Aplasia (agenesis) of the kidney

Agenesis or aplasia of the kidney is an anatomical quantitative anomaly, in which agenesis of the kidney is a complete absence of the organ, and the concept of "aplasia" suggests that the organ is represented by an undeveloped rudiment, deprived of normal renal structure. In the case of renal aplasia, its function is performed by the second paired organ, which hypertrophies due to the performance of additional compensatory work.

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Epidemiology

Ultrasound screening of 280,000 school-age children determined that renal aplasia occurs at a frequency of 1 in 1,200 people (0.083%).

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Causes aplasia (agenesis) of the kidney

Agenesis, or renal aplasia, occurs when the metanephric duct does not reach the metanephrogenic blastema. The ureter may be normal, shortened, or completely absent. Complete absence of the ureter in men is combined with the absence of the vas deferens, cystic changes in the seminal vesicle, hypoplasia or absence of the testicle on the same side, hypospadias, associated with the peculiarities of embryonic morphogenesis.

Both renal agenesis and renal aplasia are considered urinary system anomalies, congenital malformations. Severe anatomical anomalies can cause fetal death in utero, more compensated cases do not manifest clinical signs and are detected during routine examinations or by chance. Some anatomical abnormalities can progress gradually throughout life and be diagnosed in old age. Agenesis or aplasia can also provoke nephrolithiasis, arterial hypertension or pyelonephritis.

Urinary system anomalies are varied and are divided into categories – quantitative, positional anomalies, relationship anomalies and kidney structure pathologies. Bilateral renal agenesis is a complete absence of a paired organ, which fortunately is rare and diagnosed. Such pathology is incompatible with life. More often, unilateral absence or underdevelopment of the kidney is observed.

Agenesis of the kidney has been known since ancient times, Aristotle in one of his works described cases when a living creature could exist without a spleen or one kidney. In the Middle Ages, doctors were also interested in anatomical renal pathology and even an attempt was made to describe in detail aplasia (underdevelopment) of the kidney in a child. However, doctors did not conduct large-scale full-fledged studies and only at the beginning of the last century Professor N.N. Sokolov established the frequency of renal anomalies. Modern medicine has specified statistics and presents data on such an indicator - agenesis and aplasia among all pathologies of the urinary system is 0.05%. It was also found that men most often suffer from renal underdevelopment.

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Risk factors

The following provoking factors are considered clinically established and statistically confirmed:

• Genetic predisposition.
• Infectious diseases in women in the first trimester of pregnancy – rubella, flu.
• Ionizing radiation of a pregnant woman.
• Uncontrolled use of hormonal contraceptives.
• Diabetes mellitus in a pregnant woman.
• Chronic alcoholism.
• Venereal diseases, syphilis.

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Symptoms aplasia (agenesis) of the kidney

In women, the malformation may be combined with a unicornuate or bicornuate uterus, uterine hypoplasia, and vaginal underdevelopment (Rokitansky-Küster-Haser syndrome). The absence of the ipsilateral adrenal gland accompanies renal agenesis in 8-10% of cases. With this anomaly, compensatory hypertrophy of the contralateral kidney is almost always observed. Bilateral renal aplasia is incompatible with life.

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Forms

• Bilateral anomaly (complete absence of kidneys) – bilateral agenesis or arenia. As a rule, the fetus dies in utero, or the newborn child dies in the first hours or days of life due to renal failure. Modern methods allow us to combat this pathology with the help of organ transplantation and regular hemodialysis.
• Agenesis of the right kidney is a unilateral agenesis. This is an anatomical defect, which is also congenital. The healthy kidney takes on the functional load, compensating for the insufficiency as much as its structure and size allow.
• Agenesis of the left kidney is an identical case to agenesis of the right kidney.
• Aplasia of the right kidney is virtually indistinguishable from agenesis, but the kidney is a rudimentary fibrous tissue without renal glomeruli, ureter, and pelvis.
• Aplasia of the left kidney is an anomaly identical to underdevelopment of the right kidney.

Variants of agenesis are also possible, in which the ureter is preserved and functions quite normally; in the absence of the ureter, the clinical manifestations of the pathology are more pronounced.

As a rule, in clinical practice, a unilateral anomaly is encountered for quite understandable reasons - bilateral agenesis is incompatible with life.

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Agenesis of the right kidney

In terms of clinical manifestations, agenesis of the right kidney differs little from the anomaly of the left kidney, however, there is an opinion of authoritative urologists and nephrologists that the absence of the right kidney is much more common than agenesis of the left kidney, and in females. Perhaps this is due to the anatomical specifics, because the right kidney is slightly smaller, shorter and more mobile than the left, normally it should be located lower, which makes it more vulnerable. Agenesis of the right kidney can manifest itself from the first days of the child's birth if the left kidney is not capable of compensatory function. Symptoms of agenesis are polyuria (excessive urination), constant regurgitation, which can be classified as vomiting, total dehydration, hypertension, general intoxication and renal failure.

If the left kidney takes over the function of the missing right kidney, then agenesis of the right kidney practically does not manifest itself symptomatically and is detected by chance. The diagnosis can be confirmed by means of computed tomography, ultrasound examination and urography. Also, the pediatrician, as well as the parents, should be alerted by excessive puffiness of the child's face, a flattened wide nose (flat bridge of the nose and wide bridge of the nose), strongly protruding frontal lobes, excessively low-set ears, possibly deformed. Ocular hypertelorism is not a specific symptom that indicates renal agenesis, but it is often accompanied by an enlarged abdomen and deformed lower limbs.

