Table 3.

Characteristics of included studies.

Author, year, and methods	Participants	Interventions	Outcomes	Notes
Caudal versus inguinal nerve block
Abdellatif 2012 [8]  RCT, 2 groups, parallel design	Children with unilateral groin surgery Age: 1–6 yrs	US guided INB against blind CB; both done preoperatively under GA. No use of adrenaline.	CHEOPS scale and also the number of children needing rescue analgesic provided.	1 patient in CB and 2 in INB were excluded due to failure.
Fisher et al.,  1993 [9]  RCT, 3 groups, parallel design	Children having herniorrhaphy or orchidopexy Age: 0.5–10 yrs	2 groups of CB (with or without the use of epinephrine) against INB; both done after the procedure.	Primary outcome: postoperative voiding with analgesia outcomes as secondary.Single time point reporting of rescue analgesia.	For the purpose of the review the caudal groups were combined as 1 group. 4 patients in each group were excluded because of failure of interventions.
Markham et al., 1986 [10]  RCT, 2-arm parallel trial	Children having herniorrhaphy or orchiopexy Age: 1–12 years	CB against INB; both done preoperatively, without image guidance under GA. No use of adrenaline.	The outcome was intraoperative and postoperative analgesia.
Scott et al., 1989 [11]  RCT, 2-arm parallel trial	Children having herniorrhaphy or orchiopexy Age: 3–8 years	CB against INB; both done preoperatively, without image guidance under GA. No use of adrenaline.	Primary outcome: effectiveness of postoperative analgesia.
Hanallah et al., 1987 [12] RCT, 3-arm parallel trial	Orchidopexy Age: 18 months–12 years	CB against INB, with the 3rd group acting as a control. All interventions done after surgery, without image guidance No use of adrenaline.	Primary outcome: postoperative analgesia as median and range without specifying the time point.	Not included in the quantitative analysis. The authors also combined both treatment groups compared to the control group to report the use of rescue analgesia.
Caudal versus infiltration
Machotta et al., 2003 [13] RCT, 2-arm parallel trial	Children having unilateral Hernia Age: 0–5 yrs	CB against wound infiltration; both done after the surgery. No Image guidance or use of epinephrine.	Postoperative analgesia. Hannalah scale as well as children needing rescue analgesic.	Adverse events are not specifically (individually) reported.
Lafferty et al., 1990 [14] RCT, 2-arm parallel design	Children having orchiopexy Age: 2–15 years	CB done preoperatively versus wound infiltration done before full surgical closure. No image guidance or use of epinephrine.	Postoperative analgesia by a 10 cm linear analogue scale and use of rescue analgesia.	Poor reporting of methods and outcome assessment
Fell et al., 1988 [15] RCT, 2-arm parallel design	Children having inguinal herniotomy Mean age CB: 4.5 ± 2.9 yrs INF: 3.7 ± 2.5 yrs	Caudal done preoperatively versus wound infiltration after surgery. No image guidance or use of epinephrine	Analgesia rated on a 3-point scale. Proportions of patients who were pain free provided.	Calculation of the number of children needing rescue analgesic was done indirectly. 1 patient was excluded as the data was incomplete.
Conroy et al., 1993 [16] RCT, 3-arm parallel trial, with a control group.	Children having a bilateral inguinal hernia Age: 2 months–10 years	CB done preoperatively versus INF after surgery. No image guidance. Epinephrine used in both groups.	Postoperative analgesia. Specific time point used to calculate the number of rescues analgesic not clearly mentioned.	Children in the control group were not included in this review. Confusion in the randomization code, in the first 30 pts, led to more children having caudal blocks.
Jahromi et al., 2012 [17] RCT, 3-arm parallel design	Unilateral inguinal hernia Age: 0.3–7 years	Caudal versus INF, both done after the surgery. No image guidance or epinephrine was used. 3rd group of acetaminophen was not included	Analgesia in FLACC scale and also reported as the number needing rescue analgesic.	3 children in the caudal group were excluded because of failed caudal.
Schindler et al., 1991 [18] RCT, 2-arm parallel design	Unilateral inguinal hernia Age: 2 months–12 years	CB done preoperatively versus INF done before full surgical closure. No image guidance or epinephrine used.	Analgesia in CHEOPS scale and also reported as the number needing rescue analgesia.
Caudal versus combined wound infiltration and inguinal N block
Tobias et al., 1995 [19] RCT, 2-arm parallel design	Children having inguinal hernia with additional laparoscopic inspection of contralateral peritoneum Mean age CB: 1.2 ± 0.2 yrs Comparator: 1.3 ± 0.4 yrs	CB placed presurgically versus INB and INF. No image guidance. Epinephrine used in both arms.	Analgesia using Hannalah scale and also reported as the number needing rescue analgesia.	Laparoscopic inspection involved.
Splinter et al., 1995 [20] RCT, 2-arm parallel design	Children having inguinal hernia repair Age: 1–13 years	CB placed presurgically versus INB and INF placed after surgery. No image guidance. Epinephrine used in both arms.	Analgesia using mCHEOPS scale and also reported as the number needing rescue analgesic.
Cross and battett  1987 [21] RCT, 2-arm parallel design	Children having herniotomy or/and orchidopexy; unilateral or bilateral included. Age: 1–13 years	CB versus INB and INF, all placed before surgery. No image guidance. Epinephrine used only in the comparator group.	Analgesia using linear analogue scale and also reported as the number needing rescue analgesic.	The dose of local anesthetic was different depending on unilateral and bilateral surgeries.
Somri et al., 2002 [22] RCT, 2-arm parallel design	Children having orchidopexy Age: 1–8 years	CB versus combined INB and INF. No image guidance or use of epinephrine.	Primary outcome-effect of catecholamine level. Analgesia as a secondary outcome, reported as the number needing rescue analgesic.	The report is titled as a comparison of CB versus INB; however the methods mention that they supplemented the INB with INF.
Bhattarai et al., 2005 [23] RCT, 2-arm parallel design	Children having herniotomy Age: 1–14 years	CB versus combined INB and INF; all interventions done after surgery. No image guidance used.	Analgesia reported as mean duration and also as the number needing rescue analgesic.
Caudal versus others
Tug et al., 2011 [24] RCT, 2-arm parallel design	Inguinal hernia Age: 3–7 years	CB versus PVB; both placed presurgically.	Rescue analgesia at 2 and 4 hrs and also in mean (±SD scores).	2 (PVB) and 4 (CB) were excluded due to technical failures.

(RCT: randomised control trial, CB: caudal block, INB: inguinal nerve block, and INF: infiltration).