Uterine Cooling During Cesarean Delivery to Reduce Blood Loss and Incidence of Postpartum Hemorrhage

Postpartum Hemorrhage, Uterine Atony

postpartum hemorrhage, uterine atony, cesarean section, cesarean hysterectomy, acute blood loss anemia, uterotonics, obstetric hemorrhage, severe hemorrhage, blood transfusion, obstetric emergencies, obstetrics, massive hemorrhage, hemorrhage, uterine cooling

The objective of the study is to demonstrate whether cooling the uterine smooth muscle during cesarean section (following delivery of the fetus) will promote better uterine contraction and involution resulting in lower blood loss, use of fewer uterotonic medications, and fewer hysterectomies following cesarean section. The investigators suspect that it may.

Study Design: Patients will be randomly assigned to either the study group or the control group. Patients may receive regional (epidural or spinal/epidural) or general anesthesia.Initially, the investigators plan to enroll 200 subjects, 100 to the study group and 100 to the control group. Following delivery of the fetus, patients in the study group also will have Pitocin® administered to them according to the usual protocol.Immediately following delivery of the fetus the uterus will be externalized in the usual fashion and the body of the uterus cephalad to the hysterotomy incision will be wrapped in sterile surgical towels saturated in sterile, iced normal saline. These towels will come from a sterile cooling pot set to 30 degrees Fahrenheit. The skin of the abdomen will be draped to prevent contact with the cold towels. Additional uterotonic medications may be given at the discretion of the attending obstetrician. Iced saline-soaked towels will be kept in place for a minimum of 5 minutes and replaced at the discretion of the attending obstetrician until the hysterotomy is closed and the uterus is replaced into the patient's abdomen. The surface temperature of the uterus will be measured using an infrared thermometer prior to replacing the uterus into the abdomen. Two surgical suction canisters will be available. Immediately after delivery of the fetus and prior to delivery of the placenta, the amniotic fluid and blood on the surgical field will be aspirated into the first canister. The second suction canister will be used to aspirate blood and fluid until the conclusion of the operation. At the conclusion of the surgery blood loss will be calculated by measuring the content of blood in the second canister minus the amount of irrigation fluid used, and by weighing the surgical sponges. Average blood loss during cesarean sections has previously been reported as 500 to 1000 cc. The duration of cooling the uterus will be recorded. Use and amount of uterotonic medications also will be recorded. During the surgery the patient's vital signs will be monitored in the usual fashion. Particular attention will be paid to a change in her temperature. Warmed blankets and forced air warming blankets will be used to maintain normothermia, if required. At the conclusion of the study the amount of blood loss between the control and study groups, and the amount of uterotonic drugs will be calculated and compared. The number of patients in each group who require additional surgeries, e.g. hysterectomy or D&C, will be monitored. Pre-op and post-op hemograms will be compared if obtained at the discretion of the attending obstetrician. Blood product administration will be recorded. Determination of an ideal temperature of cooling towels is not an objective of the study. We're asking a qualitative question, not a quantitative question at this time. Study Rationale: The uterus is a smooth muscle whose contraction is modulated most directly by intrinsic or extrinsic oxytocin. During pregnancy the spiral arteries within the uterus and beneath the placenta enlarge to provide adequate perfusion to the placenta. After separation of the placenta the uterine smooth muscle cells contract in a pincer-like action to pinch the spiral arteries closed. When uterine contraction is inadequate (approximately 4-6% of normal pregnancies) the spiral arteries continue to bleed. If not addressed the bleeding can be excessive, even leading to maternal death. Approximately 5-8 out of 1,000 cesarean sections require hysterectomy to control bleeding. Release of calcium ions from sarcoplasmic reticulum stores is the immediate initiator of contraction, and calcium's diffusion from the muscle filaments and re-uptake by the sarcoplasmic reticulum results in relaxation of contraction. In some smooth muscles cold enhances contraction; perhaps by slowing the re-uptake of calcium. When the usual pharmacologic agents fail to induce adequate contraction of the uterine smooth muscle, the investigators suspect that application of cold may.

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