Although obesity is typically considered a risk factor for surgical complications, recent evidence suggests a possible "obesity paradox," where higher BMI may be associated with improved outcomes. This study aimed to assess the relationship between body mass index (BMI) and the frequency and severity of perioperative complications following posterior colporrhaphy.

This retrospective cohort study included 121 women who underwent posterior colporrhaphy between 2014 and 2023 at a tertiary academic medical center. Patients were stratified by BMI (≤30 vs. >30). Postoperative morbidity was evaluated using two outcomes: total complications per patient and maximum Clavien-Dindo grade. Complications were also analyzed dichotomously (grade 0 vs. ≥1). Associations between BMI and clinical/demographic variables (age, parity, hypertension, diabetes, and ethnicity) were tested using the chi-square test, Fisher’s exact test, t-tests, and the Mann-Whitney U test. A multivariable logistic regression evaluated the independent association between BMI and any complication, adjusting for age, diabetes, and ethnicity.

During the 12-month follow-up period, 62.8% of the women experienced at least one postoperative complication. Minor complications (Clavien-Dindo grade I–II) were the most common. One woman died during the follow-up, and one experienced organ failure (Clavien-Dindo grade IV), both likely unrelated to surgery. In univariable analysis, there was no statistically significant association between BMI and the occurrence of perioperative complications: 54% of women with a BMI >30 had at least one complication, compared to 69% of those with a BMI ≤30 (p = 0.092). However, a significant association was found between BMI category and both the total number of complications and the highest Clavien-Dindo grade experienced during the follow-up period (p = 0.009 and p = 0.021, respectively). Women with a BMI ≤30 had a higher number of complications and experienced more severe complications compared to women with a BMI >30. After adjusting for potential confounders such as age, diabetes, and ethnicity using a multivariable logistic regression model, BMI remained non-significantly associated with the occurrence of perioperative complications (adjusted hazard ratio [aHR] = 2.24; p = 0.061; 95% CI: 0.965–5.199).

Although BMI was not significantly associated with the overall occurrence of postoperative complications, women with a BMI ≤30 experienced a higher number and greater severity of complications compared to those with a BMI >30. This finding challenges the assumption that lower BMI confers surgical advantage. The trend toward increased risk in lower BMI groups, despite not reaching statistical significance after adjustment, suggests a need for further investigation into underlying factors such as nutritional status or frailty.

Among women undergoing posterior colporrhaphy, lower BMI was associated with greater complication burden. These findings support the obesity paradox and warrant further investigation.