Physiology & Pregnancy
Injury in Pregnancy
Assessment & Management
Pregnancy alters nearly every organ system in the body.
Remember that there are two patients.
But initial treatment priorities remain.
- best care for the fetus is to optomise the mother.
Do not withhold XRs
Consult surgeon/O+G early.
Physiology & Pregnancy
Uterus is intrapelvic until 12th week of gestation, then rises out of
- by 20wks at umbilicus
--> small fetus still relatively protected by generous amniotic fluid
- by 34-36 wks at costal margin.
--> large & thin-walled
- fetal head engages pelvis during last 2 weeks.
--> pelvic injury may lead to skull / intracranial injury to fetus.
--> bowel pushed cephalid, so mostly in upper abdo (so largely
--> but can be injured in a complicated fashion.
Placenta is non-elastic
--> shear injury can lead to abruptio placentae.
--> vasculature maximally dilated throughout gestation but very
sensitive to catecholamines
An abrupt drop in maternal circulation may compromise fetal oxygenation
despite relatively normal maternal signs.
Blood Volume & Composition
Plasma volume increases steadily through gestation
- plateaus at 34 weeks.
Smaller increase in RBC volume
- and decreased haematocrit to 31-35% (late)
May lose 1200-1500mL before signs of hypovolaemia occur.
--> although fetus may become distressed / tachycardic.
WBC count increases to 15 or even 25.
Fibrinogen and clotting factors mildly elevated.
- prothrombin / partial thromboplastin shortened but bleeding &
Albumin drops to 22-28.
CO: increases by 1-1.5L/min
due to increase in plasma volume & decrease in vascular resistance.
- supine position can decrease CO by 30% due to cava compression.
HR: Increases gradually by
BP: 5-15mmHg fall in systolic
and diastolic BP.
- may be hypotensive when supine.
Venous return: CVP is variable
with pregnancy but response to volume same.
ECG: axis leftward by 15o.,
flat/inverted Ts in III,aVF, precordial leads, more ectopics.
Resp: Minute ventilation increases, hypocapnoea is common (30)
- 35-40 may signal resp failure.
- O2 consumption is greater.
GI: gastric emptying is longer
(assume a full stomach and avoid aspiration).
Urinary: GFR increases, creat
and urea fall, system may dilate
Endocrine: Pituitary increases
30-50%, shock may cause necrosis.
widens 4-8mm and sacroiliacs increse by 7th month.
Neuro: Eclampsia can mimic
Injury & Pregnancy
Fetal impact is buffered by uterus, abdo wall and amniotic fluid but
fetal injury still very possible.
Lap belts associated with uterine rupture.
Penetrating missiles are slowed by uterus and anatomic changes means
less maternal visceral injury but greater fetal injury.
Severity of maternal injury is major determinant of both mother and
- 80% of mothers with haemorrhagic shock will experience fetal death.
- watch even minor injuries for abruptio placentae.
Assessment & Management
ABCDEs as usual.
Shock may be aggravated by vena cava reducing venous return.
- transport on left side unless spinal injury suspected.
- can logroll and support 4-6inches on left if reqd.
May lose significant blood before signs occur (while fetus is
- early resuscitation and blood are indicated.
Peritoneal signs are difficult.
Uterine rupture suggested by:
abnormal lie, easy palpation of fetus, inability to palpate fundus, or
XR of abnormality / intraperitoneal air.
--> surgical exploration.
Abruptio placentae suggested
by vaginal bleeding in 70%, uterine tenderness, frequent contractions,
uterine tetany, uterine irritability.
- USS shows the lesion but is not definitive.
Hypovolaemia and pain may accompany these two injuries.
Continuous fetal monitoring at 20-24wks, Dopper at >10wks.
Adjuncts to Primary
Monitor on left side, CVP helpful, oximetry and ABG.
Early obstetric consultation.
Same as for nonpregnant patients
Place DPL catheters above umbilicus.
Pay attention to uterine contractions
Obstetrician for pelvic exam.
- note for amniotic fluid in vagina, cervical change, presentation and
Admission is manditory if abnormality in mother / fetus.
- ie vaginal bleeding, uterine irritability, abdo tenderness, pain or
cramping, hypovolaemia, changes in fetal heart tones, or leakage of
Consider Rh immunoglobulin for all pregrant Rh-negative trauma pts
unless injury remote from uterus.
Large engorged pelvic vessels can cause massive retroperitoneal
While perimortem c-section may be successful if performed within 5
minutes for other causes of cardiac arrest, there is no data to support
this in trauma as the fetus will have been compromised for a long
A major cause of injury.
17% of injured pregnant women were traumatised by another person (60%
- injuries inconsistent with history
- diminished self-image, suicide attempts
- frequent ED visits
- symptoms suggest substance abuse
- self-blame for injury
- partner domineering and insists on being present.
Screen (65-70% sensitive)
1. Have you been kicked, hit, punched, or otherwise hurt by someone
within the past year? If so whom?
2. Do you feel safe in your current relationship?
3. Is there a partner from a previous relationship who is making you
feel unsafe now?