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Endoanal ultrasound assessment of sphincter defects and thinning – Correlation with anal manometry
Arab Journal of Gastroenterology 15 (2014) 27–31
Contents lists available at ScienceDirect
Arab Journal of Gastroenterology journal homepage: www.elsevier.com/locate/ajg
Original Article
Endoanal ultrasound assessment of sphincter defects and thinning – Correlation with anal manometry q Chatterjee Parangama a,⇑, Eapen Anu a, Nayak Sukria b a b
Department of Radiodiagnosis and Imaging, Christian Medical College, Vellore, Tamil Nadu, India Department of Colorectal Surgery, Christian Medical College, Vellore, Tamil Nadu, India
a r t i c l e
i n f o
Article history: Received 27 September 2013 Accepted 11 January 2014
Keywords: Endoanal Ultrasound Sphincter defects Anal manometry
a b s t r a c t Background and study aims: This study aims to determine if anal sphincter defects/thinning observed at endoanal ultrasound correlates with anal pressures recorded at anal manometry. Patients and methods: A total of 30 consecutive patients with history suggestive of anal sphincter pathology underwent anal endosonography with documentation of internal and external sphincter defects/ thinning. The same patients underwent anal manometry with documentation of maximum resting and maximum squeeze pressures. Patients with a sphincter defect (SD) were compared to patients without a sphincter defect (NSD) and both groups were compared with respect to findings in manometry. The Mann–Whitney U test was used for statistical analysis. This study was approved by the Institutional Ethics Committee. Results: A statistically significant correlation was found between decreased maximal resting pressure and decreased internal anal sphincter (IAS) thickness or an IAS defect. The correlation between MSP and external sphincter pathology was significantly less consistent in our study. Conclusion: Our study showed a statistically significant correlation between maximum resting pressure and observation of internal sphincter defects at endoanal ultrasound. The patients with documented internal sphincter defects have significantly reduced maximum resting pressures. There was however, no correlation between external sphincter defects and decrease in maximum squeeze pressure as has been observed in other studies. Until a manometry cut-off can be set to discriminate between the absence and presence of defects, both manometry and ultrasound should be offered to patients with history suggesting anal sphincter pathology. Ó 2014 Arab Journal of Gastroenterology. Published by Elsevier B.V. All rights reserved.
Introduction Faecal incontinence has several diverse causes. Anorectal surgery and parturition are the main causes wherein the anal sphincter and the pudendal nerve may be damaged. A systematic evaluation of the patient usually reveals the underlying pathophysiology and helps to decide treatment options [1,2]. With per rectal digital examination, the presence of an anal sphincter defect can be assessed, and anal manometry can help determine resting and squeeze pressures which can provide clues to the underlying sphincter pathology [2]. In recent times, anal endosonography
q There were no sources of support. This paper has not been presented in any meetings. ⇑ Corresponding author. Address: Department of Radiodiagnosis and Imaging, Christian Medical College, Vellore 632004, Tamil Nadu, India. Tel.: +91 9894722569/0416 2283012; fax: +91 0416 2282707. E-mail address: [email protected] (C. Parangama).
has also come to the forefront as an indispensable tool to evaluate this group of patients. During childbirth, anal sphincter damage occurs in about 18% of vaginal deliveries [3,4]. Even after repair of obstetric anal sphincter tears, within 6 months 29–53% of women report gas incontinence, 5–10% report stool incontinence [5–8] and up to 66% of primiparous women demonstrate a defect within the anal sphincter by endoanal ultrasonography (EAUS) 3 months after repair [5]. Further, occult sphincter tears (present on endosonography) occur in 23–35% of primiparous women at vaginal delivery [5–8]. Anal endosonography is the standard for radiologic evaluation of the anal sphincter. This technique reliably identifies defects or thinning of the internal anal sphincter (IAS); however, evaluation of the external anal sphincter (EAS) is more subjective, operatordependent and difficult due to the presence of confounding factors and normal anatomic variations such as an external sphincter ‘gap’ [9,10]. Overall, however, ultrasound (US) findings of anal sphincter tear are highly correlated with electromyogram and manometric
http://dx.doi.org/10.1016/j.ajg.2014.01.006 1687-1979/Ó 2014 Arab Journal of Gastroenterology. Published by Elsevier B.V. All rights reserved.
28
C. Parangama et al. / Arab Journal of Gastroenterology 15 (2014) 27–31
findings and are both sensitive and specific for anal sphincter tears [11–14]. We aimed to correlate endoanal US findings with anal manometry.
Patients and methods We prospectively studied 30 patients referred from the Department of Colorectal Surgery in our institution. Endoanal US was performed by a radiologist and verified by a senior gastrointestinal radiologist, by using a US scanner with a radial endoscopic probe and a 7.5-MHz transducer (profocus 2022, B&K Medical, Sandtoften, Denmark; 10 MHz, 360° window). A lubricated condom was placed over the probe. Subjects were examined in the supine left lateral position with their knees flexed. The probe was introduced into the anal canal, positioned at the upper aspect of the puborectalis sling and rotated so that the 12 o’clock position was anterior (3 o’clock represents the patient’s left side; and 9 o’clock, the patient’s right side). The total examination time for endoanal US ranged between 10 and 15 min. On the most representative images, at the 4 o’clock position at the midanal level, internal sphincter and external sphincter thicknesses were measured.
