Hypothesis / aims of study
Traumatic vaginal delivery is a risk factor for faecal incontinence (FI). There is scarce information about the differences in the pathophysiology of FI in women that was initiated symptoms immediately postpartum or later in life.
Our hypothesis is that women who initiated symptoms in the postpartum showed more severe structural and neurological abnormalities than women with obstetric injuries who initiated symptoms later in life.
The aim of the present study was to analyse the differences between both groups, focused on anatomical defects detected by 3D-endoanal ultrasound (EAUS) and neurological abnormalities in electrophysiological studies.
Study design, materials and methods
A cross-sectional retrospective study was designed, including patients with symptoms of FI who consecutively attended a Digestive Motility Unit. Women who initiated symptoms of FI immediately postpartum (Group 1) or years after delivery (Group 2) were compared. Women with history of caesarean section without any vaginal delivery, nulliparas, >50 years of age and women with other possible etiological factor for FI (diarrhea, anal or pelvic surgery, neurological diseases) were excluded, in order to select only women with FI related with obstetric injury. Women with only flatus incontinence were also excluded.
The following interventions were performed to all patients: Wexner questionnaire (range 0-20), anorectal manometry, 3D-EAUS (rotational probe-2052, Ultraview-800, BK Medical), external anal sphincter electromyography (EMG), and pudendal nerve terminal motor latency (PNTML) with St.Mark’s electrode.
The internal anal sphincter (IAS) was identified by EAUS as a homogeneous hypoechoic circular band, whereas the external anal sphincter (EAS) as a mixed echogenic circular structure [1]. A sphincter defect was defined by a discontinuity in the muscle ring and/or characterized by the loss of the normal architecture in the sonographic appearance of the IAS and the EAS. The severity of the defects was evañuated with the degree of the discontinuity.
Statistical analysis was performed with the SPSS software package (14.0 version, SPSS Inc, Chicago, IL). Quantitative variables were analyses using Mann-Whitney U-test, whereas qualitative variables, using Fisher exact test.
Results
A total of 75 women with FI were included in the study: 44 women in Group 1 (inmediately postpartum) and 31 women in Group 2 (later in life). Results of the comparison between groups are shown in Table-1. Results are shown by median±SD for quantitative variables and n (%) for qualitative variables.
Women of the Group 1 were younger than women of the Group 2 (37.1±5.4 vs 45.9±4.6 years old; p<0.001). No differences considering parity neither history of forceps delivery were observed between groups. The severity of the FI measured by Wexner score was also similar between both groups (Table 1).
3D-EAUS was normal in only 17 out of 44 women of the Group 1 (38.6%), whereas in 22 up to 31 women of the Group 2 (71%); p=0.009. Among the 27 patients with abnormal EAUS of the Group 1, 20 showed a defect in the EAS, 2 in the IAS, and 5 in both sphincters. Among patients of Group 2, only 7 showed a defect in EAS; 1 in IAS and 1 in both. The degree of these defects in the EAS was clearly higher in patients with symptoms inmediately postpartum (Group 1) than later in life (Group 2): 47.1±62.8 vs 17.5±39.3 degrees; p=0.02. Defects of the IAS were similar in both groups.
Results of EMG and PNTML were similar in both groups: 33 (75%) abnormal EMG in Group 1 vs 21 (67.7%) in Group 2; and 27 (61.4%) abnormal PNTML in Group 1 vs 15 (49.4%) in Group 2. However, it is important to note that EMG was abnormal in more than two thirds in both groups.
Finally, manometry results were more frequently abnormal in Group 2, pointing out that EAS and/or IAS showed insufficiency in more than two thirds of women in both groups.
Interpretation of results
Abnormal EAUS is significantly more common in women who started FI symptoms at postpartum.
Manometry and EMG was abnormal in more than two thirds in both groups.
Both ultrasound and neurophysiological studies should complement the manometry in process of diagnosis in women <50 years with FI.