Whether to Test Laboring Women for SARS-CoV-2 May Hinge on Regional Prevalence

Jake Remaly

May 29, 2020

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Labor & delivery units may need to consider regional prevalence of COVID-19 when deciding whether to test asymptomatic pregnant women for SARS-CoV-2 infection at the time of admission, research published online in Obstetrics & Gynecology suggests.

In Los Angeles, researchers stopped universal testing after none of the first 80 asymptomatic women had positive results. Researchers in Chicago, on the other hand, found a positive rate of approximately 1.6% among 614 asymptomatic patients and continue to test all patients.

"Decisions regarding universal testing need to be made in the context of regional prevalence of COVID-19 infection, with recognition that a 'one-size-fits-all' approach is unlikely to be justifiable," Torri D. Metz, MD, of University of Utah Health in Salt Lake City said in an editorial accompanying research letters that described the experience in Los Angeles and Chicago. "In the setting of low population prevalence of COVID-19 infection or in locations with limited testing availability, deferring universal testing may represent the better part of valor when weighing risks, benefits, economic burden, and unintended consequences of testing for SARS-CoV-2 infection. In high-prevalence regions, universal testing may be a valuable addition to obstetric care that will prevent infections in health care workers and neonates."

Testing all patients also may provide valuable population-level surveillance, added Dr. Metz, who is an associate professor of obstetrics and gynecology, a maternal-fetal medicine subspecialist, and vice-chair of research in obstetrics and gynecology.

One week of data

After New York hospitals reported an approximately 13% prevalence of SARS-CoV-2 infection among asymptomatic laboring women, Cedars-Sinai Medical Center in Los Angeles changed its policy from testing only women with COVID-19 symptoms to testing all women beginning April 4, 2020. "Data from New York made us very concerned about the possibility of asymptomatic infections among our own pregnant patients," Mariam Naqvi, MD, a maternal-fetal medicine specialist at Cedars-Sinai Medical Center, said in a news release. "This would have implications for them, their babies, their households, and for the health of our staff caring for them."

In 1 week, 82 pregnant women admitted to the obstetric unit were tested for SARS-CoV-2 infection. Of two women who reported COVID-19 symptoms, one tested positive for SARS-CoV-2. "Of the remaining 80 asymptomatic women, none tested positive for SARS-CoV-2 infection, and all remained symptom free throughout their hospitalizations," Dr. Naqvi and colleagues reported. "One asymptomatic patient had an inadequate nasopharyngeal specimen and declined repeat testing."

Precautions taken during universal testing meant that all members of the treatment team used valuable personal protective equipment. In some cases, mothers and newborns were separated until test results were available.

"We discontinued universal testing after a 7-day period, because we could not justify continued testing of asymptomatic women in the absence of positive test results for SARS-CoV-2 infection," they noted. "Though universal testing did not yield enough positive results on our obstetric unit to warrant continued testing at this time, our approach may change if local rates of infection increase."

20 days of testing

In a prospective case series of pregnant women admitted to Northwestern Memorial Hospital in Chicago from April 8 to April 27, 2020, universal testing did detect asymptomatic infections. Women with scheduled admissions were tested 12-36 hours before admission in a drive-through testing center, and women with unscheduled admissions received a test that has a 2- to 3-hour turnaround time. In addition, patients were screened for symptoms such as fever, shortness of breath, cough, sore throat, body aches, chills, new-onset vomiting, diarrhea, loss of taste or smell, and red or painful eyes.

"Asymptomatic women with pending tests were managed on the routine labor floor, but health care workers used personal protective equipment that included a respirator during the second stage of labor and delivery until the test result became available," wrote Emily S. Miller, MD, MPH, of Northwestern University, Chicago, and colleagues.

During the first 20 days of universal testing, 635 pregnant women were admitted, and 23 (3.6%) tested positive for SARS-CoV-2 infection. Of 21 women with COVID-19 symptoms, 13 (62%) tested positive for SARS-CoV-2 infection. Of 614 women who were asymptomatic, 10 (1.6%) tested positive for SARS-CoV-2. "Our data corroborate the observation that pregnant women with SARS-CoV-2 infection on admission do not seem to be reliably identified using symptom screening alone," the researchers wrote.

Unintended Consequences

Despite a lack of effective treatments for mild to moderate COVID-19, "knowledge of the disease state allows ... health care workers to wear appropriate personal protective equipment to avoid exposure," Dr. Metz wrote. It also allows "women to be counseled about ways to decrease transmission to neonates" and enables close monitoring of patients with infection.

At the same time, universal testing may have unintended consequences for infected patients, such as stigmatization, separation from the newborn, and delays in care related to health care providers spending more time donning personal protective equipment or changes in medical decision-making regarding cesarean delivery, she emphasized.

"Obstetricians should remain aware of disease prevalence in their communities and consider universal screening of asymptomatic women on an ongoing basis as new 'hot spots' for COVID-19 infection are identified," Dr. Metz concluded.

One of Dr. Naqvi's coauthors disclosed receiving funds from Contemporary OB/GYN, Keneka, and the American College of Obstetricians and Gynecologists and serving as a board examiner for the American Board of Obstetrics and Gynecology; her coauthors did not report any relevant financial disclosures. Dr. Metz disclosed that money was paid to her institution from Pfizer and GestVision for work related to an RSV vaccination trial and a preeclampsia test, respectively. Dr. Miller and colleagues did not report any potential conflicts of interest.

SOURCES: Naqvi M et al. Obstet Gynecol. 2020 May 19. doi: 10.1097/AOG.0000000000003987; Miller ES et al. Obstet Gynecol. 2020 May 19. doi: 10.1097/AOG.0000000000003983; Metz TD. Obstet Gynecol. 2020 May 19. doi: 10.1097/AOG.0000000000003972.

This story originally appeared on MDedge.com.

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