Pelvic floor ultrasound: a review

Ultrasound in the investigation of posterior compartment vaginal prolapse and obstructed defecation

Recent developments in diagnostic imaging have made gynecologists, colorectal surgeons and gastroenterologists realize as never before that they share a common interest in anorectal and pelvic floor dysfunction. While we often may be using different words to describe the same phenomenon (e.g. anismus/vaginismus) or attributing different meanings to the same words (e.g. rectocele), we look after patients with problems that transcend the borders of our respective specialties. Like no other diagnostic modality, imaging helps us understand each other and provides new insights into conditions we all need to learn to investigate better in order to improve clinical management. In this review we attempt to show what modern ultrasound imaging can contribute to the diagnostic work-up of patients with posterior vaginal wall prolapse, obstructed defecation and rectal intussusception/prolapse. In summary, it is evident that translabial/perineal ultrasound can serve as a first-line diagnostic tool in women with such complaints, replacing defecation proctography and MR proctography in a large proportion of female patients. This is advantageous for the women themselves because ultrasound is much better tolerated, as well as for healthcare systems since sonographic imaging is much less expensive. However, there is a substantial need for education, which currently remains unmet.

Prevalence of levator ani muscle injury in Chinese women after first delivery

OBJECTIVES

To assess the prevalence of levator ani muscle injury in Chinese women after their first delivery and investigate associated factors.

METHODS

A prospective observational study was conducted involving Chinese nulliparous women recruited in the first trimester of pregnancy. Translabial ultrasound was performed at 35-38 weeks' gestation and 8 weeks postpartum and three-dimensional volume datasets were obtained. Offline analysis to detect levator ani muscle injury was performed by investigators blinded to the delivery details.

RESULTS

339 women, with a mean age of 30.6 ± 3.9 years, completed the study. Overall, 201 (59.3%) had a spontaneous vaginal delivery, 62 (18.3%) an operative vaginal delivery (48 ventouse extraction and 14 forceps delivery), 14 (4.1%) an elective Cesarean section and 62 (18.3%) an emergency Cesarean section. No levator ani muscle injury was detected in any woman antenatally. After vaginal delivery, 57 (21.7% (95% CI, 16.7-26.7%)) women had levator ani muscle injury. The rates of injury for spontaneous vaginal delivery, ventouse extraction and forceps delivery were 15.4%, 33.3% and 71.4%, respectively. There was no levator ani muscle injury in the Cesarean section groups. Logistic regression analysis showed that only operative vaginal delivery (odds ratio, 3.09) was associated with an independent increase in the likelihood of levator ani muscle injury. Intrapartum epidural analgesics, duration of second stage of labor and infant birth weight were not independently associated with levator ani muscle injury.

CONCLUSIONS

The prevalence of levator ani muscle injury in Chinese women after their first vaginal delivery was 21.7% (95% CI, 16.7-26.7%). Operative vaginal delivery was found to increase the likelihood of women suffering such injury. A longer follow-up of these women and future studies on the effects of episiotomy are proposed.

Diagnosis of cystocele type by clinical examination and pelvic floor ultrasound

OBJECTIVES

To use the International Continence Society pelvic organ prolapse quantification (ICS POP-Q) examination to distinguish between two types of cystocele and compare findings with pelvic floor ultrasound results.

METHODS

We enrolled 94 patients who underwent a structured interview, physical examination using the ICS POP-Q, four-dimensional pelvic-floor ultrasound examination and multichannel urodynamic testing. Cystourethrocele (Green type II) and isolated cystocele (Green type III) were differentiated by the presence of an anterior vaginal wall groove on POP-Q examination and by measurement of the retrovesical angle on pelvic floor ultrasound. Clinical examination was performed by two observers, blinded to each other's results, and an ultrasound examination was subsequently performed by the first observer.

RESULTS

The agreement between two observers for the clinical diagnosis of cystocele types was moderate (κ = 0.561 and 0.544, P < 0.0001). Clinical diagnosis showed moderate to good agreement with ultrasound findings for both observers (κ between 0.318 and 0.794, P ≤ 0.001).

CONCLUSION

Radiological cystocele type (Green classification) can be distinguished both clinically and on ultrasound, and agreement between methods as well as interobserver agreement for the clinical diagnosis is moderate to good.

Does childbirth alter the reflex pelvic floor response to coughing?

OBJECTIVE

To determine the prevalence of and to quantify the effect of reflex pelvic floor activation on coughing in nulliparous pregnant women, and to assess peripartal changes and any association with stress urinary incontinence.

