History

Urinary frequency, dysuria and wetting are probably the commonest urinary symptoms. Children usually acquire daytime continence between 18 months and 3 years of age and night-time continence a year or so later. By the age of 5 years, 95% of children are dry by day and 85% of children are dry by night.

Small volumes of dark urine suggest glomerulonephritis or dehydration. Large volumes of dilute urine suggest diabetes or excessive drinking. Red urine suggests blood, but certain colourings – particularly beetroot – can be deceptive. If there is frank haematuria ask whether it is present throughout the stream or just at the end. Terminal haematuria suggests a penile cause – a meatal ulcer or urethral trauma. Children may present with oedema when puffiness of the eyes and face is the presenting feature.

Examination

Most common renal problems produce few examination findings. Check the blood pressure and look for peripheral oedema. Interpretation of blood pressure values is aided by reference to published normal ranges for blood pressure. It is important to measure blood pressure, usually in the right arm, after a period of quiet rest, with the correct size cuff, and ideally to take repeated measures, as children are prone to ‘white-coat’ hypertension.

Palpate the kidneys and feel for tenderness in the loins. Inspect the back looking for a naevus that could overlie a spinal cord anomaly. Check the lower-limb reflexes. The external genitalia should be examined, but tact is needed and you may decide the examination should be deferred unless the history specifically suggests a genital problem. The examination is not complete without testing the urine with a multiple reagent stick (see Table 11.1).

Table 11.1 Significance of urine dipstick test results

Investigations

Undescended testes

About 4% of newborn boys have an undescended testis (cryptorchidism). It is more common in premature infants. In the majority, the testes descend spontaneously by 3 months of age. By 6 months, there is little likelihood of the cryptorchid testis descending spontaneously, and orchidopexy is required to fix the testis in the scrotum. Laparoscopy may be necessary to locate abdominal testes, but in some cases the testis is simply absent as the result of intra-abdominal torsion or agenesis. If the testis cannot be located, renal ultrasound should be performed as there may be associated renal agenesis.

If both testes are undescended, intersex needs to be considered (see Chapter 12, p. 151).

There is an increased risk of malignancy in undescended testes, which persists even after orchidopexy.

Hypospadias

In hypospadias, the urethral meatus opens onto the ventral shaft of the penis or scrotum, or exceptionally, the perineum. In 60% the meatus is distal (glandular or coronal hypospadias) and in 15% proximal (perineoscrotal or perineal hypospadias), with the remainder affecting the penile shaft (subcoronal or mid-penile hypospadias). Hypospadias affects the urinary stream and may be associated with bowing of the erect penis, ‘chordee’, which will affect sexual function in later life. Proximal hypospadias may be associated with urinary tract abnormalities, and a micturating cystogram should be performed. Hypospadias with an undescended testis may be seen in intersex states (see Chapter 12, p. 151) and genetic sex determination should be performed. Surgical correction in infancy is straightforward. The parents should be advised not to have their son circumcised as the foreskin may be used as part of the surgical repair.

Inguinal hernia and hydrocele

Inguinal hernias and hydroceles arise from a patent processus vaginalis. The processus vaginalis is a pouch of peritoneum which accompanies the testis into the scrotum, and thereafter involutes. Before birth, peritoneal fluid enters the scrotum, resulting in a hydrocele. The great majority of hydroceles resolve spontaneously by 6 months but if the processus remains patent, surgery will be necessary. Inguinal hernias and hydroceles are especially common in premature infants. Presentation of hernias is usually with a variable groin swelling, particularly seen on crying or coughing, but complications include incarceration, strangulation and bowel infarction. Treatment is surgical.

Congenital anomalies of the urinary tract

Congenital anomalies of the urinary tract may affect the kidney, urinary collecting system, bladder or urine outflow tract (as in Case 11.1).

Renal agenesis or dysplasia affecting both kidneys may produce antenatal oligohydramnios with lethal pulmonary hypoplasia (Potter’s syndrome) as fetal urine is essential for lung development. Unilateral agenesis or dysplasia may be associated with other congenital abnormalities such as contralateral vesico-ureteric reflux. The remaining kidney undergoes compensatory hypertrophy in post-natal life.

Abnormalities of the ureter include obstruction at the level of the renal pelvis (pelvi-ureteric junction obstruction) or bladder, normally due to a ureterocele – a cystic dilatation of the terminal ureter with a pinhole ureteral orifice. These result in proximal dilatation and predispose to infection and renal injury. Treatment is surgical. Occasionally, the ureter may be partially or completely duplicated. Typically, the ureter draining the upper pole inserts ectopically and is commonly obstructed, whereas the lower pole ureter inserts non-obliquely into the bladder, predisposing to reflux. In girls, an ectopic ureter commonly empties into the vagina leading to constant dribbling incontinence. In boys, the insertion is commonly into the prostatic utricle, seminal vesicle or vas deferens and thus leads to obstruction (see Figure 11.1).

Figure 11.1 Left pelvi-ureteric junction obstruction with resultant dilatation of the renal pelvis (hydronephrosis). The right kidney is duplex, with two pelvicalyceal systems, in this case, each supplied by its own ureter. The lower moiety of duplex systems is commonly affected by vesico-ureteric reflux (70%) due to its more lateral and less oblique course. The upper pole ureter is more susceptible to obstruction from a ureterocoele (ballooning of the distal ureter as it enters the bladder), producing vesico-ureteric junction obstruction, as in the illustration. The insertion of the upper pole ureter is usually inferior and medial to the normal position, and may be associated with dysplasia of the upper pole.

The most important congenital bladder abnormality is neuropathic bladder, in which the nerve supply to the bladder is defective, as occurs with spina bifida or spinal dysraphism. The bladder outlet fails to relax fully, leading to hydronephrosis and renal injury. Management is usually with intermittent self-catheterization.

Obstruction to the urethra occurs with posterior urethral valves in boys, in which the prostatic urethra is obstructed by abnormal tissue leaflets which impede renal flow, producing a variable degree of obstruction. The obstruction commonly results in renal injury with one-third of boys developing chronic kidney disease.

See Table 11.2 for congenital anomalies of the kidney and urinary tract.

Table 11.2 Congenital anomalies of the kidney and urinary tract