الفهرس 
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Abstract
Preterm labor is defined as the presence of uterine contractions of sufficient frequency and intensity to effect progressive effacement and dilation of the cervix prior to term gestation (between 20 and 37 weeks). Preterm labor precedes almost half of preterm births and preterm birth occurs in approximately 12% of pregnancies and is the leading cause of neonatal mortality in the United States. In addition, preterm labour affects 7-11% of all pregnancies as it is considered the most challenging problem in the modern obstetrics and responsible for 70% of neonatal morbidity, mortality. Different methods were used to diagnose or predict preterm labour ranging from simple methods like digital examination and ultrasound to more complicated methods like biochemical markers in maternal serum or cervicovaginal secretions. Transvaginal ultrasound is a type of pelvic ultrasound.There is an evidence supporting the reliability and validity of sonographic evaluation of the cervix in the form of cervical length for the prediction of preterm birth. Screening for a short cervical length by transvaginal ultrasonography has been studied in several populations. They included asymptomatic singletons at either low or high risk for preterm birth, multiple gestations, and symptomatic women with either preterm labor or preterm premature rupture of membranes. Reports on asymptomatic singletons with risk factors for preterm birth have concentrated on women with a prior preterm birth or multiple factors.
Objectives: The aim of this work was to compare clinical predictive value between transabdominal and transvaginal ultrasound in preterm labor.
Patients and methods: This descriptive study was conducted at High-Risk Unit, Obstetrics and Gynecology Department, Faculty of Medicine, Zagazig University and El-Mabarrah Hospital, Ministry of Health. The population of the study comprised 100 pregnant women, with threatened preterm labor, having singleton pregnancy of 28-35 weeks’ gestation (calculated from the 1st day of LMP), and with unremarkable medical history. Measurement of cervical length was made The cases included in this study were subjected to the protocol of Zagazig Maternity Hospital for tocolysis. All patients were regularly followed up till delivery and data on pregnancy outcome were obtained from the Filing system in the delivery ward, and for those that delivered at home or in other hospitals, from the patients themselves through phone contacts.
Results: There was a high significant negative correlation between gestational age and cervical length. A highly significant difference in cervical length between preterm and term groups was found when measured transvaginally. Transvaginal assessment of cervical length is one of the best tests for predicting preterm birth. A cervical length < 25 mm (10th percentile) between 15 and 24 weeks’ gestation is generally agreed upon as increasing the risk of preterm labor. The shorter the cervical length, the greater the likelihood of preterm labor. The positive predictive value of a 25 mm cervix for preterm labor is dependent upon the patient’s pretest probability (i.e. high-risk or low-risk for preterm labor). Short cervix detected by U/S is a strong predictor for preterm labor. TVS seems to be superior to TAU in assessing the cervical length and for screening for spontaneous preterm delivery.
Conclusion: Trans-vaginal ultrasound is more preferred route than trans-abdomenal ultrasound for measurement of cervical length for better prediction of preterm labor in high risk pregnancy.