Image interpretation On axial sectional images, the inner hypoechoic ring of tissue represents the IAS, which is formed by the thickening and extension of the circular smooth muscle of the rectum (Figs. 1 and 2). The outer relatively echogenic ring of tissue represents the longitudinal muscle and the EAS, which is formed by the caudal continuation of the puborectalis (Figs. 3 and 4). The normal IAS is between 2 and 3 mm thick [12,15] and the normal EAS is between 7 and 9 mm thick [6,15]. The EAS tends to become thinner with age, [6] whereas the IAS becomes thicker and more echogenic with age, probably reflecting collagenisation [15]. The anal canal length varies from 25 mm for women to 33 mm for men [11,15]. An echogenic or echolucent disruption in the sphincter(s) seen on one or more images was defined as a gap (Fig. 5). They were located by clock-face position to the nearest hour, with anterior midline as 12 o’clock. The high anal canal was defined as the level midway between the inferior border of the puborectalis muscle and complete formation of the external sphincter ring anteriorly. The low canal level was defined as that immediately caudal to the termination of the internal sphincter and comprised the subcutaneous external sphincter. The intervening segment was defined as the mid-anal canal level.
Anal manometry Anorectal studies were performed with the patient in the left lateral position using a station pull-through technique with an air-filled balloon catheter using a Centromed manometer. Threshold volume and maximum tolerated volume were measured using the balloon positioned in the distal part of the rectum. The rectoanal inhibitory reflex was studied by measuring the response of the resting anal pressure to distension of the rectum. A fall of 20% denoted a positive response. Anorectal sensation was measured in the upper, middle, and lower anal canal using the mucosal electrosensitivity method. The results of anorectal manometry studies are shown in Table 1. This study was approved by the Institutional Review Board. Results During the study period, 10 male and 20 female patients with faecal incontinence were evaluated. Mean age was 35.5 years (range 21–60 years). A total of 29 patients (96.6%) had episodes of incontinence to faeces (major incontinence). One patient had episodes of incontinence to flatus (minor incontinence). These patients had stress and urge incontinence predominantly. Seven patients (23.3%) had a history of anal surgery in the past, which included haemorrhoidectomy, lateral anal sphincterotomy or fistulectomy. No patient in this series had a history of congenital anorectal atresia or any generalised disorder that could have been responsible for incontinence. Parity was assessed in female patients (para 1 = 11 patients, para 2 = eight patients, para 3 = one patient). Sixteen out of 20 female patients had a history of prior obstetric trauma. Anal US Of the 30 patients, 26 (86.6 %) had a defect or defects in the sphincter complex; 24 patients had a defect or defects in the internal sphincter, and two had a lesion or lesions in both sphincters. Isolated defects in the external sphincter were not seen. Ten patients had defects and 16 had sphincter thinning with no demonstrable defects. Therefore, patients were easily classified into two groups by EAUS: those with sphincter defects (SDs, n = 10) and those without physical defects (NSDs, n = 16). Four patients had sonologically normal sphincters. The mean internal sphincter thickness was 1.48 mm and the mean external sphincter thickness was 7 mm. Two patients had sphincter pathology in the upper anal canal, three patients in the midcanal, two patients in the lower canal and 19 patients had abnormalities in all levels.
Fig. 1. The inner hypoechoic ring of tissue represents the internal anal sphincter (IAS).
C. Parangama et al. / Arab Journal of Gastroenterology 15 (2014) 27–31
29
Fig. 2. The inner hypoechoic ring of tissue represents the internal anal sphincter (IAS).
Fig. 3. The outer echogenic ring of tissue represents the longitudinal muscle and the external anal sphincter (EAS).
Fig. 4. The outer echogenic ring of tissue represents the longitudinal muscle and the external anal sphincter (EAS).
Fig. 5. Echolucent disruption in the internal sphincter in the 12–2 o clock position.
Anorectal manometry The results of anorectal manometry studies are shown in Table 1. Overall, the mean resting pressure was 45.7 (normal 40–120), the mean squeeze pressure was 100.6 (normal
100–180), first rectal sensation was elicited at a mean of 24 (normal, <20), mean maximum rectal capacity was 199 (normal 250–540), and mean electrical sensitivity was 7 (normal 4–8). The values for the SD and NSD groups were compared. Both mean maximum resting pressure and maximum squeeze pressures were
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C. Parangama et al. / Arab Journal of Gastroenterology 15 (2014) 27–31
Table 1 Correlation between manometry findings in the sphincter deficient and non sphincter deficient group.
Mean Mean Mean Mean Mean
max resting pressure max squeeze pressure 1st rectal sensation Maximum tolerated volume (MTV) electrosensitivity
SD[10]
NSD[16]
p Value
25.6 80.5 18.2 200 8.4
58.38 113.25 27.88 198.63 6.38
0.02 0.07 0.24 0.96 0.42
lower in the SD group (resting pressure was significantly lower in the SD group, p value 0.02, squeeze pressures were not significantly lower, p value 0.07, respectively). Nine out of 10 patients in the SD group had low maximum resting pressure. Ten out of 16 in the sphincter thinning group had low maximum resting pressure. Eight out of 10 in the SD group had low maximum squeeze pressure and eight out of 16 in the sphincter thinning group had low maximum squeeze pressure. Mean pressure to elicit a first rectal sensation was higher in the NSD group than in the SD group, but not significantly higher, p value 0.24. Maximum tolerated rectal volume was not significantly different in the two groups, 200 and 198.6. Seven out of 10 in the SD group had abnormal rectal capacity and nine out of 16 in the NSD group had abnormal rectal capacity (decreased). Two out of 10 in the SD group and seven out of 16 in the NSD group had a high first rectal sensation on distension. All patients in both groups had positive rectoanal inhibitory reflexes, except one patient in the sphincter thinning (NSD) group. With regard to electrosensitivity, eight out of 10 were abnormal in the SD group and 11/16 were abnormal in the NSD group. This was not significantly different in the SD and NSD groups, p value 0.42. Comparison of the groups The SD group comprised only female patients; all patients except one in the SD group had a prior history of obstetric trauma. In the SD group, one patient had a history of previous surgery, while five patients in the NSD group had a history of prior surgery. Patients in the two groups were compared with respect to the severity of symptoms and past medical history. Seven out of 10 in the SD group had incontinence to stools, 11/16 in the NSD group had incontinence to stools and the rest were incontinent to flatus. With respect to symptoms, major incontinence was present in both groups with no statistical difference between the two groups. Statistical analysis Descriptive statistics (mean, SD, median and percentiles) was obtained for each of the study variables. As the distributions of the variables were not normal, the groups were compared using the Mann–Whitney U test (non-parametric test). All analyses were done using SPSS 11.0. The results are summarised in Table 1. Discussion The advantages of endoanal sonography are its easy availability and decreased costs. In addition, endoanal sonography has been in use longer than magnetic resonance imaging (MRI), resulting in a larger number of sonographers and sonologists who are experienced with the endoanal sonography technique [9]. The first reports on the use of US to study the anal sphincter came from St. Mark’s Hospital in the late 1980s and early 1990s.
