Sinogram Test: What It Is, Procedure and What It Detects

A sinogram test is a radiology procedure that visualizes the course of a sinus tract. A sinus tract is an abnormal channel running from the surface of the skin down into deeper tissue, usually created by infection, post-surgical changes, or a retained foreign body.

The procedure works by injecting contrast dye into the external opening of the tract and capturing real-time X-ray images as the contrast fills it under fluoroscopy.

The resulting images show where the tract goes, how long it is, how deep it penetrates, and whether it connects to bone, an abscess cavity, or any adjacent structure.

A sinogram is ordered when a wound continues to discharge fluid or pus despite appropriate wound care and antibiotic treatment, and the clinical team needs to understand what is driving it from within.

Common clinical triggers include a post-surgical wound that has not healed within the expected timeframe and continues to produce discharge, a chronic sinus tract following an old infection or trauma, suspected osteomyelitis where a persistent tract from the skin to underlying bone is the mechanism of ongoing infection, and a wound where a retained surgical material or foreign body is suspected but not visible on plain imaging.

The sinogram provides a detailed map of the sinus tract from its surface opening to its termination point. Radiologists assess several key features during the procedure.

Tract length and depth determine how extensive the internal component is and whether it reaches deep fascial planes, muscle, or bone.

The termination point identifies where the tract ends. A tract terminating in soft tissue carries different implications from one that ends at a cortical bone surface or within a joint space.

Connections to bone are clinically significant. In chronic osteomyelitis, the sinogram may reveal a tract extending directly to infected or necrotic bone, sometimes outlining a sequestrum within the tract.

Abscess cavities connected to the surface opening become clearly visible once filled with contrast, allowing accurate size and position assessment before drainage or surgical planning.

Retained foreign bodies are occasionally identified incidentally when contrast flows around a radio-opaque object within the tract.

Branching tracts are detected when contrast enters side channels not visible at the surface. These secondary branches are clinically important because incomplete treatment of any branch allows recurrence.

Preparation for a sinogram test is minimal.

Fasting is not typically required unless the procedure is being combined with sedation or another intervention requiring it. Confirm with the imaging centre at the time of booking whether any specific preparation applies.

Disclosure of contrast allergy is the most important preparation step. The iodine-based contrast used in sinogram procedures carries a risk of allergic reaction in sensitised individuals.

Any prior reaction to iodine or contrast dye must be communicated to both the referring clinician and the imaging team before the appointment is confirmed.

Pregnancy must be disclosed before the procedure because it involves ionising radiation. Alternative imaging approaches may be considered depending on gestational stage and clinical urgency.

The procedure is performed in a fluoroscopy suite by an interventional radiologist, usually with a radiographer assisting.

The skin around the sinus opening is cleaned with an antiseptic solution. Local anaesthetic is applied to the area around the opening if catheter insertion is anticipated to cause discomfort.

A small, flexible catheter or cannula is gently introduced into the tract opening, or connected directly to an existing drainage tube if one is in place.

Contrast dye is injected slowly under real-time fluoroscopic imaging. The radiologist observes the contrast filling the tract on the fluoroscopy monitor, directing the patient to change position as needed to allow contrast to flow through all branches and reach the termination point.

A sinogram test is generally safe, but several limitations and risks are relevant to informed consent.

A contrast reaction is the primary risk. Mild reactions, including flushing, nausea, and urticaria, are uncommon but possible.

Severe anaphylactic reactions are rare. Pre-procedure allergy disclosure and the availability of emergency medication at the imaging center are the standard risk management measures.

Incomplete visualization occurs when thick debris, pus, or a large abscess cavity prevents contrast from filling the full extent of the tract.

In these cases, the sinogram may underestimate the tract's extent, and follow-up CT or MRI may be required to complete the assessment.

A contraindication in active sepsis applies when a patient has signs of systemic infection, fever, and hemodynamic instability.

Contrast injection into an infected tract under these circumstances carries a risk of bacteremia. The procedure is deferred until systemic infection is controlled.

Radiation exposure is present as with any fluoroscopic procedure. The dose is low and generally considered acceptable for diagnostic purposes, but pregnancy disclosure remains important.

A sinogram result typically creates an immediate downstream need: specialist interpretation in the context of the wound's clinical history and a treatment plan based on what the tract anatomy reveals.

For most employees, navigating this across a radiology center, a referring surgeon, and a follow-up appointment involves significant coordination and delay.

Diagnostics: 8,500+ NABL-Accredited Labs and Imaging Centers. Employees can book a sinogram procedure cashlessly through Visit Health's diagnostic network across India.

Results are tracked digitally through the app and accessible without requiring physical report collection.

Teleconsultation: Orthopaedics and General Surgery. A sinogram report describing a tract extending to bone, an abscess cavity, or a retained foreign body requires specialist interpretation alongside wound assessment.

Visit Health's teleconsultation platform connects employees with orthopedic surgeons and general surgeons across 30+ specialties, same day, without a hospital visit or a separate referral chain.

AI-Powered Smart Reports: Sinogram reports contain radiological descriptions of tract course, caliber, termination, and connectivity that most patients cannot interpret independently.

Visit Health's Smart Reports to convert imaging findings into plain-language summaries explaining what was found, what it indicates clinically, and what the recommended next step is.

Visit Clinic: Bengaluru (Marathahalli, Outer Ring Road). For employees in Bengaluru who need an in-person wound review, a post-sinogram surgical consultation, or a referral for further imaging, Visit Clinic provides on-ground appointments connected to the broader diagnostic and specialist ecosystem.

A sinogram test answers a specific question that surface wound assessment and standard imaging cannot: what is the internal anatomy of this tract? Where does it end? What structures does it involve? For any wound that continues to discharge despite appropriate treatment, that answer is what determines whether further surgery, targeted debridement, or a change in antibiotic strategy is the right next step.

What is a sinogram test used for? 

Mapping the internal course of a sinus tract from a non-healing wound or chronic discharge to determine where it leads, how deep it extends, and what it connects to beneath the skin surface.

Is a sinogram test painful? 

Generally well tolerated. Local anesthetic is applied before catheter insertion where needed, and most patients experience mild pressure rather than significant pain during contrast injection.

How is a sinogram different from a fistulogram? 

A sinogram visualizes a blind-ending tract that opens onto the skin. A fistulogram visualizes a tract connecting two internal organs or cavities. The injection technique is similar, but the clinical indications differ.

What preparation is needed before a sinogram test? 

Minimal. No fasting is typically required. Disclose any contrast allergy or pregnancy before the appointment, and wear comfortable clothing without metal items near the wound site.

How long does a sinogram procedure take? 

Between 30 and 60 minutes, depending on the complexity of the tract and the number of positions required to fully document its course.

Can a sinogram detect osteomyelitis? 

It can reveal a tract extending from the skin surface to infected bone, which is a characteristic finding in chronic osteomyelitis. The sinogram documents the tract's connection to bone but does not directly characterise the bone infection itself. Further imaging, typically MRI, may be required for complete assessment.

Are there risks involved in a sinogram test? 

The primary risk is a contrast dye reaction. Incomplete visualisation is possible when debris or pus blocks contrast flow. The procedure is deferred in active systemic infection.

Can a sinogram test be booked through Visit Health? 

Yes. Through Visit Health's OPD benefit, cashlessly across 8,500+ NABL-accredited imaging centres, with digital result tracking, Smart Report interpretation, and same-day specialist teleconsultation available through the same platform.

Map your wound tract accurately, book a cashless sinogram through Visit Health and access same-day surgical specialist review.