Assessment of fetal anatomy during the second trimester using ultrasound scanning has now become standard practice in most antenatal care set-ups, thus permitting the diagnosis of most structural abnormalities in the fetus. Renal anomalies constitute about 20% of all congenital abnormalities [1], ∗[2]. As a result, prenatal identification of renal anomalies provides options for prospective parents as they significantly affect perinatal morbidity and mortality. Additionally, it also functions as a key mechanism in promoting early detection of conditions, which may otherwise present itself later on in life, conceivably with more advanced sequelae. In this chapter, we concentrate on ultrasound diagnosis of renal tract abnormalities.
The urogenital system develops from the mesodermal ridge (intermediate mesoderm) in the posterior wall of the abdominal cavity. During the stages of intrauterine life, three renal systems develop; namely the pronephros, mesonephros, and metanephros. The pronephros and mesonephros are transient excretory systems, and disappear without contributing to the permanent renal system. The mesonephric duct gives rise to some reproductive organs in male fetuses while degenerating in female fetuses.
The
Congenital abnormalities of the genitourinary tract, especially of the kidney and bladder, affect 3–4% of the population [3]. The fetal kidneys contribute to the amniotic fluid volume from about 14 weeks, and are essential for maintaining liquor volume throughout pregnancy. The presence of a structural, functional renal anomaly, or both, may result in oligohydramnios or anhydramnios, which may in turn affect pulmonary development. It is therefore necessary to establish the normalcy of the renal
Renal agenesis is the congenital absence of kidneys, and can be bilateral or unilateral. Bilateral renal agenesis is not compatible with life, and occurs in 0.1–0.3 per 1000 births. Isolated unilateral agenesis accounts for 1 in 1000 births, and is three times more common in males [6]. Renal agenesis can be an isolated finding, but is more commonly part of a syndrome and warrants a detailed anomaly scan to look for associated anomalies [7]. Various inheritance patterns exist in families with
Polycystic kidney diseases comprise two entities. Infantile polycystic kidney disease is also known as Potter type I, which has an autosomal recessive inheritance. It is the most common cystic disease in pregnancy, and carries a 25% risk in subsequent pregnancies [18]. This is a single gene disorder, and the abnormal gene is located in the short arm of chromosome 6 [18]. Prenatal diagnosis by first-trimester chorionic villous sampling can be offered to families at risk. Age of onset of this
Upper urinary tract dilatation is one of the most common abnormalities diagnosed prenatally by ultrasound scanning. It is commonly caused by transient urine flow impairment at the level of the pelvi-ureteric junction (PUJ) and vesico-ureteric junction, which improves with time in most cases [24]. Prognosis of the condition is mainly determined during the first 18 months of life. Renal tract dilatation can be detected prenatally by ultrasonography between 18 and 20 weeks. Normal renal pelvis is
Many genetic disorders are linked with renal tract anomalies. Once a renal anomaly is detected prenatally, it is important to establish whether it is a part of a genetic syndrome. To establish a proper diagnosis, it is essential to have an overall knowledge about various syndromes associated with renal anomalies. Some of the common genetic disorders associated with renal malformations are presented in Tables 1 and 2.
The fetal renal system is routinely assessed mid-trimester by ultrasound. Upper urinary tract dilatation is the most common renal anomaly detected prenatally, and both vesicoureteral reflux after vesico-ureteric junction abnormality and pelvi-ureteric junction obstructive lesions should be considered. Renal parenchymal disease could be recognised in the fetus by visualising cystic changes in the kidneys or by appearance of abnormal echogenicity. Underlying abnormalities may be associated, and
None declared. Finding megacystis during the first trimester should be incorporated into the risk assessment of aneuploidy screening. Fetal renal pelvis antero-posterior diameter 6 mm or over at 24 weeks and 10 mm or over at 30 weeks should be considered abnormal. In the case of mild renal pelvic dilatation, follow-up scanning is indicated, and aneuploidy screening should be considered with the presence of other anomalies. Presence of unilateral or bilateral renal agenesis andPractice points
Hydronephrosis, hydroureter, thickened bladder, cystic kidney, tiny or dysplastic kidney, and missing kidney are among the abnormalities found during prenatal ultrasound. A postnatal physical examination and postnatal renal ultrasound should be performed soon after birth and once more at 4–6 weeks of age [16] if renal abnormalities were detected during pregnancy. Ectopic kidneys with no symptoms and life-threatening renal agenesis are only two examples of the large range of disorders that fall under the umbrella of congenital anomalies of the kidneys and urinary tract (bilateral).
Ultrasound (US) imaging is an imaging modality widely used for the diagnosis, screening and treatment of a large number of diseases, due to its portability, low cost and non-invasive nature (Zaffino et al., 2020). In the years, US imaging has turned out to be the preferred checkup method during pregnancy (Whitworth et al., 2015; Dias et al., 2014). It is commonly used to evaluate fetus’s growth and development, as well as to monitor pregnancy and assess clinical suspicion (Bijma et al., 2008).