Subsequently, several studies demonstrated the efficacy of anal endosonography and compared it to various techniques such as manometry and needle electromyography (EMG) and to surgery. The relevance of a few such studies is discussed. Considering patient’s demographics, in the study by Chen et al. [16], the median age was 57 years (range 21–82 years). In our study, the mean age was 35.5 years (range 21–60 years). Ten of their patients (27%) had episodes of incontinence to solid faeces (major incontinence). The other 27 (73%) had episodes of incontinence to liquid stool or flces (minor incontinence). In our study, 29 patients had incontinence to faeces, while one had episodes of incontinence to flatus. In their study, of the 37 patients, nine had defects in the sphincter complex. Eight patients had defects in the internal sphincter and five had a lesion in the external sphincter. They also classified their patients into two groups by AUS depending on the presence or absence of sphincter defects. In our study, of the 30 patients, 26 had a defect or defects in the sphincter complex; 24 patients had a defect or defects in the internal sphincter, and two had lesions in both sphincters. Isolated defects in the external sphincter were not seen. Ten patients had defects and 16 had sphincter thinning with no demonstrable defects. Their patients also underwent manometry studies. The values for the SD and NSD groups were compared. They found that both mean maximum resting pressure and maximum squeeze pressures were significantly lower in the SD group. Mean pressure to elicit a first rectal sensation was higher in the SD group than in the NSD group. There was no significant difference in mean maximum tolerated rectal volume (rectal capacity). All patients in both groups had positive rectoanal inhibitory reflexes. Electrosensitivity of the upper, middle and lower anal canal was within normal limits in both groups as well. In our series, nine out of 10 patients in the SD group had low maximum resting pressure, 10 out of 16 in the sphincter thinning group had low maximum resting pressure, eight out of 10 in the SD group had low maximum squeeze pressure and eight out of 16 in the sphincter thinning group had low maximum squeeze pressure. Mean pressure to elicit a first rectal sensation was higher in the NSD group than in the SD group, but was not statistically significant; p value 0.24. Maximum tolerated rectal volume was not significantly different in the two groups, 200 and 198.6. Seven out of 10 in the SD group had abnormal rectal capacity and nine out of 16 in the NSD group had abnormal rectal capacity. Two out of 10 in the SD group and seven out of 16 in the NSD group had a high first rectal sensation on distension. All patients in both groups had positive rectoanal inhibitory reflexes, except for one patient in the sphincter thinning (the NSD group). With regard to electrosensitivity, eight out of 10 were abnormal in the SD group and 11/16 were abnormal in the NSD group. In the study by Titi et al. [17] the authors attempted to identify EAUS parameters that correlate with sphincter function. A total of 100 females with incontinence and 28 asymptomatic female volunteers were evaluated. All subjects underwent anorectal manometry and EAUS. Parameters assessed included sphincter quality (echogenicity), thickness and defect characteristics among others. They found that maximum EAS thickness significantly correlated with MSP. EAS defects were detected in 84 patients and seven controls. Full-length EAS defects were only detected in the incontinent group and had significantly lower MSP. IAS quality was significantly associated with MRP. They concluded that certain EAUS parameters could be predictive of anal sphincter function, which included the presence of an EAS defect and its length, EAS maximum thickness and IAS ring quality. Integration of these parameters can give better EAUS correlation with manometry.
C. Parangama et al. / Arab Journal of Gastroenterology 15 (2014) 27–31
Nielsen et al. [18] evaluated 48 patients with incontinence. Endosonography and measurement of anal canal pressures were performed in all patients. Endosonograms showed defects of external sphincters in 27 patients, 12 of whom had internal sphincter defects also. One patient had an abnormal thinning of the external sphincter. Eight patients had isolated defects of the internal sphincter. The sphincteric defects found by endosonography did not correlate with the anal canal pressures. The resting pressure in the anal canal is mainly attributed to the internal sphincter, and therefore low values should be found in patients with internal sphincter defects [19]. Although this may be true for some patients, overlap with normal values is considerable, and significant variations exist. Law et al. [19] also showed a strong correlation between the thickness of the internal sphincter and resting pressure in the anal canal and our study also confirmed this. One study compared US and manometric findings in 20 asymptomatic nulliparous women, 20 asymptomatic parous women and 31 women with incontinence underwent sphincteroplasty [20]. Endosonography correctly identified all of the sphincter injuries in women with incontinence. In a similar report, endorectal EUS was performed prior to surgery in 28 patients with faecal incontinence [21]. EUS correctly identified all 25 of the IAS defects and all 10 EAS defects. However, it incorrectly diagnosed an EAS defect in three patients, resulting in an overall accuracy for EUS of 89%. In one of the largest studies to date, the US appearance was prospectively compared with the operative findings in 44 patients who underwent pelvic floor repair [22]. Endorectal US was 100% sensitive in detecting either IAS or EAS defects. One IAS tear seen on endosonography was not confirmed at surgery. Other studies have found a similar association between decreased maximal squeeze pressure and decreased EAS thickness or an EAS defect [22,23]. By contrast, a similar relationship between the resting pressure in the anal canal and IAS thickness has been documented in few studies [19,23]. Limitations and potential pitfalls The anterior part of the EAS is usually shorter and slopes downward in women. This often made demonstrating a complete 360° ring of the EAS in one plane difficult [15]. The anococcygeal ligament appears as a hypoechoic triangular structure posteriorly and it can be mistaken for a sphincter defect. This however can be avoided by a thorough knowledge of anatomy and by experienced sonographers and sonologists. The internal sphincter is simpler to evaluate due to its hypoechoic nature in contrast to the hyperechoic adjacent tissues. However, the more echogenic external sphincter muscle was often difficult to demonstrate, leading to less reliable measurements. In addition, only a small number (n = 2) of our patients had isolated external sphincter defects. Ours is one of the largest series until date in Asian countries to have correlated EAUS findings with anal manometry, to the best of our knowledge. In contrast to many other reports, we demonstrated a significant correlation between decreased maximal resting pressure and decreased IAS thickness or an IAS defect. The correlation between MSP and external sphincter pathology was significantly less consistent in our study. The other findings in our study are in keeping with results of previous reports.
