Pharmacological pain control for medical abortion in pregnancies up to 14 weeks: a systematic review

Abstract

Objective To sum up the available evidence relative to pharmacological pain control options for medical abortion in pregnancies up to 14 weeks and to compare different options. Data Sources PubMed, SCOPUS, Web of Science and The Cochrane Library were searched from inception until December 2023. Methods of Study Selection This review included: comparative studies (of any sample size) between different methods of pharmacological pain control or between a method of pharmacological pain control and a placebo in medical abortion in pregnancies up to 14 weeks, studies with validated scores of pain assessment and studies in which the abortion regimen consisted of mifepristone and misoprostol. The outcome of interest was: 1 - maximum and/or median pain scores reported with each method of pain control; 2 - need for additional analgesia and 3- side effects reported, specifically nausea, vomiting, diarrhoea, and headache. Abstracts and full-text articles were screened in duplicate and risk of bias was assessed using validated tools for each study type (RoB2 tool for bias for Random Controlled Trial). Study quality was summarized with standardized tools. Meta-analysis was not conducted due to heterogeneity of study designs, interventions, and outcome reporting, but all the relevant findings were summed up in this article. Tabulation, Integration, and Results Seven Random Controlled Trials met the inclusion. Studies were summarized using the results of each one regarding the outcome of maximum/median pain reported, need for additional analgesia and relevant side effects were also summed up. - Ibuprofen + dronabinol vs ibuprofen + placebo found no superiority in pain control. - Ibuprofen + metoclopramide vs Tramadol + placebo vs 2 placebo pills found that although both the ibuprofen + metoclopramide group and tramadol group showed reduced pain, when compared with placebo; the ibuprofen + metoclopramide group were least likely to use additional analgesia and reported fewer side effects. - Oxycodone vs placebo showed no improvement on regular pain management regime (NSAIDs + ondansetron). - Dextromethorphan vs placebo added no benefit on regular pain management regime (NSAIDs + acetaminophen + opioids). - Pregabalin vs placebo proved increases satisfaction with the analgesic regimen and reduces the usage of NSAIDs and narcotics, but there seems to be little to no variation in reported pain. - Pre-emptive ibuprofen vs placebo showed that the prophylactic usage reduces need for additional analgesia post misoprostol administration. - Paracetamol vs ibuprofen found ibuprofen to be statistically significantly more effective for pain relief. Conclusion Overall ibuprofen is the most effective pain killer with fewer side effects compared to paracetamol, tramadol, oxycodone, dextromethorphan and pregabalin. There are benefits in its pre-emptive use. Several studies use, with success, an association between ibuprofen, acetaminophen, and even opioids as well as anti-emetic drugs. The prophylactic use of pregabalin may reduce the usage of these other analgesics. In regards to side effects, we found with moderate certainty evidence that tramadol may increase nausea and vomiting and with high certainty evidence that it may increase headache. Other results regarding side-effects were low certainty evidence and are better described in the manuscript of this review. It is essential to note that the method and regimen of administration chosen for misoprostol acts as a confounder and may affect the interpretation of results, especially regarding gastro-intestinal side-effects. Regarding the need for additional analgesia, we found with moderate certainty evidence that tramadol, ibuprofen + metoclopramide, isolated ibuprofen and pregabalin all decrease the likelihood of additional analgesia.