Aplasia (agenesis) of the kidney

Agenesis or aplasia of the kidney is an anatomical quantitative anomaly, in which the agenesis of the kidney is the complete absence of an organ, and the term aplasia implies that the organ is represented by an undeveloped bud, lacking a normal renal structure. In the case of aplasia of the kidney, its function is performed by the second paired organ, which is hypertrophied due to the performance of additional compensatory work.

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Epidemiology

An ultrasound screening of 280,000 school-age children determined that renal aplasia occurs with a frequency of 1 in 1200 people (0.083%).

[2], [3]

Causes of the aplasia (agenesis) of the kidney

Agenesis or aplasia of the kidney occurs when the duct of the metanephros does not grow to the metanephrogenic blastema. In this case, the ureter may be normal, shortened, or completely absent. The complete absence of the ureter is combined in men with the absence of the vas deferens, cystic changes of the seminal vesicle, hypoplasia or the absence of a testicle on the same side, hypospadias associated with the characteristics of embryonic morphogenesis.

Both kidney agenesis and aplasia of the kidney are considered abnormalities of the urinary system, congenital malformations. Severe anatomical abnormalities can cause fetal death in utero, more compensated cases are not manifested by clinical signs and are detected during dispensary examinations or randomly. Some anatomical abnormalities can progress progressively throughout life and be diagnosed in old age. Also, agenesis or aplasia can provoke kidney disease, hypertension or pyelonephritis.

Anomalies of the urinary system are diverse, they are divided into categories - quantitative, anomalies of position, anomalies of the relationship and pathology of the structure of the kidneys. Bilateral kidney agenesis is the complete absence of a paired organ, which, fortunately, is rarely found and diagnosed. This pathology is not compatible with life. Often there is a unilateral absence or underdevelopment of the kidney.

Kidney ages are known since ancient times, in one of their works, Aristotle described cases in which a living being could exist without a spleen or a single kidney. In the Middle Ages, doctors were also interested in anatomical renal pathology and even an attempt was made to describe aplasia (underdevelopment) of the kidney in a child in detail. However, physicians did not conduct large full-fledged studies, and only at the beginning of the last century, Professor N. Sokolov established the frequency of renal anomalies encountered. Modern medicine has concretized the statistics and presents data about this indicator - agenesis and aplasia among all pathologies of the urinary system is 0.05%. It was also found that underdevelopment of the kidney most often affects men.

[4], [5]

Risk factors

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

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

[6], [7], [8], [9], [10]

Symptoms of the aplasia (agenesis) of the kidney

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

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Forms

• Bilateral anomaly (complete absence of kidneys) - bilateral agenesis or arsenia. As a rule, the fetus dies in utero, or the born child dies in the first hours or days of life due to renal failure. Modern methods can combat this pathology with the help of organ transplantation and regular hemodialysis. 
• Agenesis of the right kidney - unilateral agenesis. This is an anatomical defect, which is also congenital. A healthy kidney takes over the functional load, compensating for insufficiency as much as its structure and size allows. 
• Agenesis of the left kidney is an identical case of agenesis of the right kidney. 
• Aplasia of the right kidney is practically 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 the underdevelopment of the right kidney.

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

As a rule, in clinical practice, there is a one-sided anomaly for understandable reasons - bilateral agents are not compatible with life.

[12], [13], [14]

Agenesis of the right kidney

According to clinical manifestations, right kidney agenesis is not much different from left kidney anomaly, however, there is a opinion of authoritative urologists, nephrologists, that the absence of the right kidney is much more common than the left kidney agenesis, and in women. Perhaps this is due to the anatomical specificity, because the right kidney is slightly smaller, shorter and more mobile than the left, normally it should be located below, which makes it more vulnerable. Agenesis of the right kidney can manifest from the first days of birth of the child, if the left kidney is not capable of compensatory function. Symptoms of agenesis include polyuria (excessive urination), persistent regurgitation, which can be described as vomiting, total dehydration, hypertension, general intoxication and renal failure.

If the left kidney assumes the function of the missing right one, then the agenesis of the right kidney practically does not manifest symptomatically and is found at random. The diagnosis can be confirmed by computerized tomography, ultrasound, and urography. Also, pediatricians, as well as parents, should be alerted by the excessive puffiness of a child’s face, a flattened wide nose (flat back of the nose, and broad bridge of nose), strongly protruding frontal lobes, too low auricles, possibly deformed. Ocular hypertelorism is not a specific symptom that indicates the genesis of the kidney, but often accompanies it, as well as an increase in the abdomen, deformed lower limbs.

