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Study breakdown

Cannabis Users Had Triple the Hematoma Risk After Breast Reconstruction Surgery

Retrospective CohortModerate evidence
The takeaway

Among 719 patients who had DIEP flap breast reconstruction, cannabis users had three times the risk of hematoma and nearly three times the risk of hospital readmission compared to non-users.

Cannabis users planning surgery, plastic surgeons, preoperative assessment clinicians

3x hematoma risk and 2.9x readmission risk for cannabis users

What the researchers found

Cannabis users (12.1% of the cohort) had significantly higher rates of postoperative hematoma (OR 3.078 for general hematoma, OR 3.098 for breast hematoma) and readmission (OR 2.865) after DIEP flap breast reconstruction. Cannabis users were also younger and had higher BMI. A 5-fold increase in the proportion of cannabis users was observed from 2015 to 2023.

Why it matters

As cannabis use becomes more common among surgical patients, understanding its effects on surgical outcomes is critical for preoperative risk assessment. The 5-fold increase in cannabis-using patients over the study period underscores the growing relevance of this issue.

The numbers in context

N=719 patients, 1148 flaps. 87 cannabis users (12.1%). 5-fold increase in cannabis user proportion from 2015-2023. Cannabis users younger (47.5 vs 51.7, p<0.001) and higher BMI (30.5 vs 28.9, p=0.012). Adjusted ORs: general hematoma 3.078 (p=0.013), breast hematoma 3.098 (p=0.020), readmission 2.865 (p=0.031). Longer time to last drain removal (21 vs 17 days, p<0.001).

How the study worked

Retrospective study of 719 adult patients (87 cannabis users, 632 non-users) who underwent DIEP flap autologous breast reconstruction between January 2015 and December 2023 by five plastic surgeons at a single institution. Multivariable logistic regression controlled for confounders.

What this study cannot tell us

Single institution, retrospective design. Cannabis use was self-reported and may be underestimated. Could not assess dose, frequency, or timing of last use relative to surgery. Cannabis users differed from non-users in age and BMI, and residual confounding is possible.

How to read the evidence

Moderate evidence from a reasonably large single-institution retrospective study with multivariable adjustment, though limited by self-reported cannabis use and possible residual confounding.

When this study was published

2025 study covering breast reconstruction cases from 2015-2023.

The bigger picture

Cannabis affects platelet function and vascular tone, which may explain the increased bleeding risk observed. As more plastic surgery patients disclose cannabis use, surgeons may need to incorporate cannabis history into preoperative risk discussions and potentially modify perioperative management.

Questions still open

  • Does a preoperative abstinence period reduce hematoma risk? Is the risk related to THC, other cannabinoids, or the route of consumption (smoking vs edibles)? Do these findings extend to other types of reconstructive or elective surgery?

Common questions

Why might cannabis increase surgical bleeding risk?
Cannabis affects platelet function and blood vessel tone. THC can cause changes in heart rate and blood pressure. These effects may increase the risk of hematoma (blood collection) after surgery, which was the primary complication found in this study.
Should cannabis users stop before surgery?
This study found higher complication rates among cannabis users but did not examine whether stopping before surgery reduced risk. The authors suggest cannabis users undergoing this type of reconstruction may need greater postoperative monitoring.

Read the original research

Impact of Cannabis Use on Deep Inferior Epigastric Perforator Autologous Breast Reconstruction: analysis of 719 patients and 1148 flaps: Impact of Cannabis Use in DIEP Reconstruction.

Annals of plastic surgery, 94(4S Suppl 2), S188-S193

Citation

Park, John B; Escobar-Domingo, Maria J; Tobin, Micaela; Lee, Daniela; Mahmoud, Amir-Ala; Rahmani, Benjamin; Adebagbo, Oluwaseun; Fanning, James E; Posso, Agustin N; Bloom, Joshua A; Cauley, Ryan P; Lee, Bernard T. (2025). Impact of Cannabis Use on Deep Inferior Epigastric Perforator Autologous Breast Reconstruction: analysis of 719 patients and 1148 flaps: Impact of Cannabis Use in DIEP Reconstruction.. Annals of plastic surgery, 94(4S Suppl 2), S188-S193. https://doi.org/10.1097/SAP.0000000000004214

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