Study population
The medical records of all women that presented to the SZMC emergency
room between January 2013 and December 2019 due to trauma during
pregnancy were reviewed for the following inclusion criteria: viable
pregnancy (gestational age >24.0 weeks) and at least one
FCM test was obtained during their ER visit or hospitalization. Maternal
trauma was defined as any blunt injury occurring during pregnancy
resulting in evaluation in the emergency room or hospital admission. We
excluded women with penetrating trauma as these are rare; we also
excluded women with trauma in whom FCM test was not obtained, as our aim
was to assess the predictive role of FCM, and finally we excluded women
in whom a FCM test was obtained for reasons other than trauma.
Charts of all eligible women were reviewed and the following data was
extracted: patient demographics, obstetric history, details of maternal
injury, presence of preterm contractions, preterm labor (PTL), and
placental abruption, surgical procedure(s) (if any), obstetric
complications, and neonatal outcomes: fetal injury and death. We also
devised an anatomic scoring system based on information in the medical
chart, to provide an overall score for patients with multiple injuries:
the Injury Severity Score (ISS).
The FCM data was extracted and recorded as both categorical values
(FCM-positive or -negative) and continuous data (TPH volume when
positive). According to our medical center protocol, FCM is obtained
when the following criteria are met: direct abdominal injury, all cases
of motor vehicle accident (MVA),
and other blunt trauma cases where the attending physician deems it
necessary.
Furthermore, according to local policy all such women undergo thorough
evaluation including detailed history, past and current pregnancy
information, trauma mechanism, acuteness/severity of the case,
symptoms/signs of acute abdomen, vital signs, and assessment for uterine
contractions and/or premature labor. Also, all women undergo fetal heart
rate monitoring to detect fetal compromise, tocodynamometer for
monitoring and recording uterine contractions, and sonographic
examination of the fetus and placenta by certificated technician and/or
obstetrician at the time of admission. Finally, decision regarding any
surgical intervention is made by a senior physician.
Obstetric issues were managed by the perinatology team, consistent with
the multidisciplinary approach at the SZMC and as recommended by the
ATLS and ACOG 19,20. Accordingly, women with any signs
of regular uterine contractions (more than one in 10 minutes), vaginal
bleeding, rupture of amniotic membranes, serious maternal injury,
significant abdominal/uterine pain or fetal tachycardia, decelerations,
or non-reassuring fetal heart rate tracing, were monitored for a period
of no less than 24 hours. When uterine contractions were associated with
progressive cervical dilation, the definition of PTL was met and
clinical management protocols implemented.
Following assessment by the obstetric team and judged necessary, five
milliliters of maternal venous blood were collected into EDTA tubes,
sent to the laboratory for FCM, stored at 4°C and processed within 72
hours of collection. The results of the FCM were typically available
either at noon of the same day or the following day, and usually were
not used for acute management decisions. Rather, FCM was used to decide
whether to prolong observation time beyond 24 hours. Rarely, more than
one blood sample was obtained. In women with a positive FCM test,
another blood sample was obtained. The quantification of fetal blood
hemorrhage by FCM has been described in detail
elsewhere13,21. FCM was considered positive above 30
ml FMH, a volume that may trigger Rh sensitization 15.