Obstet Gynecol Sci.  2014 Nov;57(6):427-435. 10.5468/ogs.2014.57.6.427.

Intrapartum ultrasound: A useful method for evaluating labor progress and predicting operative vaginal delivery

• Ahn KH
• Oh MJ

• KMID: 2314007
• DOI: http://doi.org/10.5468/ogs.2014.57.6.427

Abstract

The last step of a successful pregnancy is the safe delivery of the fetus. An important question is if the delivery should vaginal or operative. In addition to the use of conventional antenatal ultrasound, the use of intrapartum ultrasound to evaluate fetal head station, position, cervical ripening, and placental separation is promising. This review evaluates and summarizes the usefulness of intrapartum ultrasound for the evaluation of labor progress and predicting successful operative vaginal delivery.

Keyword

Ultrasound; Obstetric labor; Obstetrical extraction

MeSH Terms

Cervical Ripening
Extraction, Obstetrical
Female
Fetus
Head
Labor, Obstetric
Pregnancy
Ultrasonography*

Figure

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  Fig. 1 Head-perineum distance on transperineal ultrasound. Transverse perineal ultrasound image showing measurement of the shortest fetal head-perineal distance of 4.77 cm.

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  Fig. 2 Angle of progression on transperineal ultrasound. Transperineal ultrasound image (sagittal view) depicting the long axis of the pubic symphysis (a), angle of progression (b), and line extending from the lowermost point of the symphysis tangentially to the fetal skull contour (c).

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  Fig. 3 Relationships among the angle of progression, cervical length, and gestational age. (A) Angle of progression and gestational age. (B) Cervical length and gestational age. (C) Angle of progression and cervical length (From Cho GJ, et al. J Perinat Med 2014 Jun 17 [Epub], with permission from Professor Oh MJ) [15].

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  Fig. 4 Correlation between the infrapubic line and ischial spine: the parallel line running through the projected level of the ischial spines (dotted line) lies 3 cm caudal to the infrapubic line.

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  Fig. 5 Head-symphysis distance on transperineal ultrasound. Ultrasound images demonstrating fetal head-symphysis distance measurements (head-symphysis distance, 32 mm). The head-symphysis distance is the distance between the inferior edge of the symphysis pubis to the nearest point of the fetal skull along a line passing perpendicular to the long axis of the symphysis pubis.

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  Fig. 6 Head direction on intrapartum translabial ultrasound. Categorization of fetal head direction (indicated by arrows) in longitudinal translabial sonograms: (A) downward, (B) horizontal, and (C) upward direction.

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  Fig. 7 Fetal head rotation. Translabial ultrasound of the maternal pelvis in the axial plane. (A) The transducer is rotated to visualize the midline of the fetal head. Head rotation is categorized as ≥45° or <45° with respect to the angle formed by the midline of the fetal head. (B) A rotation <45° (successful internal rotation) is associated with a lower station of ≥+3 cm [20].

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