Pyelonephritis in pregnancy

In recent years, pyelonephritis during pregnancy (especially with purulent-destructive kidney lesions) has been recorded much more frequently than in pregnant women in other countries.

The increase in the prevalence of pyelonephritis during pregnancy and its complications is associated with unfavorable environmental and social factors that create conditions for the reduction of the protective mechanisms of the pregnant woman. Their breakdown is also facilitated by overfatigue, vitamin deficiency, decreased immunity, concomitant infectious diseases and other factors.

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Causes pyelonephritis in pregnancy

Pyelonephritis during pregnancy is classified as a disease that has an adverse effect on both the mother's body and the developing fetus. Its occurrence can lead to such serious complications as purulent-necrotic kidney damage and sepsis. With pyelonephritis during pregnancy, the likelihood of premature birth, miscarriages, intrauterine fetal death and other obstetric complications increases. When examined at a later date after pyelonephritis during pregnancy, many women are found to have chronic pyelonephritis, nephrolithiasis, nephrosclerosis, arterial hypertension, etc.

Acute pyelonephritis can occur during pregnancy, childbirth and the immediate postpartum period, which is why this complication is most often called acute gestational pyelonephritis.

There are acute gestational pyelonephritis of pregnant women (most often detected), women in labor and women who have given birth (postpartum pyelonephritis).

Up to 10% of pregnant women with acute pyelonephritis suffer from purulent-destructive forms of the disease. Among them, carbuncles, their combination with apostems and abscesses predominate. Most pregnant women develop unilateral acute pyelonephritis, with the right-sided process being detected 2-3 times more often than the left-sided one. Currently, pyelonephritis is the second most common extragenital disease in pregnant women. Pyelonephritis during pregnancy is more common in women during their first pregnancy (70-85%) and primiparous women than in women giving birth again. This is explained by the insufficiency of adaptation mechanisms to immunological, hormonal and other changes inherent in a woman's body during the gestation period.

Most often, pyelonephritis during pregnancy occurs in the second and third trimesters of pregnancy. Critical periods for its development are considered to be the 24th-26th and 32nd-34th weeks of pregnancy, which can be explained by the peculiarities of the pathogenesis of the disease in pregnant women. Less often, pyelonephritis during pregnancy manifests itself during childbirth. Pyelonephritis in women in labor usually occurs on the 4th-12th day of the postpartum period.

The causes of pyelonephritis during pregnancy are varied: bacteria, viruses, fungi, protozoa. Most often, acute pyelonephritis during pregnancy is caused by opportunistic microorganisms of the intestinal group (E. coli, Proteus). In most cases, it occurs as a continuation of childhood pyelonephritis. Activation of the inflammatory process often occurs during puberty or at the beginning of sexual activity (with the occurrence of defloration cystitis and pregnancy). The etiologic microbial factor is the same for all clinical forms of pyelonephritis during pregnancy, and a history of urinary tract infection is found in more than half of women suffering from pyelonephritis during pregnancy.

Asymptomatic bacteriuria found in pregnant women is one of the risk factors for the development of the disease. The bacterial agent itself does not cause acute pyelonephritis, but bacteriuria in pregnant women can lead to pyelonephritis during pregnancy. Asymptomatic bacteriuria is observed in 4-10% of pregnant women, and acute pyelonephritis is found in 30-80% of the latter. Bacteriuria in a pregnant woman is one of the risk factors for the development of pyelonephritis in newborn children. It is dangerous for the mother and fetus, as it can lead to premature birth, preeclampsia and fetal death. It is known that the urine of a pregnant woman is a good environment for the reproduction of bacteria (especially E. coli). That is why timely detection and treatment of bacteriuria is of particular importance for the prevention of possible complications.

The incidence of asymptomatic bacteriuria in pregnant women is influenced by the woman's sexual activity before pregnancy, the presence of various malformations of the urinary tract, and poor personal hygiene.

