Validating a New Method to Assess Estimated Blood Loss in the Obstetric Population

According to the World Health Organization, postpartum hemorrhage (PPH) is the leading cause
of maternal mortality in low-income countries and the primary cause of nearly one quarter of
all maternal deaths globally. An estimated blood loss (EBL) in excess of 500 mL following a
vaginal birth or a loss of greater than 1,000 mL following cesarean birth often have been
used for the definition of postpartum hemorrhage, but the average volume of blood lost at
delivery can approach these amounts when actually measured rather than estimated. More than
half of all maternal deaths occur within 24 hours of delivery, most commonly from excessive
bleeding. Worldwide, 140,000 women succumb to postpartum hemorrhage each year. The most
common antecedents to postpartum hemorrhage are uterine atony, placental disorders, and
trauma during delivery. Improving maternal health worldwide is one of the WHO's 8 Millennium
Developmental Goals. The prevention and treatment of PPH is an essential step towards the
achievement of that goal.

Estimates of blood loss at delivery are notoriously inaccurate, with under-estimation more
common than over-estimation. Traditionally, the surgeon performing the cesarean section would
estimate the blood loss by visually assessing the blood collected in the surgical drape and
counting the number of lap sponges used thru out the procedure. Current detection and
management of hemorrhage is heavily based on clinical judgment, which often leads to delay in
recognition and intervention. Often, interventions such as fluid resuscitation and blood
transfusion are not initiated until significant hemorrhage has already taken place. The
traditional method for estimating blood loss is based on the surgeon and surgical staff's
subjective assessment that is severely limited by human error and the presence of large
volumes of amniotic fluid, irrigation, or both. Another limitation is that blood loss is
frequently estimated at the end of the procedure.

Early detection and treatment of this potentially life threatening obstetric complication is
of utmost importance in the field of obstetrics. Simulations and didactic training have been
shown to improve visual estimations, but there are still poor associations between experience
level and accuracy, and a significant decay in blood loss estimation skills over time.

The Triton system (Gauss Surgical, Inc., Palo Alto, CA) is a novel mobile monitoring platform
that combines mobile computing with Gauss Feature Extraction Technology (FET) to directly
assess Hb mass (mHb) absorbed by surgical sponges from an image. The device is an iPad like
imaging device that will assess blood loss via imaging of the surgical sponges used in the
surgery. In 2014, Konig at al. showed that mobile blood loss monitoring using the Triton
system is accurate in assessing mHb on surgical sponges across a range of ambient light
conditions, sponge saturation, saline contamination, and initial blood Hb. Utilization of
this tool could significantly improve the accuracy of blood loss estimates. Holmes et al.
also showed that the novel mobile monitoring system provides an accurate measurement of mHb
on surgical sponges as compared with manual rinsing measurements, and is significantly more
accurate than the gravimetric method.

However, these studies were performed on patients undergoing a myriad of surgical procedures
not just limited to obstetrical patients. To the investigators' knowledge, this technology
has not been validated in the obstetrical population at risk for hemorrhage.

The gauss/triton colorimetric system is not standard of care at UTMB. Not enough data is
available to support its use, despite being FDA approved to estimate blood loss. Most
evidence is available in non-pregnant patients. In the obstetric population no definitive
evidence exists, and the only trial that has been performed was recently published in AJP
reports. In that trial, only the accuracy was evaluated, and the investigators believe that
further evidence is needed to support its use.

The investigators' hypothesis is that this device will enable clinicians to prospectively and
objectively assess EBL. Ultimately after its validation, their results will be used to
propose a multicenter clinical trial to the NICHD MFMU network to evaluate the clinical
utility of this system.

This study will be a prospective cohort study, in which the investigators will evaluate two
methods of evaluating intraoperative blood loss during cesarean delivery (usual clinical
assessment versus Device). Of note, the subjects consented will be used as self-controls.
Patients who are scheduled for an elective cesarean and meet criteria for inclusion in the
study will be approached for participation at same day of admission. Written informed consent
will be obtained from the patients. If patients agree to participate, a CBC (complete blood
count) will be obtained via venous puncture. The device will be used during the delivery in
the operating room. The device will be used to assess EBL by the research staff only and
results/ EBL assessment will be masked to the clinical team. Unmasking will only occur after
collecting the data from the device with purpose to perform data analysis. Patient management
will be according to the clinical team. All patients undergo a CBC postpartum. The drop in
Hgb (ΔHgb) between the pre and post cesarean CBCs will be calculated for each patient.
Patients will be divided into quartiles of ΔHgb. Cases will be those patients whose ΔHgb is
in the upper quartile, while controls will be those patients whose ΔHgb is in the lower 3
quartiles. The investigators will be comparing EBL by standard clinical assessment versus
result from the device between cases and controls.

Inclusion Criteria:

- Pregnant women between the ages of 18-50

- Scheduled cesarean delivery

Exclusion Criteria:

- Incarcerated patients

- Patient unwilling or unable to provide consent

- Intrauterine fetal demise (no fetal heart beat identified and documented by two
physicians)

- Placenta previa or other known placental anomalies

- Enrolled in another trial that may affect outcome.