Diagnostic Code 7335 · 38 CFR §4.114
An ano-rectal fistula (often shortened to fistula in ano) is an abnormal channel that develops between the anal canal or rectum and the skin around the anus. Most fistulas begin as an anal gland abscess — the gland clogs, an infection forms, the abscess drains either spontaneously or surgically, and a persistent track remains between the original infection site inside the anal canal and the skin where the abscess drained. The fistula then chronically discharges pus or fecal material onto the perianal skin. Veterans tend to develop ano-rectal fistulas from a combination of factors: chronic constipation and straining, prolonged sitting on hard surfaces (vehicle gunner positions, helicopter and transport seating), inflammatory bowel disease, or as a complication of prior anal surgery. The condition is rated based on the symptom pattern and degree of sphincter involvement, with the higher tiers reserved for fistulas that have damaged sphincter function or produced extensive perianal disease.
| Rating | Criteria |
|---|---|
| 0% | Healed fistula or asymptomatic fistula with no discharge and no functional impairment. |
| 10% | Mild disease — occasional discharge or perianal irritation, controlled with hygiene and standard local care. |
| 30% | Moderate disease — persistent or recurrent discharge requiring constant pad use, some impairment of sphincter function with occasional involuntary leakage of stool or mucus. |
| 60% | Severe disease — frequent involuntary loss of fecal material, persistent fistula tracks despite repeated surgical attempts, OR extensive perianal disease producing significant functional limitation. |
| 100% | Pronounced disease — complete loss of sphincter control with continuous fecal leakage requiring permanent appliance use, OR fistula complex destroying perianal anatomy and producing total functional impairment. |
An examination by a colorectal surgeon documenting the fistula tracks, the relationship to the anal sphincter (intersphincteric, transsphincteric, suprasphincteric, extrasphincteric), and the current sphincter function is the centerpiece. MRI of the pelvis or endoanal ultrasound characterizes complex or branching fistula systems. Records of any prior fistula surgery — fistulotomy, seton placement, advancement flap, LIFT procedure — document the disease course. Pad use records and continence-impact statements demonstrate the functional severity. A symptom log capturing discharge frequency and any episodes of incontinence supports the moderate and severe rating tiers. Service treatment records establishing the in-service onset of perianal symptoms or the initial abscess connect the condition to service.
A successful repair with no recurrence often drops the rating to 0% — the fistula is healed, no discharge, no sphincter compromise. The 0% rating still preserves service connection, which matters because fistulas recur in a notable percentage of cases. If the repair fails or sphincter function is damaged by the surgery itself, the rating remains at the appropriate tier and may be combined with a separate fecal incontinence rating.
No. Hemorrhoids (DC 7336) are swollen blood vessels in the anal canal; fistulas are abnormal channels through the anal wall caused by infection. Both can produce perianal symptoms but the rating codes, treatments, and natural histories are different. A colorectal exam distinguishes them quickly.
Prolonged sitting on hard surfaces is a contributing risk factor for the anal gland infections that initiate most fistulas, but it is rarely the sole cause. The standard nexus pathway runs through service medical records documenting the original abscess or initial fistula symptoms during active duty, combined with current physical findings. A nexus opinion from a colorectal surgeon connecting the in-service event to the current disease state strengthens the claim.