despite surgical advances , fecal incontinence and constipation remain major postoperative problems that plague children with anorectal malformations ( arm ) . in 1996 , a small sample of adolescents operated for arm revealed a significant number of mental ( 58% ) and psychological problems ( 73% ) in patients with adverse stooling outcomes . hypoplastic sphincter complex , abnormal anorectal angle , and misplacement of neorectum in relation to the sphincter complex have been implicated as causes of poor stooling outcomes . however , reports are scarce and do not shed sufficient light either on the types of anomalies or the surgical procedure performed to correct arm . the purpose of this study was to compare the stooling outcomes , types of anomalies and surgical procedure to the postoperative pelvic magnetic resonance imaging ( mri ) in children with arm . this cross - sectional study was conducted between 2010 and 2012 and involved children with arm who had at least 2 years of follow - up after completing all stages of surgery and who were at least 3 years of age at the time of the study . the patients were either contacted on the telephone and requested to attend the outpatient clinic for the interview or interviewed during routine follow - up . children who had undergone redo pull - through procedures , and permanent fecal diversion was excluded . all relevant clinical data , diagnosis , operative details , and findings were collected from the departmental arm registry , and the missing data were obtained from the hospital archive section . the subtype of arm , surgical procedure performed , and the stooling outcomes were assessed using the krickenbeck classification . pelvic mri imaging was done under sedation or general anesthesia and was done with high resolution phased array coils using a 3 tesla machine . the protocol included t1- and t2-weighted images in the axial , coronal , and sagittal planes . a 20 fr foley catheter was advanced into the rectum , and a small amount of saline was instilled to delineate the bowel in relation to the sphincter . special attention was paid to the position of the neorectum , sphincter muscle complex , perianal fat , anorectal angle , and spine . assessment of muscle quality was subjective and based on internal comparison for symmetry and comparison with pelvic mri of healthy persons . to look for mesenteric fat pulled - through inadvertently with the bowel , axial t1- and t2-weighted images without fat saturation was performed which showed fat as a halo of high signal intensity surrounding the wall of the pulled - through bowel . anorectal angle was measured as the angle formed between the rectum and the anal canal , and t2-weighted sagittal images were used to capture this angle . the normal angle is < 90 and any angle , which was obtuse was deemed abnormal . the statistical analysis was done using the spss version 15 ( chicago , illinois , usa ) software . chi - square and fischer exact tests were used for analyzing the data and p < 0.05 was considered significant . twenty patients were contacted telephonically , and the remaining 13 were interviewed during regular follow - up . the median age of the patients at the time of the study was 7.5 years ( range 4 - 14 years ) . the median age at the time of definitive procedure was 7 months ( range 25 days-12 months ) , and the median period after completion of all surgeries for arm was 4.5 years ( range 2 - 11 years ) . thirteen patients underwent primary definitive repair ( 39.4% ) while the remaining 20 ( 60.6% ) underwent staged repair . all the patients were operated upon by the two senior authors ( sa , vb ) and the decision to do a staged or single stage repair was based solely on standard clinical criteria . twenty - two patients ( 66% ) underwent posterior sagittal anorectoplasty ( psarp ) , 7 patients ( 21% ) underwent abdominoperineal pull - through ( appt ) , and 4 patients ( 13% ) underwent perineal operations . the perineal operations were an excision of h - type fistula along with perineal body repair in one patient and anoplasty in three patients . voluntary bowel movement ( vbm ) was absent in 18 patients with all cases of rectovaginal fistula ( without pouch colon ) and 88% of pouch colon having absent vbm . twenty - eight patients had soiling ; all patients with rectovaginal fistula , rectovesical fistula , no fistula , and pouch colon had soiling . twelve patients had constipation ; > 50% patients with perineal lesions , rectovaginal fistula , rectovesical fistula , and no fistula had constipation [ table 1 ] . stooling outcomes in the various subtypes of arm abnormal local findings on mri were seen in 22 patients ( 66.7% ) . both the patients of rectovaginal fistula and 63% of pouch colon patients had misplaced neorectum [ figure 1 ] with only one patient in this group having undergone psarp , the rest had undergone appt ( 86% ) . of the children who had undergone appt , 57% had atrophic muscle complex compared to 9% in the psarp group and none in the perineal operation group . this was also found to be statistically significant ( p = 0.02 ) [ table 2 ] . axial t2-weighted magnetic resonance imaging of the pelvis showing eccentric placed neorectum ( arrowhead ) to the right of sphincter muscle complex mri local abnormalities ( n = 22 ) in arm subtypes and surgical procedure twelve ( 36.4% ) patients had abnormal findings on mri imaging of the lumbosacral spine . the bony abnormalities were sacral agenesis ( > 2 vertebrae absent ) and hemivertebrae , and the cord abnormalities were diastometamyelia in one and low - lying tethered cord in seven patients [ figure 2 ] . none of the perineal lesions had spinal abnormalities while only one patient with vestibular anus had cord abnormality in the form of tethered cord [ table 3 ] . sagittal t2-weighted magnetic resonance imaging showing a low - lying tethered cord ( arrowhead ) mri spinal abnormalities ( n = 12 ) in arm subtypes correlating the mri findings with the stooling outcomes , in the patients with absent vbm , 12 ( 66.7% ) had an abnormal local finding on mri and 8 ( 44.4% ) had an abnormal findings on mri spine . among the patients