///2012 Abstract Details
2012 Abstract Details2019-08-02T19:38:42-06:00

Utilization in the Obstetrics Suite: A Methodology to Determine the Need to Hold an OR for Emergent Cases

Abstract Number: S-19
Abstract Type: Original Research

Curtis L Baysinger MD MPH1 ; Celina R Jacobi BS2; Brian Rothman MD3; Jesse M Ehrenfeld MD MPH4


OB anesthesia is unpredictable, and urgent situations require immediate intervention. ACOG recommends that the decision to delivery time for an emergency cesarean section should not exceed 30 min. Subsequent studies have shown that this value is arbitrary, and there is not a significant difference in maternal or fetal outcome for a delivery interval of up to 75 min. However, the consensus within obstetrics is that timing decisions must be made on a case by case basis.

For the most pressing cases, an OR must be available for immediate use; thus, many hospitals hold an OR open for emergent cases. When an OR must be held open for emergencies, scheduled cases are delayed. Discussion of adding a third OR at our institution to accommodate emergency cesarean sections led to the discovery that there is very little literature available regarding the appropriate number of obstetric suite ORs. There is a single existing formula in the literature provided by the U.S. Dept of Defense [1]:

Total # of C/S Rooms = Projected # of Annual Cesarean Births / 500 births per room

However this formula is unsupported by any scientific data. We therefore set out to study utilization of our obstetric suite operating rooms by assessing OR usage in minutes, rather than annual case volume, to more accurately determine the number of ORs our facility requires.


After obtaining IRB approval, we extracted all OB case data from 1/1/2008 to 12/1/2010 using our perioperative data warehouse. Statistical process control (SPC) methods were then applied to the data in order to determine: 1) if the OB suite’s monthly Labor and Delivery and OB operative case volumes are stable, 2) when the highest frequency of double occupancy occurs during the day, and 3) the incidence and probability of an emergent case occurring when both ORs are occupied.


During the 3 year period, we performed 3,012 operative deliveries and a total of 6,082 cases. There were 127 cases started while another case was already in-progress including 25 emergent cases. Over three years, both ORs were empty 81.3% of the time (1,281,437 min). One OR was in use 18.5% of the time (291,422 min) and two ORs were in use 0.33% of the time (5,266 min).


We present a novel approach to evaluating OB utilization by identifying the time segments when both ORs are being used, as well as when both are open, to determine how often patients are at risk due to fully occupied ORs. In the future, if a consensus is reached regarding how many minutes, on average, out of every day this exposure is acceptable and safe, OR utilization will appropriately measure the need for an additional OR.


1. United States Department of Defense, DoD Space Planning Criteria for Health Facilities: Labor & Delivery/Obstetric Unit. Whole Building Design Guide, 2010: p. 1-13.

SOAP 2012