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NON-SPECIFIC ULCERATIVE COLITIS: EPIDEMIOLOGY, ETIO-PATHOGENESIS
AND ISSUES OF SURGICAL TREATMENT
B.B. Mirzayev ,
D. Kholbekov
Fergana Medical Institute of Public Health
Abstract:
Non-specific ulcerative colitis (NUC) is a chronic autoimmune inflammatory disease
of the colon with a relapsing course, characterized by mucopurulent and bloody discharge from
the intestine, abdominal pain and systemic manifestations. The incidence of UC has traditionally
been high in Western countries, but in recent decades its growth has been observed in the regions
of Asia and the CIS. The mechanisms of development of UC include genetic predisposition
(many polymorphisms of interleukins and HLA), immunoregulation disorders (imbalance of
Th1/Th2 response, excessive expression of TNF-α, IL-13, etc.) and dysbiosis of intestinal
microbiota . The leading method of radical treatment of UC is colectomy with formation of
ileoanal anastomosis (IAA), which is used in severe exacerbations and complications (toxic
megacolon, uncontrolled bleeding, perforation, dysplasia/carcinoma) or in relapses refractory to
therapy. Modern minimally invasive technologies ( laparoscopy , robots) can reduce
postoperative complications and shorten the duration of hospitalization. The review considers
international and regional epidemiological data on UC, modern concepts of etiopathogenesis ,
clinical picture and indications for surgery, as well as modern surgical approaches and
unresolved issues.
Key words:
nonspecific ulcerative colitis, epidemiology, pathogenesis, surgical treatment,
minimally invasive technologies, intestinal microbiota .
Introduction
Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) and is characterized by a
persistent, relapsing course. It is characterized by chronic inflammation of the colonic mucosa,
primarily affecting the rectum and spreading further, and in severe cases, total colon
involvement [1,5,6]. The disease usually debuts at a young age (15–30 years), but a secondary
peak in incidence is also possible in old age. Ulcerative colitis is estimated to account for
approximately 20–30% of all IBD cases and causes hundreds of thousands of visits to physicians
each year; in the United States, annual direct medical costs for UC reach several billion dollars.
Constant exacerbations reduce the quality of life of patients, and surgical treatment is required
for a significant number of patients: according to large studies, only about 10% of patients with
UC require colectomy within 20 years of diagnosis . The increase in the incidence of IBD,
including UC, in countries with low and medium levels of development (Asia, the Middle East,
the CIS) increases the relevance of studying this pathology at the international and regional
levels [11,12,14]. In this regard, the review presents current data on the epidemiology of UC, the
main pathogenetic mechanisms, clinical manifestations and indications for surgical treatment,
existing approaches to surgery and prospects for further research.
Epidemiology of UC
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UC is widespread, but there are significant geographical differences. The highest incidence is
traditionally observed in Northern Europe and North America – up to 20–25 new cases per year
per 100,000 population. For comparison, in Eastern Europe and Asia these rates are significantly
lower (approximately 5–12/100,000 per year). According to meta-analyses and reviews, the
current prevalence of UC in Western countries reaches 150–300 per 100,000 population. At the
same time, in many regions with low incidence, a steady increase has been observed in recent
decades. For example, in South Korea, the annual incidence of UC increased from 0.33 to 6.58
cases per 100,000 population during 1986–2015, and in Japan, from 0.03 to 12.2/100,000 during
1955–2014. According to the review, in East Asia, about 0.1–0.2% of the population has IBD. In
South Asian countries (India, Pakistan, Sri Lanka), the average incidence is lower (several cases
per 100,000).
Data for the CIS and Central Asian regions are limited. In Kazakhstan, the prevalence of UC is
84.4 cases per 100,000 population (total IBD is 113.9/100,000). In Uzbekistan and other Central
Asian countries, there have been virtually no specialized epidemiological studies, so there are no
accurate statistics. In general, there are few studies in Central Asia, which makes it difficult to
assess the actual incidence of IBD. Thus, global trends show stabilization or a slight decrease in
incidence rates in developed countries, while there is rapid growth in developing regions of the
world.
