Table 1.
Randomised controlled trials comparing risk of instrumental vaginal delivery associated with epidural analgesia or parenteral opioids
| Trial; country | Scottish Intercollegiate Guideline Network score* | Comments |
|---|---|---|
| Bofill et al, 199723; United States | +, not blinded | Nulliparous women; included in meta-analysis |
| Chestnut et al, 198711; United States | NA | Nulliparous women; excluded, as study compared 0.75% lignocaine with saline epidural infusions during second stage labour |
| Chestnut et al 198712, United States | NA | Nulliparous women; excluded, as study compared 0.125% bupivacaine with saline epidural infusions during second stage labour |
| Chestnut et al, 199413; United States | NA | Nulliparous women; excluded as study compared early with late institution of bupivacaine epidural analgesia |
| Clark et al, 199824; United States | +, not blinded | Nulliparous women; included in meta-analysis |
| Dickinson et al, 200227; Australia | +, not blinded | Nulliparous women; included in meta-analysis, separate data available for women with spontaneous and induced labour |
| Gambling et al, 199821; United States | +, not blinded | Mixed parity women; nulliparous data not available |
| Howell et al, 200118; United Kingdom | NA | Nulliparous women; excluded as study used bupivacaine 0.25% boluses |
| Loughnan et al, 200025; United Kingdom | +, not blinded | Nulliparous women; included in meta-analysis |
| Nikkola et al, 199717; Finland | NA | Nulliparous women; excluded as study used bupivacaine 0.5% boluses, which were stopped in second stage labour |
| Noble et al, 197116; United Kingdom | NA | Mixed parity women; excluded as study used bupivacaine 0.5% boluses |
| Philipsen and Jensen, 198914; Denmark | NA | Mixed parity women; excluded as study used bupivacaine 0.375% boluses |
| Ramin et al, 199519; United States | −, not blinded, no intention to treat data | Mixed parity women; nulliparous data not available |
| Robinson et al, 198015; United Kingdom | NA | Mixed parity women; excluded as study used bupivacaine 0.5% boluses |
| Sharma et al, 199720; United States | +, not blinded | Mixed parity women; data on nulliparous women available only for caesarean section meta-analysis |
| Sharma et al, 200226; United States | +, not blinded | Nulliparous women; included in meta-analysis |
| Thorp et al, 199322; United States | +, not blinded | Nulliparous women; included in meta-analysis |
NA=not assessed.
*
Positive and minus signs indicate how well study minimised bias.