Postpartum purulent-septic diseases - Causes and pathogenesis

Causes of postpartum purulent-septic diseases

At present, there is no doubt that the cause of purulent puerperal diseases are associations of anaerobic-aerobic flora. Each patient has from 2 to 7 pathogens. The pathogens of endometritis after cesarean section are most often gram-negative bacteria of the Enterobacteriaceae family (Escherichia, Klebsiella, Proteus), with E. coli predominating, the frequency of isolation of which ranges from 17 to 37%.

Of the gram-positive cocci, enterococci are most often isolated in the association (37-52%), which is explained by the ability of these microorganisms to produce beta-lactamase. Traditional pathogens - gram-positive staphylo- and streptococci, for example, Staphylococcus aureus, are rare - 3-7%. The frequency of isolation of obligate non-spore-forming anaerobes from the uterine cavity in endometritis after cesarean section, according to some data, reaches 25-40%. Most often, bacteroids and gram-positive cocci are found - peptococci, peptostreptococci, fusobacteria.

A major role in the development of the process is currently attributed to opportunistic flora. Diseases caused by gram-negative opportunistic microorganisms and non-spore-forming anaerobes, as well as their associations with other representatives of opportunistic flora, are more common.

The role of transmissible infections is controversial and not fully understood. The pathogens of the latter are often isolated in the associative flora together with other pathogens, and it is currently difficult to objectively judge their true significance.

The percentage of detection of genital mycoplasmas in the contents of the uterine cavity is extremely high and reaches 26% for Mycoplasma hominis and 76% for Ureaplasma urealiticum. In most cases, low-pathogenic mycoplasmas are isolated during endometritis after cesarean section in association with other, much more virulent microorganisms, so it is difficult to say whether they are pathogens or just parasites.

The detection rate of Chlamydia trahomatis is 2-3%, and its role in early postpartum endometritis is questioned by many authors. At the same time, in late postpartum endometritis, the significance of chlamydial infection increases sharply.

Recently, a number of authors have identified Gardnerella vaginalis in the uterine cavity in 25-60% of patients with postpartum endometritis.

According to research data, 68.5% of patients with late (delayed) complications of cesarean section were found to have associations of aerobic and anaerobic flora, represented by Escherichia coli, Proteus, Pseudomonas aeruginosa, and Bacteroides.

According to the frequency of occurrence, the causative agents of postoperative purulent-septic complications were distributed as follows: in 67.4% of cases, the causative agents were epidermal and saprophytic staphylococci, in 2.17% - Staphylococcus aureus, in 15.2% - non-hemolytic streptococcus, in 17.4% - Escherichia coli, in 28.3% - Enterobacteria, in 15.2% - Klebsiella, with the same frequency - 4.3% - Proteus, Trichomonas, Pseudomonas aeruginosa were detected; in 26.1% of patients, yeast-like fungi were found and in 19.6% - Chlamydia.

Pathogenesis of postpartum purulent-septic diseases

In the vast majority of cases, contamination of the uterine cavity occurs in an ascending manner during labor or in the early postpartum period. During a cesarean section, direct bacterial invasion of the uterine blood and lymphatic systems is also possible. However, the mere presence of an infectious agent is not enough to trigger an inflammatory process. Favorable conditions are required to ensure the growth and reproduction of microorganisms.

Epithelialization and regeneration of the endometrium usually begin on the 5th-7th day of puerperium and end only 5-6 weeks after delivery. Lochia, blood clots, remnants of necrotic decidual tissue and gravid mucous membrane located in the uterine cavity immediately after delivery create an extremely favorable environment for the reproduction of microorganisms, especially anaerobes. In the case of a cesarean section, the above-mentioned predisposing factors are joined by those associated with additional trauma to the uterine tissues during surgery, in particular, edema, ischemia and destruction of tissues in the suture area, the formation of microhematomas, seromas, and a large amount of foreign suture material.

After a cesarean section, primary infection of the entire thickness of the suture on the uterus occurs with the development of not only endometritis, but also myometritis. Therefore, the author clearly defines the inflammatory process in the uterus after abdominal delivery as endomyometritis.

Provoking factors

Significant risk factors when performing a cesarean section are:

• urgency of the operation;
• obesity;
• labor activity before surgery;
• prolonged anhydrous period; « duration of gestation;
• anemia (hemoglobin level less than 12.0 g/100 ml).

Below are listed the most significant risk factors for the development of purulent-septic complications in women who have undergone a cesarean section.

Genital factors:

• previous history of infertility;
• presence of chronic bilateral salpingo-oophoritis;
• the presence of STIs with their activation during the current pregnancy (ureaplasmosis, chlamydia, herpes infection), bacterial vaginosis;
• wearing an IUD prior to the current pregnancy.

Extragenital factors:

• anemia;
• diabetes mellitus;
• lipid metabolism disorder;
• the presence of chronic extragenital foci of infection (bronchopulmonary, genitourinary systems), especially if they have worsened during the current pregnancy.

Hospital factors:

• repeated hospitalizations during pregnancy;
• hospital stay (more than three days) before delivery.

Obstetric factors:

• the presence of gestosis, especially severe;
• prolonged, protracted labor, anhydrous period of more than 6 hours;
• 3 or more vaginal examinations during labor;
• the presence of chorioamnionitis and endomyometritis during childbirth.

Intraoperative factors:

• location of the placenta on the anterior wall, especially placenta previa;
• performing surgery in conditions of sharp thinning of the lower segment - with full opening of the cervix, especially with prolonged standing of the head in the plane of the entrance to the small pelvis;
• the presence of technical errors during the operation, such as the use of the Gusakov technique rather than the Derfler technique, an inadequate choice of uterine incision (cervical or vaginal cesarean section), which contributes to a sharp disruption of the nutrition of the anterior lip of the cervix; the use of rough manual techniques for removing the head (forced removal of the head due to rupture of the uterine tissue, pressure on the fundus of the uterus, vaginal aids), which inevitably leads to the continuation of the incision into the rupture with the transition to the rib of the uterus, the cervix (with its partial amputation) or the wall of the bladder; as a rule, this is accompanied by bleeding and the formation of hematomas, which requires additional hemostasis, and tissue healing under conditions of hematoma or ischemia (frequent, massive sutures) in such cases sharply increases the chances of failure of the sutures on the uterus;
• unrecognized intraoperative injury to the bladder or ureters due to changes in topography (repeated operations) or due to a violation of the technique for removing the head;
• violation of the technique of suturing the incision (rupture) on the uterus, in particular frequent suturing of the uterus, suturing of tissues ad mass; all this leads to ischemia and necrosis of the lower segment;
• implementation of inadequate hemostasis, leading to the formation of hematomas in the prevesical space and (or) parametrium;
• use of continuous suture for suturing the uterus, suturing the endometrium (wick effect), use of reactogenic material, especially silk and thick catgut, use of traumatic cutting needles;
• the duration of the operation is more than 2.5 hours;
• the presence of pathological blood loss.

In addition to the infection factor and provoking risk factors, the reduction of the protective and adaptive capabilities of mothers is of no small importance in the development of postpartum complications. During pregnancy, even uncomplicated, as a result of physiological immune depression, so-called transient partial immunodeficiency occurs, compensation for which occurs during vaginal delivery only by the 5th-6th day of the postpartum period, and after cesarean section - by the 10th day. Pregnancy complications, extragenital diseases, complicated labor, abdominal delivery, pathological blood loss contribute to an even greater decrease in the immunological reactivity of the woman's body, which can lead to the progression of purulent-septic diseases.

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