A comparison of the nugent score and cultures for genital mycoplasmas in the assessment of risk for preterm delivery

PLASMAS IN THE ASSESSMENT OF RISK FOR PRETERM DELIVERY SI EUN LEE, HYO SUK SEONG, HYUN SOO PARK, HANNA JUNG, ROBERTO ROMERO, BO HYUN YOON, Seoul National University College of Medicine, Obstetrics and Gynecology, Seoul, South Korea, Grosse Pointe, Michigan OBJECTIVE: This study was performed to evaluate the relationship among the Nugent score for the diagnosis of bacterial vaginosis, the results of vaginal culture for genital Mycoplasmas, and the subsequent occurrence of preterm birth. STUDY DESIGN: The Nugent score and culture for genital Mycoplasmas were performed in vaginal fluid obtained from 977 pregnant women (gestational age 13-30 wks). The vaginal samples were obtained with sterile cotton swabs. The relationship among the Nugent score, vaginal culture results, and the occurrence of spontaneous preterm birth was examined. RESULTS: 1) Of the 977 patients, 14% (137) had a Nugent score of R8; 2) The prevalence of a positive vaginal culture for genital Mycoplasmas was 30% (288); U. urealyticum was isolated in 252 (88%), M. hominis in 9 (3%), and both in 27 (9%) patients; 3) Cases with a Nugent score of R8 had a higher rate of a positive vaginal culture for genital Mycoplasmas than those with the lower Nugent score (55% vs 25%; p!.001); 4) Women with a Nugent score of R8 had a significantly higher rate of spontaneous preterm birth !37 (10% vs 4%), !34 (5% vs 2%), and !32 (4% vs 1%) wks of gestation than those with the lower Nugent score (at each gestational age, p!.05); 5) In contrast, a positive vaginal culture for genital Mycoplasmas was not associated with an increased risk for spontaneous preterm birth; 6) Among patients with a positive culture and a Nugent score of R8, the subsequent spontaneous preterm birth (!37 wks) occurred in 10% (7/72); 7) There was no difference in the incidence of the spontaneous preterm birth according to the results of vaginal culture in patients with a Nugent score of R8 as well as in those with the lower Nugent score. CONCLUSION: A high Nugent score (R8) for the detection of bacterial vaginosis but not positive vaginal culture for genital Mycoplasmas is a risk factor for spontaneous preterm birth. Our data suggest that clinicians need not spend healthcare resources obtaining cultures of the vagina for genital Mycoplasmas for the identification of patients at risk for preterm birth.