Infectious complications and the ascending pathway
The pathogenesis of infectious lesions of the urinary bladder is closely related to the risk of microorganisms spreading beyond the primary focus. Inflammation is most often caused by representatives of the intestinal flora: E. coli, Proteus, Klebsiella, Enterobacter, as well as viruses (adenovirus), Chlamydia, and Mycoplasma.
The most frequent systemic complication is bacterial pyelonephritis. It develops due to retrograde (ascending) reflux of infected urine and microorganisms from the urinary bladder directly into the renal pelvicalyceal system.
Specific infections deserve special attention. For instance, tuberculous cystitis carries an extremely high risk of generalization and in the vast majority of cases leads to the formation of secondary renal tuberculosis.
Severe morphological forms of acute inflammation
In most cases, acute cystitis proceeds as a nonspecific inflammation with hyperemia of the mucous membrane and exudate formation. However, exposure to aggressive factors can lead to the development of severe, complicated forms of the disease:
- Ulcerative cystitis: forms under the intensive impact of pyogenic microflora. It is characterized by extensive ulceration of mucosal areas (up to total involvement of the entire inner surface of the urinary bladder).
- Phlegmonous cystitis: manifests as a massive accumulation of purulent exudate within the thickness of the wall.
- Hemorrhagic cystitis: is distinguished by a prominent hemorrhagic component in the exudate. It can be either infectious (adenoviral infection) or iatrogenic, occurring against the background of radiation therapy or the administration of cytotoxic chemotherapeutic agents (e.g., cyclophosphamide, myleran).
Consequences of chronic cystitis
Chronic cystitis occurs with prolonged persistence of the infectious agent. Its main morphological difference from the acute form lies in the altered character of the inflammatory infiltrate and structural tissue remodeling.
The main morphological consequences of chronification are:
- Fibrous thickening of the lamina propria of the mucous membrane.
- Pronounced thickening of the entire urinary bladder wall.
- Persistent loss of tissue elasticity.
Specific histological forms of chronic inflammation are also distinguished, which similarly disrupt the normal architectonics of the wall:
- Follicular cystitis: is characterized by focal accumulation of lymphocytes with the formation of lymphoid follicles in the mucosal and underlying layers.
- Eosinophilic cystitis: is accompanied by infiltration of the submucosal layer by eosinophils, active development of fibrosis, and the appearance of specific giant cells.
Obstructive complications and urolithiasis
Urinary tract diseases are frequently associated with calculus formation. Calculi can be localized in the calyces, renal pelves, and the urinary bladder itself. Statistically, in 80% of patients, stone formation is unilateral.
Macroscopically, calculi are divided into:
- Small stones: form in the renal pelves, have a diameter of 2–3 mm, can be smooth or spiked, and are often multiple.
- Staghorn calculi: form during progressive salt precipitation, representing branching staghorn-like structures that completely replicate the shape of the pelvicalyceal system.
The main complication of the presence of stones is urinary tract obstruction. Blockage leads to impaired urine outflow, which inevitably provokes the development of hydronephrosis and chronic pyelonephritis.
Medical prevention of complications
Urinary antiseptics — drugs capable of creating therapeutically high concentrations of the active substance directly in the urine — are used to treat urinary tract infections and prevent ascending complications.
A classic representative is nitroxoline (an 8-hydroxyquinoline derivative). It is indicated for:
- Acute and chronic pyelonephritis, cystitis, urethritis.
- Mixed bacterial-fungal infections (due to activity against fungi of the genus Candida).
- Prevention of infectious complications during any instrumentation procedures (urinary bladder catheterization, diagnostic cystoscopy).
To memorize the triad of chronic cystitis consequences, use the mnemonic: Fibrosis of the lamina propria, Wall thickening, Loss of elasticity.
Class and exam questions
What mechanism leads to the development of pyelonephritis against the background of cystitis?
Infection spreads via a retrograde (ascending) pathway: bacteria from the urinary bladder cavity ascend through the ureters into the renal pelves and calyces.
What is the cause of the development of ulcerative cystitis?
Ulcerative cystitis develops under the aggressive impact of pyogenic microflora, leading to ulceration of large areas or the entire mucous membrane.
Which drugs can cause hemorrhagic cystitis?
Hemorrhagic cystitis can be iatrogenic in nature and develop during the administration of cytotoxic drugs such as cyclophosphamide and myleran.
What does urinary tract obstruction by stones lead to?
Obstruction of the urinary tract lumen by calculi disrupts urine passage, which ultimately causes hydronephrosis and chronic pyelonephritis.
What else to study on this topic
- Etiological structure of acute cystitis: the role of intestinal flora and intracellular pathogens
- Iatrogenic lesions of the urinary bladder: radiation and drug-induced cystitis
- Morphogenesis of urinary stones: from small calculi to staghorn forms
- Histological features of follicular and eosinophilic cystitis
- Pharmacodynamics of urinary antiseptics: 8-hydroxyquinoline derivatives
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