with soiling , 18 ( 64.3% ) had abnormal local findings and 11 ( 39.3% ) had abnormal spine findings . in the patients who had constipation , 8 ( 66.7% ) had abnormal local findings and 3 ( 25% ) had abnormal spine findings . though the number of children with abnormal stooling outcomes and mri abnormalities was twice the number of children with abnormal stooling outcomes and normal mri findings , there was no statistical significance [ table 4 ] . comparing the individual mri parameters with poor stooling outcomes , more than half of the children ( 58% ) with adverse stooling outcomes had atrophic muscle complex [ table 5 ] , though there was no significant statistical difference . correlation of stooling outcomes and local mri abnormalities correlation of individual mri findings and stooling outcomes it is well - established that children with arm have significantly worse bowel function compared with their peers . the degree of functional impairment correlates with the severity of the arm , and the late functional sequelae of fecal incontinence and/or constipation , which may frequently continue into adulthood . a number of clinical scoring systems have been used to assess the functional and stooling pattern of children with arm . of the available and relevant imaging modalities , mri is superior because of excellent soft tissue characterization , multiplanar imaging , and lack of exposure to ionizing radiation . however , the disadvantages include the availability , cost , and the relatively frequent need for sedation or anesthesia . children with arm have variable degrees of striated muscle development from near - normal muscles to complete absence of the sphincter muscle . the sphincter muscle complex is best seen on axial images at the level of the symphysis pubis and below . after identification of the muscles of the sphincter mechanism , it is important to assess the relation between the sphincter and the pulled - through bowel . malpositioning of the rectal pull - through can be identified on axial , coronal , and sagittal images . axial and coronal images best show side - to - side displacement of the bowel . sagittal images help in the assessment of anteroposterior displacement of the bowel in relation to the sphincter . children with incontinence are more likely to have the abnormal location of the neorectum , obtuse anorectal angle , and fat herniation compared to constipated children who have dilatation of the neorectum . even when the neorectum is positioned within the sphincter complex , fat herniation alone can interfere with the continence mechanism . in addition , on long term follow - up , pelvic mri studies of incontinent adults operated for arm in childhood have shown normally positioned neorectum but atrophic levator ani and sphincter muscle complex . abdominoperineal pull - through for arm was associated with the highest incidence of local abnormalities reaching statistical significance with regard misplaced neorectum ( p = 0.0001 ) and muscle atrophy ( p = 0.02 ) . patients with local abnormalities had greater incidence of absent vbm ( 66.7% vs. 33.3% ) , soiling ( 80% vs. 20% ) , and constipation ( 66.7% vs. 33.3% ) than those without these local abnormalities . if more than two sacral vertebrae are missing or there are other major sacral deformities , such as hemivertebrae and vertebral fusions , the functional outcome is worse than in patients with normal sacrum or lesser degree of sacral maldevelopment . the spinal cord and bony abnormalities are also individual factors affecting continence independent of the location of the pulled - through bowel or muscle complex atrophy . interestingly , of the seven with tethered cord , only two had the cutaneous manifestation of occult spinal dysraphism . the incidence of absent vbm ( 44% ) and soiling ( 39% ) was higher than the incidence of constipation ( 25% ) in children with spinal abnormalities . magnetic resonance imaging is a useful imaging modality in operated children of arm with poor stooling outcomes . in addition , the study was conducted over a limited period of time and hence it was not possible to determine whether surgical correction of a misplaced neorectum or detethering of the cord would help in improving the stooling outcomes in these children . a prospective study with larger numbers and longer follow - up may help us understand the effect of surgery in this subgroup of patients .
background : though the outcomes in operated children with anorectal malformation ( arm ) have greatly improved , postoperative soiling and constipation remain major issues . among the various factors described for poor outcomes ; misplaced bowel , hypoplastic sphincters and obtuse anorectal angle bear special mention . 
 the aim of this study was to compare the stooling outcomes , type of anomalies and surgical procedure with postoperative pelvic magnetic resonance imaging ( mri).materials and methods : this was a cross - sectional study involving operated children of arm who had at least 2 years of follow - up , and who were at least 3 years of age . 
 the subtypes of arm , surgical procedures , and functional outcomes were documented using the krickenbeck classification . 
 all children were subjected to a pelvic mri.results:thirty-three eligible children were part of this study . 
 twenty - two patients underwent posterior sagittal anorectoplasty , seven patients underwent abdominoperineal pull - through ( appt ) and four patients underwent perineal operations . 
 local abnormalities were present in 66% patients , and 34% had abnormalities of the spine detected on mri . 
 poorer stooling outcomes were twice as common in children with local pelvic mri abnormalities as compared to asymptomatic children . 
 the highest incidence of local abnormalities were seen in patients treated with appt ( p = 0.0001 ) . 
 no significant difference in the pelvic mri was seen among children who were constipated and those who had soiling.conclusion:mri is a useful imaging modality in operated children of arm with poor stooling outcomes . 
 local abnormalities were the most common in children undergoing abdominoperineal pull - through procedure .