Analgesia of afterpains with transcutaneous nerve stimulation (TENS) vs. metamizole. A prospective, randomized placebo controlled double-blind study

Afterpains are occurring in approx. 30-40% of all multiparous women. A pilot study testing the efficacy of TENS vs. metamizole proved TENS to be effective. 118 of 541 multiparous women were randomly assigned to one of 4 groups. Group 1: TENS vs. metamizole; group 2: TENS vs. placebo; group 3: placebo-TENS vs. metamizole; group 4: placebo-TENS vs. placebo. 423 multipara could not be enrolled in the study, mostly due to tolerable contractions with only minimal pain. Every patient received TENS or placebo-TENS together with 25 gtt. of metamizole (625 mg) or a placebo drug. Each TENS device was delivered with a fixed stimulation frequency of 100 Hz, whereas the intensity could be adjusted individually. Pain score were obtained with the help of a visual analogous pain scale (VAS; scaled 1-10). The average duration of afterpains was 15 min in all 4 groups. The initial pain score of the study patients was 5-6 (median) on the VAS in all groups. In the placebo-TENS groups pain reduction was only 13% (after 2-10 min), in contrast to 49.5% in the TENS groups. Pain reduction was already found after 2 min of treatment in the latter groups. Comparing group 1-2 after 2 min and group 1-4 after 20 min of treatment no significant differences of pain reduction could be found. Comparing the TENS vs. placebo-TENS groups a significant pain reduction after 2 min of treatment and a significantly better uterine involution in the TENS groups could be found. The placebo effect was 11%. In conclusion TENS is easy to apply, delivering a fast pain relief without causing adverse effects. Additionally it could help minimizing puerperal endomyometritis due to an improved uterine involution. 93% of our patients who used TENS would recommend TENS for treatment of afterpains.