Abstract

The basic obstetric ultrasound examination provides an accurate and safe clinical assessment of the gravid uterus throughout a woman’s pregnancy including characterizing pregnancy location, identifying the number of embryos present, and aiding in the prenatal diagnosis of fetal anomalies.

In 2013, the American Institute of Ultrasound in Medicine (AIUM), in conjunction with the American College of Radiology (ACR) and the American College of Obstetricians and Gynecologists (ACOG), released updated Practice Guidelines for Performance of Obstetric Ultrasound Examinations.

These guidelines describe the indications and key elements of 4 major types of obstetric ultrasounds, specifically the first-trimester ultrasound, standard second or third-trimester ultrasound, and limited and specialized ultrasound examinations.

CHAPTER ONE

INTRODUCTION

1.1. Background

The prevalence of congenital abnormalities in the general population is approximately 3%-5% since the first report of the use of ultrasound in obstetrics, this has become an important tool for detection of fetal structural defects.

According to the International Society of Ultrasound in Obstetrics and Gynecology, the ideal period for screening for structural defects is the second trimester of pregnancy (weeks 18 to 22 in Cameroon, the preferred period for performing ultrasound screening in the second trimester is between 20 and 24 weeks of gestation. In developed countries, the number of referrals for ultrasound examination in the first trimester (11-13 + 6 weeks) has increased, while second –trimester ultrasound is considered to be the gold standard for detecting structural anomalies.

First-trimester ultrasound has utility for confining fetal viability and gestational age, evaluating the risk of chromosomal disorders and fetal abnormalities and detecting twin pregnancy and chronicity. Evaluation of nuchal translucency in the first trimester has emerged as a tool for screening for fetal structural abnormalities.

There is an association between increased nuchal translucency and chromosomal abnormalities, particularly trisomy 21 and structural anomalies. Greater nuchal translucency has been correlated with increased risk of trisomy 21 and fetal anomalies, especially cardiac abnormalities (Pandya et al., 1995).

More than 80% of fetal anomalies develop before 12 weeks of gestation. Therefore, good visualization of the fetus at this stage enables early detection of structural anomalies. The ultrasound detection rates for major structural anomalities in the first and second trimesters range from 13.0% to 43.6% and from 21% to 85%, respectively.  The overall sensitivity increase to 93% when first and second trimester ultrasound examinations are combined.

Detection of structural anomalies within the gestational period makes it possible to plan interventions during pregnancy or during the immediate and early postpartum period, thereby reducing perinatal and infant morbidity and mortality. In addition, early detection facilitates multidisciplinary planning for maternal –fetal intervention that may be required during the gestational period and provides greater information for parents and relatives. (Salomon et al., 2011).

1.2. Problem Statement

Ultrasound remains the main diagnostic tool in the prenatal detection of congenital abnormalities that is used in our society today.

A record review at Mt. Mary Hospital, Buea showed high values of first, second and third trimester pathologies. This is an indication that first, second and third trimester pathologies are still highly prevalent in our society. This study therefore seeks to assess the prevalence of ultrasound diagnosable first, second and third trimester pathologies at Mt. Mary Hospital, Buea.

1.3. Rational

Due to the increase rate of gestational anomalies recorded at the mount Mary Hospital, it signified that this is a public health issue and there was need to come up with the real prevalence of fetal anomalies at various levels of gestation. The results obtained seek to create awareness and hopefully appropriate authorities of Public Health use the data to manage the situation better.

1.4. Research Questions

1. What is the prevalence of pathologies during the first, second, and third trimesters at the Mt. Mary Hospital Buea?
2. What is the most frequent pathology at various trimesters?
3. Which trimester had the most cases of anomalies?

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