Rajasthan: Many Covid-19 cases go undetected in RT-PCR test

JAIPUR: Many patients are coming to hospitals who are tested negative by RT-PCR test, but they have pneumonia. Clinical features, serum markers and CT scan of chest clearly indicating Covid-19 infection.

In most of the cases, X-ray showing lungs normal but HRCT showing high CT severity score suggestive of bilateral ground glass opacity.

Covid-19 is going undetected in RT-PCR test in many cases which has increased worries of the doctors. In second wave, the low sensitivity of RT-PCR implies that a large number of Covid-19 patients will not be identified quickly and may not receive appropriate treatment.

“It looks like that in the second wave, Covid-19 is bypassing RT-PCR. People come to hospital in advance stage as Covid-19 advances symptomatically with short history,” said Dr Sudhir Bhandari, principal and controller of SMS Medical College and head of Covid-19 treatment panel of doctors.

In the Covid-19 management protocol 2021, Dr Bhandari and his team said that CT chest has a bigger role when RT-PCR is negative in Covid-19.

“Early diagnosis of Covid-19 is crucial for disease treatment and control. Compared to RT-PCR, chest CT imaging may be a more reliable, practical and rapid method to diagnose and assess Covid-19. Chest CT, a routine imaging tool for pneumonia diagnosis, is fast and relatively easy to perform. Recent research found that the sensitivity of CT for Covid-19 infection was 98% compared to RT-PCR sensitivity of 71%,” says the Covid-19 treatment protocol, 2021.

The Covid-19 treatment protocol, 2021 also highlighted case study, how quickly Covid-19 is affecting lungs and usefulness of HRCT in assessing condition of lungs. In case one, a 65-year-old male asymptomatic Covid-19 positive patient on day 3 of admission have normal looking chest X-ray, but HRCT chest suggestive of bilateral patchy ground glass opacities with CT severity score of 10/25.

Second case was of a 39-year-old man diagnosed as Covid-19 but symptomatic on day 7 of hospitalization have mild right lower zone pneumonia but HRCT chest suggestive of diffuse lung involvement of right lower zone as well as bilateral upper zone with CT severity score of 14/25. In case 3, a 65-year-old man asymptomatic Covid-19 positive patient on day 7 have normal looking chest X-ray but HRCT chest suggestive of multiple ground glass opacity with consolidation with CT severity score of 16/25. All these cases were RT-PCR negative cases.

Another case of a person tested negative by RT-PCR was of a 52-year-old male diagnosed as Covid-19 with mild fever on day 5 of hospitalization have normal appearing chest X-ray but HRCT chest suggestive of bilateral ground glass opacity with CT severity score of 18/25.