If the agenesis of the right kidney does not pose a threat to health and does not manifest itself as an obvious pathological symptomatology, as a rule, this pathology does not require special treatment, the patient is under constant observation of the urologist and undergoes regular screening examinations. It will not be superfluous to adhere to an adequate diet and adhere to preventive measures to reduce the risk of developing kidney diseases. If the agenesia of the right kidney is accompanied by persistent renal hypertension or re-injection of urine from the ureters into the kidney, life-long hypotensive therapy is prescribed, indications for organ transplantation are possible.

[15], [16]

Agenesis of the left kidney

This anomaly is almost identical to the genesis of the right kidney, except that normally the left kidney should be a little more pushed forward than the right kidney. Agenesis of the left kidney is a more burdened case, since its function must be performed by the right kidney, which is more mobile and less functional in nature. In addition, there is information, however, not confirmed by universal urological statistics, that the agenesis of the left kidney is often accompanied by the absence of the mouth of the ureter, this applies primarily to male patients. Such a pathology is combined with agenesis of the seminal duct, hypoplasia of the bladder, and anomaly of the seminal vesicles.

Visually expressed agenesis of the left kidney can be determined by the same parameters as the agenesis of the right kidney, which are formed due to congenital intrauterine malformations - lack of water and compression of the fetus: wide back of the nose, overly wide eyes (hypertelorism), a typical person with Potter syndrome - a puffy face with underdeveloped chin, low-set ears, with prominent epicantic folds.

Agenesis of the left kidney in men is more pronounced in the sense of symptomatology, it manifests itself in constant pain in the groin area, pain in the sacrum, difficulties with ejaculation, often leads to impaired sexual functions, impotence and infertility. Treatment that requires agenesis of the left kidney depends on the degree of activity of the healthy right kidney. If the right kidney compensatory increases and functions normally, then only symptomatic treatment is possible, including preventive antibacterial measures to reduce the risk of developing pyelonephritis or urinary tract uropathology. Also requires a dispensary registration with a nephrologist, and regular examinations of urine, blood, ultrasound screening. More burdened cases of agenesis are considered as indications for kidney transplantation.

[17], [18]

Aplasia of the right kidney

As a rule, the underdevelopment of one of the kidneys is considered to be a relatively favorable anomaly compared with agenesis. Aplasia of the right kidney in the normal functioning of a healthy left kidney may not show clinical signs all his life. Aplasia of the right kidney is often diagnosed randomly with a comprehensive examination for a completely different disease. Less commonly, it is defined as a possible cause of persistent hypertension or nephropathology. Only one third of all patients who have an underdeveloped or “shriveled” kidney, as it is also called, are registered with a nephrologist for aplasia during life. Clinical symptoms are not specific and, perhaps, this explains the rare detection of this anomaly.

Among the signs that may indirectly indicate that one of the kidneys is possibly underdeveloped, there are periodic complaints of nagging pain in the lower abdomen, in the lumbar region. Pain associated with the growth of embryonic fibrous tissue and the pinching of nerve endings. Also one of the signs can be persistent hypertension, which cannot be controlled by adequate therapy. Aplasia of the right kidney does not usually require treatment. A sparing diet is needed, reducing the risk of stress on a hypertrophied kidney that performs a dual function. Also, with persistent hypertension, appropriate treatment is prescribed with the help of sparing diuretics. Aplasia of the right kidney has a favorable prognosis; usually, people with one kidney live a full-fledged 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 in 5-7% of all patients with anomalies of the urinary system. Aplasia is often combined with an underdevelopment of nearby organs, for example, an abnormality of the bladder. It is believed that aplasia of the left kidney is most often diagnosed in males and is accompanied by an underdevelopment of the lungs, genital organs. In men, aplasia of the left kidney is diagnosed along with aplasia of the prostate gland, testicle, and vas deferens. In women, the underdeveloped appendages of the uterus, ureter, aplasia of the uterus itself (two-horned uterus), aplasia of the intrauterine partitions, doubling of the vagina, and so on.

Underdeveloped kidney does not have legs, pelvis and is not able to function and excrete urine. Aplasia of the left kidney, as well as aplasia of the right kidney, is called in the urological practice a solitary kidney, that is, one. This refers only to the kidney, which is forced to function, to perform double work compensatory.

Aplasia of the left kidney is detected randomly, since it does not manifest itself as clinically pronounced symptomatology. Only functional changes and pain in the collateral kidney can give rise to a urological examination.

The right kidney, which is forced to perform the work of an aplastic left kidney, is usually hypertrophied, may have cysts, but more 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, with the exception of preventive measures to reduce the risk of bacterial infection in a single solitary kidney. A sparing diet, maintaining the immune system, maximum avoidance of infection by viruses and infections ensures a completely healthy, full life for a patient with a single, functioning kidney.

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Diagnostics of the aplasia (agenesis) of the kidney

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

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