Table 1.
Characteristics of eligible trials.
| Author, Year; Country | Patient Population (n) | Technique (Methods) | Primary; Secondary Outcomes | Jadad Score |
|---|---|---|---|---|
| Abdelhamid, 2013; Egypt [39] | Adult unspecified | Spinal at L4-5 (US vs. LM group) | Number of needle insertions, number of redirections; procedure time, patient satisfaction | 2 |
| Ansari, 2014; UAE [40] | Obstetrics CS | Spinal at L3-4 or L4-5 (US vs. LM group) | Spinal procedure time; number of needle insertions/redirections, headache, backache, patient satisfaction | 3 |
| Chin, 2011; Canada [41] | Orthopedic difficult spine | Spinal (US vs. LM group) | First-attempt success; number of needle insertions/redirections, failure rate, procedure time | 3 |
| Creaney, 2016; Ireland [42] | Obstetrics, CS, difficult spine | Spinal L3-4 (US vs. LM group) | Number of redirections; total procedure time, needling time, identification time, patient satisfaction | 3 |
| Dhanger, 2017; India [43] | Obstetrics, CS | Spinal L3-4 (US vs. LM group) | Number of needle insertions; number of redirections, total procedure time, identification time | 3 |
| Ekinci, 2017; Turkey [44] | Obstetrics, difficult spine | Spinal (US vs. LM group) | Number of needle insertions; number of redirections, number of levels, procedure time, first attempt success, first-pass success | 2 |
| Li, 2018; China [45] | Obstetrics elective CS, obese | Spinal (US vs. LM group) | First-attempt success; number of insertions/redirections, total procedure time, identification time, needling time, patient satisfaction, number of levels, complications | 4 |
| Lim, 2014; Singapore [46] | Orthopedic, urologic, general surgery | Spinal (US vs. LM group) | First-attempt success; number of redirections, needling time, paresthesia, traumatic taps, supervisor interventions, patient satisfaction | 3 |
| Sahin, 2014; Turkey [47] | Obstetrics non-obese and obese | Spinal at L4-5 (US vs. LM group) | First attempt success; number of needle insertions/redirections/levels attempted, failure rate, needling time, paresthesia, headache, backache | 3 |
| Srinivasan, 2015; Ireland [48] | Orthopedic (THR, TKR) | Spinal (US vs LM group) | Number of redirections; number of attempts, identification time, needling time, level of block, complications, periprocedural pain and discomfort score | 3 |
| Srinivasan, 2018; Ireland [49] | Orthopedic (THR, TKR) | Spinal (US-guided paramedian spinal L5-S1 vs LM group) | Number of redirections; number of insertions, first attempt success, first-pass success, identification time, needling time, block level at 30′, incidence of radicular pain, paresthesia bloody tap, periprocedural pain or discomfort | 2 |
| Turkstra, 2017; Canada [50] | Obstetrics CS | Spinal (US vs LM group) | Number of insertions/redirections; procedure time, level of block, need for consultant intervention, paresthesia, bloody tap | 4 |
| Urfalioglu, 2017; Turkey [52] | Obstetrics CS, obese | Spinal L4-5 (US vs. LM group) | Number of needle insertions, number of redirections; procedure time, needling time, block level, headache, backache | 2 |
| Arzola, 2015; Canada [24] | Obstetrics labor anlagesia | Epidural (US vs. LM group) | Epidural catheterization time, number of levels attempted, number of needle redirections; total procedural time, first attempt success, number of catheterization attempts, failure rate, patient satisfaction. | 3 |
| Balaban, 2017; Turkey [25] | Obstetrics labor analgesia | Epidural at L4-5 (US vs. LM group) | Not specified; number of insertions, number of levels attempted, epidural catheterization time, complications | 2 |
| Grau, AAS 2001; Germany [26] | Obstetrics labor analgesia | Epidural (US vs. LM group) | Not specified; number of redirections, number of levels attempted, catheter advancement attempts, failure rate, headache, backache | 2 |