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Pathogenesis

Various factors play a role in the pathogenesis of pyelonephritis during pregnancy, and the mechanisms of hemo- and urodynamic disorders may change depending on the gestational age. An important role in the pathogenesis of pyelonephritis during pregnancy belongs to disorders of the urodynamics of the upper urinary tract, the causes of which may be both hormonal and compression factors. In the early stages of pregnancy, a change in the ratio of sex hormones is noted with subsequent neurohumoral effects on alpha- and beta-adrenergic receptors, leading to a decrease in the tone of the upper urinary tract. The leading pathogenetic factor of pyelonephritis during pregnancy in later stages of pregnancy is considered to be mechanical pressure of the uterus on the ureters.

In addition to the above mechanisms, urodynamic changes in the upper urinary tract, vesicoureteral reflux, suppression of the immune system and genetic predisposition play an important role in the development of pyelonephritis during pregnancy.

Dilation of the pelvic floor system is observed from the 6th to the 10th week of pregnancy and is observed in almost 90% of pregnant women. It is during this period that hormonal dissociation occurs: the content of estrone and estradiol in the blood increases significantly at the 7th to 13th week, and progesterone at the 11th to 13th week of pregnancy. At the 22nd to 28th week of pregnancy, the concentration of glucocorticoids in the blood increases. It has been established that the effect of progesterone on the ureter is similar to beta-adrenergic stimulation and leads to hypotension and dyskinesia of the upper urinary tract. With an increase in estradiol levels, alpha-receptor activity decreases. Due to the imbalance of hormones, a disorder of the urodynamics of the upper urinary tract occurs, the tone of the pelvic floor system and ureters decreases, and their kinetic reaction slows down.

Impaired urine outflow due to atony of the urinary tract leads to activation of pathogenic microflora, and possible vesicoureteral reflux contributes to the penetration of microorganisms into the interstitial substance of the medulla of the renal parenchyma.

Thus, in pregnant women, inflammatory changes in the kidneys are secondary and associated with impaired urodynamics of the upper urinary tract due to hormonal imbalance.

Changes in estrogen concentrations promote the growth of pathogenic bacteria, primarily E. coli, which is caused by a decrease in lymphocyte function. In this case, pyelonephritis as such may not occur, only bacteriuria occurs. Subsequently, pyelonephritis develops against the background of impaired urodynamics of the upper urinary tract. An increase in the concentration of glucocorticoids in the blood at 22-28 weeks of pregnancy promotes the activation of the previously started latent inflammatory process in the kidneys.

In late pregnancy, the compression of the lower ureters (especially the right one) by the enlarged uterus leads to a violation of the urine outflow from the kidneys. The violations of the urodynamics of the urinary tract in the second half of pregnancy, when acute pyelonephritis most often occurs, are mostly explained by the dynamic anatomical and topographic relationships between the anterior abdominal wall, the uterus with the fetus, the pelvic bone ring and the ureters.

Compression of the ureter by the uterus, enlarged and rotated around the longitudinal axis to the right, contributes to dilation of the upper urinary tract and the development of pyelonephritis. It has been established that dilation of the upper urinary tract occurs already at the 7-8th week of pregnancy, when there is still no mechanical effect of the pregnant uterus on the ureter. It is believed that the greater the degree of dilation of the upper urinary tract, the higher the risk of developing pyelonephritis during pregnancy. To varying degrees, pronounced dilation of the renal pelvis and ureter to the intersection with the iliac vessels is observed in 80% of pregnant women and in 95% of primiparous women.

Impaired urodynamics of the upper urinary tract in pregnant women is often associated with fetal presentation. For example, compression of the ureters is observed in most pregnant women with a cephalic presentation of the fetus and is not registered with a breech or transverse position of the latter. In some cases, impaired passage of urine from the upper urinary tract in pregnant women may be associated with right ovarian vein syndrome. In this case, the ureter and the right ovarian vein have a common connective tissue sheath. With an increase in the diameter of the vein and an increase in pressure in it during pregnancy, compression of the right ureter in the middle third occurs, leading to a violation of the outflow of urine from the kidney. Dilation of the right ovarian vein may be associated with the fact that it flows into the renal vein at a right angle. Right ovarian vein syndrome explains the more common development of acute right-sided pyelonephritis in pregnant women.

