Semaglutide and aspiration risk in surgery

In mid-August 2026, the journal Anaesthesia published a letter and a reply, both titled "Gastric content and aspiration risk after semaglutide cessation." The letter is from Chang Y^[1], and the reply comes from Nore Vlaeminck, Veerle Saldien and Peter Van de Putte, the researchers behind the study that prompted the exchange^[2]. That study, published two months earlier, used bedside ultrasound to measure how often semaglutide patients still have food or fluid in the stomach despite a standard overnight fast^[3]. The correspondence now unfolding is about what those numbers mean for the one question anaesthesia teams actually need answered: how long does a patient need to stop the drug before surgery is safe?

What the ultrasound study measured

The study behind this exchange was a prospective, multicentre, matched case-control design. Researchers scanned 44 patients taking semaglutide and 44 controls matched by age, BMI and diabetes status, using ultrasound in both the supine position and the right lateral decubitus position. They classified a patient as having a "full stomach" if solid content was visible in any position, or if the calculated gastric volume in the right lateral position exceeded 1.5 ml per kilogram of body weight^[3]. A full stomach turned up in 21 of 43 semaglutide patients, 49%, against 8 of 44 controls, 18% (odds ratio 4.29, 95% CI 1.63 to 11.29, p=0.003)^[3]. Solid content specifically, not just fluid, was also more common in the semaglutide group.

What a full stomach on ultrasound is not

A full stomach on ultrasound is a risk marker, not an aspiration event. Nobody in the 88-patient study aspirated during the scan; the ultrasound measured stomach content, not what happens under general anaesthesia. The clinically important number is how often that retained content translates into regurgitation and aspiration once a patient is intubated or sedated, and that requires a different kind of evidence: case reports of patients who actually aspirated.

A 2024 case series in Anaesthesia Reports supplies two. A 70-year-old man having an endoscopic procedure aspirated particulate gastric content, including undigested food, during rapid sequence induction, six days after his last semaglutide dose. He developed bilateral lung infiltrates and needed intensive care before being discharged a week later. A 25-year-old woman aspirated solid and liquid stomach content after airway removal following surgery, four days after her last dose, and needed re-intubation before recovering^[4]. Both patients had already stopped the drug. Neither had gone the full week that guidance recommends.

How long current guidance says to wait

The reference point both the ultrasound study and the case reports are measured against comes from a 2024 multisociety document written jointly by the American Gastroenterological Association, the American Society for Metabolic and Bariatric Surgery, the American Society of Anesthesiologists, the International Society of Perioperative Care of Patients with Obesity, and the Society of American Gastrointestinal and Endoscopic Surgeons. It recommends holding weekly semaglutide dosing one week before a procedure and holding daily formulations on the day of the procedure^[5]. The document is explicit about its own limits: it "should be considered guidance, and not an evidence-based guideline," because little controlled evidence exists on the optimal discontinuation window^[5]. It also flags who carries extra risk within that already-uncertain picture: patients in the dose-escalation phase, patients on higher doses, patients on weekly rather than daily formulations, patients with active nausea, vomiting or abdominal pain, and patients with a separate condition affecting gastric motility, such as gastroparesis.

Why the correspondence is still going

The full text of Chang's letter and the authors' reply sits behind a journal paywall, so the exact substance of the exchange is not something we can quote from directly. What is visible from the outside is the pairing itself: two months after a matched-cohort study reported a nearly 30-percentage-point gap in retained gastric content between semaglutide patients and controls, specialists in the same journal are still working through what that gap means for a fixed, one-size-fits-all hold period. A matched-cohort ultrasound study can show that semaglutide patients carry more residual stomach content on average. It cannot, by itself, tell a clinician the right number of days to wait for any individual patient, because it did not test different stop-times against each other.

Why this matters

None of this is a reason for someone on semaglutide to make their own call about stopping the drug before a procedure. The current multisociety position, the newer ultrasound data, and the case reports of aspiration despite a partial hold all point the same direction: gastric emptying on semaglutide is unpredictable enough that the decision belongs with the prescribing clinician, the surgeon and the anaesthesia team together, not with a generic rule applied without individual assessment. Some teams now use bedside ultrasound on the day of surgery specifically to check for retained content in patients who cannot confirm a clean stop, rather than relying on the calendar alone.

For background on how semaglutide works and how it is regulated in the countries we track, see our semaglutide regulation pages. This article describes published research and professional guidance. It is not medical advice, and any decision about stopping or continuing semaglutide around a surgical procedure should be made with a clinician who knows the individual case.