What is the operative technique for an open rectal biopsy in a pediatric patient to rule out Hirschsprung's disease (HD)?

Open Rectal Biopsy Technique for Hirschsprung's Disease Diagnosis

Optimal Biopsy Method

The preferred technique for open rectal biopsy to rule out Hirschsprung's disease involves obtaining a full-thickness specimen 2 cm above the dentate line under direct visualization using Gruenwald's nasal cutting forceps (NCF) after anal dilatation during general anesthesia. 1

Technical Approach

Positioning and Access

• Perform anal dilatation under general anesthesia to allow direct visualization of the rectal mucosa 1
• Position the patient appropriately to access the posterior rectal wall 2 cm above the dentate line 1

Biopsy Site Selection

• Take the biopsy exactly 2 cm above the dentate line - this single site is sufficient and provides the highest diagnostic yield 1
• Biopsies taken at 3 cm and 5 cm above the dentate line do not provide additional diagnostic information 1
• Avoid biopsies too close to the dentate line, as physiologic hypoganglionosis can occur in the distal 1 cm 2

Specimen Acquisition

• Use Gruenwald's nasal cutting forceps under direct vision to obtain adequate tissue 1
• This technique yields significantly larger specimens (4.39 ± 1.07 mm²) compared to blind suction biopsy (1.59 ± 0.39 mm²) 1
• Obtain sufficient submucosa - the specimen must include adequate submucosal tissue to definitively identify or exclude ganglion cells 3, 2

Specimen Handling

• Submit the specimen immediately in appropriate fixative for both hematoxylin-eosin staining and acetylcholinesterase (AChE) histochemistry 1, 3
• Label the specimen clearly with the exact distance from the dentate line 2

Diagnostic Criteria

Histopathologic Evaluation

• Absence of ganglion cells in the submucosa combined with positive AChE staining in the lamina propria mucosa and muscularis mucosa confirms HD 4, 3
• The specimen must contain adequate submucosa to definitively exclude ganglion cells - specimens with only lamina propria or minimal submucosa are insufficient 1

Expected Diagnostic Accuracy

• This open technique under direct vision provides 100% adequate specimens, eliminating the need for repeat biopsies 1
• Sensitivity approaches 96.84% and specificity 99.42% when adequate tissue is obtained 3

Advantages Over Suction Biopsy

Superior Tissue Quality

• Open biopsy under direct vision yields consistently larger specimens with adequate submucosa 1
• Eliminates the 24% rate of insufficient specimens seen with blind suction techniques 5
• Allows diagnosis of HD and can even detect intestinal neuronal dysplasia (IND) from a single biopsy 1

Reduced Need for Repeat Procedures

• Only 8.46% of suction biopsies require repeat procedures due to insufficient tissue 3
• The open technique under direct vision eliminates this problem entirely 1

Safety Profile

Complication Rates

• Overall complication rate for rectal biopsy is 0.65%, including persistent bleeding requiring transfusion (0.53%), bowel perforation (0.06%), and pelvic sepsis (0.06%) 3
• Complications are significantly more frequent in newborns and infants compared to older children (OR 9.00, p < 0.0001) 3
• The open technique under direct vision reported zero complications in one series 1

Critical Pitfalls to Avoid

Technical Errors

• Do not biopsy too close to the dentate line - physiologic hypoganglionosis in the distal 1 cm can lead to false-positive results 2
• Avoid obtaining only mucosal tissue without adequate submucosa - this yields inconclusive results requiring repeat biopsy 1
• Do not rely on multiple biopsy sites (3 cm, 5 cm) as they add no diagnostic value beyond the 2 cm site 1

Diagnostic Limitations

• Be aware that rectal biopsy (whether suction or open) cannot detect myenteric plexus abnormalities such as hypoganglionosis, which requires full-thickness biopsy 1
• A single negative biopsy excludes HD in only 65% of cases with suction technique; a second biopsy excludes HD in an additional 11% 5
• The open technique under direct vision eliminates this limitation by ensuring adequate tissue on first attempt 1

Age-Specific Considerations

• Exercise heightened caution in newborns and infants due to 9-fold increased complication risk 3
• However, rectal biopsy can be reliably performed even in preterm infants (sensitivity 83%, specificity 97%) with no reason to postpone the procedure 4