Vesicoureteral reflux is one of the pathogenetic mechanisms of pyelonephritis development during pregnancy. Vesicoureteral reflux is observed in almost 18% of clinically healthy pregnant women, while in pregnant women who have previously suffered acute pyelonephritis, its prevalence is more than 45%.

Recent studies have shown that both hormonal discrepancy and damage to the basement membranes of urinary tract leiomyocytes at all levels lead to the failure of the vesicoureteral segment and the development of vesicoureteral reflux in pregnant women. Rupture of the calyx vault as a consequence of renal pelvic reflux and urinary infiltration of the interstitial tissue of the kidney and urinary sinus that occurs as a result of this are accompanied by acute circulatory disorders in the kidney and organ hypoxia, which also creates favorable conditions for the development of pyelonephritis.

Normally, when the bladder is filled naturally to the physiological urge to urinate, abdominal tension and emptying of the bladder does not cause dilation of the renal pelvis, i.e. there is no reflux.

According to ultrasound data, the following types of vesicoureteral reflux in pregnant women are distinguished:

• when the abdominal muscles are tense and the bladder is filled before the physiological urge arises or after urination, an expansion of the renal pelvis is noted, but within 30 minutes after emptying the renal pelvis is completely reduced;
• when the abdominal muscles are tense and the bladder is filled before the physiological urge arises or after urination, an expansion of the renal pelvis is noted, but within 30 minutes after emptying the renal pelvis is emptied only half of its original size;
• the renal pelvis and calyces are dilated before urination, and after it the retention increases even more and does not return to its original size after 30 minutes.

During pregnancy, the lymphoid organs undergo restructuring, which is associated with the mobilization of suppressor cells. Pregnancy is accompanied by involution of the thymus gland, the mass of which decreases by 3-4 times compared to the initial one by the 14th day of pregnancy. Hypotrophy of the gland persists for more than 3 weeks after delivery.

Not only the number of T cells but also their functional activity is significantly reduced, which is associated with the direct and indirect (through the adrenal glands) influence of steroid sex hormones on it. Pregnant women suffering from acute pyelonephritis have a more pronounced decrease in the number of T lymphocytes and an increase in the content of B lymphocytes than women with a normal pregnancy. Normalization of these indicators during treatment can serve as a criterion for recovery. Pregnant women with acute pyelonephritis have not only a decrease in the phagocytic activity of leukocytes and the phagocytic index, but also suppression of nonspecific defense factors (a decrease in the content of complement components and lysozyme).

In the immediate postpartum period, not only do the same risk factors for the development of acute pyelonephritis as during pregnancy persist, but new ones also arise:

• slow contraction of the uterus, which can still create compression of the ureters for 5-6 days after birth;
• pregnancy hormones that remain in the mother's body for up to 3 months after birth and maintain dilation of the urinary tract;
• complications of the postpartum period (incomplete placental abruption, bleeding, hypo- and atony of the uterus);
• inflammatory diseases of the genital organs:
• urological complications of the early postpartum period (acute urinary retention and prolonged catheterization of the bladder).

Quite often, acute postpartum pyelonephritis is detected in women who have had acute gestational pyelonephritis during pregnancy.

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Symptoms pyelonephritis in pregnancy

Symptoms of pyelonephritis during pregnancy have changed in recent years, which complicates early diagnosis. Symptoms of acute pyelonephritis in pregnant women are caused by the development of inflammation against the background of impaired urine outflow from the kidney. The onset of the disease is usually acute. If acute pyelonephritis develops before 11-12 weeks of pregnancy, then patients have predominantly general symptoms of inflammation (fever, chills, sweating, high body temperature, headache). Weakness, adynamia, tachycardia are noted. In later stages of pregnancy, local symptoms of pyelonephritis during pregnancy also occur (pain in the lumbar region, painful urination, a feeling of incomplete emptying of the bladder, macrohematuria). Pain in the lumbar region can radiate to the upper abdomen, groin area, labia majora.

