Int J Colorectal Dis (2012) 27:931–937 endoprobe with two crystals, covering 2–16 MHz (focal range 2–4.5 cm) (diameter 1.7 cm), producing a 360° view. During recording, the crystals were automatically pulled back by an internal puller, allowing longitudinal distances to be measured. After the endosonography, images were reconstructed into 3D images using computer software. Further details of the methodology of anal endosonography have been previously published [20]. The aspect of the puborectal muscle, external anal sphincter (ESD), internal anal sphincter and submucosa were described. Defects in the ESD were described as hypoechogenic lesions and the extent of the defect was axially measured in hours. The 12 o’clock position was designated as anterior and the 3 o’clock position as left lateral. The 3 o’clock position was located at 90 degrees rotating clockwise. The length of the defect was indicated as proximal, distal or total. Internal anal sphincter defects (ISD) were described as disruption or irregularity of the hypo-echogenic ring. Atrophy of the EAS was judged upon its reflection of the outer interface (border ESD and sub-adventitial fat), reflection pattern and length [21]. Statistical analysis Fisher’s exact test and Pearson chi-square test were used to compare proportions where appropriate. Student’s t- test was used to compare continuous data. Spearman correlation coefficients were used to determine relation- ships between the anal pressures and the Vaizey score and Wexner score. All P values were two-tailed and statistical significance was taken as a P value of less than 0.05. Analyses were performed with the statistical software SPSS version 15.0. Results Clinical features In total, 626 patients underwent anorectal function evalua- tion. Of them, 218 patients met the inclusion criteria for FI and were included in the study (Table 1). Ten patients (5%) were men. Of the remaining 208 female patients, 192 (92%) had at least one previous vaginal delivery (mean 2.2, range 0–9). The mean duration of FI was 4.9 years. Anorectal manometry Anal pressures Male patients had a higher MSP (39 vs. 28 mmHg; P 0 0.03) and longer SL (3.6 vs. 3.0 cm; P 0 0.04) than female patients 933 Table 1 Demographic and anorectal manometry measurements of the patients with and without sphincter defects on anal endosonography Age (years) Female (%) Medical history Diabetes mellitus (%) Multiple sclerosis (%) Parkinson’s disease (%) Vascular problems (%) Surgical history No surgical history (%) Colorectal/anal (%) Urogenital (%) Othera (%) Anorectal manometry MBP (mmHg) MSP (mmHg) SL (cm) Relaxation Yes (%) No (%) Paradox (%) RAIR Yes (%) No (%) FS (ml) Urge (ml) RC (ml) Patients with no defects, n0107(49%) 63 (33–90)¶£ 98 (92%) Patients with Patients with small defects, large defects, n071(33%) n040(18%) 57 (31–83)¶ 70 (99%) 49 (21–73)£ 40 (100%) 6 (6) 4 (4) 1 (1) 5 (5) 38 (36)$# 15 (15) 53 (49) 1 (1) 40 (10–80)^ 30 (5–80) 3.1 (1–6)% 98 (93) 6 (6) 2 (2) 3 (4) 0 1 (1) 0 11 (15)# 8 (11) 53 (74) 0 37 (10–70) 28 (5–60) 3.0 (1–5) 63 (89) 5 (7) 3 (4) 1 (3) 0 0 0 0$ 11 (28) 29 (73) 0 35 (10–65)^ 28 (10–80) 2.8 (1–4)% 37 (97) 0 1 (3) 105 (98) 69 (97) 40 (100) 2 (2) 2 (3) 0 82 (15–300) 66 (10–240) 66 (15–200) 142 (35–300) 116 (30–250) 117 (50–240) 209 (70–350)*& 172 (65–300)* 172 (90–350)& Small defect <25% circumference Large defect >25% circumference MBP maximum basal pressure, MSP maximum squeeze pressure, SL sphincter length, RAIR rectoanal inhibitory reflex, FS first sensation, RC rectal capacity a Other: surgery for lumbar disc herniation ¶ P00.001 £ P<0.001 $ P<0.001 # P00.004 ^ P00.09 % P00.07 *P<0.001 & P00.006 (Table 1). Forty-three (20%) patients had normal pressures (MBP and MSP ≥40 mmHg). Fifty (23%) and ten (5%) patients had low pressures and very low pressures (MBP and MSP <40 and <20 mmHg, respectively). Nine patients (8%) could not relax their pelvic floors properly on clinical examination and manometry.