Studies on female genital tract infections and the role of nitric oxide in diagnosis

Female genital tract infections are among the most common conditions causing individuals to seek medical care, and are associated with a high gynaecologic and reproductive morbidity. Thus, prompt and precise diagnosis of genital tract infections is essential to institute effective therapy and prevent sequelae. It is therefore desirable to develop an easily performed, objective test that can be useful to the practicing physician. Local measurement of nitric oxide (NO) gas in hollow organs has been used to detect and monitor inflammatory processes, but as of today NO has not been studied in the female genital tract.

The aim of the present thesis was to investigate whether it is possible to measure accurate NO formation in the female genital tract. We also sought to explore the role of NO as a diagnostic marker for inflammation in the female genital tract. Finally we wanted to evaluate the effect of bacterial vaginosis (BV) on the pharmacokinetics (plasma concentration Cmax, Tmax and bioavailability measured as the AUC240) of vaginally administered misoprostol in the first trimester of pregnancy.

NO has a very short half-life in biological tissues, but it is more stable in the gaseous phase, which makes it possible to measure this free radical in luminal structures. We have developed a new method for measurement of luminal NO formation involving the insertion of a silicon catheter in the vagina or the uterine cavity. The balloon is filled with air, which is incubated in the vagina or the uterine cavity for sampling of NO from the vagina or the uterus respectively.

We observed an almost 100-fold increase in intrauterine concentration of NO in patients diagnosed with pelvic inflammatory disease compared to those diagnosed with appendicitis or healthy controls. Uterine NO levels were uniformly low in healthy women throughout the menstrual cycle. Intrauterine NO levels did not rise after manipulation in the uterine cavity, and after an incubation time of just two minutes, NO levels were significantly increased in patients with diagnosed PID compared to control subjects. Moreover, in patients with symptoms of vaginitis, NO concentration was almost 100-fold increased compared to healthy controls. Vaginal NO levels were uniformly low among healthy women, both of reproductive age and in menopause.

Finally, we observed that the bioavailability of misoprostol was reduced in patients with BV, but there was no significant difference in the pharmacokinetics of vaginally administered misoprostol between the patients with BV and healthy control subjects.

In conclusion, BV did not affect the pharmacokinetics of vaginally administered misoprostol in early pregnancy. Furthermore, we describe a simple, reliable, rapid, safe and well tolerated method for measuring NO in the female genital tract. We also suggest that NO could be further evaluated as a biomarker of inflammatory disease in the female genital tract.

List of scientific papers

I. Sioutas A, Ehrén I, Lundberg JO, Wiklund NP, Gemzell-Danielsson K (2008). "Intrauterine nitric oxide in pelvic inflammatory disease." Fertil Steril 89(4): 948-52. Epub 2007 Aug 6
https://pubmed.ncbi.nlm.nih.gov/17681299

II. Sioutas A, Ehrén I, Gemzell-Danielsson K (2008). "Measurement of nitric oxide in the vagina." Acta Obstet Gynecol Scand 87(10): 1055-9
https://pubmed.ncbi.nlm.nih.gov/18798053

III. Sioutas A, Gemzell-Danielsson K, Lundberg JO, Ehrén I (2010). "Measurement of luminal nitric oxide in the uterine cavity using a silicon balloon catheter." (Submitted)

IV. Sioutas A, Sandström A, Fiala C, Watzer B, Schweer H, Gemzell-Danielsson K (2010). "Effect of bacterial vaginosis on the pharmacokinetics of vaginally administered misoprostol in early pregnancy" (Submitted)