Ultrasound in Plastic Surgery - How I Use It in My Practice

Ultrasound is not new to medicine. What is less common is its use as a routine point-of-care tool in plastic surgery, not just to confirm a diagnosis, but to guide clinical decisions in real time and spare patients unnecessary procedures and associated risks. The cases below illustrate how.

Case 1 - Ultrasound-Guided Filler Injection

A patient underwent hyaluronic acid filler injection to the chin for augmentation, specifically targeting the labiomental crease, the fold between the lower lip and the chin. Addressing this crease softens the chin profile and improves projection without surgery.

Before injecting, point-of-care ultrasound (POCUS) was performed. This is widely misunderstood. US-guided filler injection does not mean injecting while watching the screen in real time as that is impractical and not the point. The purpose is twofold: first, to map the vasculature in the intended injection zone before the needle goes in; and second, to confirm the depth of placement after injection.

Doppler ultrasound was used to identify vessels in the area. None were found at the midline injection site. The midline chin is anatomically lower risk for vascular injury than more lateral facial zones, but no location carries zero risk. The confirmation that the field was clear before proceeding is the safety step that POCUS provides. Vascular occlusion from filler injection, where filler inadvertently enters a vessel and causes tissue necrosis, is one of the most serious complications of facial filler. It is rare, but the risk of which is much reduced with adequate pre-injection assessment on top of in-depth anatomical knowledge.

Following injection, POCUS was used to confirm the depth of placement. The filler was sitting supra-periosteal, directly on the surface of the mandible, the correct plane for this indication. Correct depth in this location matters beyond the immediate aesthetic result as the supraperiosteal placement reduces the risk of filler migration over time compared to more superficial injections into soft tissue planes. Clinically, the labiomental crease was well-effaced, confirming both the correct placement and the desired aesthetic outcome, and obviated the need for further "blind" filler injections.

Case 2 - Trigger Finger: Confirming the Diagnosis Before Injecting

An elderly patient presented with a three to four month history of triggering of the ring finger, requiring passive straightening (straightening it out) to unlock. Clinically, the triggering was localised to the A1 pulley, at the base of the finger, the most common site. There had been no prior treatment so a steroid injection was the first line of treatment.

Before injecting, I performed a POCUS assessment. This did not reveal any discrete lump or mass. What it did show was a slightly thickened tendon (most likely due to inflammation) just distal to the A1 pulley, which confirmed why the finger was catching. As the finger bends, this thickened segment slides under A1 but then catches against its edge (see figure below), producing the "triggering" that the patient experiences. Sometimes, this gets stuck which results in the finger being "locked", and stretching it out (so that the thickened part slides back under A1) then may or may not work.

While POCUS was used to confirm the diagnosis, it also enabled me to exclude other possible causes such as a ganglion. A steroid injection (triamcinolone mixed with local anaesthetic) was then given near the A1 pulley so that it flows along the tendon sheath to act on the inflamed tendon. The value of POCUS here is therefore primarily diagnostic rather than purely for injection guidance. The patient was told to expect the sensation of fluid flowing up and down the finger as the injection went in. This was a useful heads-up that prevents unnecessary alarm for the patient.

He improved within two weeks and is happy with the result when I reviewed him at four weeks after his initial visit. This is consistent with the evidence base for steroid injection in trigger finger. The choice of steroid, is associated with up to 83% resolution when triamcinolone was given. For first-time patients, the success rate of one steroid injection alone ranges between 35 to 56%, with an overall recurrence rate of 20.3% that tended to occur around 1 year later. Surgery, at this stage, is then associated with the final and lowest triggering rate of 10%.

The evidence thus supports a stepwise approach: one injection, reassess, a second if indicated, and surgical A1 pulley release only if conservative management fails. Proceeding directly to surgery without a trial of injection is not justifiable in most cases - it is more invasive (risk of nerve damage), more costly, and unnecessary for the majority of patients who will respond to injection alone. Surgical release under WALANT is the definitive solution for those who do not respond after two injections in my practice.

Case 3 - Post-operative Seroma: When Ultrasound Prevents an Unnecessary Procedure

A patient returned after VASER liposuction performed abroad with concerns about post-operative swelling. She mentioned that her pre-operative weight was 56 kg yet her current weight was 59 kg. This was a 3 kg gain that was not explained to her. More importantly, this is a clinically significant finding. Post-operative weight gain of this magnitude after liposuction is not normal - it likely reflects a combination of fluid accumulation from a seroma, residual tumescence fluid (which the body gradually reabsorbs), and post-operative fluid shifts. This is exactly the kind of change that structured aftercare following cosmetic surgery is designed to detect and intervene, as it can potentially be life-threatening.

In fact, she had already had the seroma drained once by the overseas clinic before returning home. However, after the drainage, she noticed that her compression garments had become too loose, but she was not provided with a replacement or adjusted garments. In my opinion, after seroma aspiration, the evacuated space must be compressed immediately and adequately to minimise the risk of re-accumulation. A loose garment after drainage provides no meaningful compression.

Not unexpectedly, when the seroma re-accumulated at 2 weeks, she was already back in Singapore and did not contact the overseas clinic. It was not because she did not want to, but rather, she knew they could not do anything from afar. She had also approached several local clinics for help and no one responded. That is the reality of the lack of aftercare after cosmetic surgery done abroad.

