What are the associations and management of anorectal malformations?

Anorectal Malformations: Associations and Management

Associated Anomalies

Anorectal malformations (ARM) are associated with additional congenital defects in approximately 67% of patients, most commonly involving the urogenital tract (43%), skeleton (38%), gastrointestinal tract (24%), cardiovascular system (21%), and central nervous system (15%). 1

VACTERL Association

• VACTERL association occurs in 44% of ARM patients, representing the most common pattern of associated anomalies, encompassing Vertebral, Anorectal, Cardial, Tracheo-Esophageal, Renal and Limb defects 1
• Between 10% and 52% of children with ARM have associated dysraphic spinal malformations, which significantly impact long-term bowel and bladder function 2
• The incidence of sacral anomalies is 11% in low-type ARM but increases to 43% in complex malformations 2

LUMBAR/SACRAL/PELVIS Syndrome

• LUMBAR syndrome refers to Lower body hemangioma and other cutaneous defects, Urogenital anomalies and Ulceration, Myelopathy, Bony deformities, Anorectal malformations, Arterial anomalies, and Renal anomalies 3
• This represents the "lower half of the body" variant of PHACE syndrome, with associated segmental lumbosacral or anogenital hemangiomas 3

Specific Associated Conditions

• Sacral anomalies include sacral agenesis (partial or complete), hemisacral agenesis with "scimitar sacrum," and Currarino triad 2
• Maternal gestational diabetes is a well-described risk factor for sacral agenesis 2
• Trisomy 21 combined with ARM without a fistula represents a notable association 1
• Syndromes are recognized in 5% of ARM patients, and sequences in 2% 1

Classification and Surgical Planning

Anatomical Classification

ARM should be classified as low, intermediate, or high based on the relationship to the levator ani muscle, as this directly impacts surgical planning. 2

• Low malformations typically require perineoplasty in the neonatal period 2
• Intermediate and high malformations require staged repair with initial colostomy followed by definitive pull-through procedures 2
• Complex malformations have a higher association with spinal dysraphism compared to simple malformations 2

Diagnostic Evaluation

• Correct type classification requires invertography, fistelography, and urethrography in the neonatal period 4
• MRI is essential for accurate diagnosis when clinical examination suggests a deep abscess or complex anatomy, as it is the only modality that can determine the level and type of malformation, fistula type, sphincter muscle complex development, and presence of associated anomalies 5
• Urodynamic evaluation before surgical correction provides information about sacral spinal cord involvement and serves as a baseline for postoperative comparison 2

Management Approach

Surgical Strategy by Type

Low-type malformations:

• Principally managed with neonatal perineoplasty 4
• Use minimally invasive operative methods to preserve native continence mechanisms 6
• In patients with obvious fistula, fistulotomy should only be performed at abscess drainage if the fistula is low and does not involve sphincter muscle 2

Intermediate and high-type malformations:

• Initial colostomy followed by pull-through operation during infancy 4
• Posterior sagittal anorectoplasty (PSARP) or laparoscopy-assisted surgery are accepted alternative procedures 4
• Preoperative distal colostography with diverting colostomy is useful for deciding surgical procedure in atypical fistula cases 7

Evaluation for Tethered Cord

• Secondary urinary incontinence, especially when combined with fecal incontinence and/or constipation, may indicate tethered cord syndrome requiring urodynamic evaluation and potential neurosurgical intervention 2
• Not all sacral dimples require imaging; however, lumbosacral dermal sinus tracts are abnormal and require surgical correction 2

Long-Term Outcomes and Complications

Functional Prognosis

• One-third of adult patients with high- or intermediate-type malformations occasionally complain of fecal incontinence after surgery 4
• Many patients with low anomalies suffer from long-term anorectal functional problems, especially constipation, with soiling occurring in a significant percentage 6
• Most patients with ARM have normal urinary function if they do not have urinary tract or sacral anomalies 4

Sexual and Reproductive Function

• Associated urinary tract or sacral anomalies influence prognosis for sexual function, especially in males 4
• Some female patients have experienced normal vaginal delivery and had children 4
• In patients with cloacal malformation, fertility or sexual problems are often present 4

Critical Pitfalls

• Only well-planned and systematic treatments based on correct neonatal classification can provide good functional prognosis 4
• Atypical fistula courses (rectoscrotal, rectoperineal running near urethra) may require modified surgical strategies with non-detaching approaches to prevent urethral injury 7
• The goal of surgery is to achieve good bowel, urinary, and sexual functions to enable children to become healthy adults 4