Hectic temperature increase, occurring in patients at certain intervals, can be associated with the formation of purulent foci and bacteremia in the kidney. During childbirth, the symptoms of pyelonephritis during pregnancy are veiled by the body's reaction to the birth act. Some women with acute pyelonephritis in mothers are mistakenly diagnosed with endometritis, perimetritis, sepsis, appendicitis. It usually occurs on the 13th-14th day after childbirth and is characterized by tension, pain in the muscles of the right iliac region, radiating to the lower back, high temperature, chills, vague symptoms of peritoneal irritation, which often serves as a reason for appendectomy.

Diagnostics pyelonephritis in pregnancy

The use of many diagnostic methods for acute gestational pyelonephritis during pregnancy is limited. This is especially true for X-ray examination. The radiation load on the fetus should not exceed 0.4-1.0 rad. However, excretory urography, even in this mode, poses a serious threat to it. It is known that with irradiation from 0.16 to 4 rad (average dose - 1.0 rad), the risk of developing leukemia in a child increases almost twofold, and the risk of developing malignant neoplasms in newborns - three times or more. Excretory urography is used in pregnant women only in exceptional cases - in extremely severe forms of pyelonephritis during pregnancy. Usually, it is prescribed only to those patients who, for medical reasons, will undergo termination of pregnancy.

X-ray and radioisotope research methods are recommended to be used only in the immediate postpartum period for the diagnosis of postpartum pyelonephritis.

Laboratory tests are a mandatory method for diagnosing pyelonephritis during pregnancy; their complex includes a general urine and blood test, a bacteriological blood test to determine the degree of bacteriuria and the sensitivity of isolated organisms to antibiotics, and determination of the functional activity of platelets.

The most informative and objective criteria for the severity of acute pyelonephritis are the indicators of the blood coagulation system and immunological tests, the leukocyte intoxication index and the content of medium-molecular peptides.

A method for calculating kidney temperature based on their microwave radiation is proposed, which is completely harmless to the mother and fetus and can be used as an additional method for diagnosing pyelonephritis during pregnancy.

Instrumental methods of diagnosing pyelonephritis during pregnancy, including catheterization of the ureters and renal pelvis, are rarely used. Even performing a suprapubic puncture of the bladder for urine analysis in pregnant women is considered dangerous, which is associated with a possible change in the topographic-anatomical relationships of the urinary and genital organs during pregnancy.

Catheterization of the bladder is not recommended, since any passage of an instrument through the urethra into the bladder is fraught with the risk of infection from the anterior to the posterior part of the urethra and bladder. However, if a ureteral catheter or stent is to be inserted for therapeutic purposes, then preliminary catheterization of the ureters is advisable to obtain urine from the affected kidney (for selective examination).

The leading role in diagnostics of pyelonephritis during pregnancy belongs to ultrasound of kidneys. It allows not only to determine the degree of dilation of the upper urinary tract and the condition of the renal parenchyma, but also to detect indirect signs of vesicoureteral reflux. During ultrasound, a rarefaction halo around the kidney is determined, its mobility is limited, and dilation of the upper urinary tract is reduced in various body positions. Ultrasonographic signs of pyelonephritis during pregnancy include an increase in kidney size, a decrease in the echogenicity of the parenchyma, the appearance of foci of reduced echogenicity of an oval-round shape (pyramid), and a decrease in kidney mobility.

Sometimes an increase in the thickness of the renal parenchyma to 2.1±0.3 cm and an increase in its echogenicity are noted. In carbuncles and abscesses, heterogeneity of the parenchyma is determined in combination with unevenness of its thickness, foci of echogenicity with a diameter of 1.7-2.7 cm, complete lack of mobility of the kidney during deep breathing and expansion of the renal pelvis. Modern ultrasound devices provide the ability to quantitatively assess echo density, which is widely used in the diagnosis of pyelonephritis during pregnancy.