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Conflict of interest The authors declared that there was no conflict of interest Acknowledgement Prasanna Samuel is acknowledged for helping with statistical analysis. References [1] Osterberg A, Edebol Eeg-Olofsson K, Graf W. Results of surgical treatment for faecal incontinence. Br J Surg 2000;87:1546–52. [2] Diamant NE, Kamm MA, Wald A, et al. AGA technical review on anorectal testing techniques. Gastroenterology 1999;116:735–60. [3] Sultan AH, Kamm MA, Hudson CN, et al. Anal-sphincter disruption during vaginal delivery. N Engl J Med 1993;329:1905–11. [4] Meyenberger C, Bertschinger P, Zala GF, et al. Anal sphincter defects in fecal incontinence: correlation between endosonography and surgery. Endoscopy 1996;28:217–24. [5] Fitzpatrick M, Behan M, O’Connell PR, et al. A randomized clinical trial comparing primary overlap with approximation repair of third-degree obstetric tears. Am J Obstet Gynecol 2000;183:1220–4. [6] Haadem K, Dahlstrom JA, Lingman G. Anal sphincter function after delivery: a prospective study in women with sphincter rupture and controls. Eur J Obstet Gynecol Reprod Biol 1990;35:7–13. [7] Haadem K, Ohrlander S, Lingman G. Long-term ailments due to anal sphincter rupture caused by delivery: a hidden problem. Eur J Obstet Gynecol Reprod Biol 1988;27:27–32. [8] Borello-France D, Burgio KL, Richter HE, et al. Fecal and urinary incontinence in primiparous women. Obstet Gynecol 2006;108:863–72. [9] Bollard RC, Gardiner A, Lindow S, et al. Normal female anal sphincter: difficulties in interpretation explained. Dis Colon Rectum 2002;45:171–5. [10] Fritsch H, Brenner E, Lienemann A, et al. Anal sphincter complex: reinterpreted morphology and its clinical relevance. Dis Colon Rectum 2002;45:188–94. [11] Felt-Bersma RJ, Cuesta MA, Koorevaar M, et al. Anal endosonography: relationship with anal manometry and neurophysiologic tests. Dis Colon Rectum 1992;35:944–9. [12] Sultan AH, Kamm MA, Talbot IC, et al. Anal endosonography for identifying external sphincter defects confirmed histologically. Br J Surg 1994;81:463–5. [13] Tiandra JJ, Milsom JW, Schroeder T, et al. Endoluminal ultrasound is preferable to electromyography in mapping anal sphincter defects. Dis Colon Rectum 1993;36:689–92. [14] Sultan AH, Kamm MA, Hudson CN, et al. Endosonography of the anal sphincters: normal anatomy and comparison with manometry. Clin Radiol 1994;49:368–74. [15] Romano G, Rotondano G, Esposito P, et al. External anal sphincter defects: correlation between preoperative anal endosonography and intraoperative findings. Br J Radiol 1996;69:6–9. [16] Chen MD Herbert, Smilgin Humphreys RGN M, Michael GW, et al. Anal Ultrasound Predicts the Response to Nonoperative Treatment of Fecal Incontinence in Men. Annals of surgery 1999;229(5):739–44. [17] Titi MA, Jenkins JT, Urie A, et al. Correlation between anal manometry and endosonography in females with faecal incontinence. Colorectal Dis. 2007 Oct;23(17):956–8. [18] Nielsen MB, Hauge C, Pedersen JF, et al. Endosonographic evaluation of patients with anal incontinence: findings and influence on surgical management. AJR Am J Roentgenol 1992;160:771–5. [19] Law PJ, Kamm MA, Bartram CI. Anal endosonography in the investigation of faecal incontinence. Br J Surg 1991;78:312–4. [20] Shobeiri SA, Nolan TE, Yordan-Jovet R, et al. Digital examination compared to trans- perineal ultrasound for the evaluation of anal sphincter repair. Int J Gynaecol Obstet 2002;78:31. [21] Gravante G, Giordano P. The role of three-dimensional endoluminal ultrasound imaging in the evaluation of anorectal diseases: a review. Surg Endosc 2008;22:1570. [22] Sentovich SM, Blatchford GJ, Rivela, et al. Diagnosing anal sphincter injury with transanal ultrasound and manometry. Dis Colon Rectum 1997;40:1430. [23] Deen KI, Kumar D, Williams JG, et al. Anal sphincter defects. Correlation between endoanal ultrasound and surgery. Ann Surg 1993;218:201.
