Differential Diagnosis for Pregnant Female with Abdominal Pain After Blunt Trauma

The American College of Radiology recommends prioritizing life-threatening maternal and fetal complications, including placental abruption, uterine rupture, and direct fetal injury, in the differential diagnosis of a pregnant patient with abdominal pain following blunt trauma 1, 2
Ultrasound sensitivity for detecting placental abruption is only 40-50%, meaning normal imaging does not exclude this diagnosis 2
Uterine rupture is a life-threatening emergency that can occur from blunt abdominal trauma, particularly in the gravid uterus, and requires immediate surgical intervention to prevent maternal and fetal death 2
Direct fetal injury, including fetal intracranial injury, fractures, and direct trauma to fetal structures, can be assessed via ultrasound evaluation of fetal anatomy and biophysical profile 2

Intra-abdominal solid organ injury, such as splenic or hepatic injury from blunt trauma, may present with delayed bleeding and requires contrast-enhanced CT for definitive diagnosis if clinically indicated 1, 2
Bowel or mesenteric injury can occur with blunt abdominal trauma, presenting with peritoneal signs and free fluid, and may have delayed presentation as bowel perforation develops 1

Non-Traumatic Obstetric Causes

Ruptured ectopic pregnancy is a critical diagnosis in early pregnancy with abdominal pain, presenting with hemodynamic instability and positive β-hCG 3

Appendicitis is the most common cause of abdominal pain requiring emergency surgery in pregnant patients, and can present atypically in pregnancy due to anatomical displacement of the appendix 3, 4
MRI has 97% sensitivity and 95% specificity for diagnosing appendicitis in pregnancy 4
Urolithiasis and pyelonephritis are common causes of abdominal pain during pregnancy, diagnosed with ultrasound initially, and MRI if needed 3, 5
Ovarian torsion can cause acute abdominal pain in pregnancy, diagnosed with ultrasound showing enlarged ovary with decreased or absent Doppler flow 6, 7
Cholecystitis increases the risk of gallstone formation in pregnancy, diagnosed with ultrasound showing gallbladder wall thickening >3mm, pericholecystic fluid, and sonographic Murphy sign 8

The American College of Radiology recommends immediate assessment priorities, including hemodynamic status, fetal heart rate monitoring, peritoneal signs, and vaginal bleeding, to identify life-threatening complications in pregnant trauma patients 2, 3
Essential laboratory studies include complete blood count, coagulation profile, and urinalysis 3
The imaging algorithm includes FAST ultrasound, obstetric ultrasound, MRI abdomen/pelvis without contrast, and CT abdomen/pelvis with IV contrast, with the choice of imaging modality depending on the clinical scenario and suspected diagnosis 1, 2, 4, 5, 6, 7