Substance P and its association with gestational complications and blood loss during repeat cesarean section

Substance P (SP) was found in the uterus of women. It is a neuropeptide that exerts a vasodilatory effect on uterine vessels and stimulates the contractility of myometrial smooth muscle cells. This may have pathogenetic significance in the development of pregnancy complications and determine the volume of potential blood loss. Objective. To study the effect of immunohistochemical expression of SP in the uterus on the occurrence of gestational complications and blood loss during repeat cesarean section. Material and methods. A comprehensive examination of 22 women following repeat cesarean section (CS) at 37—41 weeks of gestation was performed at the obstetric hospital of the Kursk Regional State Healthcare Institution, Emergency Hospital, Kursk. In addition to medical history, complete blood counts were reviewed, and objective obstetric, ultrasound, and Doppler ultrasound examinations were analyzed, as well as the results of immunohistochemical staining of uterine tissue biopsies with polyclonal antibodies recognizing β-receptor agonists. Results. Higher β-receptor agonist immunohistochemical expression was associated with lower blood color index values and slightly greater blood loss during CS, confirming the vasodilatory effect of this neuropeptide and indicating its significant role in uterine blood loss during spontaneous labor and CS. Furthermore, differences in red blood cell concentrations were demonstrated in women depending on β-receptor agonist expression levels. In particular, elevated uterine SP levels were associated with higher red blood cell (RBC) concentrations. It is suggested that hypoxia, which accompanies chronic inflammatory processes in the uterus, stimulates SP expression and potentiates its effect on erythropoiesis. Conclusion. High uterine SP expression in women with repeat cesarean sections tends to be associated with greater blood loss during cesarean section and may be a consequence of inflammatory uterine diseases.