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Keywords:

  • endoanal sonography;
  • fecal incontinence;
  • obstetric trauma

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. References

Objectives

Fecal incontinence is a common, incapacitating and largely unrecognized medical problem and can be caused by various factors. Obstetric trauma is the most common cause of fecal incontinence secondary to trauma. We aimed to analyze the role of endoanal ultrasound in assessment of this type of fecal incontinence, and report the functional results of surgical treatment.

Methods

We reviewed the records of all 22 patients with fecal incontinence secondary to obstetric trauma who were evaluated by endoanal ultrasound and underwent surgical management in our department from April to 1997 to April 2002. Pre- and postoperative evaluation of the degree of incontinence was done using the incontinence score of Jorge and Wexner.

Results

The patients had a median age of 43 (range, 29–68) years. All had vaginal deliveries, five of which (22.7%) were instrumental. Most of the patients had total fecal incontinence (solids) with preoperative incontinence score values of 15–20 (median, 18). Endoanal ultrasound confirmed structural defects in the anterior external anal sphincter alone in 16 (72.7%) patients, and both anterior external and internal sphincter defects in six (27.3%) patients. A thinned perineal body was present in all patients. All patients received surgical treatment with overlapping sphincteroplasty and there was improvement of continence in 19 (86.4%) patients with postoperative incontinence score values between 4 and 0 (median, 2).

Conclusions

Endoanal sonography is an accurate method for assessing sphincter anatomy, delineating both internal and external anal sphincters. Surgical treatment of sphincter defects is associated with good outcome. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. References

Fecal continence is a complex function that involves anatomical and physiological factors. Its maintenance depends on sphincter integrity, anorectal angle, rectal sensation, rectal compliance, colonic transit and volume and consistency of stools.

Fecal incontinence has been defined as an involuntary excretion of feces at an inadequate moment or place twice in a month1, 2. It occurs principally in elderly and female populations, with a reported incidence of 1–10% in the adult population. However, because of the stigma of this condition, the true incidence remains unknown3. Its etiology can be idiopathic, congenital, neurological, or it can be secondary to trauma; obstetric trauma is the most common cause of traumatic fecal incontinence3–7.

Management of obstetric-related fecal incontinence can be problematic, and the optimal approach depends on the severity of the trauma. Endoanal ultrasound has a role in mapping post-traumatic defects of the anal sphincter complex, and is tolerated by patients better than is electromyography6, 8, 9.

The purpose of this study was to analyze the role of endoanal ultrasound in assessment of a group of patients with obstetric fecal incontinence and to present the results of their surgical management.

Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. References

We reviewed the records of all patients with fecal incontinence following obstetric trauma who were evaluated by endoanal ultrasound and underwent anterior sphincter repair at the Colorectal Surgery Department, Hospital de Especialidades, Mexico City, between April 1997 and April 2002.

All 22 patients were evaluated by physical examination and had scar tissue in the perineum with an anterior defect in the anal sphincter complex. The degree of incontinence suffered was evaluated by the incontinence score of Jorge and Wexner10 (Table 1) both pre- and postoperatively. All patients with neural damage were excluded. Electromyography with an intra-anal plug electrode was performed on all patients and cases of neuropathy (prolongation of action potential and elevated fiber density) or denervation of the striated muscles were excluded.

Table 1. Incontinence scale of Jorge and Wexner10
TypeFrequency*
NeverRarelySometimesUsuallyAlways
  • *

    Rarely is < 1/month; Sometimes is < 1/week but > 1/month; Usually is < 1/day but > 1/week; Always is > 1/day. A total score of 0 = perfect; 20 = complete incontinence.

