Comparison of Chest Computed Tomography Findings between Pregnant and Non-Pregnant Women with COVID-19 Infection in Douala Gyneco-Obstetric and Pediatric Hospital, Cameroon

Introduction: Pregnancy is a physiologic state associated with decreased immunity, and the use of medical imaging modalities with ionizing radiation must be justified as potential benefits must outweigh the risk of any harm. However, in the wake of SARS-CoV-2 virus pandemic, chest computed tomography (CT) is necessary to assess the severity of the disease. The objective of this study was to compare the chest CT findings of pregnant and non-pregnant women with SARS-CoV-2 viral pneumonia at a tertiary hospital setting. Materials than 3 affected lobes (50.0% vs. 22.7%, p = 0.04) with a middle lobe predilec-tion (77.8% vs. 31.8%, p = 0.02). CT predictors of COVID-19 pneumonia in the group of pregnant women after the multivariable logistic regression analysis were the presence of nodules (aOR = 13.9; 95% CI: 1.25 - 134.2; p = 0.032) and linear bands of interlobular septal thickening (aOR = 17.8; 95% CI: 1.46 - 217.6; p = 0.024). Conclusion: In this study, the chest CT of pregnant women with COVID-19 pneumonia revealed mostly a combination of findings compared to non-pregnant women, with more affected lobes. These findings suggest the likelihood of a greater CT severity of COVID-19 pneumonia among pregnant women and therefore the need for timely and appro-priate management.


Introduction
More than one year after the declaration of the Coronavirus Disease-19 (COVID- 19) pandemic [1], the number of confirmed cases continues to increase, estimated worldwide at 161,513,458 as of May 15, 2021, according to the World Health Organization (WHO) [2], and affecting, in particular, the various populations at risk.
Concerning pregnant women, a recently published study did not show any significant difference, in the absence of comorbidity, on the clinical, biological and radiological aspects related to COVID-19 in pregnant women [3]. This differs from other epidemics, including the Middle East Respiratory Syndrome coronavirus (MERS-CoV) in 2012, where significant complications had been described in pregnant women, compared to the general population [4]. In general, pregnancy is a physiological state that leads to a decrease in immunity [5] and limits certain explorations, such as medical imaging modalities with ionizing radiation. The use of this type of examination must be justified, as the potential benefits must outweigh the risk of any harm [6].
However, if it is established that the diagnosis of COVID-19, is made using the Real Time Polymerase Chain Reaction test (RT-PCR), which is the reference test and usually obtained by nasal or pharyngeal swab [7]. The contribution of medical imaging, through the thoracic scanner, is very important in the detection of pneumonia [8], and also in the follow-up of the evolution of the parenchymal damage [9].
At a time when several countries, including our own, are stepping up their efforts, in particular through the intensification of vaccination [10], it seemed important to us to highlight and compare the different thoracic CT characteristics of pregnant and non-pregnant patients, especially since few studies have been carried out on the subject in our context [5], and thus to present the experience of our hospital structure.

Type of Study
This is a retrospective, cross-sectional, descriptive study.

Sampling
The sampling technique is non-probability based on the consecutive recruitment of files from patients who meet the eligibility criteria.
The sample size is summed up to the study population itself according to pre-established criteria.

Location of the Study
This monocentric study was carried out in the radiology and medical imaging department of the DGOPH, which has a recent CT scan.

Patients
We retrospectively included admission records of pregnant and non-pregnant patients aged 15 -49 years during the period from April to July 2020 at DGOPH. Patients were briefly briefed by a radiology technician on the examination procedure, and oral informed consent for the CT scan was obtained.
Data were obtained via their standardized reports, using a collection form. The authors declare no conflicts of interest.

Variables
Variables of primary interest The primary variable of interest for this study was the chest CT examination result related to the presence or absence of at least one of the following signs: Ground-glass opacities, parenchymal condensation, and the appearance of crazy paving.
Secondary variables The data for our study were extracted from the survey sheets for the collection of information. The following information was collected.
Secondary variables were age, and clinical data such as symptoms (fever with temperature > 37.5˚C, fatigue, cough, sputum, dyspnea, nasal discharge, sudden anosmia, sore throat, headache, diarrhea, and loss of appetite).

