31 August–4 September 2003, Paris, France Poster abstracts P277 Sonographic cervical length in singleton pregnancies with intact membranes presenting with threatened preterm labour I. Fuchs *, W. Henrich†, K. Osthues†, K. Nicolaides* and J. W. Dudenhausen† *Dep. Obstetrics, Charit´ e Campus Virchow, Germany and †Harris Birthright Research Cent for Fetal Medicine, England Objective: In threatened preterm labour less than 15% of the women will progress to active labour and delivery. This study investigates if cervical length measurements by transvaginal ultrasound can discriminate between true and false labour in women presenting with preterm contractions. Methods: Cervical length was measured by transvaginal ultrasound in 253 women with singleton pregnancies presenting with painful uterine contractions at 24–36 (median 30.5) weeks of gestation. Women presenting in active labour defined by cervical dilatation, with ruptured membranes and those that underwent prior or subsequent cervical cerclage were excluded from the study. The clinical management was determined by the attending obstetrician without taking into account the cervical length. Primary outcome of the study was delivery within seven days of presentation. Results: Delivery within seven days of presentation occurred in 21 of the 253 (8.2%) pregnancies and this was inversely related to cervical length. In 209 cases the cervical length was 15 mm or more and only two of these (1%) delivered within seven days. In the 44 with cervical length less than 15 mm delivery within seven days of presentation occurred in 19 (43.2%). Logistic regression analysis demonstrated that significant independent contribution in the prediction of delivery within seven days was provided by cervical length (p < 0.0001), previous contraction frequency at presentation (p < 0.009), history of preterm delivery (p < 0.01) and vaginal bleeding (p < 0.019) with no significant contribution from gestation at presentation, ethnic origin, maternal age, parity, cigarette smoking or the administration of tocolysis, antibiotics or steroids. Conclusions: Sonographic measurement of cervical length helps to avoid over-diagnosis of preterm labour in women with preterm contractions and intact membranes and may be helpful to avoid unnecessary intervention. P278 Research of some risks of premature rupture of membrane M. Faramarzi Babol University of Medical Science, Iran Objective: Preterm birth is the most common causes of infant mortality. Premature rupture of membrane is the most common cause known of preterm birth. Method: A descriptive study of case – control planned on 200 normal partuient in Yahyaneghad hospital of Babol in 2001. Conclusive diagnosis of PROM were performed with on sterile speculum to identify fluid coming from the cervix or pooled in vagina. Finding: Premature preterm rupture of membrane (PROM) observed in 20% of case group History of abortion, PROM in previous Pregnancy, acute stress among recent month an symptomatic vaginitis during last month were in case and control groups subsequently: 8.2%–8.2%–16.2% and 8.4% that statistically these differences were significant. There is no difference between two groups according to Body Mass Index, education, job, place of life, age, parity, activity, of intercourse more than four during last month was twice in case group (20% versus 10%) that statistic test show significant difference. Conclusion: Exact history of patient, especially in third trimester can be helped us to predict PROM and Prevent from it’s dangerous outcome. P279 Effects of preterm rupture of membrane on pregnancy outcome M. Faramarzi Babol University of Medical Sciences, Iran Objective: Prematurity is 65% cause of neonatal mortality and premature rupture of membrane is the most common cause known of preterm birth. Method: A descriptive study of case – control planned on 200 normal parturients in Yahyaneghad hospital of Babol in 2001. Conclusive diagnosis of PROM were Performal with on sterile speculum to identify fluid coming from the cervix or pooled in vagina. Findings: Eight women (20%) of PROM were under 35 weeks that managed observatively. Induction of labour, cesarean delivery in case and control groups were subsequently: 58.38%–30.15% that statistical tests shows significant difference. In case group duration of first labour was shorter than control (P = 0/00 7/15 versus 9 h) but second labor was longer (p = 0/00 30, 51 vers 24). In case group post partum hemorrhage was 6% whereas there was no one in control (P = 0/00). fetal distress and resuscitation of neonatal in case and control were subsequently (12.5%–6.2% P = 0/01). Conclusion: In women’s PROM with elimination of preterm birth complications are more such as: cesarean delivery, fetal distress, resuscitation of neonate, second and third stage of delivery. P280 Patients with preterm labor with intact membranes and preterm prom with ‘failure of physiologic transformation of the spiral arteries have a higher impedance to flow in the uterine arteries J. Espinoza *, T. Chaiworapongsa*, Y. M. Kim*, L. F. Goncalves*, E. Bujold†, N. Camacho* and R. Romero* *Perinatology Research Branch, NICHD/NIH, USA and †Hutzel Hospital, Detroit, MI, USA Objective: The purpose of this study was to determine if failure of physiologic transformation of the spiral arteries in placental bed biopsies of patients with preterm labor with intact membranes and preterm PROM is associated with changes in the impedance to flow in the uterine arteries. Study design: A retrospective cohort study was conducted to evaluate the association of the histopathologic findings in the placental bed of patients with preterm labor and intact membranes (n = 14) and preterm PROM (n = 18), with the uterine artery RI and PI assessed by pulsed Doppler ultrasound. Immunohistochemistry was used to detect trophoblast and fibrinoid. Changes in the spiral arteries were scored as: 1) complete transformation: all vessels were transformed (n = 7); 2) mixed: transformed and non-transformed vessels or partially transformed vessels (replacement of the muscular media in less than 50% of the vessel wall) (n = 20); and 3) all vessels non-transformed (n = 5). Results: The median RI and PI of the uterine arteries were significantly higher in patients with complete failure of physiologic transformation compared to patients with mixed pattern or complete physiologic transformation of the spiral arteries (median RI: 0.73, range: 0.54–0.74 vs. median RI: 0.53, range: 0.41–1.84; p = 0.01 and median PI: 1.3, range: 0.84–1.7 vs. median PI: 0.81, range: 0.55–3.5; p = 0.04, respectively). Conclusion: 1) Abnormal hemochorial placentation defined as failure of physiologic transformation of the myometrial segment of the spiral arteries is present in 15.6% of patients with preterm labor and preterm PROM and thus this lesions is not specific to pre-eclampsia and SGA; 2) Patients with preterm labor/PROM with failure of physiologic transformation of the spiral arteries have increase impedance to flow in the uterine arteries. Ultrasound in Obstetrics & Gynecology 2003; 22 (Suppl. 1): 71–175 145