Tissue and Denervation Removed in Single-Column Hemorrhoidectomy
A single-column hemorrhoidectomy removes one of the three main hemorrhoidal cushions (typically 2–4 cm of vascular tissue and overlying mucosa) along with its associated sensory nerve endings above the dentate line, while preserving the remaining two cushions to maintain anal continence and fine sensory discrimination.
Anatomical Extent of Tissue Removal
Volume and Structure
- Each hemorrhoidal cushion represents approximately one-third of the circumferential corpus cavernosum recti, which is a normal component of the anorectal continence mechanism 1.
- The excised tissue includes the hyperplastic vascular plexus, redundant mucosa, and the submucosal connective tissue anchoring the cushion to the internal sphincter muscle 2, 3.
- Complete removal of all three cushions inevitably results in incontinence, underscoring that only the diseased segment adjacent to the muscle layer should be resected 1.
Preservation of Continence Structures
- Adequate hemorrhoidectomy technique must spare sufficient corpus cavernosum tissue to maintain the anal canal's fine-tuning function for continence 1.
- Modern techniques emphasize symptom control rather than radical tissue removal, recognizing that hemorrhoidal cushions are normal anatomical structures 3.
Degree of Sensory Denervation
Sensory Nerve Distribution
- The dentate line marks the transition between visceral (insensate) rectal mucosa above and somatic (pain-sensitive) anoderm below 4.
- Rubber band ligation must be placed at least 2 cm proximal to the dentate line to avoid severe pain, demonstrating that somatic sensory afferents are absent above the anal transition zone 4.
Denervation Pattern in Single-Column Excision
- Excision of one hemorrhoidal column removes the visceral sensory nerve endings within that cushion's mucosa, which normally detect rectal distension and contribute to sampling reflex 3.
- The procedure preserves sensory innervation in the remaining two-thirds of the anal canal circumference, maintaining adequate rectal sensation for continence 1.
- Up to 12% of patients develop sphincter defects documented by ultrasonography and manometry after hemorrhoidectomy, likely from excessive retraction rather than direct nerve injury 5.
Critical Technical Considerations
Avoiding Excessive Tissue Loss
- Excessive retraction with extensive dilation of the anal canal is responsible for sphincter injury and incontinence following hemorrhoidectomy 5.
- Anal stenosis occurs in 0–6% of cases when too much tissue is excised or when wounds are not properly reconstructed 4.
- The anal cushion lifting method dissects the cushion from the internal sphincter muscle and ligates it at the proper position without excision, potentially preserving more tissue 2.
Comparison with Multi-Column Excision
- Three-quadrant hemorrhoidectomy removes substantially more tissue and carries higher risks of stenosis and altered sensation 6.
- Circumferential excisional hemorrhoidectomy removes all three cushions but reconstructs the anal canal with undermined mucoanodermal flaps to prevent stenosis, though this represents maximal tissue removal 6.
Functional Implications
Preserved vs. Lost Function
- The remaining two hemorrhoidal cushions maintain the anal canal's ability to achieve complete closure and fine sensory discrimination for gas, liquid, and solid stool 1.
- Altered rectal sensation after hemorrhoidectomy appears related to scar tissue and anatomical changes rather than true nerve injury, as biofeedback does not correct measurable physiological sensory defects 4.