Another method of quantitative assessment is Dopplerography with determination of the intensity and pulsatility index, systolic-diastolic ratio of volumetric blood flow velocity and diameter of the renal artery.

The diagnostics of destructive forms of pyelonephritis during pregnancy presents significant difficulties and is based on clinical, laboratory and ultrasound data analyzed in dynamics. The leading criterion for the severity of the condition is the severity of intoxication. The alarming signs indicating destructive changes in the kidney are considered to be a constantly high body temperature resistant to antibiotic therapy. an increase in the concentration of creatinine and bilirubin in the blood. In case of a kidney carbuncle, large-focal areas of the parenchyma with an increase or decrease in echogenicity (depending on the phase of development of the process) and deformation of the outer contour of the kidney are visualized. An abscess of the kidney is defined as a rounded formation with contents of reduced echogenicity.

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Treatment pyelonephritis in pregnancy

In recent years, the incidence of complicated forms of pyelonephritis during pregnancy requiring surgical treatment remains high. When examining women in the late stages after pyelonephritis during pregnancy, chronic pyelonephritis, nephrolithiasis, arterial hypertension, chronic renal failure and other diseases are often detected, so the problems of prevention, timely diagnosis and treatment of pyelonephritis during pregnancy are considered very relevant.

Treatment of pyelonephritis during pregnancy is carried out only in hospital conditions. Early hospitalization of patients contributes to improved treatment results.

Treatment of pyelonephritis during pregnancy begins with restoring the outflow of urine from the renal pelvis. Positional drainage therapy is used, for which the pregnant woman is placed on her healthy side or in the knee-elbow position. Antispasmodics are prescribed at the same time: baralgin (5 ml intramuscularly), drotaverine (2 ml intramuscularly), papaverine (2 ml of a 2% solution intramuscularly).

If the therapy is ineffective, catheterization of the renal pelvis is performed, using a ureteral catheter or stent to drain urine. Sometimes, percutaneous puncture or open nephrostomy is performed. Percutaneous nephrostomy has certain advantages over internal drainage:

• form a well-controlled short external drainage channel;
• drainage is not accompanied by vesicoureteral reflux:
• The drainage is easy to maintain and there is no need for repeated cystoscopies to replace it.

At the same time, percutaneous nephrostomy is associated with a certain social maladjustment. Against the background of restoration of urine outflow from the pelvis, antibacterial treatment, detoxification and immunomodulatory therapy are carried out. When prescribing antimicrobial drugs, it is necessary to take into account the features of their pharmacokinetics and possible toxic effects on the body of the mother and fetus. In purulent-destructive forms of pyelonephritis during pregnancy, surgical treatment is performed, more often - organ-preserving (nephrostomy, kidney decapsulation, excision of carbuncles, opening of abscesses), less often - nephrectomy.

When choosing a method of drainage of the upper urinary tract for pyelonephritis during pregnancy, the following factors must be taken into account:

• duration of pyelonephritis attack;
• features of microflora;
• degree of dilation of the renal pelvis and calyces;
• presence of vesicoureteral reflux;
• pregnancy terms.

The best results of urinary tract drainage are achieved with a combination of positional and antibacterial therapy, satisfactory results are achieved with the installation of a stent, and the worst results are achieved with catheterization of the kidney with a conventional ureteral catheter (it may fall out, which is why the procedure must be repeated multiple times).

