ORIGINAL ARTICLE

Accuracy of the digital anal examination in womenwith fecal incontinence

Peter C. Jeppson & Marie Fidela R. Paraiso &

J. Eric Jelovsek & Matthew D. Barber

Received: 10 May 2011 /Accepted: 17 October 2011 /Published online: 5 November 2011# The International Urogynecological Association 2011

AbstractIntroduction and hypothesis This study aims to determinethe accuracy of digital rectal examination (DRE) to detectanal sphincter defects when compared to endoanal ultra-sound (US) in women with fecal incontinence (FI).Methods Seventy-four patients identified by retrospectivechart review who presented with complaints of bothersomeFI who underwent endoanal US are the subjects of thisanalysis. Sensitivity, specificity, and positive and negativelikelihood ratios were calculated for the ability of the DREto detect anal sphincter defects.Results Anal sphincter defect was suspected on DRE in75%. At endoanal US, external sphincter defects werenoted in all three segments in 41% (complete defect) whilepartial defects were noted in 30%. DRE demonstrated asensitivity of 82%, specificity of 32%, +likelihood ratio 1.2(95% confidence interval (CI), 0.95–1.16) and −likelihoodratio of 0.6 (95% CI, 0.2–1.24) for detecting a completeEAS defect on endoanal US.Conclusion DRE has poor specificity for detecting analsphincter defects seen on endoanal US.

Keywords Anal sphincter . Anal sphincter defect . Digitalrectal examination . Endoanal ultrasound . Fecalincontinence

Introduction

Fecal incontinence (FI) is defined as the involuntary passageof stool or flatus [1]. This is a common problem estimated toaffect 9% of women in the USA [2]. The etiology of FI isdiverse with each underlying cause amenable to specifictherapeutic treatment; subsequently, correct diagnosis of theunderlying cause of fecal incontinence is imperative toprovide appropriate intervention [3]. FI caused by analsphincter disruption can be surgically repaired via analsphincteroplasty. FI caused by neurogenic disorders orabnormal stool consistency, such as chronic diarrhea, areusually managed using behavioral or medical therapies;neuromodulation could be used if these conservative treat-ments fail [4]. Digital rectal examination (DRE) is a standardpart of any evaluation for a patient with fecal incontinenceand has been recommended as a screening test to detect analsphincter defects despite the controversy surrounding itsdiagnostic role [1, 3, 5]. Endoanal ultrasound is the currentstandard for demonstrating anal sphincter defects [6]. Theobjective of this study was to determine the accuracy of DREto detect external anal sphincter defects in comparison toendoanal ultrasound in women with fecal incontinence.

Materials and methods

After approval by the institutional review board, theelectronic medical records of all patients who presented toa tertiary care urogynecology clinic and evaluated byendoanal ultrasound were reviewed. Records were reviewedfrom January 2000 through March 2009. Past medical andsurgical histories were reviewed. Patients identified with a

P. C. Jeppson (*) :M. F. R. Paraiso : J. E. Jelovsek :M. D. BarberObstetrics, Gynecology,& Women’s Health Institute, Cleveland Clinic,Cleveland Clinic 9500 Euclid Ave–A81,Cleveland, OH 44195, USAe-mail: peterjeppson@gmail.com

Int Urogynecol J (2012) 23:765–768DOI 10.1007/s00192-011-1590-1

history of rectovaginal fistula, dementia, stroke, multiplesclerosis, inflammatory bowel disease, irritable bowelsyndrome, chronic neurologic conditions, prior rectal/analsurgery such as hemorrhoidectomy, rectal prolapse repair,or sphincteroplasty—or the absence of standardized DRE atthe time of evaluation were excluded. Patients less than18 years old at the time of evaluation were also excluded.

All patient records included duration and frequency ofFI, FI type (solid, liquid, gas), number of bowel movementsper day, rectal prolapse, hemorrhoids, rectal bleeding,parity, number of vaginal deliveries, number of operativevaginal deliveries (forceps or vacuum), and history of aprior third or fourth degree laceration. Only the results ofthe initial ultrasound report were used; endoanal ultrasoundrecords were not reinterpreted. At initial evaluation, allpatients underwent a standardized examination in lowlithotomy position that included DRE with assessment ofthe presence or absence of an anal sphincter defect,assessment of anal tone (absent, weak, normal), analsphincter squeeze strength (0–5), levator ani strength (0–5), perineal sensation, and sacral reflexes. Based on thisevaluation patients were subsequently scheduled for endoa-nal ultrasound. Ultrasound was performed with the patientin low lithotomy position using a 6.5-MHz, 360° transducer(type 8661, B&KMedical, Naerum, Denmark). The presence

and degree of any internal or external anal sphincter defects onendoanal ultrasound (US) were recorded for the proximal,middle, and distal sphincter. A defect was defined as adiscontinuity of the muscle visualized as a hyperechoic lesionwithin the internal anal sphincter or a hypoechoic lesionwithin the external anal sphincter. We defined a completedefect as a lesion through the entire EAS including theproximal, middle, and distal segments while a partial defectwas defined as any defect in the EAS that did not include theentire EAS. The diagnostic characteristics of the DRE todetect anal sphincter defect on US were then determined.Sensitivity, specificity, positive, and negative likelihood ratioswere calculated for the ability to detect the presence orabsence of external anal sphincter disruption using DRE.

