The head direction to the angle of progression ratio: a quantitative parameter for intrapartum evaluation of cephalic malposition

Published:September 22, 2022DOI:


      No previous study has evaluated the transitions of intrapartum transperineal ultrasound parameters during labor progression in cephalic malposition.


      We aimed to quantitate the characteristic trends of fetal head position and descent in cephalic malposition by analyzing the transitions of intrapartum transperineal ultrasound parameters and explore an indicator associated with the degree of cephalic malposition.


      We retrospectively analyzed pregnant women who delivered at term from January 2018 to December 2020 at the University of Tokyo Hospital. The fetal occipital position was classified as occiput anterior and nonocciput anterior according to the fetal occipital angle of 0° to 75° and 75° to 180°, respectively. Fetal occipital angle was defined by the midline angle and position of the ocular orbit. The differences in the trends of head direction, head–symphysis distance, and progression distance relative to the angle of progression between occiput anterior and nonocciput anterior cases were evaluated. In addition, the parameters that showed differences were analyzed to evaluate their relationship to the degree of cephalic malposition.


      A total of 502 images (occiput anterior, 319; nonocciput anterior, 183) met the inclusion criteria. The distribution of head direction values relative to the angle of progression was smaller in the nonocciput anterior group than in the occiput anterior group, whereas the head–symphysis distance and progression distance values relative to the angle of progression showed no difference in their distribution between the occiput anterior and nonocciput anterior groups. The ratio of head direction to the angle of progression was significantly smaller in the nonocciput anterior group than in the occiput anterior group (median [interquartile range], 0.03 [−0.02 to 0.10] vs 0.21 [0.12–0.28]; P<.0001). Furthermore, this ratio was negatively correlated with fetal occipital angle (Spearman correlation coefficient, −0.66).


      Our results indicated that the head direction to angle of progression ratio reflects the deviation in the fetal head direction toward the maternal dorsal side, and decreases in proportion to the degree of cephalic malposition. This concept of deviation in the head direction as an indicator for evaluating cephalic malposition with intrapartum transperineal ultrasound may contribute to improving labor management in the case of cephalic malposition.