Contents lists available at ScienceDirect
Arab Journal of Gastroenterology journal homepage: www.elsevier.com/locate/ajg
Original Article
Endoanal ultrasound assessment of sphincter defects and thinning – Correlation with anal manometry q Chatterjee Parangama a,⇑, Eapen Anu a, Nayak Sukria b a b
Department of Radiodiagnosis and Imaging, Christian Medical College, Vellore, Tamil Nadu, India Department of Colorectal Surgery, Christian Medical College, Vellore, Tamil Nadu, India
a r t i c l e
i n f o
Article history: Received 27 September 2013 Accepted 11 January 2014
Keywords: Endoanal Ultrasound Sphincter defects Anal manometry
a b s t r a c t Background and study aims: This study aims to determine if anal sphincter defects/thinning observed at endoanal ultrasound correlates with anal pressures recorded at anal manometry. Patients and methods: A total of 30 consecutive patients with history suggestive of anal sphincter pathology underwent anal endosonography with documentation of internal and external sphincter defects/ thinning. The same patients underwent anal manometry with documentation of maximum resting and maximum squeeze pressures. Patients with a sphincter defect (SD) were compared to patients without a sphincter defect (NSD) and both groups were compared with respect to findings in manometry. The Mann–Whitney U test was used for statistical analysis. This study was approved by the Institutional Ethics Committee. Results: A statistically significant correlation was found between decreased maximal resting pressure and decreased internal anal sphincter (IAS) thickness or an IAS defect. The correlation between MSP and external sphincter pathology was significantly less consistent in our study. Conclusion: Our study showed a statistically significant correlation between maximum resting pressure and observation of internal sphincter defects at endoanal ultrasound. The patients with documented internal sphincter defects have significantly reduced maximum resting pressures. There was however, no correlation between external sphincter defects and decrease in maximum squeeze pressure as has been observed in other studies. Until a manometry cut-off can be set to discriminate between the absence and presence of defects, both manometry and ultrasound should be offered to patients with history suggesting anal sphincter pathology. Ó 2014 Arab Journal of Gastroenterology. Published by Elsevier B.V. All rights reserved.
Introduction Faecal incontinence has several diverse causes. Anorectal surgery and parturition are the main causes wherein the anal sphincter and the pudendal nerve may be damaged. A systematic evaluation of the patient usually reveals the underlying pathophysiology and helps to decide treatment options [1,2]. With per rectal digital examination, the presence of an anal sphincter defect can be assessed, and anal manometry can help determine resting and squeeze pressures which can provide clues to the underlying sphincter pathology [2]. In recent times, anal endosonography
q There were no sources of support. This paper has not been presented in any meetings. ⇑ Corresponding author. Address: Department of Radiodiagnosis and Imaging, Christian Medical College, Vellore 632004, Tamil Nadu, India. Tel.: +91 9894722569/0416 2283012; fax: +91 0416 2282707. E-mail address: [email protected] (C. Parangama).
has also come to the forefront as an indispensable tool to evaluate this group of patients. During childbirth, anal sphincter damage occurs in about 18% of vaginal deliveries [3,4]. Even after repair of obstetric anal sphincter tears, within 6 months 29–53% of women report gas incontinence, 5–10% report stool incontinence [5–8] and up to 66% of primiparous women demonstrate a defect within the anal sphincter by endoanal ultrasonography (EAUS) 3 months after repair [5]. Further, occult sphincter tears (present on endosonography) occur in 23–35% of primiparous women at vaginal delivery [5–8]. Anal endosonography is the standard for radiologic evaluation of the anal sphincter. This technique reliably identifies defects or thinning of the internal anal sphincter (IAS); however, evaluation of the external anal sphincter (EAS) is more subjective, operatordependent and difficult due to the presence of confounding factors and normal anatomic variations such as an external sphincter ‘gap’ [9,10]. Overall, however, ultrasound (US) findings of anal sphincter tear are highly correlated with electromyogram and manometric
http://dx.doi.org/10.1016/j.ajg.2014.01.006 1687-1979/Ó 2014 Arab Journal of Gastroenterology. Published by Elsevier B.V. All rights reserved.
28
C. Parangama et al. / Arab Journal of Gastroenterology 15 (2014) 27–31
findings and are both sensitive and specific for anal sphincter tears [11–14]. We aimed to correlate endoanal US findings with anal manometry.
Patients and methods We prospectively studied 30 patients referred from the Department of Colorectal Surgery in our institution. Endoanal US was performed by a radiologist and verified by a senior gastrointestinal radiologist, by using a US scanner with a radial endoscopic probe and a 7.5-MHz transducer (profocus 2022, B&K Medical, Sandtoften, Denmark; 10 MHz, 360° window). A lubricated condom was placed over the probe. Subjects were examined in the supine left lateral position with their knees flexed. The probe was introduced into the anal canal, positioned at the upper aspect of the puborectalis sling and rotated so that the 12 o’clock position was anterior (3 o’clock represents the patient’s left side; and 9 o’clock, the patient’s right side). The total examination time for endoanal US ranged between 10 and 15 min. On the most representative images, at the 4 o’clock position at the midanal level, internal sphincter and external sphincter thicknesses were measured.