Etiopathogenesis
The causes of UC are complex and include the interaction of genetic factors, immune disorders,
changes in microbiota and external factors. It is generally accepted that UC develops against the
background of genetic predisposition and immune regulation disorders . Thus, having a close
relative with UC increases the risk of the disease by approximately 4 times. Many
polymorphisms of genes associated with inflammation regulation (IL23R, IL12B, IL10, HLA,
etc.) have been identified; genetic studies of recent years emphasize the influence of variations in
interleukins and their receptors on the predisposition to UC.
Immunopathogenesis of UC is characterized by an excessive inflammatory response to
environmental factors and microbial antigens. In UC, a predominantly Th2-type response is
observed (in contrast to Th1/Th17 in Crohn's disease) - cytotoxic CD4^+^ Th2 cells are
activated, levels of IL-13, as well as TNF-α and other proinflammatory cytokines are increased.
Innate components of immunity play an important role: patients have been shown to have
dysfunction of the epithelial barrier (impaired mucin composition and cellular contacts), as well
as increased expression of TL receptors on dendritic cells of the mucosa [2,3,15,26]. Against the
background of barrier impairment, commensal intestinal bacteria can provoke an excessive
immune response. The result is a chronic disruption of the "microbe - immune system"
homeostasis: the composition and diversity of the microbiota changes , which further stimulates
inflammation and damage to the intestinal mucosa. In particular, with UC, there is a decrease in
the number of beneficial bacteria ( Faecalibacterium prausnitzii , etc.) and an increase in
opportunistic strains, which can be both a cause and a consequence of inflammation [30,32,34].
External environmental factors also modify the risk of UC. Among them, smoking has been
studied the most: interestingly, smokers are less likely to develop UC, and in former smokers,
the disease often proceeds more severely [4,5,6]. Exacerbation of UC may develop upon quitting
smoking. Appendectomy at a young age is associated with a decrease in the risk of UC (by about
69%). The attractiveness of the "Western" lifestyle (diet with a predominance of fats and sugars,
lack of fiber) and the use of a number of drugs (NSAIDs, oral contraceptives) are discussed as
potential risk factors. Thus, it is known that non-steroidal anti-inflammatory drugs often provoke
relapses of UC [7,8,13,14]. The influence of warm moist infections and antibiotics, which
disrupt the intestinal microbiota , is also assumed . Together, all these factors contribute to the
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high variability of the course of UC, but the exact mechanisms are still not fully understood.
Clinical picture and indications for surgery
UC is characterized by a chronic remitting course with acute and latent phases. The main
symptoms are diarrhea with blood and mucus, abdominal pain (usually in the left iliac region),
tenesmus and false urges (imperative urges without evacuation). Non-specific manifestations are
often added - weight loss, subfebrile temperature, anemia, general weakness [18,21,22,30]. The
course of UC is variable: from proctitis, in which only the rectum is affected (which occurs in
30-60% of patients at debut), to left-sided colitis (16-45%) and total ( pancolitis ) (14-35%). On
examination, the intestine looks "fragile", with an erased vascular pattern, erythematous and
ulcerated areas, evenly spreading from the rectum to the proximal parts. Important markers of
activity are elevated ESR, CRP, leukocytosis, and in 60–70% of cases, the presence of
perinuclear ANCA (p-ANCA) [9,10,11,18]. UC is often accompanied by extraintestinal
manifestations: 10–30% of patients develop arthritis, eye inflammation ( episcleritis , uveitis ),
skin diseases (erythema nodosa , pyoderma gangrenosum ), and other inflammations associated
with colitis activity. Chronic UC is associated with primary sclerosing cholangitis (PSC), which
increases the risk of colorectal cancer.