Thoracic CT Protocols and CT Image Analysis
Patients were informed of the procedure, and informed consent for the scan was obtained. The abdominopelvic region was covered by a lead apron in pregnant women, and according to the date of the last menstrual period in some patients. All the images of the selected patients were analyzed in mediastinal (width: 350 HU; level: 40 HU) and pulmonary (width: 1500 HU; level: −550 HU) windows, by 3 radiologists, in a collegial way, via the Evolucare Imaging system, which is a PACS system (Pictures Archiving and Communication System) The main CT characteristics of COVID pneumonia were defined by the Fleischner Society [11], and included the type of lesions, such as lung ground-glass opacities (increased lung density respecting the pulmonary blood vessels and bronchial walls), parenchymal condensation (higher hyperdensity erasing the blurred margins of the pulmonary blood vessels and bronchial tubes), and the appear-

Statistical Analysis
Statistical analyses were performed with SPSS 23 -0 (IBM, New York, NY).
Quantitative variables were described as mean (standard deviation, SD) or median (interquartile range, IQR). Categorical data were expressed as frequency (percentage).

The Scanographic Characteristics of COVID-19 of the 2 Groups
Concerning the CT characteristics of the 31 patients in our study population.

Discussion
In our environment, where several studies have been carried out on COVID-19, Open Journal of Medical Imaging very few have highlighted an association with pregnant women, who constitute a fragile segment of the population. During the first wave of the epidemic, some pregnant women who tested positive for Covid-19, by RT-PCR test, were able to benefit from a thoracic scanner, which was requested, more often for an evaluation of the pulmonary involvement, than for diagnostic purposes. However, it is useful to specify that if radiating examinations are not recommended in pregnant women [12], their use is not formally forbidden and depends on the indications [6]. In our study, the scans were carried out in low dose, which remains without risk for the fetus, as stated by Liu et al. [13] [14]. Likewise, these examinations did not require any injection of iodinated contrast medium, which, if necessary, depending on the indications, does not constitute any teratogenic risk, as demonstrated by studies in animals [6] [15]. Therefore, in order to contribute to the improvement of patient management in general, and pregnant women in particular, we conducted the present study, which is one of the first in our context, and which allowed us to compare the CT characteristics of 9 preg-  [16], while this is close to the data of Diouf et al., in Senegal, where the median age in 9 pregnant women testing positive for COVID was 28 years [17]. This discrete age difference between African and Asian populations may be due to our small sample sizes, but also to the relatively young age of pregnant women in sub-Saharan Africa [18].
Clinically, asthenia was the most frequent symptom in our two groups, sometimes associated with fever in pregnant women, and more often with headache in non-pregnant women, although this was not statistically significant. Ngalame et al. also found fever to be the predominant symptom in 18 pregnant women [19], as did Chawki Mrazguia in 11 other cases [20]. As a severity factor, usually encountered in the general population of our context [21], dyspnea was frequently encountered in our 2 groups (p: 0.024). Thus, this similarity of clinical data between pregnant and non-pregnant patients corroborates the results of the metanalysis of Yang et al., which also described no significant difference [22].
Regarding CT features, the combination of ground-glass opacity images and parenchymal condensation, was frequently encountered in the 2 groups (p: 0.024), going in the direction of Huanhuan findings [16]. This was in slight contrast to the results of Xiaoping, where they were also associated with fibrous bands [23]. This discrepancy in the results is probably related to the delay in performing the CT scan, which varies between individuals, depending on the onset of the symptomatology. It is worth noting that the natural history of COVID-19 pneumonia is usually characterized by regression of the initial ground glass images, followed later by the progressive development of alveolar  [24]. In our pregnant women, the involvement was mainly of a mixed axial distribution, mostly bilateral, which without being significantly specific, was however similar to the results of the meta-analysis in 427 pregnant women by Oshay et al. [12]. In our 2 groups, the middle and lower right lobes were the most frequently affected, which was also consistent with the analyses of Shi et al. in a general population of 81 patients [25]. These authors assumed that the anatomical characteristics of the right bronchus, in particular its shortness, might be a factor favoring this unilateral right predominance. The other abnormalities commonly found in COVID-19 and present in both groups, such as pleural effusion, were rather a sign of severity [3] [22], although it is common to find it in early post-partum [14]. Specifically, and after multivariate analysis, only the pseudo-nodular and linear band lesion types were significantly found in both groups, although the pseudo-nodular form is described in only about 10% of cases, according to the literature [3].
Limitations of this study include the poor maintenance of many medical records, which hindered the collection of laboratory data, as well as the small size of our sample, and the retrospective nature.

Conclusion
CT lung lesions are more common in pregnant women compared with nonpregnant women of childbearing age who test positive for COVID-19 at DGOPH.
Pseudonodular and linear banded images are the most significantly encountered lesions in our setting. Early CT diagnosis of key lung lesions would improve the outcome of pregnant women during this pandemic.