Image interpretation On axial sectional images, the inner hypoechoic ring of tissue represents the IAS, which is formed by the thickening and extension of the circular smooth muscle of the rectum (Figs. 1 and 2). The outer relatively echogenic ring of tissue represents the longitudinal muscle and the EAS, which is formed by the caudal continuation of the puborectalis (Figs. 3 and 4). The normal IAS is between 2 and 3 mm thick [12,15] and the normal EAS is between 7 and 9 mm thick [6,15]. The EAS tends to become thinner with age, [6] whereas the IAS becomes thicker and more echogenic with age, probably reflecting collagenisation [15]. The anal canal length varies from 25 mm for women to 33 mm for men [11,15]. An echogenic or echolucent disruption in the sphincter(s) seen on one or more images was defined as a gap (Fig. 5). They were located by clock-face position to the nearest hour, with anterior midline as 12 o’clock. The high anal canal was defined as the level midway between the inferior border of the puborectalis muscle and complete formation of the external sphincter ring anteriorly. The low canal level was defined as that immediately caudal to the termination of the internal sphincter and comprised the subcutaneous external sphincter. The intervening segment was defined as the mid-anal canal level.
Anal manometry Anorectal studies were performed with the patient in the left lateral position using a station pull-through technique with an air-filled balloon catheter using a Centromed manometer. Threshold volume and maximum tolerated volume were measured using the balloon positioned in the distal part of the rectum. The rectoanal inhibitory reflex was studied by measuring the response of the resting anal pressure to distension of the rectum. A fall of 20% denoted a positive response. Anorectal sensation was measured in the upper, middle, and lower anal canal using the mucosal electrosensitivity method. The results of anorectal manometry studies are shown in Table 1. This study was approved by the Institutional Review Board. Results During the study period, 10 male and 20 female patients with faecal incontinence were evaluated. Mean age was 35.5 years (range 21–60 years). A total of 29 patients (96.6%) had episodes of incontinence to faeces (major incontinence). One patient had episodes of incontinence to flatus (minor incontinence). These patients had stress and urge incontinence predominantly. Seven patients (23.3%) had a history of anal surgery in the past, which included haemorrhoidectomy, lateral anal sphincterotomy or fistulectomy. No patient in this series had a history of congenital anorectal atresia or any generalised disorder that could have been responsible for incontinence. Parity was assessed in female patients (para 1 = 11 patients, para 2 = eight patients, para 3 = one patient). Sixteen out of 20 female patients had a history of prior obstetric trauma. Anal US Of the 30 patients, 26 (86.6 %) had a defect or defects in the sphincter complex; 24 patients had a defect or defects in the internal sphincter, and two had a lesion or lesions in both sphincters. Isolated defects in the external sphincter were not seen. Ten patients had defects and 16 had sphincter thinning with no demonstrable defects. Therefore, patients were easily classified into two groups by EAUS: those with sphincter defects (SDs, n = 10) and those without physical defects (NSDs, n = 16). Four patients had sonologically normal sphincters. The mean internal sphincter thickness was 1.48 mm and the mean external sphincter thickness was 7 mm. Two patients had sphincter pathology in the upper anal canal, three patients in the midcanal, two patients in the lower canal and 19 patients had abnormalities in all levels.
Fig. 1. The inner hypoechoic ring of tissue represents the internal anal sphincter (IAS).
C. Parangama et al. / Arab Journal of Gastroenterology 15 (2014) 27–31
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Fig. 2. The inner hypoechoic ring of tissue represents the internal anal sphincter (IAS).
Fig. 3. The outer echogenic ring of tissue represents the longitudinal muscle and the external anal sphincter (EAS).
Fig. 4. The outer echogenic ring of tissue represents the longitudinal muscle and the external anal sphincter (EAS).
Fig. 5. Echolucent disruption in the internal sphincter in the 12–2 o clock position.
Anorectal manometry The results of anorectal manometry studies are shown in Table 1. Overall, the mean resting pressure was 45.7 (normal 40–120), the mean squeeze pressure was 100.6 (normal
100–180), first rectal sensation was elicited at a mean of 24 (normal, <20), mean maximum rectal capacity was 199 (normal 250–540), and mean electrical sensitivity was 7 (normal 4–8). The values for the SD and NSD groups were compared. Both mean maximum resting pressure and maximum squeeze pressures were
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C. Parangama et al. / Arab Journal of Gastroenterology 15 (2014) 27–31
Table 1 Correlation between manometry findings in the sphincter deficient and non sphincter deficient group.
Mean Mean Mean Mean Mean
max resting pressure max squeeze pressure 1st rectal sensation Maximum tolerated volume (MTV) electrosensitivity
SD[10]
NSD[16]
p Value
25.6 80.5 18.2 200 8.4
58.38 113.25 27.88 198.63 6.38
0.02 0.07 0.24 0.96 0.42
lower in the SD group (resting pressure was significantly lower in the SD group, p value 0.02, squeeze pressures were not significantly lower, p value 0.07, respectively). Nine out of 10 patients in the SD group had low maximum resting pressure. Ten out of 16 in the sphincter thinning group had low maximum resting pressure. Eight out of 10 in the SD group had low maximum squeeze pressure and eight out of 16 in the sphincter thinning group had low maximum squeeze pressure. Mean pressure to elicit a first rectal sensation was higher in the NSD group than in the SD group, but not significantly higher, p value 0.24. Maximum tolerated rectal volume was not significantly different in the two groups, 200 and 198.6. Seven out of 10 in the SD group had abnormal rectal capacity and nine out of 16 in the NSD group had abnormal rectal capacity (decreased). Two out of 10 in the SD group and seven out of 16 in the NSD group had a high first rectal sensation on distension. All patients in both groups had positive rectoanal inhibitory reflexes, except one patient in the sphincter thinning (NSD) group. With regard to electrosensitivity, eight out of 10 were abnormal in the SD group and 11/16 were abnormal in the NSD group. This was not significantly different in the SD and NSD groups, p value 0.42. Comparison of the groups The SD group comprised only female patients; all patients except one in the SD group had a prior history of obstetric trauma. In the SD group, one patient had a history of previous surgery, while five patients in the NSD group had a history of prior surgery. Patients in the two groups were compared with respect to the severity of symptoms and past medical history. Seven out of 10 in the SD group had incontinence to stools, 11/16 in the NSD group had incontinence to stools and the rest were incontinent to flatus. With respect to symptoms, major incontinence was present in both groups with no statistical difference between the two groups. Statistical analysis Descriptive statistics (mean, SD, median and percentiles) was obtained for each of the study variables. As the distributions of the variables were not normal, the groups were compared using the Mann–Whitney U test (non-parametric test). All analyses were done using SPSS 11.0. The results are summarised in Table 1. Discussion The advantages of endoanal sonography are its easy availability and decreased costs. In addition, endoanal sonography has been in use longer than magnetic resonance imaging (MRI), resulting in a larger number of sonographers and sonologists who are experienced with the endoanal sonography technique [9]. The first reports on the use of US to study the anal sphincter came from St. Mark’s Hospital in the late 1980s and early 1990s.
