Three-dimensional/four-dimensional transperineal ultrasound: clinical utility and future prospects

Figures & data

Figure 1 Two-dimensional view of the midsagittal plane of the pelvic floor.

Note: The main structures identified on this plane are, from left to right, symphysis pubis (SP), urethra (U), urinary bladder (UB), vagina (V), rectum (R) and the puborectalis muscle (PR) passing behind the rectum.

Figure 2 A comparison of the images of the axial view using the three methods for the demonstration of levator ani muscle.

Notes: Image (A) was obtained using the multiplanar mode (sectional planes) and includes a single two-dimensional slice of the three-dimensional volume. Image (B) shows the previously reported render technique and (C) shows the image obtained by the Omniview-VCI.

Figure 3 Tomographic ultrasound imaging of the levator ani muscle obtained by three-dimensional/four-dimensional transperineal ultrasound.

Notes: The transducer is placed in the midsagittal plane. (A) Findings are normal, with no avulsions noted. (B) An avulsion of the muscle (arrow heads) is shown.

Figure 4 Measurement of the levator–urethra gap (LUG) on tomographic ultrasound imaging (TUI).

Notes: The images show the three central TUI slices used for determination of the LUG in a normal patient (the upper three images, A) and in a patient with unilateral avulsion (lower three images, B). The patient’s left side is shown on the right in all images. All measurements in (A) are normal and <25 mm. Conversely, there is an obvious left-sided levator avulsion injury visible in (B) with measurements >25 mm. LUG should be measured on both sides for all three central images, but for clarity reasons in the images, only one LUG is measured on one side for each woman.

Figure 5 Three-dimensional transperineal tomographic ultrasound images of anal sphincter.

Note: Normal external (anechogenic, indicated by the arrows) and internal (hyperechogenic, indicated by the arrow heads) anal sphincters are shown.

Figure 6 Technique for transperineal ultrasound scan for fetal head descent assessment on the midsagittal plane.

Notes: The convex transducer, covered by a sterile glove, is positioned translabially on the median plane (A and B) demonstrating the pubic symphysis (PS) and the fetal skull (B). On this plane, the angle of progression (C and D) can be measured as the angle between two lines: the first one running along the long axis of the PS and the second one extending from the most inferior portion of the PS tangentially to the fetal skull contour. The fetal head–symphysis distance (E and F) is the distance between the lowest edge of the pubic symphysis and the nearest point of the fetal skull along a line passing perpendicular to the long axis of PS and tangential to its lower border (reproduced from Youssef et al with permission).^67,87

Figure 7 Technique for transperineal ultrasound scan for fetal head descent and rotation assessment on the axial plane.

Notes: The convex transducer, covered by a sterile glove, is positioned translabially on axial plane (A and B). On this plane, the midline angle (C) and the head–perineum distance (D) can be measured (reproduced from Youssef et al with permission).⁶⁹

Figure 8 A multiplanar view of three-dimensional transperineal volume performed in labor.

Notes: (A) A midsagittal view of the fetal head descent below the symphysis pubis. (B) An axial view. (C) A coronal view.

Figure 9 The subpubic arch angle (SPA).

Notes: The technique of probe positioning translabially in the median plane (A) and the corresponding two-dimensional image (B) are shown. By drawing a line on the long axis of the pubic symphysis, it is possible to obtain a satisfactory view of the pubic rami (C). The SPA is then measured by the two-line function (D) (reproduced from Youssef et al with permission).⁸⁴

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