The
vaginal bleeding patterns observed during the use of the single-rod
progestin-only implant,
Implanon, compared with those seen during the use of the six-
capsule implant,
Norplant, have been analyzed. The acceptability of these
bleeding patterns was also assessed. An integrated analysis of 13 different trials was done, studying reference periods (RP) of 90 days. These trials included totals of 1716
Implanon users and 689
Norplant users. There were statistically significant lower mean values over RP 2-8 the range over RP 2-8 is presented) for
Implanon, for the number of
bleeding-
spotting days (15.9-19.3 vs 19.4-21.6; p = 0.0169), the number of
bleeding days (7.5-10.0 vs. 11.7-13.1; p < 0.001), and the number of
bleeding-
spotting episodes (2.2-2.7 vs. 3.1-3.3; p < 0.0001). The
bleeding patterns of
Implanon users appeared to be more variable than those observed with
Norplant:
Implanon users had more
amenorrhea, and slightly more infrequent
bleeding, frequent
bleeding, and prolonged
bleeding than
Norplant users. The difference was only statistically significant for
amenorrhea (17.9%-24.8% with
Implanon compared with 2.0%-7.0% for
Norplant over RP 2-8). There were no statistically significant differences in the acceptability of the two products as indicated by the discontinuation rates, which were 30.2% and 0.9% in Europe and Southeast Asia, respectively, for
Implanon, and 22.5% and 1.4%, respectively, in the two regions, for
Norplant. The individual
bleeding pattern was not predictable. However, in general, it can be stated that women initially without
bleeding or with infrequent
bleeding have only a small chance of becoming frequent bleeders, and vice versa.
Dysmenorrhea clearly improved during use of both
Implanon and
Norplant. Neither
Implanon nor
Norplant caused
anemia.