Universal screening for SARS‐CoV‐2 in asymptomatic obstetric patients in Tokyo, Japan

Short abstract

The prevalence of COVID‐19 in asymptomatic obstetric patients in Tokyo was shown to be 4% when universal screening was implemented. Physicians should pay attention to asymptomatic patients to prevent nosocomial infections.

Asymptomatic transmission of SARS‐CoV‐2 is a major issue in healthcare settings, and management in perinatal wards requires particular caution. Located in central Tokyo as a tertiary center, Keio University Hospital implemented universal PCR testing on patients before admission starting April 6 2020, in response to a nosocomial outbreak of COVID‐19. The present study reports a retrospective review of 52 obstetric patients universally tested for SARS‐CoV‐2 admitted to this hospital between April 6 and April 27, 2020.

PCR test results were confirmed in all patients prior to admission, except for two who were in labor before testing. The two patients were isolated and treated in negative‐pressure rooms until results confirmed them negative. Of the 52 women, none presented with symptoms of COVID‐19, yet two (3.8%) were confirmed positive when tested using PCR, and one (1.9%) was treated as positive due to close contact with her COVID‐19‐confirmed husband. For these patients, we performed elective cesarean deliveries in negative‐pressure operation rooms after obtaining informed consent, followed by postpartum care in isolation rooms. The patients remained asymptomatic, with subsequent repeated negative PCR results. The newborns were admitted to the NICU isolation area with negative ventilation; none tested positive for SARS‐CoV‐2 after birth (Table 1).

Table 1.

PCR‐confirmed and clinically suspicious cases of SARS‐CoV‐2.

Case	Age	PCR (mother)	GA	Covid‐19 symptom	PH	BW (g)	Apgar (1/5 min)	PCR (neonate)	Note
1	33	Positive	39 + 4	None	None	3715	7/8	Negative	None
2	32	Positive	37 + 2	None	None	2805	8/9	Negative	None
3	31	Negative	37 + 2	None	Hypothyroidism	2998	9/9	Negative	Husband: PCR‐positive

Abbreviations: Apgar, Apgar score; BW, birth weight; GA, gestational age (weeks + days); PH, past history.

Our findings showed that the prevalence of COVID‐19 in Tokyo among asymptomatic obstetric patients (4%) was low in comparison with other cities such as New York, where prevalence was reported to be 13%. ¹ Since the number of positive cases had likely been underestimated due to the government’s policy of solely testing symptomatic cases in Japan, the present data might offer an estimation of the asymptomatic proportion of COVID‐19 in the area. Additionally, the research highlighted the importance of preventing viral shedding from certain asymptomatic cases with regard to nosocomial infection. ²

Management of COVID‐19 obstetric patients can be greatly affected by the characteristics of a facility, such as the number of deliveries and medical staff, availability of effective isolation environments and personal protective equipment (PPE), and the crisis situation. Although there is no definitive evidence of negative‐pressure delivery rooms reducing nosocomial infections, ISUOG guidance recommends them for confirmed cases. ³ In our case, the hospital was under extreme burden of dealing with a widespread nosocomial outbreak, which led to scarcities of staffing and PPE. However, by universally testing patients before admission and determining isolation practices based on screening results, we were able to prevent transmission of SARS‐CoV‐2 within the perinatal ward while maintaining the function of a tertiary care hospital.

AUTHOR CONTRIBUTIONS

DO, YK, and MT were involved in the conceptualization, investigation, writing of the original draft, and editing and review of the manuscript. MI and SI were involved in the writing, review, and editing, and investigation of the study. MT was also responsible for the supervision of the study.

CONFLICTS OF INTEREST

The authors have no conflicts of interest.