If agenesis of the right kidney does not pose a threat to health and does not manifest itself with obvious pathological symptoms, as a rule, this pathology does not require special treatment, the patient is under constant supervision of a urologist and undergoes regular screening examinations. It would be useful to follow an adequate diet and preventive measures to reduce the risk of developing kidney diseases. If agenesis of the right kidney is accompanied by persistent renal hypertension or reverse flow of urine from the ureters to the kidney, lifelong hypotensive therapy is prescribed, and organ transplantation may be indicated.

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Agenesis of the left kidney

This anomaly is practically identical to agenesis of the right kidney, except that normally the left kidney should be slightly more advanced than the right one. Agenesis of the left kidney is a more complicated case, since its function should be performed by the right kidney, which is more mobile and less functional by its nature. In addition, there is information, however, not confirmed by global urological statistics, that agenesis of the left kidney is often accompanied by the absence of the ureteral orifice, this concerns primarily male patients. Such pathology is combined with agenesis of the spermatic duct, underdevelopment of the urinary bladder and anomaly of the seminal vesicles.

Visually expressed agenesis of the left kidney can be determined by the same parameters as agenesis of the right kidney, which are formed as a result of congenital intrauterine defects - oligohydramnios and fetal compression: a wide bridge of the nose, excessively wide-set eyes (hypertelorism), a typical face with Potter syndrome - a puffy face with an underdeveloped chin, low-set ears, with protruding epicanthic folds.

Agenesis of the left kidney in men is more pronounced in terms of symptoms, it manifests itself in constant pain in the groin area, pain in the sacrum, difficulty with ejaculation, often leads to a violation of sexual functions, impotence and infertility. The treatment that requires agenesis of the left kidney depends on the degree of activity of the healthy right kidney. If the right kidney compensatorily increases and functions normally, then only symptomatic treatment is possible, including preventive antibacterial measures to reduce the risk of developing pyelonephritis or uropathology of the urinary system. Also required is dispensary monitoring by a nephrologist, and regular examinations of urine, blood, ultrasound screening. More complicated cases of agenesis are considered an indication for kidney transplantation.

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Aplasia of the right kidney

As a rule, underdevelopment of one of the kidneys is considered a relatively favorable anomaly compared to agenesis. Aplasia of the right kidney with normal functioning of the healthy left kidney may not manifest clinical signs throughout life. Often, aplasia of the right kidney is diagnosed by chance during a comprehensive examination for a completely different disease. Less often, it is determined as a possible cause of persistent hypertension or nephropathology. Only one third of all patients with an underdeveloped or "shrunken" kidney, as it is also called, are registered with a nephrologist for aplasia during their lifetime. Clinical symptoms are nonspecific and, perhaps, this explains such a rare detection of this anomaly.

Among the signs that may indirectly indicate that a person may have an underdeveloped kidney, there are periodic complaints of nagging pain in the lower abdomen, in the lumbar region. Painful sensations are associated with the growth of rudimentary fibrous tissue and pinched nerve endings. Also, one of the signs may be persistent hypertension that cannot be controlled with adequate therapy. Aplasia of the right kidney, as a rule, does not require treatment. A gentle diet is necessary, reducing the risk of stress on the hypertrophied kidney, which performs a dual function. Also, with persistent hypertension, appropriate treatment is prescribed using gentle diuretics. Aplasia of the right kidney has a favorable prognosis; usually, people with one kidney live a full, high-quality life.

Aplasia of the left kidney

Aplasia of the left kidney, as well as aplasia of the right kidney, is quite rare, no more than 5-7% of all patients with urinary system anomalies. Aplasia is often combined with underdevelopment of nearby organs, for example, with an anomaly of the urinary bladder. It is believed that aplasia of the left kidney is most often diagnosed in males and is accompanied by underdevelopment of the lungs and genitals. In men, aplasia of the left kidney is diagnosed together with aplasia of the prostate gland, testicle and vas deferens. In women - underdevelopment of the uterine appendages, ureter, aplasia of the uterus itself (bicornuate uterus), aplasia of the intrauterine septa, doubling of the vagina, etc.

An underdeveloped kidney has no stalk, no pelvis, and is unable to function and excrete urine. Aplasia of the left kidney, as well as aplasia of the right kidney, is called a solitary kidney in urological practice, i.e. single. This refers only to the kidney that is forced to function, to perform double work as a compensation.

Aplasia of the left kidney is detected by chance, since it does not manifest itself with clinically expressed symptoms. Only functional changes and pain in the collateral kidney can give reason for urological examination.

The right kidney, which is forced to do the work of the aplastic left kidney, is usually hypertrophied and may have cysts, but most often it has a completely normal structure and completely controls homeostasis.

Aplasia of the left kidney in both children and adults does not require specific treatment, except for preventive measures to reduce the risk of bacterial infection in a single solitary kidney. A gentle diet, maintaining the immune system, and maximum avoidance of viruses and infections ensure a completely healthy, full life for a patient with one functioning kidney.

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Diagnostics aplasia (agenesis) of the kidney

The disease is diagnosed using X-ray renal angiography, as well as spiral CT or MSCT and magnetic resonance angiography. Agenesis, aplasia of the kidney is not diagnosed using other diagnostic methods.

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