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82 Fecal Incontinence in Females With a Past History of Vaginal Delivery [2002년 11월 DCR] 2011-11-17 3342
 
Significance of Anal Sphincter Defects Detected by Ultrasound
 
Henri Damon, M.D.,* Luc Henry, M.D.,* Xavier Barth, M.D.,† Franc¸ois Mion, M.D.*
 
From the *Fe´de´ration des Spe´cialite´s Digestives and †Urgences Visce´rales, Hoˆpital E. Herriot, Lyon, France
 
PURPOSE: The aim of this study was to determine the significance of anal sphincter defects detected by ultrasonography, in a population of fecal incontinent parous females without previous anoperineal surgery.
METHODS: From 100 consecutive incontinent patients, 61 females with at least one previous vaginal delivery and no past anoperineal surgery were studied. The severity of fecal incontinence was assessed by the Cleveland Clinic questionnaire score. Lesions of the internal or external anal
sphincters, and the radial size of these defects were assessed by ultrasonography. Anal vector manometry was performed to measure anal pressures at rest and during voluntary squeeze, and the anal asymmetry index.
RESULTS: Twenty-three had a normal sphincter (38 percent), and 38 (62 percent) had a defect detected by ultrasonography: 20 isolated defects of the external sphincter and 18 combined defects of the internal and external sphincters. Combined defects were significantly larger. The radial size of the defects was positively correlated with the severity of clinical symptoms. Anal pressure asymmetry index was significantly increased in the group with combined defects compared with the two other groups. An index of 25 percent or greater had a very high (100 percent) negative predictive value for the presence
of a defect larger than 90°.
CONCLUSIONS: This study confirms the high prevalence of anal sphincter defects detected by ultrasonography in a population of incontinent parous females without previous proctologic surgery. The
clinical symptoms are related to the size of these defects. Anal vector manometry may be a useful tool to confirm the relation between echographic anal sphincter lesions and fecal incontinence.
 
Fecal incontinence more frequently affects females, with a prevalence greater than 5 percent in patients older than 45 years. The main factor to explain the higher prevalence of this disease in females is thought to be childbirth. Vaginal delivery is a well-known traumatic factor for the anal sphincter: defects are found in approximately 35 percent of females after their first vaginal delivery. However, the exact role of these defects in the delayed onset of fecal incontinence remains unknown. Indeed, anal sphincter defects detected by transanal ultrasonography (TAU) may be found in up to 65 percent of incontinent females with previous childbirth, but also in 43 percent of continent females after childbirth. TAU may also induce false-positive diagnosis of sphincter defects in 5 to 25 percent of cases according to Sentovich et al. From these findings, the real significance of anal sphincter defects detected in patients with fecal incontinence remains to be determined.
 
The goals of this study were to assess the prevalence of anal sphincter defects in a population of anal
incontinent females, with a past history of vaginal delivery and no perineal surgery, and to evaluate the
functional and clinical consequences of anal sphincter defects diagnosed at TAU in this population.
 
DISCUSSION
The prevalence of fecal incontinence, estimated around 10 percent of the general population in some
studies, represents a major public health issue. Although several causes are known to be responsible
for this often severe handicap, it is frequently regarded as an ineluctable late complication of childbirth
in females. Two main consequences of vaginal deliveries are thought to be responsible for the higher
prevalence of fecal incontinence in females: direct trauma to the sphincter and pudendal neuropathy. Anal sphincter defects are detected by TAU in up to 60 percent of fecal incontinent patients, but also in a
significant number of continent females with a past history of childbirth. These lesions are usually regarded as the consequence of direct accidental or surgical tears inflicted on the sphincter, or in females as the consequence of childbirth. Indeed, recent studies have shown that approximately 35 percent of the first vaginal deliveries lead to TAU-detected anal sphincter lesions. It is, however, difficult to relate the late onset of fecal incontinence to these postobstetric lesions, especially when these patients may have had further perineal surgery during their lives. In an attempt to elucidate this question, we report here clinical, manometric, and ultrasonographic data obtained in a set of females presenting with fecal incontinence, at least one occurrence of vaginal delivery, and no previous history of anoperineal surgery.
 
In this selected population the prevalence of anal sphincter defects was high (62 percent), but similar to
other results published in the literature. One interesting finding was the high prevalence of combined defects of the internal and external sphincters (47.4 percent of patients with sphincter defects) in this population, a much higher rate than the one reported in immediate postpartum studies. This may indicate that these combined defects may more frequently lead to clinical symptoms. In favor of this hypothesis, we found that combined defects were significantly larger than isolated defects of the external sphincter, that there was a significant correlation between the radial extension of external sphincter defects and the severity of clinical symptoms. Finally, although the difference was not statistically significant, we observed that the symptoms of fecal incontinence tended to appear earlier in life in females with combined anal sphincter defects. However, anal physiologic measurements were similar in the group of females with combined defects compared with the groups with intact sphincter or isolated lesions of the external sphincter. Our results confirm that vaginal delivery does not induce isolated defects of the internal sphincter, as shown by others.
 
It is, however, clear that anal sphincter defects do not represent, in this selected population of females,
the only cause of fecal incontinence. Medical conditions such as diabetes or inflammatory bowel diseases may be found responsible, and pudendal neuropathy, although not specifically looked for in this study, could explain some cases of fecal incontinence in females without sphincter lesions at TAU and even participate in the occurrence of symptoms in females with sphincter defects. For example, we found a higher occurrence (although not statistically significant) of symptoms of dyschesia, a condition associated with pudendal neuropathy, in the group of females with a normal echographic sphincter. It is
thus important to try to define which sphincter lesions are clinically relevant in order to select adequately the patients that may benefit most from a surgical sphincter repair procedure.
 
Large defects (>90°) of the sphincter, which most of the time represent combined defects of the internal
and external sphincters, are probably the most relevant lesions in terms of clinical symptoms of fecal incontinence. In this study we looked at the possible use of anal vector manometry in the prediction of these lesions. Fynes et al.recently showed, in a study of postpartum anal sphincter injury, that anal vector symmetry index could discriminate between females with significant sphincter disruption (full-thickness defects of more than 90°) and those without (normal sphincter or smaller defects at TAU). Similarly, although they used a different index for measuring anal pressure asymmetry, Jorge and Habr-Gama also demonstrated that anal vector manometry could differentiate among patients with fecal incontinence between those with and without anal trauma. Our study confirms and extends those data: in anal incontinent females with previous vaginal delivery, an anal asymmetry index (measured during voluntary squeeze) lower than 25 percent indicates a very low risk of large defect of the anal sphincter (high negative predictive value). However, the positive predictive value of this index was only 54 percent,
indicating that a significant proportion of patients with small sphincter defects had an increased anal
asymmetry index. It is quite possible that these smaller defects at TAU associated with high anal
asymmetry index have the same clinical significance as the one of large defects. Although Fynes et
al. used a different calculation for their anal vector symmetry index, their results were strikingly similar to ours, with a 100 percent sensitivity and a 61 percent positive predictive value.