Sonofistulogram Ultrasound Scan

• Purpose: Map perianal fistulas clearly and safely.
• Technique: High-frequency sound waves create 3-D images.
• Setting: Comfortable outpatient room, no hospital stay.

Definition and purpose

A Sonofistulogram Ultrasound Scan uses a slender ultrasound probe to produce detailed pictures of the fistula tract, its internal opening in the rectum or anus, and any side branches or abscess pockets.

How it differs from traditional fistulography

• Endoanal ultrasound: Probe placed inside the anal canal for close-up detail.
• Transperineal ultrasound: Probe on the skin between anus and scrotum/vagina for deeper views.
• 3D/4D enhancements: Adds volume data and live motion for surgeons to “walk” through the tract.

1. Primary tract length – how far the fistula travels.
2. Internal & external openings – exact entry and exit points.
3. Secondary extensions/abscesses – hidden pockets needing drainage.
4. Sphincter involvement classification – Grade I–V to protect continence.

• Clarify diagnosis when clinical exam is unclear.
• Decide between fistulotomy, seton placement, or laser closure.
• Monitor healing in Crohn’s disease.

Common symptoms warranting the scan

• Recurrent perianal pain or swelling
• Pus or blood discharge near the anus
• Suspected abscess after previous surgery

Pre-surgical planning vs. post-surgical follow-up

• Before surgery: Plan the safest, least-invasive route.
• After surgery: Confirm complete healing or detect new tracts early.

• Real-time imaging – see the tract live.
• No radiation – safe for repeated follow-ups.
• Outpatient procedure – go home the same hour.
• Guides minimally invasive surgery – shorter operating time, smaller incisions.

• Simple & complex perianal fistulas
• Rectovaginal fistulas
• Crohn’s-related fistulas

• Diet & bowel prep: Clear-liquid dinner night before; 1 Fleet enema 2 hours prior.
• Medication considerations: Pause blood thinners 24 h after consulting your doctor.
• What to bring: ID, referral slip, loose clothing, sanitary pad for minor spotting.

• Completed consent form.
• Recent blood reports if abscess or fever present.

• Within 1 week of flare-up symptoms for accurate tract mapping.
• Morning slots preferred for optimal bowel prep.

Who can undergo the scan

• Adults (18+ years) with suspected or confirmed fistulas.
• Pregnant women (after first trimester) – zero radiation makes it safe.

Contra-indications

• Acute severe anal pain preventing probe insertion.
• Untreated severe rectal stricture.

1. Check-in & vitals.
2. Change into gown; lie on left side.
3. Apply gel; insert slim probe or place on perineum.
4. Capture 3-D images while you relax for 10–15 minutes.
5. Wipe gel; receive preliminary findings instantly.

• Inform staff of latex allergies or cardiac pacemakers (rare interaction with probe sensors).
• Eat a light snack post-scan to avoid low blood sugar.

Minimal risks

• Mild discomfort when the probe is inserted (relieved with lubricant).
• No radiation or contrast dye reactions.

Limitations in complex or deep tracts

• May need an MRI if the tract crosses the pelvic cavity or involves small bowel loops.