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        • Ghi T
        • Eggebø T
        • Lees C
        • et al.
        ISUOG Practice Guidelines: intrapartum ultrasound.
        Ultrasound Obstet Gynecol. 2018; 52: 128-139
        • Molina FS
        • Terra R
        • Carrillo MP
        • Puertas A
        • Nicolaides KH.
        What is the most reliable ultrasound parameter for assessment of fetal head descent?.
        Ultrasound Obstet Gynecol. 2010; 36: 493-499
        • Ramphul M
        • Ooi PV
        • Burke G
        • et al.
        Instrumental delivery and ultrasound: a multicentre randomised controlled trial of ultrasound assessment of the fetal head position versus standard care as an approach to prevent morbidity at instrumental delivery.
        BJOG. 2014; 121: 1029-1038
        • Kalache KD
        • Dückelmann AM
        • Michaelis SA
        • Lange J
        • Cichon G
        • Dudenhausen JW.
        Transperineal ultrasound imaging in prolonged second stage of labor with occipitoanterior presenting fetuses: how well does the ‘angle of progression’ predict the mode of delivery?.
        Ultrasound Obstet Gynecol. 2009; 33: 326-330
        • Malvasi A
        • Giacci F
        • Gustapane S
        • Sparic R
        • Barbera A
        • Tinelli A.
        Intrapartum sonographic signs: new diagnostic tools in malposition and malrotation.
        J Matern Fetal Neonatal Med. 2016; 29: 2408-2413
        • Chan VYT
        • Lau WL
        • So MKP
        • Leung WC.
        Measuring angle of progression by transperineal ultrasonography to predict successful instrumental and cesarean deliveries during prolonged second stage of labor.
        Int J Gynaecol Obstet. 2019; 144: 192-198
        • Bultez T
        • Quibel T
        • Bouhanna P
        • Popowski T
        • Resche-Rigon M
        • Rozenberg P.
        Angle of fetal head progression measured using transperineal ultrasound as a predictive factor of vacuum extraction failure.
        Ultrasound Obstet Gynecol. 2016; 48: 86-91
        • Henrich W
        • Dudenhausen J
        • Fuchs I
        • Kämena A
        • Tutschek B.
        Intrapartum translabial ultrasound (ITU): sonographic landmarks and correlation with successful vacuum extraction.
        Ultrasound Obstet Gynecol. 2006; 28: 753-760
        • Bellussi F
        • Salsi G
        • Simonazzi G
        • et al.
        A simple sonographic finding is associated with a successful vacuum application: the fetal occiput or forehead sign.
        Am J Obstet Gynecol MFM. 2019; 1: 148-155
        • Lau WL
        • Leung WC
        • Chin R.
        What is the best transperineal ultrasound parameter for predicting success of vacuum extraction?.
        Ultrasound Obstet Gynecol. 2009; 33: 735
        • Gardberg M
        • Laakkonen E
        • Sälevaara M.
        Intrapartum sonography and persistent occiput posterior position: a study of 408 deliveries.
        Obstet Gynecol. 1998; 91: 746-749
        • Lieberman E
        • Davidson K
        • Lee-Parritz A
        • Shearer E.
        Changes in fetal position during labor and their association with epidural analgesia.
        Obstet Gynecol. 2005; 105: 974-982
        • Akmal S
        • Tsoi E
        • Howard R
        • Osei E
        • Nicolaides KH.
        Investigation of occiput posterior delivery by intrapartum sonography.
        Ultrasound Obstet Gynecol. 2004; 24: 425-428
        • Hjartardóttir H
        • Lund SH
        • Benediktsdóttir S
        • Geirsson RT
        • Eggebø TM.
        When does fetal head rotation occur in spontaneous labor at term: results of an ultrasound-based longitudinal study in nulliparous women.
        Am J Obstet Gynecol. 2021; 224 (514.e1–9)
        • Fitzpatrick M
        • McQuillan K
        • O'Herlihy C
        Influence of persistent occiput posterior position on delivery outcome.
        Obstet Gynecol. 2001; 98: 1027-1031
        • Ponkey SE
        • Cohen AP
        • Heffner LJ
        • Lieberman E.
        Persistent fetal occiput posterior position: obstetric outcomes.
        Obstet Gynecol. 2003; 101: 915-920
        • Benavides L
        • Wu JM
        • Hundley AF
        • Ivester TS
        • Visco AG.
        The impact of occiput posterior fetal head position on the risk of anal sphincter injury in forceps-assisted vaginal deliveries.
        Am J Obstet Gynecol. 2005; 192: 1702-1706
        • Cheng YW
        • Shaffer BL
        • Caughey AB.
        The association between persistent occiput posterior position and neonatal outcomes.
        Obstet Gynecol. 2006; 107: 837-844
        • Wu JM
        • Williams KS
        • Hundley AF
        • Connolly A
        • Visco AG.
        Occiput posterior fetal head position increases the risk of anal sphincter injury in vacuum-assisted deliveries.
        Am J Obstet Gynecol. 2005; 193: 525-528
        • Palatnik A
