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.
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
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
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.
- Pregnant adult women of any gravidity, and gestational duration who present for
cesarean section at Baylor University Medical Center in Dallas and who have given
informed consent to be in the study.
- Women who refuse to be in the study, and women who are unable to consent due to
emergent nature of the cesarean section will be excluded. Women who are unable to
understand the nature of the study due to mental illness, mental retardation, medical
condition, or other communication barrier will be excluded.
- Inability to exteriorize the uterus during c-section.