Impact of surgeon annual volume on short-term maternal outcome in cesarean delivery

The annual procedure volume is an accepted marker for quality of care and has been documented in various medical fields. Surgeon volume has been shown to correlate with morbidity and mortality rates in surgical and high-risk medical procedures. Although cesarean delivery is 1 of the most common surgical procedures in the United States, the link between a surgeon's annual cesarean delivery volume and maternal outcome has never been tested.

The purpose of this study was to evaluate the impact of a surgeon's annual volume on short-term maternal outcome in cesarean deliveries.

We performed a retrospective cohort study in a single tertiary center between 2006 and 2013. Cesarean deliveries were categorized into 2 groups based on the annual volume of cesarean delivery of the attending obstetrician. The "low" group included obstetricians with a low annual volume, whose annual volume of cesarean delivery was lower than median. The "high" group comprised obstetricians with a high annual volume whose annual volume was at median and above. Further analyses were done for quartiles and for 4 clinical relevant groups according to the annual number of cesarean deliveries that were performed/supervised by the attending obstetrician (≤20, 21-60, 61-120, and >120). The primary outcome was a composite adverse maternal outcome that included ≥1 of the following outcomes: urinary or gastrointestinal tract injuries, hemoglobin drop >3 g/dL, blood transfusion, relaparotomy, puerperal fever, prolonged maternal hospitalization, and readmission. Secondary outcomes were operative times (skin incision to delivery and overall).

A total of 11,954 cesarean deliveries were included; the median annual number of cesarean deliveries that were performed/supervised by 1 obstetrician was 48. Unadjusted analysis suggested that the patients in the high group had fewer urinary and gastrointestinal injuries (18/9278 [0.2%] vs 16/2676 [0.6%] injuries; P < .001), less blood loss as measured by hemoglobin drop >3 g/dL (1053/9278 [11.5%] vs 366/2676 [13.8%]; P < .001), and fewer cases of prolonged maternal hospitalization (80/9278 [0.9%] vs 39/2676 [1.5%]; P = .006). The rate of blood transfusion, relaparotomy, puerperal febrile morbidity, and readmission to hospital did not differ between groups. Multivariable regression analysis showed that cesarean delivery performed/supervised by the high group resulted in a significantly lower composite adverse maternal outcome (15.8% vs 18.9%; odds ratio, 0.86; 95% confidence interval, 0.78-0.95; P = .004). This was related primarily to a decreased frequency of urinary and gastrointestinal injuries, lower likelihood of hemoglobin drop >3 g/dL, and lower incidence of prolonged maternal hospitalization. Operative times were significantly shorter for the high group. Composite adverse maternal outcome ranged from 21.8% in the lowest quartile to 17.9% in quartile 2, to 17.4% in quartile 3, and 15.6% in quartile 4. quartile 4 served as the reference; quartile 3 had an odds ratio of 1.14 (95% confidence interval, 1.01-1.29; P = .029); quartile 2 had an odds ratio of 1.18 (95% confidence interval, 1.02-1.36; P = .021, and quartile 1 had an odds ratio of 1.51 (95% confidence interval, 1.14-1.99; P = .004) for composite adverse maternal outcome. Composite adverse maternal outcome ranged from 21.5% in clinical group 1 to 17.5% in clinical group 2, to 17.9% in clinical group 3, and 15.2% in clinical group 4 (P = .001). Cesarean delivery performed/supervised by clinical groups 2, 3, and 4 in comparison with clinical group 1 were associated with a statistically significant risk reduction, (23%, 25%, and 34% respectively).

Maternal composite morbidity is decreased as the volume of cesarean deliveries that are performed or supervised by obstetricians increases.