Advanced ultrasound techniques in small animal reproduction imaging

Ultrasonography is the imaging technology of choice for the evaluation of the reproduction system and of pregnancy in both humans and animals. Over the past 10 years, there have been significant technological improvements of the equipment, while new technologies have been developed. Doppler, contrast-enhanced ultrasonography, elastography, and 3D/4D ultrasonography are advanced ultrasound techniques that have been designed as methods to increase the diagnostic sensitivity of two-dimensional (b-mode) ultrasound, and not as stand-alone tests. The basic physics as well as the advantages and limitations of these advanced ultrasound methods are briefly described. In the reproductive diagnostics of small animals, these techniques have gained an increased popularity as proved by the increased publication of several reports that are also briefly summarized in this review. Clinical applicability is to date limited because of a lack of research on the diagnostic value in concrete situations. Future research projects should focus also on standardization of the used techniques, on determination of thresholds to discriminate between healthy or diseases or fertile versus infertile and on the predictive value of advanced ultrasound findings. Continuing development and optimization of different ultrasound techniques as well as the increase of related scientific interest and worldwide research promises that the clinical interest on the use of advanced ultrasound techniques will increase in future.

Echogenicity of puborectalis muscle, cervix and vastus lateralis muscle in pregnancy in relation to mode of delivery

OBJECTIVES

To confirm our previous observation that levator hiatal dimensions and mean echogenicity of the puborectalis muscle (MEP) are significantly different at 12 weeks' gestation in women who delivered by Cesarean section due to failure to progress compared with those who delivered vaginally. The secondary objective was to assess the association between the echogenicity of the cervix and vastus lateralis muscle and mode of delivery.

METHODS

In this prospective multicenter study, 306 nulliparous women with a singleton pregnancy underwent ultrasound assessments of the pelvic floor at rest, on maximum pelvic floor muscle contraction and on maximum Valsalva maneuver, of the cervix and of the vastus lateralis muscle at 12 weeks' gestation. Dimensions of the levator hiatus, MEP and mean echogenicity of the cervix and vastus lateralis muscle were measured and compared according to mode of delivery.

RESULTS

Two hundred and forty-nine women were included in the analyses. We were unable to confirm our previous finding that MEP and levator hiatal transverse diameter and area at 12 weeks' gestation are associated significantly with mode of delivery. In addition, we could not demonstrate a significant association between echogenicity of the cervix or vastus lateralis muscle and mode of delivery. Overall, MEP was a mean of 20 points lower in women in the new database as compared with the previous study, despite the use of the same ultrasound equipment.

CONCLUSION

In a second, independent multicenter dataset, we were unable to confirm our previous finding that levator hiatal dimensions and MEP on pelvic floor muscle contraction are associated significantly with mode of delivery. We also found no association between echogenicity of the cervix or vastus lateralis and mode of delivery. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Structural changes in puborectalis muscle after vaginal delivery

OBJECTIVE

To evaluate the structural composition of the puborectalis muscle before and at several timepoints after first vaginal delivery, by the use of echogenicity and area measurements, in order to explore its recovery.

METHODS

Twenty nulliparous women with a singleton pregnancy underwent 3D/4D transperineal ultrasound assessments at rest, on pelvic floor muscle contraction and on Valsalva maneuver at 12 weeks' gestation and at 1 day and 1, 2, 3, 4, 6, 12, 18 and 24 weeks after vaginal delivery. The puborectalis muscle was delineated for measurements of mean echogenicity (MEP) and area (PMA). To assess changes in MEP and PMA over time, linear mixed model analysis was used. The exact number of days after delivery at each ultrasound examination was used as a covariate.

RESULTS

For all timepoints after delivery, MEP was significantly decreased compared with that at 12 weeks' gestation. MEP values increased significantly over time from 1 day to 24 weeks after delivery. Although not statistically significant, a decrease in MEP was observed between 3 and 4 weeks after delivery for all maneuvers. PMA at rest and on Valsalva maneuver remained constant after delivery.

CONCLUSION

When compared with measurements taken during pregnancy, a sharp decrease in MEP was observed soon after vaginal delivery, which was most likely caused by stretch trauma to the puborectalis muscle and subsequent formation of (micro) hematoma and edema. Subsequent increases in MEP may reflect the disappearance of hematoma and edema, and also the formation of connective and scar tissue. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Recovery of puborectalis muscle after vaginal delivery: an ultrasound study

OBJECTIVES

To assess change in levator hiatal dimensions between pregnancy and different timepoints after vaginal delivery, and map recovery of the hiatus in order to contribute to secondary prevention of symptoms of pelvic floor disorders.

