Contraceptive Ring Appears Well Tolerated, May Improve Vaginal Flora

Yael Waknine

October 08, 2004

Oct. 8, 2004 — Contraceptive ring use is well tolerated and may have a beneficial effect on vaginal health, according to the results of a randomized, crossover study published in the September issue of Obstetrics & Gynecology. Some women using the ring may experience a benign increase in vaginal wetness.

"Despite evidence for the positive effects of estrogen-releasing vaginal rings and lack of evidence that they may cause injury to vaginal epithelium, several studies list vulvovaginal symptoms as frequent side effects," write Sharry Veres, MD, from St. Joseph's Hospital and Medical Center Family Medicine in Phoenix, and colleagues, noting that one study has reported vaginal discharge (21% - 27%) as being the most common adverse effect of ring use.

"It is not clear whether it is the contraceptive vaginal ring or the use of contraceptive hormones in a sexually active population not using a barrier method that is responsible for causing these symptoms," the authors write.

The investigators compared genital signs and symptoms, examinations, and laboratory findings in 80 women randomized to use of a combination contraceptive vaginal ring (n = 40; 15 µg ethinyl estradiol/120 µg etonogestrel; NuvaRing, Organon USA, Inc.) or combination oral contraceptive (OC) pills (n = 40; 20 µg ethinyl estradiol/100 µg levonorgestrel) for a period of three 28-day cycles, followed by a crossover to three cycles of the study drug not originally assigned.

Pelvic examinations were conducted at baseline, cycles 2 and 4, and at the end of the study. Daily genital symptoms were self-scored by patients on a scale of 1 to 4. Eighty percent of the women completed the study, with no significant difference in completion rates between groups (ring-first group, 82.5%; OC-first group, 77.5%; P = .58).

The ring was well tolerated; the few genital symptoms reported were generally scored as mild and their incidence was similar to that reported with OC use, with the exception of vaginal wetness.

Increased vaginal wetness was reported with 2.74-fold incidence (95% confidence interval [CI], 1.80 - 4.18; P < .001) in ring users compared with those using OCs (ring, 63% vs OCs, 43%). "Women who reported more vaginal wetness did not differ on laboratory findings from women who did not report this symptom," the authors note.

Laboratory findings showed that the concentration of Lactobacillus colony-forming units positive for hydrogen peroxide (H2O2) also significantly increased during ring use (fold difference, 2.67; CI, 1.49 - 4.78; P < .001), although the percentage of women positive for Lactobacillus did not change significantly from baseline (83.8%) with ring or OC use (P = .28).

"The contraceptive vaginal ring use results in low systemic [ethinyl estradiol] exposure, but it is possible that there is a 'uterine-first-pass' or some sort of preferential delivery of vaginally administered hormones to the genital tissues," the authors suggest.

Other laboratory findings did not differ significantly by method of contraception, including yeast colony counts (P = .08), Nugent Gram stain score (P = .51), vaginal white blood cell count (P = .66), vaginal pH, and discharge weight.

Limitations of the study include its small size and short duration.

"This study provides some reassurance that an increase in vaginal wetness reported by a woman using the combination vaginal ring most likely does not represent pathology," the authors write, adding that increased H2O2-producing Lactobacillus concentrations may even indicate a favorable effect on vaginal health by preventing viral and bacterial infections.

"This increase in H2O2-producing Lactobacillus concentrations with combination vaginal ring use should be further explored," the authors conclude.

The study was funded by an unrestricted educational grant from Organon USA, Inc., the maker of NuvaRing.

Obstet Gynecol. 2004;104:555-563  

Reviewed by Gary D. Vogin, MD