With the restored urine outflow from the kidney, conservative treatment of pyelonephritis during pregnancy is carried out, which includes etiologic (antibacterial) and pathogenetic therapy. The latter complex includes non-steroidal anti-inflammatory drugs (NSAIDs), angioprotectors and saluretics. It is necessary to take into account the peculiarities of the pharmacokinetics of antibacterial drugs, their ability to penetrate the placenta, into breast milk. When treating pyelonephritis in women in labor, sensitization of the newborn is possible due to the intake of antibiotics with mother's milk. Women with pyelonephritis during pregnancy are preferably prescribed natural and semi-synthetic penicillins (devoid of embryotoxic and teratogenic properties) and cephalosporins. In recent years, macrolide antibiotics (roxithromycin, clarithromycin, josamycin, etc.) have become more widely used.

Pipemidic acid (urotractin), which belongs to the group of quinolones, penetrates the placenta only in small quantities. The drug content in the milk of women in labor 2 hours after taking a dose of 250 mg does not exceed 2.65 mcg / ml, and then gradually decreases and after 8 hours is not detected at all. Aminoglycosides should be administered with caution and for no more than ten days. Sulfonamides are not recommended for use throughout pregnancy. Gentamicin is prescribed with caution, since damage to the VIII cranial nerve in the fetus is possible.

Treatment of complicated forms of pyelonephritis during pregnancy remains one of the difficult tasks for urologists and obstetricians-gynecologists. There is no single classification of complications of the disease. In addition, a tendency towards an increase in the prevalence of purulent-destructive forms of pyelonephritis during pregnancy has been noted. Among the possible causes of which one can single out frequent infection with highly virulent gram-negative microorganisms, immunodeficiency states, late diagnosis of the disease and untimely initiation of treatment.

An important component of detoxification therapy for complicated forms of pyelonephritis during pregnancy is the use of extracorporeal detoxification methods, such as plasmapheresis. Advantages of the method: ease of implementation, good tolerability by patients, no contraindications to its use in pregnant women. Plasmapheresis eliminates the deficiency of cellular and humoral immunity. Already after the first session, most patients experience normal body temperature, a decrease in the severity of clinical and laboratory signs of intoxication, and improved well-being; the condition of patients stabilizes, which allows for surgical intervention with minimal risk.

In the complex treatment of pyelonephritis during pregnancy, it is recommended to include ultraviolet irradiation of autologous blood. The most effective is the early use of this method (before the serous stage of the disease turns into purulent).

Indications for surgical treatment of pyelonephritis during pregnancy:

• ineffectiveness of antibacterial therapy within 1-2 days (increase in leukocytosis, increase in the number of neutrophils in the blood and ESR, increase in creatinine concentration);
• obstruction of the urinary tract due to stones;
• inability to restore urodynamics of the upper urinary tract.

Only early and adequately sized surgeries in pregnant women with purulent-destructive pyelonephritis can stop the infectious and inflammatory process in the kidney and ensure normal fetal development.

The choice of the surgical method depends on the clinical features of pyelonephritis during pregnancy: the degree of intoxication, damage to other organs, macroscopic changes in the kidneys. Timely surgical intervention in most cases allows preserving the kidney and preventing the development of septic complications.

In case of purulent-destructive changes limited to 1-2 segments of the kidney, nephrostomy and kidney decapsulation are considered an adequate method of surgical treatment. In case of widespread purulent-destructive organ damage and severe intoxication threatening the life of the pregnant woman and the fetus, nephrectomy is the most justified. In 97.3% of pregnant women, the use of various surgical interventions made it possible to achieve clinical cure of purulent-destructive pyelonephritis.

Termination of pregnancy due to pyelonephritis during pregnancy is rarely performed. Indications for it:

• fetal hypoxia;
• acute renal failure and acute liver failure;
• intrauterine fetal death;
• miscarriage or premature birth;
• hypertension in pregnant women;
• severe gestosis (if therapy is unsuccessful for 10-14 days).

Recurrence of the disease is observed in 17-28% of women with inadequate or late treatment. To prevent recurrence of the disease, it is recommended to have a dispensary observation of women who have had pyelonephritis during pregnancy, a thorough examination of them after childbirth, which allows for timely diagnosis of various urological diseases, prevention of complications, and planning of subsequent pregnancies.