Sphincter saving anorectoplasty (SSARP) for the reconstruction of Anorectal malformations
© Pratap et al; licensee BioMed Central Ltd. 2007
Received: 07 August 2007
Accepted: 24 September 2007
Published: 24 September 2007
This report describes a new technique of sphincter saving anorectoplasty (SSARP) for the repair of anorectal malformations (ARM).
Twenty six males with high ARM were treated with SSARP. Preoperative localization of the center of the muscle complex is facilitated using real time sonography and computed tomography. A soft guide wire is inserted under image control which serves as the route for final pull through of bowel. The operative technique consists of a subcoccygeal approach to dissect the blind rectal pouch. The separation of the rectum from the fistulous communication followed by pull through of the bowel is performed through the same incision. The skin or the levators in the midline posteriorly are not divided. Postoperative anorectal function as assessed by clinical Wingspread scoring was judged as excellent, good, fair and poor. Older patients were examined for sensations of touch, pain, heat and cold in the circumanal skin and the perineum. Electromyography (EMG) was done to assess preoperative and postoperative integrity of external anal sphincter (EAS).
The patients were separated in 2 groups. The first group, Group I (n = 10), were newborns in whom SSARP was performed as a primary procedure. The second group, Group II (n = 16), were children who underwent an initial colostomy followed by delayed SSARP. There were no operative complications. The follow up ranged from 4 months to 18 months. Group I patients have symmetric anal contraction to stimulation and strong squeeze on digital rectal examination with an average number of bowel movements per day was 3–5. In group II the rate of excellent and good scores was 81% (13/16). All patients have an appropriate size anus and regular bowel actions. There has been no rectal prolapse, or anal stricture. EAS activity and perineal proprioception were preserved postoperatively. Follow up computed tomogram showed central placement the pull through bowel in between the muscle complex.
The technique of SSARP allows safe and anatomical reconstruction in a significant proportion of patients with ARM's without the need to divide the levator plate and muscle complex. It preserves all the components contributing to superior faecal continence, and avoids the potential complications associated with the open posterior sagittal approach.
Posterior sagittal anorectoplasty (PSARP), popularized by de Vries and Peña has become the preferred technique for surgical management of anorectal malformations (ARM) . The PSARP involves incision from coccyx to perineal body, to widely expose the external sphincter, the levators, the rectum, and distal fistula to facilitate surgical repair. Dividing the sphincter posteriorly can affect the pudendal nerve and its terminal branches to the sphincter in these patients, who already may be having widespread lumbar and sacral lesions . Despite excellent exposure of the anatomy and exact placement of the distal rectum within the muscle complex, continence often is less than ideal [3, 4]. In an attempt to preserve the neurophysiological function of the sphincter we describe a sphincter saving approach to reconstruct ARM.
Between March 2005 and May 2007, 26 children have undergone a sphincter saving anorectoplasty (SSARP) for high ARM. This study was conducted in accordance with the principles of the Declaration of Helsinki and 'good clinical practice' guidelines. The protocol was approved by the Ethical Review Board of B.P. Koirala Institute of Health Sciences (Ethical Review Board number: 497/062/063). Prior to the surgery written informed consent was obtained from the parents of children.
Patients with cloacal malformations, rectovesical fistula, rectovestibular fistula and low ARM were excluded from the study. Hospital charts and surgical notes were reviewed and clinical characteristics tabulated.
A thorough perineal examination, urine analysis and an invertogram was done to distinguish between high and low anorectal defects. An echocardiogram was done to evaluate congenital heart defects.
Preoperative electromyography of external anal sphincter
Patients older than 3 years were subjected to preoperative electromyography (EMG) of the external anal sphincter (EAS). Electrical activity was evaluated by needle electrodes in all the patients. A disposable 37 mm standard concentric needle electrode was inserted into the EAS as described by Podnar et al, to evaluate both the superficial part and deep parts of the muscle . The subcutaneous part of the EAS was evaluated by placing the needle electrode perpendicularly to the anoderm at a depth of a few millimeters at the site of anal dimple.
Preoperative localization of muscle complex
Augmented-pressure distal cologram
This examination was done on children with previously constructed colostomy. A lateral radiogram of the pelvis was made after injecting the contrast medium via a Foley catheter into the distal bowel with sealing of the distal stoma .
Primary or staged SSARP
The decision to perform a primary SSARP was determined by the neonate's general condition, and the presence of the air column within the rectum blind pouch within 1 cms of the last ossified vertebral bone (Figure 1). If the baby was unwell with features of sepsis or a very high pouch a high sigmoid colostomy was made and SSARP performed at a later date.
Two weeks after the repair, the patient was started on a protocol of anal dilatations. If a colostomy was constructed it was closed after the neoanus accepted the desired size of dilator.
