Original contribution
Normal sonographic values of maternal spleen size throughout pregnancy

https://doi.org/10.1016/j.ultrasmedbio.2006.06.017Get rights and content

Abstract

This study aims to establish normal range of sonographically measured maternal spleen size throughout pregnancy. Currently, 288 healthy pregnant women between 6 and 42 weeks’ gestation underwent ultrasonographic measurements of spleen length and width. The relationships between ultrasound measurements with prepregnancy body mass index (BMI) and gestational age were assessed using the Pearson correlation coefficient. A linear regression model was applied to construct the appropriate equation for measuring the spleen area relative to BMI and gestational age. A significant correlation (R) was found between gestational age and spleen dimensions length (R = 0.486; p < 0.001), width (R = 0.455; p < 0.001) and area (R = 0.522; p < 0.001)) as well as between prepregnancy BMI and spleen length [(R = 0.314; p < 0.001), width (R = 0.380; p < 0.001) and area (R = 0.413; p < 0.001)]. We divided the spleen area by the BMI, thus enabling to perform a linear regression analysis with gestational age (weeks) as an independent continuous variable. A high multiple correlation (R) between spleen area and this variable was found (R2 = 0.47; p < 0.001). The equation [spleen area/BMI = 1.598 + 0.032 × gestational age in weeks] was performed for calculating the spleen area throughout pregnancy. A significant overall growth pattern of spleen area in pregnancy with increasing gestational age was found. Normograms from these data can be used to evaluate splenomegaly throughout pregnancy. (E-mail: [email protected])

Introduction

The spleen is the largest organ in the reticuloendothelial system. Common clinical practice has been to use splenic size as an indicator of a number of disorders. Normal physiological changes in pregnancy, however, may also influence the size of this organ, such as an increase in the maternal blood volume by up to 45% above the nonpregnant levels (Whittaker et al. 1996). Increased blood volume results from an increase in both plasma and erythrocytes and moderate erythrocyte hyperplasia is present in the bone marrow and the reticulocyte count is slightly elevated throughout normal gestation (Cunningham et al. 2001). Normal pregnancy also involves increase in platelet width and volume (Whittaker et al. 1996). Similarly, there is a marked increase in the leukocyte count, as well as in various inflammatory proteins, such as C3 and C4 complement factors, C-reactive protein and leukocyte alkaline phosphatase, all leading to an elevated erythrocyte sedimentation rate (Whittaker et al. 1996).

Ultrasonography (US) is an established noninvasive, safe and accurate method with reproducible results for calculating splenic dimensions. Standards of normal spleen sizes have been developed for the general adult population (Niederau et al 1983, Perlmutter 1990) for children (Megremis et al 2004, Rosenberg et al 1991) and even for tall healthy athletes (Spielmann et al. 2005), thereby enabling US diagnosis of splenomegaly. Extrapolation of data from the normal population to pregnant women might, however, may be inaccurate because of the physiological changes throughout gestation.

This study aims to determine sonographic normative maternal spleen data and to suggest upper limits throughout normal pregnancy.

Section snippets

Materials and methods

This prospective cross-sectional study was conducted between January, 2005 and October, 2005. A consecutive series of 288 apparently healthy pregnant women between six and 42 weeks of normal pregnancy were examined. The gestational age was calculated from the first day of the last menstrual period (LMP) and later confirmed by biometric measurements. The figures were rounded off to whole gestational weeks. Each pregnant woman was examined once.

All the women were scanned routinely for the purpose

Results

The relevant variables of the 288 women studied are presented in Table 1. A significant correlation (Pearson; R) was found between gestational age and splenic dimensions: length (R = 0.486; p < 0.001), width (R = 0.455; p < 0.001) and area (R = 0.522; p < 0.001). Similarly, a significant correlation was found between prepregnancy BMI and splenic length (R = 0.314; p < 0.001), width (R = 0.380; p < 0.001) and area (R = 0.413; p < 0.001). From the above parameters, the highest correlation was

Discussion

To the best of our knowledge, this is the first study to evaluate and establish normal spleen size variation among healthy pregnant women throughout their pregnancy. Our findings showed that there is an overall linear increase in spleen size, as measured by ultrasound, throughout normal pregnancy. This observation is in accordance with the increased size of other abdominal organs throughout normal pregnancy. Bailey and Rolleston (1971) found that the kidney was 1.5 cm larger during the early

Acknowledgments

Esther Eshkol is thanked for editorial assistance.

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