Despite the improvement of medical treatment (5-aminosalicylates, glucocorticoids,
immunosuppressants, biological drugs), a significant proportion of patients sooner or later
require surgical treatment [22,23,26,35,38]. Various studies note that from 10% to 30-40% of
patients with UC undergo colectomy during their life . Indications for surgery are divided into
emergency and planned. Emergency indications include severe complications or a life-
threatening condition: acute severe colitis that cannot be relieved with medication, toxic
megacolon (extensive expansion of the colon with a toxic state), massive bleeding, intestinal
perforation. In such situations, an urgent subtotal colectomy is performed with the formation of
an ileostomy , often with preservation of the rectum ( Hartmann stages), or a proctocolectomy
with an ileostomy or ileoanal anastomosis is performed immediately , depending on the patient's
condition. Elective indications for colectomy include failure of long-term drug therapy (relapses
after multiple courses of therapy), low quality of life with persistent symptoms, dysplasia or
early colon cancer in UC. If high-grade dysplasia or cancer is detected, colorectal risk is
considered an indication for total proctocolectomy with ileoanal anastomosis. The choice of
surgical tactics is largely determined by the severity and extent of inflammation, as well as the
general condition of the patient.
Modern approaches to surgical treatment
Surgical treatment of UC is considered radical and can lead to complete disappearance of
intestinal symptoms, but surgery is a serious intervention with its own risks. In UC treatment
programs, the main role is given to total proctocolectomy with the formation of an ileoanal
anastomosis (IAA), which allows preserving the anal sphincter [14,17,19,25,26]. Classically, this
operation is performed in 2-3 stages (to reduce the risk of taking corticosteroids): first, removal
of the colon and formation of a temporary ileostomy (preservation of the rectum or its suturing),
then removal of the rectum and restoration of the intestine from the ileal loop. In emergency
cases, a less radical operation is often performed - subtotal colectomy with ileostomy ( Hartman
technique ) to stabilize the patient, and then, during the second operation, complete the removal
of the rectum and form the anastomosis.
In recent decades, laparoscopic technique has become the standard of preparation for colorectal
surgery . Laparoscopy in UC has a proven effect of reducing postoperative morbidity, the
number of early complications (including incisional infections) and shortens the duration of
hospitalization [16,18,20, 31-33]. Randomized and observational studies have shown that with
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laparoscopic IARA, the overall complication rate is comparable to open surgery (odds ratio
≈1.12 without statistical difference), but the duration of the operation is usually longer. At the
same time, after laparoscopy, the average duration of hospitalization is significantly shorter (in
the meta-analysis 11.2 ± 4.8 days versus 26.4 ± 4.3 days with open surgery). In addition, the
tolerability of laparoscopy is especially important in young patients with a potentially large
number of surgeries. A systematic review showed that laparoscopic intestinal restoration (IARA)
provides comparable results with open access in terms of morbidity and mortality. Several
studies have noted the benefit of laparoscopy in reducing the incidence of short-term
complications in patients who received corticosteroids before surgery.
In addition to classical laparoscopy, robotic technologies and single-laparoscopic access are used
in modern proctology. Robotic proctocolectomy allows for more precise work in the pelvis and
can reduce the conversion rate in complex cases, although the final results are still limited to
small series. Single-incision techniques (SILS) and trans-anal approaches are also being actively
introduced for outpatient expansion of indications. An important aspect is the minimization of
the number of operations and stages: in a favorable situation, one-stage IARA can be performed,
but in high-risk patients (immunosuppression, active inflammation), two- or three-stage options
are more often used. In general, modern surgical approaches seek to ensure complete removal of
the inflammation focus and adequate intestinal reconstruction with minimal trauma.
Conclusion.
Thus, despite the progress in understanding UC, many aspects remain incompletely
understood. The etiology of the disease remains unclear: it is unknown which specific
environmental triggers initiate the inflammatory cascade in genetically susceptible individuals
and how immune and metabolic disturbances influence it. The exact role of the gut microbiota
remains to be determined : although dysbiosis in UC has been documented, therapeutic methods
of flora correction (e.g. faecal microbiota transplantation ) have not yet become standard
treatment. Genetic studies are constantly expanding the list of associated loci, but still do not
explain all clinical phenotypes of UC.
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