Pregnancy with a single kidney is a gestation that occurred in a woman with an undeveloped or removed kidney. With the normal operation of the remaining organ, there are no specific symptoms. In the presence of disorders, the condition is manifested by changes in the volume and color of urine, morning facial edema, lower back pain, headaches, dizziness, subfebrility, weakness. It is diagnosed by ultrasound of the kidneys, laboratory blood and urine tests, thermal imaging are used to assess functional activity. With an uncomplicated course, phytouroseptics are prophylactically prescribed, antibiotics, hormones, tocolytics, antispasmodics and other drugs are used to correct complications.
Under the supervision of obstetricians and gynecologists, pregnant patients with a single functioning kidney are relatively rare. According to research results, the prevalence of such pathology does not exceed 4.4-9.0% of cases per 1,000 births. This is due to the low frequency of renal aplasia (0.067-0.11%) with a predominant lesion of men, as well as an increase in the effectiveness of conservative therapy of urological diseases. Despite the narrowing of the number of direct indications for nephrectomy, surgical intervention often becomes the only possible method of treatment for benign and malignant kidney tumors, organ destruction due to inflammatory, destructive processes, severe injuries.
The disorder, as a rule, occurs long before the current gestation and is etiologically unrelated to it. However, physiological changes that occur in the pregnant woman’s body and affect urodynamics can worsen the patient’s health. Urological pathology can be congenital and acquired. There are two main clinical situations in which the kidney is the only one:
- Agenesis (aplasia) of the kidney. The frequency of detection of such a congenital anomaly, according to studies, ranges from 1:1,000 to 1:4,000 patients with renal pathology. With the functional viability of the organ, dysontogenetic disorder usually remains unrecognized and is diagnosed during pregnancy. Due to the generality of embryogenesis, underdevelopment of the kidney is often combined with defects of the reproductive organs. Therefore, pregnant women with a one-horned uterus, vaginal septum and uterine cavity should be carefully examined for timely detection of a single kidney.
- Consequences of nephrectomy. In obstetric practice, pregnant women are more common after removal of one of the kidneys, gestation occurs in 0.1-1% of women who have undergone this surgical intervention. Nephrectomy is performed for pionephrosis, tuberculosis of the kidneys, tumors, pyelonephritis with therapeutically resistant hypertension. Less often, such operations are performed for hydronephrosis, urolithiasis, traumatic injuries or for transplantation to a relative with terminal renal insufficiency. In 10-12% of cases, the reason for the removal of the affected kidney is malignant neoplasia.
In the presence of a single kidney, the functional load on its nephrons increases. The organ increases in size, the renal blood flow increases by 30-50%. In congenital malformations, compensatory changes develop gradually, after nephrectomy — in two stages. First, there is a relative functional insufficiency of the remaining kidney with the activation of all nephrons. There is a mobilization of the reserve capacity of the organ for the removal of primarily water and sodium chloride. The accumulation of nitrogenous compounds in the blood contributes to the volume-functional hypertrophy of the glomerular and tubular zones. Over time, the filtering abilities of the organ increase by 85-95%, the functional reserve of nephrons is restored. It takes 1.5 to 2 years for the kidney to achieve full functionality.
Despite the high reserve capacity of the organ, in which up to 25% of the parenchyma normally functions, additional loads during pregnancy contribute to the functional depletion of the only kidney. The development of renal pathology in pregnant women is caused by an increase in the volume of circulating blood, dilation of the calyx-pelvic system, expansion, elongation, decrease in the contractile activity of the ureters, displacement of the urinary system organs under the pressure of the growing uterus. As a result, the blood supply to the kidneys and renal filtration increase by 35-40%, reflux occurs, contributing to the upward spread of infections. Since a single kidney has a smaller functional reserve, urodynamic disorders provoke decompensation of the condition.
Features of the course of pregnancy
With an anatomically correct position and a satisfactory level of functioning of the organ, the course of gestation does not differ from the usual one. The damage to the remaining kidney is indicated by an increase or decrease in the volume of urine excreted, a change in its color (turbidity, the appearance of blood impurities), pain in the lumbar region with possible irradiation to the groin, external genitals, hip, morning swelling on the face, increased blood pressure with dizziness, headaches, ringing in the ears. Asthenic signs of pregnancy are increasing — weakness, drowsiness, fatigue. When gestation is combined with inflammatory renal pathology, the body temperature rises to 37.5-38.0 ° C or more, chills are possible.
The most common urological pathology that complicates gestation with one kidney is pyelonephritis, detected in 78% of patients (for comparison, in pregnant women with two kidneys, this disorder is diagnosed in 2-20% of cases). A more severe course of inflammation is noted after nephrectomy, which is associated with an increased predisposition to infection 4-5 years after surgery.
In the presence of urolithiasis, excretory anuria becomes a formidable complication, in the event of which an urgent surgical intervention is required. In the first trimester of pregnancy with a single kidney, the threat of spontaneous miscarriage is more often noted. The prevalence of gestosis increases by 1.87 times, detachment of a normally located placenta — by 1.96 times, premature birth — by 2.46 times, intrauterine development delays — by 2.92 times. Prenatal mortality can reach 6.1%. In 39.4% of cases, gestation ends with cesarean section.
