Gestational age at cervical length measurement and preterm birth in twins.

OBJECTIVES: To estimate the risk of preterm delivery of twin pregnancies based upon sonographic cervical length measurement and gestational age at measurement. METHODS: Twin pregnancies that delivered between 1999 and 2005 and that underwent sonographic measurement of cervical length between 13 and 34 + 6 weeks' gestation were identified and a retrospective review performed. Women with anomalous pregnancies, multifetal reduction, cerclage placement or medically indicated deliveries before 35 weeks were excluded. Logistic regression analysis was used to estimate the risk of preterm delivery before 35 weeks. RESULTS: A total of 561 women underwent 2975 sonographic cervical length measurements during the study period. The rate of preterm delivery before 35 weeks was 19.4%. The risk of delivery before 35 weeks decreased by approximately 5% for each additional mm of cervical length (odds ratio (OR) 0.95 (95% CI, 0.93-0.97); P < 0.001) and by approximately 6% for each additional week at which the cervical length was measured (OR 0.94 (95% CI, 0.92-0.96); P < 0.001). CONCLUSION: The gestational age at which cervical length is measured is an important consideration when estimating the risk of spontaneous preterm birth in twins. The risk of preterm delivery is increased at earlier gestational ages and as cervical length decreases.

Rhinosporidium seeberi: a human pathogen from a novel group of aquatic protistan parasites.

Rhinosporidium seeberi, a microorganism that can infect the mucosal surfaces of humans and animals, has been classified as a fungus on the basis of morphologic and histochemical characteristics. Using consensus polymerase chain reaction (PCR), we amplified a portion of the R. seeberi 18S rRNA gene directly from infected tissue. Analysis of the aligned sequence and inference of phylogenetic relationships showed that R. seeberi is a protist from a novel clade of parasites that infect fish and amphibians. Fluorescence in situ hybridization and R. seeberi- specific PCR showed that this unique 18S rRNA sequence is also present in other tissues infected with R. seeberi. Our data support the R. seeberi phylogeny recently suggested by another group. R. seeberi is not a classic fungus, but rather the first known human pathogen from the DRIPs clade, a novel clade of aquatic protistan parasites (Ichthyosporea).