This study was designed to examine maternal-perinatal outcomes in pregnant women with suspected coronavirus disease 2019 (COVID-19) according to the result of a real-time reverse transcription polymerase chain reaction (RT-PCR) test and to investigate possible variables that could be useful for predicting a negative RT-PCR result. Participants of this retrospective cohort study were obstetrics patients with suspected COVID-19 who underwent an RT-PCR test in a tertiary hospital in Madrid, Spain. Maternal-perinatal features were analysed according to the results of this test. Clinical, radiological and analytical characteristics that could be associated with a negative result were also explored. In a final subgroup analysis, patients were included if they had pneumonia and a negative test result for the virus. Out of the 111 obstetric patients with suspected COVID-19 that were enrolled, 38.7% returned a negative result. In this RT-PCR-negative group, we recorded lower rates of pneumonia (21.4% vs. 45.6%, p = 0.009), severe or critical clinical features (4.7% vs. 11.8% and 0.0% vs. 5.9%, p = 0.02, respectively), lower lactate dehydrogenase (LDH) levels (168 UI/L vs. 224.5 UI/L, p = 0.003), a greater need for maternal treatment (60.3% vs 24.4%, p < 0.001), a reduced need for oxygen therapy (2.4% vs 28.8%, p < 0.001) and a lower rate of intensive care unit admission (0.0% vs. 3.7%, p = 0.046) than the RT-PCR-positive group. While no differences were found in other variables, the monocyte count was higher (946.2/μL vs. 518.8/μL, p = 0.022) in this group. The predictive model for a negative test result included the monocyte count, LDH level and no need for oxygen therapy. This model was able to identify 73.5% of patients with a negative RT-PCR result. Only 11% of the patients with pneumonia testing negative for the virus had IgG antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The proportion of pregnant women with suspected COVID-19 and a negative RT-PCR result was nearly 39%. In these patients, the symptoms were mild and the systemic severity of the disease was lower. The monocyte count, LDH level and no need for oxygen therapy were the factors that were more related to a negative test result in this group. These variables could be used to guide the management of patients with suspected COVID-19, mainly while waiting for RT-PCR results or in settings where this test is not available.
Keywords: COVID-19; RT-PCR negative result; SARS-CoV-2; maternal-perinatal outcomes; pregnancy.