Overview
Definition:
A redo Posterior Sagittal Anorectoplasty (PSAR) is a surgical procedure performed to correct residual anatomical or functional deficits following an initial PSAR for anorectal malformations (ARMs)
It aims to improve fecal continence, relieve obstructive symptoms, and address complications like anal stenosis, rectovaginal fistula, or wound breakdown from the primary surgery.
Epidemiology:
ARMs occur in approximately 1 in 2000-5000 live births
While primary PSAR has a high success rate, a significant minority of patients (estimated 5-20%) may require reoperation due to persistent issues or development of new complications over time.
Clinical Significance:
Redo PSAR is crucial for optimizing long-term functional outcomes in patients with ARMs
Inadequate initial repair can lead to severe psychosocial distress, chronic constipation, fecal impaction, recurrent urinary tract infections, and anal fissures, significantly impacting a child's quality of life
Expertise in redo PSAR is vital for pediatric surgeons managing these complex cases.
Indications For Redo
Primary Indications:
Persistent or recurrent anal stenosis
Inadequate anoperineal distance or poor pull-through of the rectum
Persistent rectovaginal fistula not closing spontaneously
Significant fecal soiling or incontinence despite a seemingly well-positioned anus
Wound dehiscence or infection leading to anatomical distortion
Presence of a residual blind pouch or inappropriate anal canal length.
Secondary Indications:
Development of new fistulas
Malrotation of the pulled-through bowel
Adhesions causing bowel obstruction or functional deficits
Poor visualization or misinterpretation of anatomy during the initial surgery.
Timing Of Intervention:
Indications for redo PSAR can become apparent early in the postoperative period or many years later
Early intervention is typically for complications like stenosis or dehiscence, while late presentations often involve functional issues like incontinence or persistent soiling.
Diagnostic Approach
History Taking:
Detailed birth history including type of ARM and initial repair
Previous surgical records are essential
Current symptoms: frequency and consistency of stools, soiling, constipation, impaction, pain, recurrent urinary tract infections, signs of fistula formation
Family history of ARMs or other congenital anomalies.
Physical Examination:
General examination for associated anomalies (VACTERL association)
Detailed perianal inspection: location and caliber of the anus, presence of fistulas, skin tags, evidence of stool soiling
Digital rectal examination (DRE) to assess anal tone, rectal vault patency, and identify any obstructions or masses
In female patients, careful examination for rectovaginal fistula or rectourethral fistula
Assessment of sacral and gluteal nerve function.
Investigations:
Contrast studies (e.g., distal colongram or MRI) to delineate the rectal anatomy, confirm fistulas, and assess the pull-through length and position
Anorectal manometry to evaluate sphincter function and resting pressure
Urodynamic studies if neurogenic bladder is suspected
Pelvic MRI for detailed assessment of pelvic musculature and innervation
Stool culture and sensitivity if infection is suspected.
Surgical Management
Preoperative Preparation:
Optimization of bowel function: regular bowel irrigations, laxatives, and dietary management to clear impacted stool
Antibiotic prophylaxis
Anesthesia and meticulous surgical planning based on prior imaging and examination findings
Ensuring availability of appropriate surgical instruments, including specialized retractors and dilators.
Surgical Techniques:
Re-exploration of the perineal plane and dissection of the neoanus
Mobilization of the distal rectum if scarred or adherent
Creating an adequate anoperineal distance
Redundant rectal mobilization if needed
For stenosis, formal dilatation or wedge resection of stenotic segments
For rectovaginal fistulas, complete dissection and closure of the fistula, with rerouting of the rectum if necessary
Placement of a temporary diverting colostomy if significant contamination or complex reconstruction is anticipated
Reconstruction of the anal canal with appropriate muscle flap or local tissue augmentation if needed.
Postoperative Care:
Pain management
Serial anal dilatations are crucial to prevent restenosis, starting within days of surgery and continuing for several months
Bowel management program to ensure regular, soft stools and prevent impaction
Wound care and monitoring for infection
Nutritional support
Gradual weaning from any diverting colostomy once bowel continuity is restored and healing is satisfactory.
Complications
Early Complications:
Wound infection
Rectal stump dehiscence
Rectal injury or perforation
Hemorrhage
Undiagnosed or incomplete closure of rectovaginal fistula
Formation of new fistulas
Anal stenosis developing acutely.
Late Complications:
Persistent or recurrent anal stenosis
Persistent rectovaginal fistula
Fecal soiling
Incontinence
Constipation and fecal impaction
Poor cosmetic appearance of the neoanus
Adhesions leading to bowel obstruction
Poorly functioning sphincter mechanism.
Prevention Strategies:
Meticulous surgical technique with careful dissection
Adequate anoperineal distance and tension-free repair
Strict adherence to postoperative anal dilatations
Aggressive bowel management to prevent constipation and impaction
Early recognition and treatment of wound infections
Careful closure of fistulas.
Prognosis
Factors Affecting Prognosis:
The underlying severity of the initial ARM
The presence and number of associated anomalies
The quality of the anal sphincter and sacral innervation
The surgeon's experience with redo procedures
Patient compliance with postoperative care, particularly anal dilatations
Presence of comorbidities.
Outcomes:
Outcomes vary significantly
Success is often defined by improved continence, relief of obstructive symptoms, and acceptable cosmetic results
Some patients may achieve good to excellent continence, while others may continue to struggle with soiling or constipation, requiring lifelong bowel management
Redo PSAR can significantly improve quality of life compared to no intervention.
Follow Up:
Long-term, regular follow-up is essential
This includes assessment of bowel habits, continence, anal caliber, and psychosocial well-being
Patients often require ongoing bowel management programs and intermittent anal dilatations
Specialist multidisciplinary clinics involving pediatric surgeons, gastroenterologists, and continence nurses are beneficial.
Key Points
Exam Focus:
Indications for redo PSAR, common anatomical pitfalls, importance of contrast studies and MRI, principles of anal sphincter preservation, critical role of postoperative dilatations, management of rectovaginal fistulas, and associated VACTERL anomalies
DNB/NEET SS questions often focus on decision-making for reoperation and management of specific complications.
Clinical Pearls:
Always review the original surgical notes and imaging if available
Careful intraoperative visualization and dissection are paramount
Do not underestimate the importance of patient compliance with dilatations
Consider the entire pelvic floor and sacral nerve function
A diverting colostomy may be a life-saving adjunct in complex cases to ensure initial healing.
Common Mistakes:
Inadequate correction of anoperineal distance
Incomplete mobilization of the distal rectum
Failure to adequately dissect and close rectovaginal fistulas
Insufficient attention to scar tissue and adhesions
Underestimating the need for prolonged and regular anal dilatations
Neglecting associated anomalies.