BACKGROUND: Primary bladder closure of classic bladder exstrophy (CBE) is a major operation that occasionally requires intraoperative or postoperative (within 72 h) blood transfusions. OBJECTIVE: This study reported perioperative transfusion rates, risk factors for transfusion, and outcomes from a high-volume exstrophy center in primary bladder closure of CBE patients. STUDY DESIGN: A prospectively maintained, institutional exstrophy-epispadias complex database of 1305 patients was reviewed for primary CBE closures performed at the authors' institution (Johns Hopkins Hospital) between 1993 and 2017. Patient and surgical factors were analyzed to determine transfusion rates, risk factors for transfusions, and outcomes. Patients were subdivided into two groups based upon the time of closure: neonatal and delayed closure. RESULTS: A total of 116 patients had a primary bladder closure during 1993-2017. Seventy-three patients were closed in the neonatal period, and 43 were delayed closures. In total, 64 (55%) patients received perioperative transfusions. No transfusion reactions were observed. Twenty-five transfusions were in the neonatal closure group, yielding a transfusion rate of 34%. In comparison, 39 patients were transfused in the delayed closure group, giving a transfusion rate of 91%. Pelvic osteotomy, delayed bladder closure, higher estimated blood loss (EBL), larger pubic diastasis, and longer operative time were all associated with blood transfusion. In multivariable logistic regression, pelvic osteotomy (OR 5.4; 95% CI 1.3-22.8; P < 0.001), higher EBL-to-weight ratio (OR 1.3; 95% CI 1.1-1.6; P = 0.029), and more recent years of primary closure (OR 1.1; 95% CI 1.0-1.2; P = 0.018) remained independent predictors of receiving a transfusion (Summary Table). No adverse transfusion reactions or complications were observed. DISCUSSION: This was the first study from a single high-volume exstrophy center to explore factors that contribute to perioperative blood transfusions. Pelvic osteotomy as a risk factor was unsurprising, as the osteotomy may bleed both during and immediately after closure. However, it is important to use osteotomy for successful closure, despite the increased transfusion risk. The risks accompanying contemporary transfusions are minimal and osteotomies are imperative for successful bladder closure. CONCLUSIONS: More than half of CBE patients undergoing primary closure at a single institution received perioperative blood transfusions. While there was an association between transfusions and osteotomy, delayed primary closure, larger diastasis, increased operative time, and increased length of stay, only the use of pelvic osteotomy, higher EBL-to-weight ratio, and recent year of closure independently increased the odds of receiving a transfusion on multivariate analysis.