Short answer
Rectal STI testing swabs the rectal mucosa for NAAT detection of chlamydia and gonorrhea (with LGV typing when proctitis is severe). Covering the site genital tests cannot see, where silent infections concentrate.
Anyone with receptive anal exposure needs it; genital-only testing misses rectal infections routinely, and missed rectal infections transmit onward for months.
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See Tests & Prices →Who needs it. Exposure defines the indication
- Receptive anal exposure in any gender. The core indication, regardless of symptoms, since most rectal infections are silent.
- MSM on routine multi-site schedules (rectal swabs ride with throat, genital, and blood testing).
- Rectal pain, discharge, or bleeding with exposure history. Event-driven testing regardless of schedule position.
- Partners of rectal-infection diagnoses. Network testing that closes transmission loops.
Without anal exposure, rectal testing is generally unnecessary; honest exposure history keeps testing appropriately targeted rather than wastefully broad.
Collection methods. Undramatic by design
Clinician-collected swabs (sometimes anoscopy-guided): seconds of mild pressure in a routine clinical setting. Staff perform them daily without remark.
Validated self-collected rectal swabs: private room, simple printed instructions, accuracy equal to clinician collection.
Ask explicitly. Many clinics default to clinician collection unless patients request self-collection.
No bowel prep, no fasting, no anesthesia, no recovery.
Discomfort ranks lowest among STI sampling; the awkwardness fades by the second visit, while undetected infection persists for months without the swab.
What panels include. The complete multi-site set
- Rectal NAAT for gonorrhea and chlamydia.
- LGV molecular typing for severe proctitis or MSM-associated cases (rectal LGV mimics Crohn’s disease closely enough to misdiagnose without exposure history. See Rectal Pain and Possible STIs).
- Standard blood panels (HIV, syphilis) and genital sampling complete the multi-site set in the same visit.
One visit, complete coverage, no site left to assumption.
After positives. Treatment plus network care
- Organism-directed antibiotics (extended courses for LGV. Three weeks versus single-dose or week-long regimens for non-LGV).
- Abstinence until resolution for patient and partners.
- Partner evaluation and treatment covering the exposure window.
- Retesting per schedules (reinfection surveillance, not distrust of the cure).
Severe cases mimicking inflammatory bowel disease get gastroenterology co-evaluation when STI workups are negative. But STI testing comes first where exposures fit, because antibiotics resolve in weeks what immunosuppression would worsen.
When to seek care
After anal exposures (request rectal swabs explicitly), for rectal pain/discharge/bleeding, and on multi-site schedules with ongoing risk.