SONOGRAPHIC EVALUATION OF THE LIVER IN PREGNANT WOMEN

CHAPTER ONE

INTRODUCTION

1.1 Background of Study

The variations in the sizes of the various organs during pregnancy is well known with various organs of the body lincreasing in size throughout pregnancy and returning to their pre-pregnant state during the pueperium (Melamedet al., 2011). The liver is the largest abdominal organ with function in filtering and storage of blood, metabolizing of carbohydrates, proteins, hormones and strange chemicals; to form bile, storage of vitamins and iron; and production of clothing factors. Also, the liver size estimation is important in the diagnosis and follow up of various disease occurring in pregnancy like hepatitis, and hypertensive diseases of pregnancy (Wennet, 2001). Thus, the knowledge of the normal sonographic liver size is important.

Ultrasonography is the best method for the assessment of abdominal organs during pregnancy as it is non-invasive non-ionizing thus safe in pregnancy. It is also readily available, quick, cheap and accurate (Kerstin and Brennan 1992). Examination is in real time, three-dimensional and independent of organ function thus the internal structures can be assessed easily. It has advantages over other radiological imaging modalities such as conventional radiography and computed axial tomography in that ionizing rays which are harmful to the developing fetus are used. With ultrasound, sound energy is used and has been found to have no adverse effect on the developing fetus, thus it is safe. It can be used at any stage of pregnancy (Miller et al., 1984). Physical examination of the liver through palpation and percussion is less accurate compared to ultrasound estimation of the size especially in detecting small increases in size (Rosemeriet al., 2010).

The liver occupies 5% of the mature fetus body cavity and it constitutes 2.5% of the adult body weight (Ronald, 2003). Liver weight in the adult male is approximately 1400-1500g2 and it serves over 500 physiological functions related to metabolism, digestion, immunity and storage of nutrients (Moore, et al., 2010).

Conventional and pulsed color Doppler ultrasonography are considered to be indicated for the study of gestation and maternal organs on account of the multiplicity of morphological and hemodynamic data that they provide for being innocuous for their noninvasive and relatively low cost. The Doppler modality is utilized for qualitative and quantitative evaluation of the arterial and venous perfusion and can increase the ultrasonography accuracy, identifying the blood flow in the vessels and their respective resistivity and pulsatility indices as well as the study of their indices in the physiological alterations observed during pregnancy.

Accurate measurement of the liver by sonography is particularly relevant when hepatic diseases are suspected. As a noninvasive and inexpensive method, when compared to other methods (Tchelepici, et al., 2002), diagnostic sonography is particularly useful to evaluate liver size and texture. In recent years, diagnostic sonography has shown specificity and positive predictive value in assessing the liver and its various diseases (Hung, et al., 2003). But according to a number of validated sources, measurements of liver length still varies greatly across modalities and techniques used by the operator (Rumack, et al., 2011).

Conventional and pulsed color Doppler ultrasonography are considered to be indicated for the study of gestation and maternal organs on account of the multiplicity of morpho- logical and hemodynamic data that they provide, for being innocuous, for their noninvasiveness and relatively low cost.

The Doppler modality is utilized for qualitative and quantitative evaluation of the arterial and venous perfusion and can increase the ultrasonography accuracy, identifying the blood flow in the vessels and their respective resistivity (RI) and pulsatility (PI) indices, as well as the study of their indices in the physiological alterations observed during pregnancy. Studies involving Doppler ultrasonography of maternal organs during pregnancy present contradicting results, with little information related to alterations observed during that period. Thus, the authors have developed the present prospective longitudinal study with B-mode ultrasonography and pulsed color Doppler ultrasonography of maternal kidneys and liver in low-risk pregnancy to establish and quantify normality parameters, correlating them with the physiological alterations observed during the gestation.

1.2 Statement of Problem

There are few studies that have critically investigated on the ultrasonographic evaluation of the liver in pregnant women around the globe. Earlier studies concluded that that there were positive correlations between the liver length and body mass index but not with the parity gestational age. Thus, this study is needed in order to document the possible observations commonly seen as regard the length of the liver in the pregnant women at the Agbor general Hospital using ultrasonographic measures.

1.3 The Aim (General Objective)

The general objective of this study is to investigate on the ultrasonographic evaluation of the liver in pregnant women at the Agbor general Hospital.

1.4 The (Specific) Objectives

1) To study, by means of conventional ultrasonography, kidneys, liver and the bile ducts in pregnant patients, establishing the morphological changes of the kidneys and liver in low-risk pregnant women.

2) To establish, by means of pulsed color Doppler ultrasonography, velocity, RI and PI of the renal arteries.

3) To establish, by means of pulsed color Doppler ultrasonography, RI and PI of intra-renal arteries (segmental, interlobar and arcuate) and the initial systolic acceleration of the segmental arteries.

4) To establish the presence of renal lithiasis.

5) To establish, by means of pulsed color Doppler ultrasonography, portal vein flow velocities.

6) To establish, by means of pulsed color Doppler ultrasonography, the flow and wave pattern of the right hepatic vein.

7) To establish the presence of cholelithiasis.

8) To correlate the observed results with the physiological changes in pregnancy.

1.5 Rationale of the Study / Significance

Several studies have identified that body tends to increase in size throughout pregnancy and also returns to their pre-pregnant state during the pueperium (Melamedet al., 2011) and also it has been reported from prior studies there are positive correlation between the liver length and body mass index but not with the parity gestational age, while studies on the ultrasonographic evaluation of the liver in pregnant women in Nigeria have been neglected in previous literatures. Therefore, this study concentrates on the investigating of the liver length in pregnant women using ultrasonogrpahic measures. The findings of this study will be useful to researchers and also will serve as a data base for researchers in the area of the ultrasonographic evaluation of the liver in pregnant women.

1.6 Justification of Study

Ugbomaet al., (2011) conducted a pilot study of the normal sonographic measurements of the liver in normal pregnant women in the University of PortHarcout Teaching Hospital and found out that there were positive correlations between the liver length and body mass index but not with the parity gestational age. Kratzeret al., (2003) carried out a study on the ultrasonographic evaluation of liver in pregnant women of Indian and from the study it was revealed the average longitudinal diameter of the liver (midclavicular line) to be 13.11+1.73cm (median, 13.2cm; range, 7.0-16.4cm). From the result, it was further revealed that the multivariate analysis showed no positive correlation between the liver length and gestational age. Studies on the ultrasonographic evaluation of liver in pregnant women using Agbor general Hospital as a case study has not been documented in the literature.

1.7 Scope of Study

This research work was focused on the ultrasonographic evaluation of liver in pregnant women. The research was conducted among pregnant women at the Agbor general Hospital. A total number of one hundred and fifty (150) normal pregnant women were evaluated for this study.

1.8 Limitation of the Study

The study been constrained by a lot of factors such as cost of transportation to the various hospitals during the period of data collection and time consuming.