METHODS

Between April 2008 and March 2010, 131 nulliparous pregnant women were recruited from an antenatal clinic. All participants were interviewed and underwent four-dimensional translabial ultrasound examination at antepartum (35.8 (mean) weeks' gestation) and postpartum (4.6 (mean) months) visits. Four-dimensional ultrasound volume datasets of the pelvic floor during coughs were obtained at a minimum frame rate of 16 Hz, using a 10° volume acquisition angle. To quantify a reflex levator contraction we measured the midsagittal hiatal diameter at multiple time points. Levator integrity was determined using tomographic ultrasound imaging.

RESULTS

From 131 women recruited, 47 datasets were technically suboptimal, leaving 84. There was a visible pelvic floor reflex in 82 (98%) cases. At the postpartum visit this was reduced to 63/84, i.e. 75% (P < 0.001). The magnitude of a reflex contraction was markedly reduced postpartum, from 4.8 mm to 2.0 mm (P < 0.001), and this effect was associated with delivery mode (P = 0.042). There was a trend towards an association between lower reflex contraction magnitude and stress incontinence (0.87 ± 3.18 mm vs. 2.36 ± 3.5 mm; P = 0.08) at the postpartum follow-up visit.

CONCLUSIONS

Pelvic floor reflexes are altered by childbirth. This alteration may be associated with vaginal delivery. Reflex magnitude may be associated with postpartum stress urinary incontinence. The clinical significance of this finding is uncertain.

Obstetric levator ani muscle injuries: current status

Levator ani muscle (LAM) injuries occur in 13-36% of women who have a vaginal delivery. Although these injuries were first described using magnetic resonance imaging, three-dimensional transperineal and endovaginal ultrasound has emerged as a more readily available and economic alternative to identify LAM morphology. Injury to the LAM is attributed to vaginal delivery resulting in reduced pelvic floor muscle strength, enlargement of the vaginal hiatus and pelvic organ prolapse. There is inconclusive evidence to support an association between LAM injuries and stress urinary incontinence and there seems to be a trend towards the development of fecal incontinence. Longitudinal studies with long-term follow-up assessing the LAM before and after childbirth are lacking. Furthermore, the consequence of LAM injuries on quality of life due to prolapse and/or urinary and fecal incontinence have not been evaluated using validated questionnaires. Direct comparative studies using the above-mentioned imaging modalities are needed to determine the true gold standard for the diagnosis of LAM injuries. This would enable consistency in definition and classification of LAM injuries. Only then could high-risk groups be identified and preventive strategies implemented in obstetric practice.

Doppler ureteric jet in urogenital prolapse

INTRODUCTION AND HYPOTHESIS

This work was conducted to study the Doppler ureteric jets in the assessment of pelvic organ prolapse (POP) patients.

METHODS

Forty POP-Q stage ≧ III patients and 20 without POP were assessed with color Doppler ultrasonography.

RESULTS

Among 40 POP, 28 had bladder outlet obstruction (BOO) and 4 had hydronephrosis. Comparing POP and controls, the difference in mean frequency, mean duration, and mean maximum velocity of ureteric jets was not statistically significant. The ureteric jets of POP with BOO are of longer duration and lower velocity. The frequency of ureteric jets was lower in POP with hydronephrosis. Plateau-type waveforms were much more common among POP associated with voiding and ureteric dysfunction.

CONCLUSIONS

The longer duration and lower velocity of the ureteric jet are strongly correlated with prolapse-associated BOO. The plateau-type waveform and decrease in frequency of ureteric jets indicate possible hydronephrosis. Further investigation is needed to confirm the consistency of this study.

How the cervix shortens: an anatomic study using 3-dimensional transperineal sonography and image registration in singletons and twins

OBJECTIVES

The purpose of this study was to use a fixed reference to study movement (displacement) of the cervical internal os from the second to the third trimester in singletons and twins. The rationale was to gain insight into anatomic changes associated with cervical shortening.

METHODS

For each patient, 2 transperineal scans were performed 12 weeks apart (20 and 32 weeks). The internal os and symphysis pubis were visualized in the same field of view. Image registration techniques were used to align the 2 scans using the symphysis as a fixed reference. Total displacement, anterior displacement, and inferior displacement of the internal os were measured. Displacements were correlated with cervical shortening. Bland-Altman plots and interobserver intraclass correlation coefficients were calculated.

RESULTS

A total of 42 healthy participants were studied: 28 with singletons and 14 with twins. The mean ± SD values for total displacement were 2.1 ± 1.2 and 2.0 ± 1.2 cm for singletons and twins, respectively (P = .75). The direction of displacement was significantly different. The mean anterior displacement was 1.1 cm greater for singletons than for twins (95% confidence interval, 0.29-2.0 cm, P = .01). Mean inferior displacement was 1.3 cm greater for twins than for singletons (95% confidence interval, 2.2-0.1 cm; P = .03). Only inferior displacement correlated with cervical shortening (P < .001; R(2) = 0.74). For every 2.2 cm of inferior displacement, the cervix shortened 1.0 cm. Assessments of reliability showed good agreement between 2 observers.