Solid01234
Liquid01234
Gas01234
Wears pad01234
Lifestyle alteration01234

Endoanal sonography was performed by a single operator and the results were evaluated by two experienced endoanal sonographers. The ultrasound machine used was a 2001 Leopard (Brüel & Kjaer, Copenhagen, Denmark) with an endocavitary probe equipped with a 10-MHz rotating transducer with a focal length of 3 cm. The 360° rotating transducer was covered with a hard sonolucent plastic cone. Patients received an enema and were placed in the left lateral decubitus position. Anal canal structures were studied at three levels (identified by anatomical structures): the upper anal canal and the puborectalis muscle (Figure 1), the mid-anal canal with the internal and external anal sphincters (Figure 2), and the distal anal canal representing the subcutaneous external anal sphincter (Figure 3). The position of the sphincter defects was recorded in terms of ‘hours’ using the standard clock-face, with 12 o'clock being the anterior midline point. Perineal body measurement was done in the mid-anal canal by inserting a finger into the vagina, holding it gently against the posterior vaginal wall, and measuring the distance between the inner surface of the internal sphincter and the sonographic reflection of the finger tip (Figure 4). As in the study of Zetterström et al.11, perineal body measurements of less than 10 mm were considered as abnormal.

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Figure 1. Transverse ultrasound image of the upper anal canal showing normal anatomy. The arrows indicate the puborectal muscle. a, anterior; p, posterior; r, right; l, left.

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Figure 2. Ultrasound image showing normal anatomy of the middle third of the anal canal. IAS, hypoechoic internal anal sphincter; EAS, hyperechoic external anal sphincter.

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Figure 3. Ultrasound image showing lower anal canal with normal hyperechoic subcutaneous external anal sphincter (EAS). a, anterior; p, posterior; r, right; l, left.

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Figure 4. Perineal body measurement at the middle of the anal canal. Distance between inner surface of internal sphincter and sonographic reflection of finger tip (zone between arrows) = 9.7 mm.

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Preceding surgery, all patients underwent mechanical bowel preparation and received prophylactic antibiotics. Spinal anesthesia was administered and the patient was placed in the prone position. A curvilinear incision was made between the anus and vagina and the anoderm was dissected to separate the two structures from the underlying sphincter complex and scar tissue. The entire scar and sphincter were then dissected from the fat in the ischiorectal fossa laterally; mobilization was sufficient to allow overlap of the muscle without tension. Resection of the fistula was performed when necessary and where appropriate we performed levatorplasty. The perineal body was reconstructed and the skin closed. No patient required a protecting colostomy. A Foley catheter was inserted to avoid urine contact with the wound for 3 days, during which time the patients remained hospitalized.

Data on patient age, number of deliveries, degree of incontinence pre- and postoperatively, sonographic findings, morbidity and outcome were recorded.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. References

Patient data are summarized in Table 2. The 22 patients had a median age of 43 (range, 29–68) years. All had vaginal deliveries, 11 were primiparous, five were secundiparous and six were multiparous. All patients had undergone episiotomy in at least one pregnancy, 14 posterolateral episiotomies and eight in the midline. Five patients (22.7%) had an instrumental delivery. At physical examination the anus was situated abnormally close to the introitus (Figure 5), and the rectovaginal septum was narrow or absent in all cases. In addition, three (13.6%) patients had a rectovaginal fistula secondary to third-degree injury (Figure 6).

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Figure 5. (a) Photograph demonstrating damage after obstetric trauma with patient in prone position: anus situated abnormally close to introitus, with a thin rectovaginal septum. (b) Ultrasound image of patient in (a) showing defect in both sphincters (zone between lines).

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Figure 6. (a) Photograph demonstrating damage after obstetric trauma with patient in prone position: third-degree injury, with associated rectovaginal fistula. a, anus; v, vagina. (b) Ultrasound image of patient in (a) showing anterior defect in both sphincters (zone above lines).

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Table 2. Summary of patient data
nAge (years)Deliveries (n)Preop. scorePostop. scoreUltrasound findingsComplications
  • *

    Patients with no significant improvement. Both, defect in both sphincters; EAS, defect in external anal sphincter only; Postop. score, postoperative incontinence score; Preop. score, preoperative incontinence score; SD, skin dehiscence.