        • Grobman WA
        • Hellendag MG
        • Janetos TM
        • Gossett DR
        • Miller ES.
        Predictors of failed operative vaginal delivery in a contemporary obstetric cohort.
        Obstet Gynecol. 2016; 127: 501-506
        • Murphy DJ
        • Liebling RE
        • Patel R
        • Verity L
        • Swingler R.
        Cohort study of operative delivery in the second stage of labour and standard of obstetric care.
        BJOG. 2003; 110: 610-615
        • Murphy DJ
        • Liebling RE
        • Verity L
        • Swingler R
        • Patel R.
        Early maternal and neonatal morbidity associated with operative delivery in second stage of labour: a cohort study.
        Lancet. 2001; 358: 1203-1207
        • Ghi T
        • Maroni E
        • Youssef A
        • et al.
        Sonographic pattern of fetal head descent: relationship with duration of active second stage of labor and occiput position at delivery.
        Ultrasound Obstet Gynecol. 2014; 44: 82-89
        • Bellussi F
        • Livi A
        • Cataneo I
        • Salsi G
        • Lenzi J
        • Pilu G.
        Sonographic diagnosis of fetal head deflexion and the risk of cesarean delivery.
        Am J Obstet Gynecol MFM. 2020; 2100217
        • Frick A
        • Kostiv V
        • Vojtassakova D
        • Akolekar R
        • Nicolaides KH.
        Comparison of different methods of measuring angle of progression in prediction of labor outcome.
        Ultrasound Obstet Gynecol. 2020; 55: 391-400
        • Kamel R
        • Negm S
        • Montaguti E
        • et al.
        Reliability of transperineal ultrasound for the assessment of the angle of progression in labor using parasagittal approach versus midsagittal approach.
        J Matern Fetal Neonatal Med. 2021; 34: 3175-3180
        • Youssef A
        • Maroni E
        • Ragusa A
        • et al.
        Fetal head-symphysis distance: a simple and reliable ultrasound index of fetal head station in labor.
        Ultrasound Obstet Gynecol. 2013; 41: 419-424
        • Dietz HP
        • Lanzarone V.
        Measuring engagement of the fetal head: validity and reproducibility of a new ultrasound technique.
        Ultrasound Obstet Gynecol. 2005; 25: 165-168
        • Tutschek B
        • Braun T
        • Chantraine F
        • Henrich W.
        A study of progress of labour using intrapartum translabial ultrasound, assessing head station, direction, and angle of descent.
        BJOG. 2011; 118: 62-69
        • Ghi T
        • Farina A
        • Pedrazzi A
        • Rizzo N
        • Pelusi G
        • Pilu G.
        Diagnosis of station and rotation of the fetal head in the second stage of labor with intrapartum translabial ultrasound.
        Ultrasound Obstet Gynecol. 2009; 33: 331-336
        • Bellussi F
        • Ghi T
        • Youssef A
        • et al.
        The use of intrapartum ultrasound to diagnose malpositions and cephalic malpresentations.
        Am J Obstet Gynecol. 2017; 217: 633-641
        • Kamel R
        • Youssef A.
        How reliable is fetal occiput and spine position assessment prior to induction of labor?.
        Ultrasound Obstet Gynecol. 2019; 53: 535-540
        • Cunningham FG
        • Kenneth JL
        • Steven LB
        • et al.
        25th ed. Williams obstetrics. 1. McGraw Hill Education, New York, NY2018
        • Wiafe YA
        • Whitehead B
        • Venables H
        • Dassah ET.
        Comparing intrapartum ultrasound and clinical examination in the assessment of fetal head position in African women.
        J Ultrason. 2019; 19: 249-254
        • Blasi I
        • D'Amico R
        • Fenu V
        • et al.
        Sonographic assessment of fetal spine and head position during the first and second stages of labor for the diagnosis of persistent occiput posterior position: a pilot study.
        Ultrasound Obstet Gynecol. 2010; 35: 210-215
        • Souka AP
        • Haritos T
        • Basayiannis K
        • Noikokyri N
        • Antsaklis A.
        Intrapartum ultrasound for the examination of the fetal head position in normal and obstructed labor.
        J Matern Fetal Neonatal Med. 2003; 13: 59-63
        • Takeda S
        • Takeda J
        • Koshiishi T
        • Makino S
        • Kinoshita K.
        Fetal station based on the trapezoidal plane and assessment of head descent during instrumental delivery.
        Hypertens Res Pregnancy. 2014; 2: 65-71
        • Barbera AF
        • Pombar X
        • Perugino G
        • Lezotte DC
        • Hobbins JC.
        A new method to assess fetal head descent in labor with transperineal ultrasound.
        Ultrasound Obstet Gynecol. 2009; 33: 313-319
        • Ghi T
        • Contro E
        • Farina A
        • Nobile M
        • Pilu G.
        Three-dimensional ultrasound in monitoring progression of labor: a reproducibility study.
        Ultrasound Obstet Gynecol. 2010; 36: 500-506