Human uterine wall tension trajectories and the onset of parturition.

Uterine wall tension is thought to be an important determinant of the onset of labor in pregnant women. We characterize human uterine wall tension using ultrasound from the second trimester of pregnancy until parturition and compare preterm, term and twin pregnancies. A total of 320 pregnant women were followed from first antenatal visit to delivery during the period 2000-2004 at the John Hunter Hospital, NSW, Australia. The uterine wall thickness, length, anterior-posterior diameter and transverse diameter were determined by serial ultrasounds. Subjects were divided into three groups: women with singleton pregnancies and spontaneous labor onset, either preterm or term and women with twin pregnancies. Intrauterine pressure results from the literature were combined with our data to form trajectories for uterine wall thickness, volume and tension for each woman using the prolate ellipsoid method and the groups were compared at 20, 25 and 30 weeks gestation. Uterine wall tension followed an exponential curve, with results increasing throughout pregnancy with the site of maximum tension on the anterior wall. For those delivering preterm, uterine wall thickness was increased P < 0.05 compared with term. For twin pregnancies intrauterine volume was increased compared to singletons (P < 0.001), but wall thickness was not. There was no evidence for increased tension in those delivering preterm or those with twin gestations. These data are not consistent with a role for high uterine wall tension as a causal factor in preterm spontaneous labor in singleton or twin gestations. It seems likely that hormonal differences in multiple gestations are responsible for increased rates of preterm birth in this group rather than increased tension.

Prevalence of Chlamydia trachomatis infection among low- and high-risk Filipino women and performance of Chlamydia rapid tests in resource-limited settings.

The prevalence of urogenital Chlamydia trachomatis infection was determined with a PCR-based test of women from low- and high-risk populations in Iloilo City, Philippines, between August 2002 and March 2006. Two rapid tests for C. trachomatis, Clearview Chlamydia MF and the Chlamydia Rapid Test (CRT), were also evaluated in these resource-limited settings. Specimens were obtained from female sex workers (FSWs; n = 1,484) attending a social hygiene clinic (SHC) and from women (n = 838) attending an obstetrics-gynecology (OB-GYN) clinic. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the rapid tests were determined, with PCR as the gold standard. The PCR positivity rate for SHC participants (72% asymptomatic) ranged from 17.9 to 32.0% during the study period. Compared with those of PCR, the sensitivities and specificities of the Clearview test were 53.5 and 99.1%, respectively, with endocervical swab specimens (CS; n = 822) from the FSWs and 31.1 and 95.2%, respectively, with vaginal swab specimens (VS; n = 333) from these women. The sensitivity, specificity, PPV, and NPV of the CRT with VS from the FSWs were 71.0, 99.0, 97.1, and 87.9%, respectively. At the OB-GYN site, the PCR positivity rate with VS was 6.3%. The sensitivity, specificity, PPV, and NPV of the CRT with these specimens were 86.8, 99.6, 93.9, and 99.1%, respectively. The performance of the Clearview test at the SHC was thus markedly lower with VS than with CS, whereas the CRT performed well with VS from both populations.