Introduction:
This study aimed to evaluate the effect of manual strangulation of the uterine isthmus on the amount of blood loss during cesarean section.

Material and methods:
This is a prospective randomized controlled trial. A total of 118 participants were enrolled in the study. Manual strangulation of the uterine isthmus just after placental removal was performed during cesarean section in group I (n = 57; the strangulation group). Strangulation was not performed in group II (n = 61; the control group). Preoperative and postoperative venous blood hemoglobin, capillary hemoglobin, and absorbed blood levels during the operation were compared between the two groups.

Results:
The median age of the patients was 28.5 (19–41). The median body mass index of the patients in the study was 27 (21–42). There were no significant differences in the demographic characteristics of the patients between the groups. The median difference between the preoperative and postoperative 4–6 h capillary hemoglobin values was significantly lower in the strangulation group (2.0 (0–9)) than in the control group (3.0 (0–8)). The amount of absorbed blood during the operation was also significantly lower in the strangulation group (164.5 ml (69–1310)) than in the control group (230 ml (35–3223)).

Conclusions:
Manual uterine strangulation of the uterine isthmus immediately after the removal of the placenta may induce a 30% decrease in blood loss during cesarean section.