The clinical question when I saw her in clinic was straightforward - is there residual seroma, and if so, does it need to be drained again? I performed a POCUS and it showed minimal fluid collection, approximately 0.6 cm in thickness in the subcutaneous layer only. In fact, she was quite a thin patient and I could see her bowels moving (this is a normal finding) right under. Based on the POCUS findings, I made the decision not to drain. The collection was small enough to resolve spontaneously, and an unnecessary aspiration carries its own risks such as discomfort, infection, or worse, bowel perforation and injury given how close they were.

This is where POCUS changes management. Without imaging, the clinical options are to aspirate empirically (and accept the risks above) or to watch and wait. With imaging, the decision is well-informed both for the patient and me. The size, location, and character of the collection are visible, and the threshold for intervention becomes objective rather than estimated. She was reassured and I made arrangements for her to be fitted with a new compression garment. No further intervention was required.

Case 4 & 5: Using POCUS to Pivot from "Standard" to Targeted Care in Revision Rhinoplasty

Ultrasound is particularly transformative in revision rhinoplasty, where anatomy is often distorted by previous surgeries or trauma. These cases demonstrate how objective imaging moves a clinical plan away from empirical treatment toward evidence-based interventions.

(1) Assessing Structural Deformity Post-Trauma

A patient presented with a persistent "dent" in the scroll area of the nose. Her history was complex - she had sustained a nasal bone fracture that was for whatever reason, left uncorrected during an initial rhinoplasty that focused, instead, on her tip. Following that, she experienced significant scarring, was treated with multiple rounds of steroid injections to no avail. This was followed by a revision abroad involving what sounded like some kind of cadaveric rib allograft. Three years later, the patient presented to me with the same "dent". I suspect that the rib allograft had most likely resorbed. The literature suggests that resorption rates as high as 30 percent occur in irradiated rib allografts, but in this patient, this was academic as POCUS showed no sonographic evidence of any remaining graft material (see picture below).

POCUS assessment showing soft tissue thickness of 5.7 mm at the supratip region (patient's mouth is towards left of the picture, and forehead towards the right). Notice the irregular whitish areas which represents scar tissue (extending both left and right). Finally, note the piece of white irregular structure which is likely the nasal bone that has not healed in the right position, and most certainly contributed to the "dent".

Perviously, she was able to mask the "dent" with HA fillers, but these migrated over time and were eventually dissolved. While prior steroid injections had successfully softened some of the scar tissue and this was visible on POCUS as a reduction in scar density within the soft tissue layer under the skin, I advised against further steroid injections, as the upper lateral cartilages (ULC) are in the immediate vicinity and at risk. POCUS was the definitive tool here as it mapped the bony architecture, confirming a clear "step-off" deformity at the old fracture site, and measured the soft tissue thickness at 5.70 mm (see picture above). This objective data allowed me to confidently design a surgical plan of targeted cartilage grafting to address the bony depression, combined with supratip scar excision and tip refinement to address her concerns about a bulbous nose.

(2) Managing Chronic Post-Surgical Scarring

Another patient presented with a history of seven prior rhinoplasties, complaining of significant fullness and stiffness all around. My initial inclination was to treat the skin with roaccutane and CO2 laser as the pores were highly visible, which suggested thick oily skin with overactive sebaceous glands. However, I immediately changed my plan after POCUS.

A longitudinal scan along the nose revealed a dense, hyperechoic band of mature fibrosis (see picture below), while the transverse view confirmed significant soft tissue thickening throughout, with the most pronounced accumulation in the supratip region. This thickness is most likely a consequence of failing to adequately close off the dead space, which then affects the supratip area and tip appearance. This is a topic that I have explored and tried to address in my published research.

POCUS assessment revealed soft tissue thickness was approximately 7 mm and replaced completely with dense scar tissue (white), in keeping with seven previous rhinoplasties.

Based on these findings, I pivoted to a protocol of intralesional triamcinolone injections at a higher concentration of 20 mg/mL (rather than 10 mg/mL) given the density of the scar tissue. Injections were placed in the right, left, and middle of the supratip regions, guided both by the POCUS findings and the patient's own assessment of the thickest areas in front of the mirror. As expected, there was a lot of resistance from the scars during the injection. I am now monitoring his progress at 6-week intervals, allowing sufficient time for the corticosteroid to exert its full effect on collagen remodeling.

Why POCUS Matters in Plastic Surgery

These cases illustrate the same principle, that ultrasound in the plastic surgery clinic is not about replacing clinical judgment or imaging but rather, informing in real-time. The absence of blood vessels before injecting filler, a thickened tendon that explains a triggering finger, a seroma too small to drain, and nasal envelope thickness due to scar rather than just thick, oily skin - these findings change what happens next, on the same day. In my practice, POCUS spares patients procedures that they don't need, and it provides me with a level of certainty that clinical examination alone may not afford.

For patients considering precision non-surgical facial rejuvenation, and hand and wrist surgery in Singapore, you can read more about fillers, and hand & wrist procedures under WALANT at ZNG. For those interested in liposuction and body contouring, as well as rhinoplasty, you can read more about my liposuction-assisted , TAP blocks in abdominoplasty, and preservation approaches to the nose respectively at ZNG.

Written by Dr Ng Zhi Yang, Singapore Plastic Surgeon, and Founder & Medical Director of Doctor Stitch, a specialist-led cosmetic surgery aftercare, and same-day minor surgery service.

References

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