Pain control in first-trimester and second-trimester medical termination of pregnancy: a systematic review

Pain is a predictable feature of medical abortion in both the first trimester and the second trimester. We sought to evaluate optimal analgesia regimens during medical abortion.

We searched the PubMed and Cochrane databases from inception to March 2010 for publications of trials comparing methods of pain control during first-trimester medical abortion (<12 completed weeks' gestation) and second-trimester medical abortion (13-24 completed weeks' gestation). Standard data abstraction templates were used to systematically assess and summarize data.

Of 363 articles, 10 articles reporting the results of nine studies met inclusion criteria. Heterogeneity of analgesia regimens and medical abortion protocols prevented meta-analysis. Four studies conducted in women with pregnancies <8 completed weeks' gestation found that prophylactic acetaminophen, acetaminophen+codeine, ibuprofen or alverine did not reduce medical abortion pain; however, administration of ibuprofen after onset of cramping reduced pain and subsequent analgesia use. In second-trimester medical abortion, one study found that women treated with fentanyl (50 mcg) patient-controlled analgesia (PCA) had better satisfaction and pain relief than women treated with fentanyl (25 mcg) or morphine PCA, but found no difference in delivery/demand ratio; three studies found little effect of adjuvant treatment with metoclopramide or paracervical block on pain; one study found that women at >15 weeks' gestation who received diclofenac with the first misoprostol dose required less opioid analgesia than women who received acetaminophen+codeine.

Few studies examine pain management during medical abortion, and heterogeneity of existing data limits comparison. Further research is needed to determine the optimal analgesia regimens for first-trimester and second-trimester medical termination of pregnancy. To facilitate comparability of data, researchers should use contemporary medical abortion regimens, outcomes and study instruments to measure pain.