Two trials gave an ordinary drug before surgery to prevent a complication, and both worked

Perioperative prophylaxis is unglamorous territory. Nobody announces a breakthrough for giving an existing drug shortly before an operation to reduce the chance of a known complication. But it is among the cheapest ways to improve surgical outcomes, because the drug already exists, the population is identified in advance, and the window is short.

Two 2026 randomised trials did exactly this in unrelated specialties, and reported positive results of very different magnitudes.

Tranexamic acid in placenta praevia

Placenta praevia carries a high risk of postpartum haemorrhage at caesarean delivery. Tranexamic acid, an antifibrinolytic, is already used to treat obstetric haemorrhage; the question here was prophylaxis.

Of 1,732 women with placenta praevia randomised, 38 were excluded because they withdrew consent or were determined ineligible after randomisation, and primary outcome data were available for 99.8% (1,691 of 1,694) of the remainder [s1]. Placenta accreta spectrum was diagnosed in 303 participants (17.9%) [s1]. All had caesarean delivery and received prophylactic oxytocin [s1].

The primary outcome occurred in 29.7% (251 of 845) of the tranexamic acid group against 35.1% (297 of 846) of the placebo group, a relative risk of 0.85 (95.2% CI, 0.75 to 0.96; P = 0.01) [s1].

Serious adverse events were the same in both arms: 0.5% (4 of 837) against 0.5% (4 of 845), a relative risk of 1.01 (95% CI, 0.25 to 4.00) [s1].

The authors describe the reduction as statistically significant yet modest, with no signal of increased serious adverse events [s1]. That is the right characterisation. An absolute difference of 5.4 percentage points, from 35.1% to 29.7%, in a complication that occurred in roughly a third of women either way [s1].

Follow-up of 99.8% is exceptional and worth noting, because loss to follow-up is the usual way an obstetric trial goes wrong [s1]. The safety comparison is the weakest part: four events against four events produces a confidence interval from 0.25 to 4.00, which cannot exclude a fourfold increase in serious harm [s1]. Thrombosis risk is the standing concern with antifibrinolytics, and eight events across 1,682 women is not enough to settle it.

Dapagliflozin before cardiac surgery

Acute kidney injury after cardiac surgery is common, consequential and has resisted prevention. SGLT2 inhibitors have kidney-protective effects in chronic disease, and this trial asked whether a short perioperative course helps.

Of 784 participants enrolled, 778 (99%) completed follow-up testing, with a median age of 68 years (61–74), 76% male, 97% White, a median body mass index of 27 (IQR, 25–30), and a median estimated glomerular filtration rate of 80 mL/min/1.73 m2 (IQR, 67–89) [s2]. Participants received four doses of dapagliflozin beginning the day before surgery [s2].

Dapagliflozin reduced the incidence of acute kidney injury over 7-day follow-up: 28% against 52%, a relative risk of 0.54 (95% CI, 0.45 to 0.65; P < .001) [s2].

Atrial fibrillation and reoperation were the most frequent adverse events, and neither differed between groups: atrial fibrillation in 45% (176 of 392) in both arms, and reoperation in 11% (43 of 392) against 10% (39 of 392) [s2].

A 24-percentage-point absolute reduction from four doses of a widely available oral drug is a large effect for perioperative prophylaxis [s2].

Two cautions. The first is the control-arm rate: 52% is a high incidence of acute kidney injury, which depends heavily on the definition used and how intensively creatinine is measured [s2]. Trials using sensitive definitions capture many small, transient creatinine rises alongside the clinically important injuries, and a treatment can move the former without moving the latter. The abstract reports incidence over 7 days, not dialysis, not length of stay, not mortality [s2].

The second is generalisability. This population was 97% White with a median eGFR of 80 mL/min/1.73 m2 — good baseline kidney function [s2].

Comparing them

The trials are not comparable on effect size in any meaningful way — different populations, complications and definitions — but the contrast in what would change practice is instructive.

Tranexamic acid produced a modest relative reduction of 0.85 on a common, well-defined, clinically unambiguous outcome [s1]. Dapagliflozin produced a large relative reduction of 0.54 on an outcome whose incidence depends on where the threshold sits [s2].

A smaller effect on a hard outcome and a larger effect on a softer one can carry similar practical weight. Which matters more depends on how much of that 24-point difference represents kidney injury a patient would notice.

Both drugs are off-patent or widely available, both interventions are short, and neither showed a safety signal in these trials [s1][s2]. That is the appeal of this kind of research: the cost of being wrong is low, so a modest, well-measured benefit can be enough to change practice.

What to watch

Whether the tranexamic acid finding is incorporated into obstetric guidance for placenta praevia specifically, and whether pooled data across antifibrinolytic trials can resolve the thrombosis question that eight events cannot [s1]. And whether dapagliflozin's kidney benefit tracks to outcomes patients experience — dialysis, length of stay, kidney function months later — rather than a creatinine threshold at 7 days [s2].

This article describes published trial results. It is not medical advice, and decisions about perioperative medication belong with the clinical team.