Blunt Trauma in Pregnancy: Mind the Bump

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Authors: Tamir Zitelny, MS4; Blake Briggs, MD; Iltifat Husain, MD


Trauma is the most common non-obstetric cause of death, with motor vehicle accidents and inter-partner violence accounting for most cases.1-3 The unique case of having “two patients” may shift associated complications, evaluation, and management. In a pregnant patient, compression of the abdomen during injury is typically what differentiates major blunt trauma from minor.4 In this review, we will focus on blunt trauma and how to approach these patients.


Presentation and Initial Evaluation

Upon arrival, the standardized blunt trauma algorithm should be followed, with medical priorities paralleling management of a nonpregnant patient. The best fetal resuscitation is focusing on maternal resuscitation.

Evaluation begins with assessment of the “ABCs”: airway, breathing, and circulation. It is crucial to maintain adequate blood pressure and oxygenation as two patients are at risk of hemodynamic compromise. Do not hesitate to address these concerns if they are clear on presentation.


Additional measures should be taken to determine the level of uterine height in an effort to estimate gestational age.  In a normal anatomic pregnancy, the uterus begins to rise above the pelvis and is palpable in the abdominal cavity at around 8 to 12 weeks gestation. It will approach the level of the umbilicus around week 20, and thereafter grow approximately 1 cm per week until about 40 weeks gestation. In the case of a stable patient, this estimate may be corroborated with a measurement of fundal height or ultrasound.5 Any significant discrepancy between uterine height (or measured fundal height/ultrasound findings) and a previously known gestational age should raise concern for uterine trauma.


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There are several findings that are concerning for a more serious mechanism of injury to the uterus and fetus: vaginal bleeding, ruptured membranes, bulging perineum, presence of contractions, or abnormal fetal heart rate.

During your evaluation, it is also important to keep in mind that notable normal physiologic changes of pregnancy may bias emergency interventions. In pregnancy:

·               Lower cardiac output due to compression of the inferior vena cava by the gravid uterus; more pronounced as the patient approaches term, and when in the supine position.6-8

·               Greater risk of aspiration and difficult intubation due to a transient decrease in lower esophageal sphincter tone as the pregnancy progresses, coupled with increased generalized edema (including airway edema).9-11

·               EKG findings in pregnant patients may display a mild left axis deviation and/or benign transient ST/T wave changes.12-13

·               Some lab findings which are otherwise abnormal become normal, including decreased serum creatinine, mild leukocytosis, increased fibrinogen, and mild thrombocytopenia.14-16



After consulting the obstetrics team and evaluating the “ABCs”, the most immediate concern in these patients is assessing the necessity of an emergency cesarean section. For an unstable expectant mother refractory to stabilizing interventions, a c-section may be indicated to relieve uterine compression of maternal vasculature and restore maternal hemodynamics. This is very rare, and hopefully you never have to do this in your career.

Much more commonly, here are the top two things you need to take care of when dealing with a pregnant patient in blunt trauma: determining RhD status and fetal monitoring.

1.      Assess maternal RhD status. Fetomaternal bleeding is relatively common in pregnant trauma patients, with complications including maternal alloimmunization, fetal anemia, or fetal death.6,17 Following initial stabilization, RhD negative mothers should undergo further testing to determine dosing of prophylactic anti-D-immunoglobulin (Rhogam) to prevent complications of alloimmunization.

2.      Assessing fetal stability is crucial, and fetal monitoring should begin as soon as maternal vitals allow it. Fetal complications can occur even in cases with no significant maternal injury, and an abnormal fetal heart rate is often the first sign of concern for potential fetal instability. Fetal and uterine monitoring can be discontinued after 4 hours in cases where there are no fetal heart rate abnormalities, uterine contractions/bleeding, or uterine tenderness.17 An otherwise concerning presentation warrants leaving the patient under monitoring and coordination of care with an obstetrician.


When undergoing further evaluation with imaging modalities, risks of radiation should be considered. Ultimately, however, the information obtained to adequately treat these patients typically outweighs the radiation risk to the fetus.19 Ultrasound is often the preferred imaging modality due to its safety profile. As in acute trauma management of any patient, ultrasound can detect free intraperitoneal blood after blunt trauma during the FAST exam and should be used as such in pregnant cases as well. A Focused Assessment with Sonography for Obstetrics (FASO) is a modified FAST exam for pregnant patients that limits visualized areas to intraperitoneal sites that is sometimes employed in these cases.20 Additionally, ultrasound has great utility in evaluating fetal heartbeat, gestational age (in a stable patient), and fetal trauma.21-23


Following stabilization of the expectant mother, a widely utilized mnemonic for a focused history in pregnant trauma patients is CODE:21

Complications of pregnancy

Obstetric history and provider

Dating method and estimated due date

Event details


It is important to keep in mind that a digital vaginal examination should be avoided in pregnancies over 20 weeks, as undiagnosed placenta previa can result in massive hemorrhage.24 It is highly recommended that the post-stabilization portion of the patient evaluation be performed in conjunction with an obstetrician.



Once hemodynamic and patient stability have been addressed, an obstetrician can begin to assess whether the patient has any obstetric complications. A large majority of patients who develop obstetric complications experience uterine contractions, vaginal bleeding, and/or abdominal pain, though some may present with minimal symptoms, if at all.25


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2.       Weiss, H. B., Songer, T. J., & Fabio, A. (2001). Fetal deaths related to maternal injury. JAMA, 286(15), 1863–1868.