Results

A total of 112 patients were evaluated for fecal inconti-nence and received endoanal ultrasound during the studyperiod. After the exclusion criteria were reviewed, 74patients were included as the subjects of this report. Ofthe 38 patients excluded only two were excluded forincomplete documentation of the standardized DRE. Themedian age at presentation was 58 (±15) years. Subjects

Table 1 Patient demographicsof 74 patients examined forexternal anal sphincter defects

FI fecal incontinence

Patient demographics

Median Standard deviation Min Max

Age (years) 58 15 29 86

Body mass index (kg/m2) 29 6 19 49

Vaginal deliveries 3 2 0 8

Largest vaginal delivery (g) 3,770 585 1,984 5,453

Operative vaginal delivery 1 1 0 5

Days between examinations 53 227 0 1,535

Duration of FI (months) 43 57 1 329

FI episode per month 8 28 0 120

Number of bowel movements per day 1 1 0 6

Table 2 Diagnostic test characteristics of 74 patients evaluated for acomplete external anal sphincter defect

Complete EAS Defect

EAS defect by endoanal ultrasound

EAS defect by DRE Present Absent Totals

Positive 27 28 55

Negative 6 13 19

Totals 33 41 74

DRE digital rectal examination, EAS external anal sphincter

Table 3 Diagnostic test characteristics of 74 patients evaluated for apartial external anal sphincter defect

Partial EAS defect

EAS defect by endoanal ultrasound

EAS defect by DRE Present Absent Totals

Positive 20 36 56

Negative 3 15 18

Totals 23 51 74

EAS external anal sphincter, DRE digital rectal examination

766 Int Urogynecol J (2012) 23:765–768

reported a median duration of FI of 42.5 months (range, 1–329 months), and a median of eight episodes of FI per month(range, 0–120 per month; one patient reported two episodes ofFI per year). Many patients reported incontinence to acombination of flatus, liquid, and solid stool; stratified byseverity, 1% reported incontinence to flatus only, 34% toliquid, and 65% to solid stool. All but one patient (99%) had ahistory of vaginal delivery with a median vaginal parity of 3(range, 0–8) and 43% reported a prior third or fourth degreelaceration (Table 1). Sixty-six patients were initially exam-ined by one of four attending physicians while the remainingeight patients were initially examined by one of six fellows.All endoanal US were performed by an attending physician.The DRE and endoanal US were performed by the samephysician on 14 patients.

An anal sphincter defect was suspected on DRE in 75%of patients. At endoanal US, external sphincter defects werenoted in all three segments in 41% (complete defect) whilepartial defects were noted in 30%. An internal analsphincter defect was found in 43% of the patients. DREdemonstrated a sensitivity of 82%, specificity of 32%,positive likelihood ratio of 1.2 (95% confidence interval(CI), 0.95–1.16) and negative likelihood ratio of 0.6 (95%CI, 0.2–1.24) for detecting a complete EAS defect onendoanal US (Table 2). The results were similar for theability to detect a partial EAS defect (sensitivity 87%,specificity 30%) (Table 3), and for combined IAS and EASdefects (sensitivity 81%, specificity 26%). No significantdifference was noted in the digital assessment of anal tone,anal squeeze strength, or the presence of sacral reflexesbetween those with and without an anal sphincter defect onultrasound; however, those subjects with a complete EASdefect had greater levator ani muscle strength than thosewithout (median 2 (range, 0–5) vs. 1 (0–3), p<0.01).

Discussion

Our investigation shows that DRE has poor specificity andmoderate sensitivity for detecting anal sphincter defectsseen on endoanal ultrasound. Prior studies have reportedconflicting correlation between DRE and endoanal ultra-sound. In Sultan’s series comparing endoanal ultrasoundwith histology specimens after surgery, the clinical exam-ination was only 50% accurate at predicting anal sphincterdefects [7]. A second study by Dobben et al. reportedincreased correlation between DRE and endoanal ultra-sound based on size of the sphincter defect [6]. This studyreported that 36% of sphincter defects were detected withDRE when the defect was less than 90 degrees, but 100%detected when the defect was between 150 to 270 degrees.Our study did not differentiate degree of defect; however,our specificity was low for both partial and complete

defects, which would seem to indicate DRE is a poor testregardless of sphincter defect size.

At least one study has claimed the accuracy of DRE isdependent on clinician experience [8]. In our study 89% ofpatients were evaluated by a urogynecology attendingphysician with experience managing patients with FI, sowe are unable to evaluate the effect of clinician experienceon DRE accuracy. However, it is worth noting that evenwith the majority of examinations being performed by“experienced” examiners the specificity for identifyingdefects was poor.

The limitations of the study are that all patients werereferred to endoanal ultrasound by a physician who was notblinded to the patients’ medical history or physical examina-tion. Because the patient records are electronic, it is unknownif the clinician performing the endoanal ultrasound wasblinded to the patients prior history introducing the possibilityof bias. However, one would expect that if a provider had priorknowledge of the physical examination finding, particularlythe sphincter examination, this would increase the likelihoodand perhaps even bias the US results in the direction of findinga defect. In spite of this potential bias, the specificity of DREwas poor. Finally, this study only looked at the specificity ofdetecting defects in the patients evaluated by endoanalultrasound and does not address the negative predictive valueof DRE as a screening tool in determining intact EAS nor didwe look at the predictive value of other forms of testing suchas anal manometry.

Despite the poor specificity of DRE to detect sphincterdefects, DRE is still an important aspect of the evaluation of apatient with FI to differentiate other potential causes such astumor or fecal impaction. Because of this, we agree with priorstudies which report the workup for FI should include both aDRE and endoanal ultrasound [5]. However, surgicalintervention should not be based on a test with a specificityof 32%; subsequently, DRE is not an adequate screening testfor anal sphincter defects in patients with bothersome FI.

Conflict of interest None.

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