Subsequently, several studies demonstrated the efficacy of anal endosonography and compared it to various techniques such as manometry and needle electromyography (EMG) and to surgery. The relevance of a few such studies is discussed. Considering patient’s demographics, in the study by Chen et al. [16], the median age was 57 years (range 21–82 years). In our study, the mean age was 35.5 years (range 21–60 years). Ten of their patients (27%) had episodes of incontinence to solid faeces (major incontinence). The other 27 (73%) had episodes of incontinence to liquid stool or flces (minor incontinence). In our study, 29 patients had incontinence to faeces, while one had episodes of incontinence to flatus. In their study, of the 37 patients, nine had defects in the sphincter complex. Eight patients had defects in the internal sphincter and five had a lesion in the external sphincter. They also classified their patients into two groups by AUS depending on the presence or absence of sphincter defects. In our study, of the 30 patients, 26 had a defect or defects in the sphincter complex; 24 patients had a defect or defects in the internal sphincter, and two had lesions in both sphincters. Isolated defects in the external sphincter were not seen. Ten patients had defects and 16 had sphincter thinning with no demonstrable defects. Their patients also underwent manometry studies. The values for the SD and NSD groups were compared. They found that both mean maximum resting pressure and maximum squeeze pressures were significantly lower in the SD group. Mean pressure to elicit a first rectal sensation was higher in the SD group than in the NSD group. There was no significant difference in mean maximum tolerated rectal volume (rectal capacity). All patients in both groups had positive rectoanal inhibitory reflexes. Electrosensitivity of the upper, middle and lower anal canal was within normal limits in both groups as well. In our series, nine out of 10 patients in the SD group had low maximum resting pressure, 10 out of 16 in the sphincter thinning group had low maximum resting pressure, eight out of 10 in the SD group had low maximum squeeze pressure and eight out of 16 in the sphincter thinning group had low maximum squeeze pressure. Mean pressure to elicit a first rectal sensation was higher in the NSD group than in the SD group, but was not statistically significant; p value 0.24. Maximum tolerated rectal volume was not significantly different in the two groups, 200 and 198.6. Seven out of 10 in the SD group had abnormal rectal capacity and nine out of 16 in the NSD group had abnormal rectal capacity. Two out of 10 in the SD group and seven out of 16 in the NSD group had a high first rectal sensation on distension. All patients in both groups had positive rectoanal inhibitory reflexes, except for one patient in the sphincter thinning (the NSD group). With regard to electrosensitivity, eight out of 10 were abnormal in the SD group and 11/16 were abnormal in the NSD group. In the study by Titi et al. [17] the authors attempted to identify EAUS parameters that correlate with sphincter function. A total of 100 females with incontinence and 28 asymptomatic female volunteers were evaluated. All subjects underwent anorectal manometry and EAUS. Parameters assessed included sphincter quality (echogenicity), thickness and defect characteristics among others. They found that maximum EAS thickness significantly correlated with MSP. EAS defects were detected in 84 patients and seven controls. Full-length EAS defects were only detected in the incontinent group and had significantly lower MSP. IAS quality was significantly associated with MRP. They concluded that certain EAUS parameters could be predictive of anal sphincter function, which included the presence of an EAS defect and its length, EAS maximum thickness and IAS ring quality. Integration of these parameters can give better EAUS correlation with manometry.
C. Parangama et al. / Arab Journal of Gastroenterology 15 (2014) 27–31
Nielsen et al. [18] evaluated 48 patients with incontinence. Endosonography and measurement of anal canal pressures were performed in all patients. Endosonograms showed defects of external sphincters in 27 patients, 12 of whom had internal sphincter defects also. One patient had an abnormal thinning of the external sphincter. Eight patients had isolated defects of the internal sphincter. The sphincteric defects found by endosonography did not correlate with the anal canal pressures. The resting pressure in the anal canal is mainly attributed to the internal sphincter, and therefore low values should be found in patients with internal sphincter defects [19]. Although this may be true for some patients, overlap with normal values is considerable, and significant variations exist. Law et al. [19] also showed a strong correlation between the thickness of the internal sphincter and resting pressure in the anal canal and our study also confirmed this. One study compared US and manometric findings in 20 asymptomatic nulliparous women, 20 asymptomatic parous women and 31 women with incontinence underwent sphincteroplasty [20]. Endosonography correctly identified all of the sphincter injuries in women with incontinence. In a similar report, endorectal EUS was performed prior to surgery in 28 patients with faecal incontinence [21]. EUS correctly identified all 25 of the IAS defects and all 10 EAS defects. However, it incorrectly diagnosed an EAS defect in three patients, resulting in an overall accuracy for EUS of 89%. In one of the largest studies to date, the US appearance was prospectively compared with the operative findings in 44 patients who underwent pelvic floor repair [22]. Endorectal US was 100% sensitive in detecting either IAS or EAS defects. One IAS tear seen on endosonography was not confirmed at surgery. Other studies have found a similar association between decreased maximal squeeze pressure and decreased EAS thickness or an EAS defect [22,23]. By contrast, a similar relationship between the resting pressure in the anal canal and IAS thickness has been documented in few studies [19,23]. Limitations and potential pitfalls The anterior part of the EAS is usually shorter and slopes downward in women. This often made demonstrating a complete 360° ring of the EAS in one plane difficult [15]. The anococcygeal ligament appears as a hypoechoic triangular structure posteriorly and it can be mistaken for a sphincter defect. This however can be avoided by a thorough knowledge of anatomy and by experienced sonographers and sonologists. The internal sphincter is simpler to evaluate due to its hypoechoic nature in contrast to the hyperechoic adjacent tissues. However, the more echogenic external sphincter muscle was often difficult to demonstrate, leading to less reliable measurements. In addition, only a small number (n = 2) of our patients had isolated external sphincter defects. Ours is one of the largest series until date in Asian countries to have correlated EAUS findings with anal manometry, to the best of our knowledge. In contrast to many other reports, we demonstrated a significant correlation between decreased maximal resting pressure and decreased IAS thickness or an IAS defect. The correlation between MSP and external sphincter pathology was significantly less consistent in our study. The other findings in our study are in keeping with results of previous reports.