 15742017*BothNo
 263220 2EASSD
 344318 2EASNo
 443117 0EASNo
 56041610*EASSD
 643117 0BothSD
 732115 2BothSD
 855117 0EASNo
 962518 2EASNo
1048217 3EASSD
1151217 4EASNo
1242116 0BothNo
1337120 0EASNo
1433315 0EASNo
1539118 2EASSD
1629118 2BothSD
1735118 4EASSD
1831118 0EASNo
196822016*BothSD
2031220 0EASNo
2129317 2EASNo
2230120 2EASSD

Most of the patients had total incontinence (solid stools) with preoperative values on the incontinence score between 15 and 20 (median, 18). Endoanal ultrasound confirmed structural defects in the anterior external anal sphincter alone in 16 (72.7%) patients (Figure 7), and both anterior external and internal defects in six patients (27.3%). A thinned perineal body was present in all patients. All patients received surgical treatment with overlapping sphincteroplasty (Figure 8 and 9).

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Figure 7. Transverse ultrasound image showing external anal sphincter defect in right anterior quadrant; arrows indicate sphincter edges.

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Figure 8. Postoperative photograph of patient shown in Figure 5 in prone position, with perianal body and sphincter defects reconstructed.

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Figure 9. Postoperative transverse ultrasound image; arrow indicates anterior overlapping sphincteroplasty.

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There was no mortality. Ten (45.5%) patients had skin dehiscence, but this delayed wound healing did not affect functional results. Postoperative incontinence values improved in 19 patients (86.4%), with values between 4 and 0 (median 2), and in three patients there was no significant improvement of continence, perhaps because they suffered from a combination of sphincter lesion and generalized weakening of the pelvic floor with age. They received biofeedback therapy for the pelvic floor. Follow-up varied from 2 to 61 (mean, 29.5) months; further follow-up of these patients is desirable because functional results can deteriorate with time12.

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. References

Fecal incontinence is a common, incapacitating and largely unrecognized medical problem. It is more frequent in females than in males, primarily as a result of traumatic vaginal delivery, with 4% of patients experiencing some degree of incontinence after their first vaginal delivery13, 14.

Incontinence following obstetric trauma is due to two mechanisms, direct injury (more often during the first delivery), and traction neuropathy of the pudendal nerves (for consecutive deliveries)7, 13. Anal sphincter lesions occur more often during the first delivery3, 5 (50% of those in our study were primiparous). Instrumental delivery and a prolonged second stage of labor are factors that increase the risk of sphincter injury7, 15–17. Cumulative injury, particularly to the pudendal nerve, may occur during successive vaginal deliveries18.

Defects in the sphincter complex cannot always be accurately detected on physical examination, especially in the presence of excessive scarring9. Endoanal ultrasound has a role in the assessment of anal incontinence as it can accurately delineate the site of an anal sphincter defect4, 6–8 and is much less uncomfortable compared with concentric needle electromyography mapping8, 9, 19. Normal sonographic anatomy has been described previously9, 20–24: in the upper third of the anal canal it is possible to visualize the hyperechoic puborectalis sling, and the internal anal sphincter is markedly hypoechoic; in the middle third of the anal canal are visualized both sphincters (hyper and hypoechoic); in the lower anal canal is visualized the hyperechoic external anal sphincter. Oliveira and Wexner2 reported 100% accuracy for sonographic examination of anal sphincter defects; in our study all patients had a sphincter injury demonstrable by endoanal sonography.

As in previous reports5 we found that the majority of anal sphincter disruptions concerned the external anal sphincter, which is close to the site of episiotomy.

Anal sphincter repair for sphincter defects due to obstetric trauma is a well established surgical procedure that results in acceptable continence for 70–80% of patients6, 13, 25–27; we achieved clinical improvement in 86% of cases. The principal complications in surgery are those related to skin closure, urinary retention and bleeding26; in our patients 45% developed skin dehiscence.

A different sonographic approach, transvaginally, to assess anal incontinence has been reported with variable results28, 29. It is our opinion that the use of endoanal sonography allows better evaluation because it delineates the circumference of the sphincter complex in its entirety (i.e. 360° ).

To conclude, endoanal sonography is an accurate and painless method for assessing sphincter anatomy. It delineates internal and external anal sphincters and identifies sphincter defects, helps direct therapy and surgical decision-making, and is essential for the evaluation of incontinence. Treatment by overlapping anterior sphincteroplasty has a good (70–80%) success rate, with low morbidity.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. References