In the presence of data on the transferred nephrectomy, the diagnosis does not present any difficulties. Since before pregnancy, patients with aplasia often have no clinical manifestations of kidney failure, when complaints characteristic of renal pathology appear, it is necessary to exclude congenital underdevelopment. An important task of the diagnostic search is to assess the functionality of the existing organ. The most informative are such studies as:
- Ultrasound of the kidneys. Due to its safety and informative value, echography is the preferred diagnostic method for suspected congenital kidney aplasia in a pregnant woman. During ultrasound examination, the renal parenchyma, individual structural elements of a single urinary organ are visualized. Additional Doppler ultrasound of the renal vessels allows to obtain data on the features of the renal vascular network.
- Thermography (thermal imaging) of the lumbar region. Visual assessment and high-precision measurement of infrared thermal radiation of the body surface in the projection of the kidneys indirectly reflects the functional activity of the organ, can additionally confirm the presence of inflammatory processes. The advantages of the method are non-invasiveness and the possibility of using it to monitor changes in dynamics against the background of ongoing treatment.
- General analysis of urine. A common screening study that allows you to quickly identify urological pathology. Diagnostically significant are the determination of the number of leukocytes, erythrocytes, protein, cylinders in the urine. In leukocyturia and bacteriuria, the analysis is supplemented by sowing urine on the microflora, during which the causative agent of the infectious process is verified, its sensitivity to antibiotics is clarified.
- Biochemical blood analysis. Determination of creatinine, nitrogen, urea, uric acid, sodium, potassium, calcium, inorganic phosphorus is aimed at assessing the filtering ability of the remaining kidney. The study is often supplemented with a nephrological complex of analyzes (renal urine samples), a Rehberg test to assess the ability to filter and a Zimnitsky test to detect violations of the concentrating function.
Although congenital renal aplasia can be confirmed with the greatest certainty during aortography and phlebography, and the functional capabilities of the organ can be conveniently assessed using dynamic scintigraphy, such studies are not carried out during pregnancy with a single kidney due to the radiation load on the fetus. In the absence of information about nephrectomy, the condition is differentiated with urological pathology — gestational pyelonephritis, exacerbation of glomerulonephritis, nephrolithiasis, volumetric neoplasm, asymptomatic bacteriuria. A urologist is involved in the management of the patient. If necessary, consultations of a therapist, a nephrologist, an ophthalmologist, a phthisiologist, an oncologist are appointed.
Management of pregnancy with a single kidney
The main medical tasks when detecting such a condition are to determine the possibility of prolongation of gestation, timely detection and correction of possible complications. The absolute contraindications for maintaining pregnancy are hydronephrosis, nephrolithiasis, tuberculosis, other diseases of the single kidney, azotemia and arterial hypertension. In such cases, it is recommended to perform a medical abortion before 10-12 weeks of the gestational period.
In the absence of pathological processes and the functional viability of the existing organ, dynamic observation of an obstetrician-gynecologist and urologist, regular urine screening is necessary. For preventive purposes, during the entire gestation period of a pregnant woman, the use of herbal uroseptics is indicated. If signs of inflammation or obstetric complications are detected, drug therapy is carried out with the appointment of such groups of drugs as:
- Antibiotics. In the 1st trimester, semi-synthetic penicillins of a wide spectrum of action are used to exclude mutagenic and toxic effects on the fetus, including in a therapeutically effective combination with clavulonic acid. In the 2-3 trimesters after the end of organogenesis, the use of cephalosporins, nitrofurans, monobactams is allowed.
- Hormones in combination with tocolytics. Since pregnant patients with a single working kidney are more likely to have a threat of termination of pregnancy, gestagens, methylxanthines, antispasmodic drugs, magnesia may be recommended to reduce the tone of the myometrium. Additionally, sedative phytopreparations are prescribed to relieve emotional stress.
If other obstetric complications are detected, appropriate treatment protocols are used. The timing and method of delivery are determined taking into account the course of pregnancy and the functional state of the remaining kidney. Early delivery is indicated when the symptoms of kidney failure appear and increase. In other cases, natural delivery is preferable. Cesarean section is performed in the presence of obstetric indications (clinically narrow pelvis, premature detachment or placenta previa, threat of rupture of the uterus and other life-threatening conditions of a woman or fetus).
Prognosis and prevention
The outcome of pregnancy in women with a single preserved kidney depends on the etiology of the underlying disease, the timing of nephrectomy, and the functional usefulness of the remaining organ. With proper medical support and timely correction of emerging complications, the prognosis is favorable in 95% of cases. According to observations in the field of obstetrics, women with a single left kidney tolerate pregnancy more easily. It is recommended to plan gestation taking into account the opinion of the urologist no earlier than 2 years after nephrectomy.
For the prevention of complications, early registration in a women’s consultation is necessary, correction of the diet with a restriction of the amount of water consumed, table salt, protein, supplementing the diet with fruits, vegetables, cereals, low-fat dairy products, refusal of coffee. It is important to avoid hypothermia, normalize the work and rest regime, and refuse to lift weights.