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Conflict of interest The authors declared that there was no conflict of interest Acknowledgement Prasanna Samuel is acknowledged for helping with statistical analysis. References [1] Osterberg A, Edebol Eeg-Olofsson K, Graf W. Results of surgical treatment for faecal incontinence. Br J Surg 2000;87:1546–52. [2] Diamant NE, Kamm MA, Wald A, et al. AGA technical review on anorectal testing techniques. Gastroenterology 1999;116:735–60. [3] Sultan AH, Kamm MA, Hudson CN, et al. Anal-sphincter disruption during vaginal delivery. N Engl J Med 1993;329:1905–11. [4] Meyenberger C, Bertschinger P, Zala GF, et al. Anal sphincter defects in fecal incontinence: correlation between endosonography and surgery. Endoscopy 1996;28:217–24. [5] Fitzpatrick M, Behan M, O’Connell PR, et al. A randomized clinical trial comparing primary overlap with approximation repair of third-degree obstetric tears. Am J Obstet Gynecol 2000;183:1220–4. [6] Haadem K, Dahlstrom JA, Lingman G. Anal sphincter function after delivery: a prospective study in women with sphincter rupture and controls. Eur J Obstet Gynecol Reprod Biol 1990;35:7–13. [7] Haadem K, Ohrlander S, Lingman G. Long-term ailments due to anal sphincter rupture caused by delivery: a hidden problem. Eur J Obstet Gynecol Reprod Biol 1988;27:27–32. [8] Borello-France D, Burgio KL, Richter HE, et al. Fecal and urinary incontinence in primiparous women. Obstet Gynecol 2006;108:863–72. [9] Bollard RC, Gardiner A, Lindow S, et al. Normal female anal sphincter: difficulties in interpretation explained. Dis Colon Rectum 2002;45:171–5. [10] Fritsch H, Brenner E, Lienemann A, et al. Anal sphincter complex: reinterpreted morphology and its clinical relevance. Dis Colon Rectum 2002;45:188–94. [11] Felt-Bersma RJ, Cuesta MA, Koorevaar M, et al. Anal endosonography: relationship with anal manometry and neurophysiologic tests. Dis Colon Rectum 1992;35:944–9. [12] Sultan AH, Kamm MA, Talbot IC, et al. Anal endosonography for identifying external sphincter defects confirmed histologically. Br J Surg 1994;81:463–5. [13] Tiandra JJ, Milsom JW, Schroeder T, et al. Endoluminal ultrasound is preferable to electromyography in mapping anal sphincter defects. Dis Colon Rectum 1993;36:689–92. [14] Sultan AH, Kamm MA, Hudson CN, et al. Endosonography of the anal sphincters: normal anatomy and comparison with manometry. Clin Radiol 1994;49:368–74. [15] Romano G, Rotondano G, Esposito P, et al. External anal sphincter defects: correlation between preoperative anal endosonography and intraoperative findings. Br J Radiol 1996;69:6–9. [16] Chen MD Herbert, Smilgin Humphreys RGN M, Michael GW, et al. Anal Ultrasound Predicts the Response to Nonoperative Treatment of Fecal Incontinence in Men. Annals of surgery 1999;229(5):739–44. [17] Titi MA, Jenkins JT, Urie A, et al. Correlation between anal manometry and endosonography in females with faecal incontinence. Colorectal Dis. 2007 Oct;23(17):956–8. [18] Nielsen MB, Hauge C, Pedersen JF, et al. Endosonographic evaluation of patients with anal incontinence: findings and influence on surgical management. AJR Am J Roentgenol 1992;160:771–5. [19] Law PJ, Kamm MA, Bartram CI. Anal endosonography in the investigation of faecal incontinence. Br J Surg 1991;78:312–4. [20] Shobeiri SA, Nolan TE, Yordan-Jovet R, et al. Digital examination compared to trans- perineal ultrasound for the evaluation of anal sphincter repair. Int J Gynaecol Obstet 2002;78:31. [21] Gravante G, Giordano P. The role of three-dimensional endoluminal ultrasound imaging in the evaluation of anorectal diseases: a review. Surg Endosc 2008;22:1570. [22] Sentovich SM, Blatchford GJ, Rivela, et al. Diagnosing anal sphincter injury with transanal ultrasound and manometry. Dis Colon Rectum 1997;40:1430. [23] Deen KI, Kumar D, Williams JG, et al. Anal sphincter defects. Correlation between endoanal ultrasound and surgery. Ann Surg 1993;218:201.