3.       Mendez-Figueroa, H., Dahlke, J. D., Vrees, R. A., & Rouse, D. J. (2013). Trauma in pregnancy: an updated systematic review. American journal of obstetrics and gynecology, 209(1), 1–10.

4.       Al-Thani, H., El-Menyar, A., Sathian, B., Mekkodathil, A., Thomas, S., Mollazehi, M., Al-Sulaiti, M., & Abdelrahman, H. (2019). Blunt traumatic injury during pregnancy: a descriptive analysis from a level 1 trauma center. European journal of trauma and emergency surgery : official publication of the European Trauma Society, 45(3), 393–401.

5.       Huls, C. K., & Detlefs, C. (2018). Trauma in pregnancy. Seminars in perinatology, 42(1), 13–20.

6.       Metcalfe, J., & Ueland, K. (1974). Maternal cardiovascular adjustments to pregnancy. Progress in cardiovascular diseases, 16(4), 363–374.

7.       Kerr M. G. (1965). THE MECHANICAL EFFECTS OF THE GRAVID UTERUS IN LATE PREGNANCY. The Journal of obstetrics and gynaecology of the British Commonwealth, 72, 513–529.

8.       Almeida, F. A., Pavan, M. V., & Rodrigues, C. I. (2009). The haemodynamic, renal excretory and hormonal changes induced by resting in the left lateral position in normal pregnant women during late gestation. BJOG : an international journal of obstetrics and gynaecology, 116(13), 1749–1754.

9.       Bainbridge, E. T., Temple, J. G., Nicholas, S. P., Newton, J. R., & Boriah, V. (1983). Symptomatic gastro-oesophageal reflux in pregnancy. A comparative study of white Europeans and Asians in Birmingham. The British journal of clinical practice, 37(2), 53–57.

10.     Van Thiel, D. H., Gavaler, J. S., Joshi, S. N., Sara, R. K., & Stremple, J. (1977). Heartburn of pregnancy. Gastroenterology, 72(4 Pt 1), 666–668.

11.     Fisher, R. S., Roberts, G. S., Grabowski, C. J., & Cohen, S. (1978). Altered lower esophageal sphincter function during early pregnancy. Gastroenterology, 74(6), 1233–1237.

12.     Clark, S. L., Cotton, D. B., Lee, W., Bishop, C., Hill, T., Southwick, J., Pivarnik, J., Spillman, T., DeVore, G. R., & Phelan, J. (1989). Central hemodynamic assessment of normal term pregnancy. American journal of obstetrics and gynecology, 161(6 Pt 1), 1439–1442.

13.     Oram, S., & Holt, M. (1961). Innocent depression of the S-T segment and flattening of the T-wave during pregnancy. The Journal of obstetrics and gynaecology of the British Empire, 68, 765–770.

14.     Lopes van Balen, V. A., van Gansewinkel, T. A. G., de Haas, S., Spaan, J. J., Ghossein-Doha, C., van Kuijk, S. M. J., van Drongelen, J., Cornelis, T., & Spaanderman, M. E. A. (2019). Maternal kidney function during pregnancy: systematic review and meta-analysis. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology, 54(3), 297–307.

15.     KUVIN, S. F., & BRECHER, G. (1962). Differential neutrophil counts in pregnancy. The New England journal of medicine, 266, 877–878.

16.     Reese, J. A., Peck, J. D., Deschamps, D. R., McIntosh, J. J., Knudtson, E. J., Terrell, D. R., Vesely, S. K., & George, J. N. (2018). Platelet Counts during Pregnancy. The New England journal of medicine, 379(1), 32–43.

17.     Chames, M. C., & Pearlman, M. D. (2008). Trauma during pregnancy: outcomes and clinical management. Clinical obstetrics and gynecology, 51(2), 398–408.

18.     ACOG educational bulletin. Obstetric aspects of trauma management. Number 251, September 1998 (replaces Number 151, January 1991, and Number 161, November 1991). American College of Obstetricians and Gynecologists. (1999). International journal of gynaecology and obstetrics: the official organ of the International Federation of Gynaecology and Obstetrics, 64(1), 87–94.

19.     Robson, S. C., Hunter, S., Boys, R. J., & Dunlop, W. (1989). Serial study of factors influencing changes in cardiac output during human pregnancy. The American journal of physiology, 256(4 Pt 2), H1060–H1065.

20.     Oba, T., Hasegawa, J., Arakaki, T., Takita, H., Nakamura, M., & Sekizawa, A. (2016). Reference values of focused assessment with sonography for obstetrics (FASO) in low-risk population. The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians, 29(21), 3449–3453.

21.     MacArthur, B., Foley, M., Gray, K., & Sisley, A. (2019). Trauma in Pregnancy: A Comprehensive Approach to the Mother and Fetus. American journal of obstetrics and gynecology, 220(5), 465–468.e1.

22.     Sadro, C. T., Zins, A. M., Debiec, K., & Robinson, J. (2012). Case report: lethal fetal head injury and placental abruption in a pregnant trauma patient. Emergency radiology, 19(2), 175–180.

23.     Härtl, R., & Ko, K. (1996). In utero skull fracture: case report. The Journal of trauma, 41(3), 549–552

24.     King, L. J., Dhanya Mackeen, A., Nordberg, C., & Paglia, M. J. (2020). Maternal risk factors associated with persistent placenta previa. Placenta, 99, 189–192.

25.     Goodwin, T. M., & Breen, M. T. (1990). Pregnancy outcome and fetomaternal hemorrhage after noncatastrophic trauma. American journal of obstetrics and gynecology, 162(3), 665–671.

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