Assessment of continence
At the follow-up visit, modified Wingspread Scoring  was adopted to investigate the fecal condition in children older than 3 years. The operative outcome was designated as "excellent," "good," "fair," and "poor." Continence was defined as the ability to stay clean without staining or soiling both day and night without pads or diapers. Soiling was defined as an inadvertent loss of small amounts of feces staining the underwear. Incontinence was defined as regular loss of solid feces. Constipation was defined as less than 3 spontaneous bowel movement per week, rectal impaction, or abdominal fecalomas.
Post operative electromyography of external sphincter
Post operative EMG was performed 3 weeks after anorectoplasty. Any sphincter abnormality was assessed by investigating the location, integrity and activity of EAS. Activity at rest and under voluntary contraction were analyzed and compared to their preoperative values.
Patient Characteristics and types of anomalies
Age at SSARP
Follow up (months)
Agenesis of left kidney
Sacral hemi vertebra
Sacral hemi vertebra
Sacral hemi vertebra
Bowel function in neonates (Group I)
The 10 neonates and infants, who are yet too young to be evaluated for continence, have symmetric anal contraction to stimulation and strong squeeze on digital rectal examination. The average number of bowel movements per day was 3–5, without the need for any laxative or enema.
Bowel function in older children (Group II)
Results according to Clinical, Radiological and Electromyography assessment
Parameters for assessment of anorectal function
Group II N = 16
Excellent and good
Fair and Poor
Sensation of perineum and anal canal after surgery
External anal sphincter integrity on EMG
CT pelvis for placement of bowel
Preoperative perception of heat cold and painful stimuli was present in all 16 children. These children continued to appreciate the sensations with the same magnitude in the postoperative period.
Follow up Computed Tomography
Electromyographic studies of EAS
The skin is not violated in posterior midline sagitally. This preserves the proprioceptive nerves, allowing better sensation which may assist in attainment of continence by providing a "sensory warning zone" .
Complete preservation of levator muscle ensures integrity of the neurovascular bundle. 4) Central placement of pull through bowel without having to divide the muscle complex in the midline. 5) Finally, the cosmetic appearance of the perineum is satisfactory, resembling the normal surface anatomy (Figure 18). One may argue that dividing the sphincter exactly in the midline, as in PSARP, is relatively safe regarding preservation of the neurovascular bundle, however, violation of this strictly midline approach is common during the "learning curve" for PSARP which may damage the sphincter. Studies have also shown that even cutting the sphincter muscle exactly in the midline was associated with decrease in mean amplitude on EMG of external anal sphincter . Under a technical perspective the only advantage of PSARP is opportunity to directly visualize the muscle complex which assists correct placement of the rectal tube. This aspect is probably the most crucial step in anorectal reconstruction and every effort should be made to correctly place the pull through bowel. SSARP achieves the same goal without having to divide and open the muscle complex. In our study we used CT scan to confirm the correct placement of guide wire preoperatively and the pull through bowel in the postoperative period. Despite the crucial role of a CT scan in this study, the risk of radiation needs to be addressed. Magnetic resonance imaging and intraoperative ultrasound are attractive alternatives to CT scan where these facilities are available. Otherwise strategies to reduce or eliminate unnecessary radiation that children get from CT examinations need to be implemented. These include focused CT examinations by limiting the field of view to the region of interest, and reducing the tube current by 50%. These strategies decrease the radiation dose by 50% without loss of information. Perfect continence is probably not realistic in patients with ARM. The results of clinical evaluation in postoperative patients with anorectal malformations vary depending on the operative methods used by various investigators. In most series continence rates are reported between 8% to 75% and improve with time [3, 16]. In our study, sphincter integrity was preserved after SSARP in all the 13 patients who showed EMG activity preoperatively. The remaining three children who had sacral agenesis had no EAS activity on EMG and were found to have fair continence scores. These three children however, have preserved proprioception in the perineum to cold, hot and painful stimuli. It is anticipated that the continence in them will improve with time primarily because of motivation and intact perineal sensation. Fortunately, we did not encounter any case with a high rectum necessitating a laparotomy. However, if the rectum is not found after opening the precoccygeal fascia, the patient can be turned supine and a laparotomy or laparoscopic mobilization of colon can be performed to gain sufficient length to proceed for a SSARP.
Recently, authors have popularized exclusive laparoscopically assisted anorectal pull-through (LAARP) to reduce the amount of posterior dissection required for accurate placement of the bowel into the muscle complex [17, 18]. In comparison to the above described technique, the step in the laparoscopic procedure of passage of the trocar through the perineum has the potential of injuring the urinary system. In addition, the incidence of postoperative prolapse is not yet known but may be a concern because of the avoidance of several key PSARP steps, most notably tacking of the rectum to the pelvic muscles . Although the early results of SSARP are encouraging, long-term functional outcome of these patients are awaited. In conclusion, sphincter saving anorectoplasty (SSARP) allows safe, minimally invasive and anatomical reconstruction of the anorectum with a satisfactory function and cosmetic outcome.
The Authors thank all the inpatient pediatric staff and operating theatre staff.
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