Why are the kidneys vulnerable during pregnancy?
Physiological reorganization of the body creates conditions for urine stasis and ascending infection:
- Hormonal factor: progesterone relaxes the musculature of the ureters, reducing the rate of urine flow.
- Mechanical factor: the growing uterus compresses the ureters, leading to dilatation of the renal pelves and the development of physiological hydronephrosis.
- Refluxes: decreased bladder tone and compression of the pathways provoke vesicoureteral and ureteropelvic refluxes, facilitating the path of bacteria to the upper sections.
Asymptomatic bacteriuria
This is a condition in which more than 100,000 bacteria per 1 ml are detected in the urine, but clinical symptoms are absent. Despite its latent course, bacteriuria is dangerous:
- Increases the risk of spontaneous abortion.
- Increases the likelihood of preterm birth.
- Is a risk factor for the development of acute pyelonephritis.
Timely antibacterial therapy and the use of herbal urinary antiseptics can prevent the development of complications in 70–80% of cases.
Gestational pyelonephritis
A disease that arises for the first time during gestation or in the postpartum period. Most often (48%) develops specifically in pregnant women.
Clinical features:
- Symptoms do not differ from those in non-pregnant individuals.
- Often proceeds as a monoinfection, but with a prolonged course transitions into a mixed infection.
- Complications include intrauterine hypoxia, intrauterine growth restriction (IUGR), and preeclampsia.
Treatment is carried out strictly in a hospital setting with the participation of a physician and a urologist, based on antibacterial therapy and restoration of urine outflow.
Briefly: answers to topical questions
What are the complete diagnostic criteria and urine collection rules to confirm asymptomatic bacteriuria?
The diagnosis of asymptomatic bacteriuria is based on the detection of a significant number of bacteria in the absence of a clinical picture.
Criteria for confirming the diagnosis:
- Absence of clinical symptoms of the disease.
- Detection of bacterial growth in two consecutive urine samples with an interval of more than 24 hours.
- The titer of one of the microorganism species is $\ge 10^5$ CFU/ml (more than 100,000 bacteria in 1 ml).
- Presence of no more than two species of bacteria in the sample.
- Isolation of the same species of bacteria upon repeated testing.
Specific rules for urine collection for this condition are not specified in the materials.
What microorganisms are the main causative agents of urinary tract infections in pregnant women?
The main causative agents of urinary tract infections in pregnant women are representatives of the intestinal microflora and other pathogens.
- Enterobacteria (Escherichia coli, Klebsiella, Proteus) are the most common cause, with Escherichia coli predominating.
- Staphylococci (Staphylococcus saprophyticus) are often found in young women.
- Enterococci (Enterococcus spp.) and streptococci.
- Pseudomonas aeruginosa (Pseudomonas aeruginosa).
- Yeast-like fungi (Candida spp.).
- Anaerobes and protozoa (trichomonads).
In an acute process, monoinfection predominates, while in a prolonged course, mixed infection predominates.
What methods of restoring urine outflow are used in the treatment of gestational pyelonephritis?
Instrumental drainage methods are used to restore impaired urine passage in gestational pyelonephritis.
- Stent placement — used in the urinary tract to ensure urine outflow.
- Percutaneous puncture nephrostomy — performed under ultrasound guidance (ultrasound) in acute secondary pyelonephritis in cases where stent placement is impossible.
These interventions are aimed at eliminating impaired urine outflow from the upper urinary tract.
Which groups of antibacterial drugs are approved for the treatment of gestational pyelonephritis depending on the trimester?
The sources do not specify the distribution of antibiotics for the treatment of gestational pyelonephritis strictly by trimesters, but list the general approved groups during pregnancy.
The drugs of choice are:
- Penicillins (penicillin, ampicillin, amoxicillin).
- Cephalosporins — approved as they do not possess embryotoxic properties (with the exception of cephalexin, cefaclor, and cefradine).
- Macrolides (erythromycin).
- Sulfonamides — not contraindicated, but long-acting drugs are used with caution due to the risk of kernicterus in the fetus.
Therapy is prescribed taking into account the sensitivity of the identified microorganisms.
With which acute surgical diseases is it necessary to differentiate gestational pyelonephritis?
Differential diagnosis of pyelonephritis considers acute appendicitis, renal colic, ruptured right-sided ectopic pregnancy, ruptured corpus luteum cyst, and ovarian mass torsion in the first trimester. In the second half of pregnancy, right-sided pyelonephritis is differentiated from acute appendicitis, urolithiasis, and acute cholecystitis.
An important differential diagnostic sign of pyelonephritis is changes in urinalysis — leukocyturia and hematuria; urine must be collected using a catheter.
The "12-23-32" rule: 12 weeks — hormones (progesterone), 23 weeks — corticosteroids, 32 weeks — mechanics (uterine compression).
Class and exam questions
What is the danger of asymptomatic bacteriuria?
It increases the risk of preterm birth and spontaneous abortion, and often precedes the development of acute pyelonephritis.
Why does pyelonephritis more frequently affect the right kidney?
This is due to a mechanical factor: the enlarged uterus compresses the right ureter more strongly.
What diagnostic methods are standard?
The urinalysis, Nechiporenko and Zimnitsky tests, urine culture, and renal ultrasound are used.
What else to study on this topic
- Differential diagnosis of acute and chronic pyelonephritis.
- Considerations for antibiotic selection taking into account the safety profile for the fetus.
- Methods for restoring urine flow in obstruction.
- Impact of concomitant urolithiasis on management tactics.
- Specifics of postpartum pyelonephritis.
Master the entire topic in the "Obstetrics and Gynecology" course
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