Pregnancy testing on the day of surgery

AORN Journal, June, 2008 by George Allen

Anesthesia and Analgesia April 2008

Elective surgery generally is postponed when a patient is pregnant because there appears to be an increased incidence of spontaneous abortion in women undergoing surgery during the first trimester of pregnancy, and there also may be an increased risk of congenital defects in offspring of women exposed to anesthesia during this period. Consequently, identifying a pregnancy alters clinical management of the patient.

A large cohort of women was prospectively studied to determine the incidence of unrecognized pregnancy in women presenting for elective ambulatory surgery and the effect of a positive pregnancy test in this population. In that study, however, the pregnancy test was performed as many as six days before the scheduled surgery. Human chorionic gonadotropin (hCG) concentrations can increase from undetectable to detectable during this period. Testing on the day of surgery would eliminate this problem and identify as many pregnancies as possible.

To optimize informed decision making, the Hospital for Special Surgery in New York, New York, implemented a pregnancy testing policy in November 2004 in which women of childbearing age were routinely tested for the presence of hCG in their urine on the day of surgery. The purpose of this retrospective study was to determine the results and associated cost of this policy during a one-year period and determine whether it was effective in detecting otherwise unrecognized pregnancy, subsequently altering the surgical course for elective surgery.

The medical records of all female surgical patients between January 3, 2005, and January 2, 2006, were retrospectively reviewed. The following data were collected:

* eligibility for pregnancy testing as outlined in the policy;

* reasons for exclusion from testing (eg, patient report of hysterectomy or bilateral salpingo-oophorectomy but not inclusive of tubal ligation); and

* patient refusal.

The results of urine hCG also were recorded, as was the disposition of all patients with a positive result.

The cost to implement the policy during the year was estimated using the cost of the reagents and laboratory technician time as supplied by the chief laboratory technologist. Additionally, a number-needed-to-treat analysis was performed. The positive predictive value for each positive designation was calculated as the ratio of true positives to all positives. Common statistical techniques were used to analyze the data.

FINDINGS. During the first year of the policy implementation, 2,588 of the 2,595 patients of childbearing age underwent hCG testing. Five patients had a positive result and surgery was cancelled. Of these five, three had previously unrecognized pregnancies; one had an unrecognized, asymptomatic ectopic pregnancy; and one perimenopausal woman had a false-positive result. Three other woman had a "weak positive" urine result, followed by a negative serum hCG. The incidence of unrecognized true positive pregnancies on the day of surgery was four of 2,588 or 0.15% (95% confidence interval [CI] 0.003-0.31), whereas the incidence of true plus false positives was eight of 2,588 or 0.30% (95% CI 0.10-0.52). The labor and material cost for one year of urine hCG testing was $13,046, or $3,262 per true positive result.

CLINICAL IMPLICATIONS. The results of this study revealed that routinely performing a urine hCG pregnancy test in women of childbearing age on the day of surgery was effective in detecting unrecognized pregnancies, although the costs were not insignificant. Perioperative managers should consider evaluating similar hCG urine testing policies in their facilities.

Khan RL, Stanton MA, Tong-Ngork S, Liguori GA, Edmonds CR, Levine DS. One-year experience with day-of-surgery pregnancy testing before elective orthopedic procedures. Anesth Analg. 2008;106(4): 1127-1131.

GEORGE ALLEN, PHD, RN, CNOR, CIC

GEORGE ALLEN

PHD, RN, CNOR, CIC

DIRECTOR OF INFECTION CONTROL

DOWNSTATE MEDICAL CENTER

BROOKLYN, NY