| Grau, 2002; Germany [27] | Obstetrics | Epidural (US vs. LM group) | Not specified; number of redirections, number of levels attempted, number of attempts to thread the catheter, VAS scores, rate of incomplete analgesia, headache, backache | 2 |
| Kawaguchi, 2011; Japan [28] | Orthopedics (THA) | Epidural (US vs. LM group) | Successful ipsilateral dominant epidural block; failure rate, efficacy of ipsilateral-dominant block by PCEA with respect to analgesia and modified Bromage scores | 1 |
| Malik, 2018; USA [29] | Obstetrics, labor analgesia | Epidural at L5-S1 (US vs. LM group) | Incidence of S2 block 30′ after local anesthetic administration; pain during labor or during delivery, catheter replacement | 3 |
| Perna, 2017; Italy [30] | Obstetrics labor analgesia | Epidural to L3-4 or L2-3 (US vs. LM group) | Number of attempts (redirections and insertions); number of redirections, number of insertions, first-pass success | 4 |
| Vallejo, 2010; USA [31] | Obstetrics labor analgesia | Epidural L3-4 or L4-5 (US vs. LM group) | Technical failure rate; number of redirections/reinsertions, unintended dural puncture | 3 |
| Wilkes, 2017; USA [32] | Obstetrics | Epidural L2-S1 (US vs. US-Sham group) | Pressure pain threshold; number of redirections, number of reinsertions | 3 |
| Chin, 2018; Australia [33] | Obstetrics, CS | CSE below L1-L2 | First-attempt success, procedure difficulty; block quality, patient experience, complications | 4 |
| Grau, RAPM 2001; Germany [34] | Obstetrics, CS | CSE L3-L4 (US vs. LM group) | Not specified; first attempt success, number of levels attempted, identification time | 1 |
| Grau, 2004; Germany [35] | Obstetrics | CSE (Real-time US vs. pre-procedural US vs. LM group, 3 groups) | Number of needle insertions; number of redirections, number of levels attempted, incomplete analgesia, complications, patient satisfaction, VAS scores | 2 |
| Nassar, 2014; Egypt [36] | Obstetrics, Labor analgesia | CSE (US vs. LM group) | First-attempt success; number of insertions, no redirections, procedure time, identification time, needling time | 3 |
| Tawfik, 2017; Egypt [37] | Obstetrics CS | CSE at L2-3 or L3-4 (US vs. LM group) | First-direction success; first attempt success, number of redirections/ insertions, needling time, patient satisfaction, complications | 4 |
| Wang, 2012; China [38] | Obstetrics CS, obese | CSE at L3-4 (US vs. LM group) | First-attempt success; procedure time, complications, puncture site hemorrhage | 2 |
| Lahham, 2016; USA [20] | ER | LP (US vs. LM group) | Number of redirections, number of reinsertions, needling time, failure rate | 2 |
| Mofidi, 2013; Iran [21] | ER | LP (US vs. LM group) | Procedure time; number of needle insertions, traumatic LPs, pain score | 2 |
| Nomura, 2007; USA [22] | ER | LP (US vs. LM group) | Success of LP; number of attempts, ease of procedure | 4 |
| Peterson, 2014; USA [23] | ER | LP (US vs. LM group) | Number of insertions/redirections, success of LP; pain score, needling time, traumatic taps, patient satisfaction | 2 |
Abbreviations and definitions: US: Pre-procedural ultrasound scan; LM: conventional landmark technique (palpation unless otherwise stated); LP: lumbar puncture; ER: emergency room; CS: cesarean section; THA: total hip arthroplasty; TKA: total knee arthroplasty; CSE: combined spinal-epidural anesthesia; first-attempt success: a single needle insertion with or without redirections; identification time: time for identifying landmarks (by US or LM method); procedure time: total procedure time from start to end (palpation/US imaging + needling time) unless otherwise stated. Technical failure rate was defined as the need to (i) use alternative techniques (e.g., use of ultrasound in the conventional landmark group or vice versa) to achieve the effect, (ii) conversion to general anesthesia or (iii) discontinuation of the technique.