12 OR #13 OR #14 OR #15 OR #16 OR #17 OR #18 OR #19 OR #20
("fetal pillow" or "fetal disimpacting system")
#5 AND #21
#22 OR #23
Inclusion criteria
The following inclusion criteria were applied to the abstracts identified by the literature search.
Publication type: clinical studies were included with emphasis on identifying good quality studies. Abstracts were excluded if they did not report clinical outcomes. Reviews, editorials, and laboratory or animal studies, were also excluded and so were conference abstracts, because of the difficulty of appraising study methodology, unless they reported specific adverse events not available in the published literature.
People having an emergency caesarean during the second stage of labour, with an impacted fetal head.
Intervention or test: balloon disimpaction.
Outcome: articles were retrieved if the abstract contained information relevant to the safety, efficacy, or both.
If selection criteria could not be determined from the abstracts the full paper was retrieved.
Potentially relevant studies not included in the main evidence summary are listed in Appendix B: Other relevant studies.
Find out more about how NICE selects the evidence for the committee.
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