95: Detecting plasma desmosine as a marker for elastic fiber degradation in pelvic floor connective tissue during the postpartum period

Abstract

Elastic fibers in pelvic floor connective tissue are critical for pelvic organ support. Their breakdown and incomplete repair following parturition has been hypothesized as a mechanism to explain the association between childbirth and pelvic floor disorders. Desmosine and isodesmosine (desmosine) are amino acids detectable in bodily fluids, capable of reflecting elastic fiber degradation in elastin rich tissue. Their ability to reflect elastic fiber degradation in the pelvic floor is unknown. Therefore, we investigated whether the detection of plasma desmosine could reflect elastic fiber degradation in pelvic floor connective tissue. We hypothesized that direct trauma to pelvic floor tissue incurred during vaginal delivery will cause greater elastic fiber disruption resulting in an increased level of detectable plasma desmosine postpartum when compared to cesarean delivery. Forty-one primiparous women following uncomplicated pregnancies agreed to participate in this study, 24 following vaginal delivery and 17 following cesarean delivery. Twenty-three reproductive age nulliparous women also participated. Blood draws for plasma collection were performed early (1-4 days) and late (6-8 weeks) postpartum. Desmosine quantification was performed using liquid chromatography tandem mass spectroscopy. Our primary outcome was the comparison of desmosine concentration by mode of delivery early postpartum. The Mann Whitney U test was applied with p < 0.05 noting significance. Age, race, maternal weight, and gestational age were similar between postpartum groups. Median infant birth weight was greater in the cesarean delivery group (3538.8 grams vs. 3103.3 grams, p = 0.004). Median desmosine level was greater in the cesarean delivery group (0.51 ng/ml vs 0.40 ng/ml, p = 0.04). However, upon linear regression modeling controlling for age and infant birth weight, this difference did not remain significant (95% CI -0.01 to 0.20). The desmosine level in reproductive age nulliparous women, with a median age of 29.0 years, was 0.23 ng/ml. Counter to our hypothesis plasma desmosine concentration was higher following cesarean delivery. We suspect this finding reflects uterine elastic fiber remodeling after a hysterotomy, though this result may be confounded by infant birth weight. Antepartum plasma desmosine values would aid our understanding of this relationship. Another important observation was the low desmosine level seen in young, nulliparous women. Taken together, these findings confirm that plasma desmosine can reflect reproductive tract elastic fiber degradation. Further research is needed to determine if elastic fiber degradation occurring in pelvic floor tissue can be detected by plasma desmosine quantification.