Secondary outcomes for the study groups
| Variable | Catheter group, N=16 | Opioid group, N=14 | Median difference (SE; 90% CIhigh) | Risk ratio (SE; 90% CIhigh) |
| Pain scores, median (IQR) | 2 (1–3) | 2 (1–3) | 0 (0.5; 90% CIhigh 0.0) | |
| Any pain scores>10 in the first 72 hours, N (%) | 3 (19%) | 2 (14%) | 1.31 (1.51; 90% CIhigh 14.28) | |
| Number of opioid boluses, N (%) | 6 (38%) | 6 (43%) | 0.88 (1.42; 90% CIhigh 3.13) | |
| Cumulative enteral morphine, µg/kg, median (IQR) | 0 (0–4090) | 0 (0–3800) | 0 (1370.5; 90% CIhigh 300.0) | |
| Cumulative paracetamol, mg, median (IQR) | 415 (341–539) | 462 (189–612) | −47 (129.0; 90% CIhigh 162.5) | |
| Duration of mechanical ventilation post surgery, hours, median (IQR) | 44 (24–90) | 59 (41–115) | −14 (22.3; 90% CIhigh 13.1) | |
| Ventilated at 72 hours post surgery, N (%) | 5 (31%) | 5 (36%) | 0.88 (1.46; 90% CIhigh 3.13) | |
| Time to reach feeds 120 mL/kg/day post surgery, hours, median (IQR) | 230.4 (187.2–273.6) | 202.8 (141.6–312) | 27.4 (77.8; 90% CIhigh 60.0) | |
| Duration of neonatal intensive care unit stay post surgery, days, median (IQR) | 15.9 (11.4–25.4) | 17.8 (13.9–37.1) | −1.9 (4.7; 90% CIhigh 5.0) | |
| Duration of hospital stay post surgery, days, median (IQR) | 17.9 (11.4–31.9) | 17.8 (13.9–37.1) | 0.1 (8.6; 90% CIhigh 9.5) | |
| Inotropes, N (%) | 4 (25%) | 5 (36%) | 0.70 (1.52; 90% CIhigh 3.11) | |
| Bladder catheterisation, N (%) | 4 (25%) | 8 (57%) | 0.44 (1.56; 90% CIhigh 1.02) | |
| Wound infection | 0 | 1 (7%) | 0.00 (3.44; 90% CIhigh 5.86) |