Vasopressin Regimen for Hemorrhage Control During Repeat Cesarean Section with Intramural Myoma
Primary Recommendation
The safest approach is to avoid myomectomy entirely during repeat cesarean section and defer fibroid removal to an interval procedure 2-3 months postpartum, as concurrent myomectomy significantly increases hemorrhage risk in an already high-risk surgical setting. 1
However, if myomectomy must be performed during cesarean delivery despite increased risks, use intramyometrial vasopressin injection at a dose of 20 units diluted in 20-60 mL normal saline, injected directly into the myometrium surrounding the myoma to achieve vasoconstriction and reduce blood loss. 2, 3
Critical Context: Why Concurrent Myomectomy Should Be Avoided
Repeat cesarean delivery with a 6 cm intramural myoma already carries substantially elevated baseline risks including wound hematoma, transfusion requirement, and emergency hysterectomy. 1
Myomectomy at the time of operative delivery is particularly hazardous due to the dramatically increased vascularity of the gravid myometrium during pregnancy, making significant intraoperative blood loss highly likely. 2
The American College of Obstetricians and Gynecologists specifically recommends against concurrent myomectomy in this clinical scenario, advocating instead for interval myomectomy 2-3 months postpartum when uterine vascularity has normalized. 1
Vasopressin Dosing Protocol (If Myomectomy Proceeds)
Standard Regimen
Dose: 20 units vasopressin diluted in 20-60 mL normal saline for intramyometrial injection. 3, 4
Administration technique: Inject directly into the myometrium surrounding the myoma before enucleation to achieve local vasoconstriction. 2
Evidence of efficacy: This regimen reduces median blood loss from 675 mL to 225 mL (67% reduction) and eliminates transfusion requirements in controlled trials. 3
Volume Considerations
Both dilute (20 U in 400 mL) and concentrated (20 U in 60 mL) solutions demonstrate comparable efficacy when the same 10-20 unit dose is administered, so higher volume does not provide additional benefit. 4
The critical factor is the total vasopressin dose (20 units), not the dilution volume, as randomized trials show no difference in blood loss between high-volume versus low-volume administration. 4
Critical Safety Warnings
Dose Limitations
Never exceed 20 units total dose for intramyometrial injection, as higher doses (60 units) have caused severe peripheral arterial vasospasm mimicking cardiovascular collapse. 5
Doses above recommended levels can cause loss of peripheral pulses and nonmeasurable blood pressure due to severe vasospasm rather than true hypotension, leading to dangerous misinterpretation and inappropriate vasopressor administration. 5
Monitoring for Vasospasm
If pulselessness or nonmeasurable blood pressure occurs after vasopressin injection, consider severe peripheral vasospasm rather than global hypotension before initiating Advanced Cardiac Life Support protocols or additional vasopressors. 5
Treatment with additional vasopressors when vasospasm is misinterpreted as hypotension has been associated with cardiac complications, making accurate diagnosis essential. 5
Delayed Bleeding Risk
- Monitor carefully for postoperative myometrial incisional bleeding after vasopressin clearance, as the vasoconstrictive effect is temporary and bleeding may occur once the drug effect dissipates. 2
Adjunctive Hemorrhage Control Measures
Mechanical Techniques
Apply tourniquets to vascular pedicles in addition to vasopressin injection to further reduce blood flow to the surgical field. 2
Consider loop ligation of the myoma pseudocapsule combined with vasopressin, which reduces average blood loss, hospital stay, and conversion to laparotomy rates compared to vasopressin alone. 6
Make a single vertical incision over the myoma when possible to minimize the number of uterine entry sites and achieve meticulous hemostasis with multilayer closure. 1
Pharmacologic Adjuncts
Administer prophylactic oxytocin infusion to promote uterine contraction and reduce postpartum hemorrhage risk. 7
Consider bilateral uterine artery ligation in addition to vasopressin if the myoma is large or hemorrhage risk is particularly high. 7
Preoperative Optimization
Correct anemia preoperatively with iron supplementation or erythropoietin to improve hemoglobin levels before surgery. 1
Arrange autologous blood storage to reduce the risk of requiring allogeneic transfusion. 1
Ensure blood products are immediately available and do not proceed unless the patient has been counseled about hysterectomy as a potential rescue procedure. 1
Surgical Team Requirements
The surgical team must have experience with complex myomectomy and hemorrhage management, as this is not a procedure for inexperienced operators. 1
Only the most experienced surgeons should attempt myomectomy during cesarean delivery, given the substantially elevated technical difficulty and complication risk. 7