CONCLUSIONS

The anatomic position of the internal cervical os depends on gestational age and fetal number. Cervical shortening correlated most strongly with inferior displacement.

Pelvic floor ultrasound in incontinence: what's in it for the surgeon?

There is increasing interest in imaging techniques such as magnetic resonance and ultrasound amongst pelvic floor surgeons, as evidenced by the number of workshops and conference presentations in this field. Ultrasound is employed more commonly, due to much lower costs, greater accessibility and practicability. Consequently, this review focuses on sonography. At this time, imaging is probably under-utilised in urogynaecology and female urology, although it has the potential to greatly benefit our patients. In this review, I will outline the main uses of imaging in the work-up of women with urinary incontinence, before and after treatment, and focus on areas in which this benefit to patients and clinicians is most evident.

State of the art: an integrated approach to pelvic floor ultrasonography

Surgical management of pelvic floor disorders depends on a comprehensive understanding of the structural integrity and function of the pelvic floor. For visualizing this region, ultrasonography has emerged as a procedure that is relatively easy to perform, cost-effective and widely available. In this review, pelvic floor ultrasonography, including two-dimensional (2D), three-dimensional (3D) and 4D imaging as well as transvaginal, endoanal and transperineal techniques, is discussed from a global and multicompartmental perspective, rather than using a compartmentalized approach. The role of the different sonographic modalities in the major disorders of the pelvic floor-urinary and fecal incontinence, pelvic organ prolapse and obstructed defecation syndrome-is evaluated critically.

Mesh contraction: myth or reality?

OBJECTIVE

Mesh implants are widely used in surgery for female pelvic organ prolapse. Mesh shrinkage is thought to be common and caused by immunological processes. In this longitudinal study, we examined mesh dimensions at 2 time points after implantation.

STUDY DESIGN

We analyzed translabial 4-dimensional ultrasound (US) volume datasets of women seen 3-52 months after anterior compartment mesh. Datasets of first and last postoperative appointments were analyzed, with the operator blinded against all other data.

RESULTS

Forty women were assessed at least twice, comprising 59.6 woman-years. Thirty-seven of 40 (93%) were satisfied at their last appointment. Eighteen of 40 considered themselves cured, and 18 of 40 felt improved. Objective recurrence (cystocele stage 2 or greater) was seen in 16 of 40. Midsagittal mesh length increased significantly (35.8 vs 32.7; P = .006), and coronal mesh diameters increased nonsignificantly (37.4 vs 36.6 mm; P = .44).

CONCLUSION

Over an observation period of almost 60 woman-years, we found no evidence of mesh contraction.

Motion estimation in ultrasound imaging applied to the diagnostic of pelvic floor disorders

The main purpose of this paper is to show the potential of tissue motion estimation in ultrasound imaging for the diagnostic of pelvic floor disorders. We propose to evaluate the tissue motion using a method based on a local deformable model and on image features (local phase and orientation) extracted from the monogenic signal. The proposed method is well adapted to the pelvic organ deformations and estimates motion with subpixel precision without the need for interpolation. The estimated motion is used to visualize the bladder local deformation and to extract quantitative figures such as the deformation parameters and the bladder angle variation. These results could potentially be interesting to characterize the degree of the pelvic organ prolapse.

MRI pelvic landmark angles in the assessment of apical pelvic organ prolapse

PURPOSE

The aim of the study was to evaluate the utility of magnetic resonance imaging (MRI) pelvic landmark angles and lines in the assessment of apical vault prolapse.

METHODS

Seventeen women were evaluated as part of a prospective surgical trial. Baseline data are presented as a pilot study of the utility of MRI in addition to this evaluation of 6 nulliparous volunteers without prolapse and 11 parous women with symptomatic ≥ stage II uterine prolapse. Each patient underwent assessment for pelvic organ prolapse quantification (POPQ) and pelvic MRI. Pelvic landmark angles and lines were measured. Mann-Whitney Rank sum test and Spearman's Rank order correlation test were used to assess agreement.

RESULTS

Women with prolapse had a significantly larger h angle, g angle, and e angle at rest than those without prolapse. Correlation between apical vault descent was measured clinically by POPQ point C with MRI measurements: h angle (r = 0.61, p = 0.01), g angle (r = 0.64, p = 0.005), and e angle (r = 0.62, p = 0.007).

CONCLUSION

MRI measurements of pelvic landmark angles reliably differentiate between women with and without uterine prolapse and correlate best with POPQ point C.