**1. Introduction**

The present chapter addresses the main renal anomalies. It will be structured on nine subjects made to help the reader orientate easily when facing an anomaly in everyday practice. Information regarding the moment an anomaly is visible has taken into account midrange ultrasound machines that are responsible for most of the anomaly screening.

Kidneys are visible at 12–14 weeks of gestational age, easier with transvaginal examination, and the renal architecture is seen first at 16–18 weeks. Current protocols advise documenting the presence of the normal kidneys at the second and third trimester ultrasound. A special attention must be given not to confuse them with "lying-down" adrenal structures. We recommend using both transversal and longitudinal views; coronal views are helpful in the diagnosis of the horseshoe kidneys. Color Doppler ultrasound can be used to identify the renal

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Incidence: 1:2000–1:5000.

Differential diagnosis:

diagnosis).

Clinical facts:

7, 10, 21, 22).

hypoplasia) (**Figure 1**).

**Figure 1.** Renal agenesis (absence of renal arteries).

take the time to measure the heart/chest ratio.

Pathology: it results from failure of development of the ureteric bud. The consequence for the pregnancy is Potter sequence: oligohydramnios, Potter face, clubbed hands and feet, and

Renal Anomalies

273

http://dx.doi.org/10.5772/intechopen.71925

Ultrasound findings: we notice severe oligohydramnios and fail to see the kidneys and the bladder. Sometimes, lying-down adrenals may be confused with kidneys in the conditions of poor visibility associated with low amniotic fluid/absence of amniotic fluid. Color Doppler interrogation fails to demonstrate the renal arteries. A small thorax is noticed, especially if we

• PROM (patient history and the presence of kidneys and bladder point us the right

• Risk of chromosomal anomalies is low (though there have been described cases of trisomy

• You should always examine carefully not to confuse adrenal glands with kidneys; keep in mind that adrenal arteries can also mimic renal arteries, so Doppler is not always a solution. • Bilateral agenesis is always lethal (one-third stillbirth, the rest die at birth from pulmonary

pulmonary hypoplasia which leads to death in the cases that reach birth [2].

• Severe IUGR (kidneys are present, and there are abnormal Doppler values).

• It may be part of a nonchromosomal syndrome (COF syndrome, VACTERL).

• Oligohydramnios is an associated sign only after 16 weeks.

**Table 1.** Mean renal length by gestational age.

arteries. Normal measurements for renal length are shown in **Table 1** [1]. The renal circumference to abdominal circumference is about one-third. The anterior-posterior renal pelvis is usually less than 4 mm before 22 weeks and less than 7 mm in the third trimester.

#### **2. Renal agenesis**

Definition: this chapter will address only bilateral renal agenesis, a condition defined as the absence of both kidneys which is invariably lethal.

Incidence: 1:2000–1:5000.

Pathology: it results from failure of development of the ureteric bud. The consequence for the pregnancy is Potter sequence: oligohydramnios, Potter face, clubbed hands and feet, and pulmonary hypoplasia which leads to death in the cases that reach birth [2].

Ultrasound findings: we notice severe oligohydramnios and fail to see the kidneys and the bladder. Sometimes, lying-down adrenals may be confused with kidneys in the conditions of poor visibility associated with low amniotic fluid/absence of amniotic fluid. Color Doppler interrogation fails to demonstrate the renal arteries. A small thorax is noticed, especially if we take the time to measure the heart/chest ratio.

Differential diagnosis:


Clinical facts:

arteries. Normal measurements for renal length are shown in **Table 1** [1]. The renal circumference to abdominal circumference is about one-third. The anterior-posterior renal pelvis is

Definition: this chapter will address only bilateral renal agenesis, a condition defined as the

usually less than 4 mm before 22 weeks and less than 7 mm in the third trimester.

**Weeks of gestation Fetal renal mean longitudinal length (cm) (±SD)**

 1.7 (0.3) 1.8 (0.1) 2.0 (0.0) 2.3 (0.3) 2.1 (0.1) 2.1 (0.1) 2.4 (0.3) 2.5 (0.3) 2.8 (0.1) 2.9 (0.2) 2.8 (0.1) 3.0 (0.1) 3.3 (0.3) 3.5 (0.2) 3.4 (0.3) 3.6 (0.1) 3.7 (0.2) 3.7 (0.2) 3.8 (0.2) 3.9 (0.3) 4.1 (0.3) 4.3 (0.3) 4.2 (0.3) 4.2 (0.2) 4.3 (0.2) 4.1 (0.2)

272 Congenital Anomalies - From the Embryo to the Neonate

**2. Renal agenesis**

**Table 1.** Mean renal length by gestational age.

absence of both kidneys which is invariably lethal.


**Figure 1.** Renal agenesis (absence of renal arteries).
