Orange Oily Rectal Discharge: Keriorrhea from Indigestible Fish Oils
Orange oily anal leakage is almost certainly keriorrhea caused by consumption of fish containing indigestible wax esters, particularly oily fish species like escolar or Japanese Mero sea bass commonly served as sashimi. This is a benign, self-limiting condition that requires only dietary counseling and reassurance—no further investigation or treatment is needed 1.
Clinical Presentation and Diagnosis
The hallmark features that confirm this diagnosis include:
- Inadvertent, massive orange oily leakage without sphincter sensation or warning, causing significant patient alarm 1
- Recent consumption of oily fish, especially raw preparations (sashimi) or cooked versions of escolar, Mero sea bass, or similar species rich in wax esters 1
- Self-limiting course with spontaneous resolution after the indigestible oils are expelled 1
- Absence of pain, fever, or systemic symptoms that would suggest infectious or inflammatory pathology 1
The diagnosis is purely clinical based on dietary history and characteristic symptoms—colonoscopy and other investigations are unnecessary and should be avoided 1.
Pathophysiology
The mechanism involves:
- Accumulation of indigestible wax esters present in certain oily fish species that cannot be absorbed or digested by the human gastrointestinal tract 1
- Rectal accumulation and spontaneous filtration of these oils, which may also induce toxin-related sphincter dysfunction 1
- The oils remain liquid at body temperature and leak involuntarily, creating the characteristic orange oily discharge 1
Management Algorithm
Step 1: Confirm dietary exposure
- Obtain detailed dietary history focusing on fish consumption in the preceding 24-48 hours, specifically asking about sashimi, escolar, or oily white fish 1
Step 2: Exclude red flag conditions
- Ensure absence of fever, abdominal pain, rectal pain, or systemic symptoms that would suggest abscess, perforation, or other anorectal emergencies 2
- If any concerning features are present, perform digital rectal examination to exclude abscess (tender, indurated area) or other pathology 2
Step 3: Provide reassurance and dietary counseling
- Inform the patient this is a benign, self-limiting condition that will resolve spontaneously within 24-48 hours 1
- Advise avoidance of escolar, oilfish, Mero sea bass, and similar species known to contain high levels of wax esters 1
- No medications, antibiotics, or further investigations are required 1
Critical Pitfalls to Avoid
Do not order colonoscopy or extensive workup for isolated orange oily discharge with clear dietary history—this wastes resources and exposes patients to unnecessary procedures 1. The self-limiting nature and dietary association are diagnostic.
Do not prescribe antibiotics or antidiarrheals—these are ineffective against indigestible oils and provide no benefit 1.
Do not miss serious pathology by assuming all rectal discharge is keriorrhea. If the patient has pain, fever, swelling, or no clear dietary exposure to oily fish, perform digital rectal examination to exclude perianal abscess, which requires urgent surgical drainage 2, 3.
When Keriorrhea is NOT the Diagnosis
Reconsider the diagnosis if:
- No recent fish consumption or symptoms persist beyond 48 hours after dietary elimination 1
- Presence of pain, fever, or palpable mass suggests abscess requiring immediate surgical evaluation 2
- Rectal bleeding or mucus rather than pure oily discharge suggests hemorrhoids, fissure, or inflammatory conditions 4, 5