METHODS

Twenty nulliparous women with a singleton pregnancy underwent ultrasound assessment of the pelvic floor at rest, on maximum pelvic floor muscle contraction (PFMC) and on Valsalva maneuver at 12 weeks' gestation and at 1 day and 1, 2, 3, 4, 6, 12, 18 and 24 weeks after vaginal delivery. Dimensions of the levator hiatus were measured and contractility and distensibility were calculated. The Wilcoxon signed rank test was used to compare each postpartum value with that at 12 weeks' gestation.

RESULTS

Levator hiatal area at rest, on PFMC and on Valsalva maneuver was significantly increased at 1 day and at 1 and 2 weeks after vaginal delivery compared with measurements at 12 weeks' gestation. Hiatal area at rest and on PFMC from 3 weeks postpartum onward, as well as contractility from 6 weeks onward, were comparable to values at 12 weeks' gestation, whereas, a significant difference remained on Valsalva maneuver until 24 weeks after delivery. Moreover, distensibility was still increased at 24 weeks postpartum compared with measurements at 12 weeks' gestation.

CONCLUSION

The puborectalis muscle has the ability to recover anatomically from a first vaginal delivery, and recovery occurs mainly during the first 3 weeks after delivery. Stretching of the puborectalis muscle, as reflected by distensibility, persisted 24 weeks after the first vaginal delivery. The data provide a better understanding of the early 'normal' regeneration process and we hypothesize that the first 3 weeks postpartum is the best window in which to start secondary prevention. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Method and reliability of measuring midurethral area and echogenicity, and changes during and after pregnancy

Introduction and hypothesis

Internal closure of the urethral sphincter is one of the mechanisms in maintaining continence. Little is known about changes in the urethral sphincter during pregnancy. We designed this study to develop a reliable method to measure the area and mean echogenicity of the midurethra during and after pregnancy and to assess changes over time.

Methods

Two observers independently segmented the urethra as follows: in the sagittal plane, the urethra was positioned vertically, the marker was placed in the middle section of the lumen of the urethra, and eight tomographic US images of 2.5 -mm slices were obtained. The central image was selected, and area and mean echogenicity were calculated automatically. Intra- and interobserver reliability were determined by intraclass correlation coefficients (ICC) and their 95% confidence intervals (CI). Two hundred and eighty women underwent TPUS at 12 weeks and 36 weeks of gestation and 6 months postpartum, and 3D/4D transperineal ultrasound (TPUS) images of 40 pregnant nulliparous women were used for the reliability study. Paired t tests were used to assess changes in echogenicity and area.

Results

The ICC for measuring the area was substantial, at 0.77 and for measuring mean echogenicity was almost perfect, at 0.86. In the total study group (n = 280), midurethral area and mean echogenicity were significantly lower 6 months after delivery compared with 12 and 36 weeks of gestation.

Conclusions

Our protocol for measuring area and mean echogenicity of the midurethra is reliable. This study indicates that structural changes in the midurethraoccur during pregnancy.

Mean echogenicity and area of puborectalis muscle in women with stress urinary incontinence during pregnancy and after delivery

Introduction and hypothesis

Pregnancy and childbirth are risk factors for the development of stress urinary incontinence (SUI). Urinary continence depends on normal urethral support, which is provided by normal levator ani muscle function. Our objective was to compare mean echogenicity and the area of the puborectalis muscle between women with and those without SUI during and after their first pregnancy.

Methods

We examined 280 nulliparous women at a gestational age of 12 weeks, 36 weeks, and 6 months after delivery. They filled out the validated Urogenital Distress Inventory and underwent perineal ultrasounds. SUI was considered present if the woman answered positively to the question “do you experience urine leakage related to physical activity, coughing, or sneezing?” Mean echogenicity of the puborectalis muscle (MEP) and puborectalis muscle area (PMA) were calculated. The MEP and PMA during pregnancy and after delivery in women with and without SUI were compared using independent Student’s t test.

Results

After delivery the MEP was higher in women with SUI if the pelvic floor was at rest or in contraction, with effect sizes of 0.30 and 0.31 respectively. No difference was found in the area of the puborectalis muscle between women with and those without SUI.

Conclusions

Women with SUI after delivery had a statistically significant higher mean echogenicity of the puborectalis muscle compared with non-SUI women when the pelvic floor was at rest and in contraction; the effect sizes were small. This higher MEP is indicative of a relatively higher intramuscular extracellular matrix component and could represent diminished contractile function.

The benefits of 3D-4D fetal echocardiography

In the last decade 3D and live 3D ultrasound or the so called 4D (3D/4D) in examination of the fetal heart evolved very rapidly with the development of the new technique called Spatiotemporal Image Corelation - STIC, which enables the aquisition of a volume data concomitent with the beating heart. It appears that 3D/4D ultrasound in fetal echocardiography may make an important contribution to the diagnosis of congenital heart disease, to interdisciplinary management, to parental counseling and to medical personal training.