2Sherer DM, Miodovnik M, Bradley KS, et ai. Intrapartum fetal headposition I : comparison between transvaginal digital examination andtransabdominal ultrasound assessment during the active stage oflabor. Ultrasound Obstet Gynecol ,2002,19 (3 ) : 258-263.
3Fuchs I,Tutschek B, Henrich W. Visualization of the fetal fontanelsand skull sutures by three-dimensional translabial ultrasound duringthe second stage of labor. Ultrasound Obstet Gynecol,2008 ,31 (4):484486.
4Barbera AF,Pombar X, Perugino G, et al. A new method to assessfetal head descent in labor with transperineal ultrasound. UltrasoundObstet Gynecol,2009,33(3) :313-319.
5Kalache KD, Diickelmann AM, Michaelis SA, et al. Transperinealultrasound imaging in prolonged second stage of labor with occipitoanteriorpresenting fetuses : how well does the 7 angle of progression ^ predict themode of delivery. Ultrasound Obstet Gynecol ,2009,33 ( 3) :326-330.
6Ghi T, Contro E, Farina A, et al. Three-dimensional ultrasound inmonitoring progression of labor : a reproducibility study. UltrasoundObstet Gynecol,2010,36(4) :500-506.
7B Henrich W, Dudenhausen J, Fuchs I, et al. Intrapartum translabialultrasound (ITU) : sonographic landmarks and correlation with successfulvacuum extraction. Ultrasound Obstet Gynecol ,2006,28 (6) :753-760.
8Ghi T,Farina A,Pedrazzi A,et al. Diagnosis of station and rotation ofthe fetal head in the second stage of labor with intrapartum translabialultrasound. Ultrasound Obstet Gynecol,2009,33(3) :331-336.
9Diickelmann AM,Bamberg C,Michaelis SA,et al. Measurement of fetalhead descent using the 'angle of progression'on transperineal ultrasoundimaging is reliable regardless of fetal head station or ultrasoundexpertise. Ultrasound Obstet Gynecol ,2010,35 (2 ) :216-222.