Laboratory Studies
Complete blood count (CBC)
The hemoglobin and hematocrit are helpful in estimating blood losses. However, in a patient with acute hemorrhage, several hours may pass before these levels change to reflect the blood loss and platelet count.
If the white blood cell count is elevated, suspect endometritis or toxic shock syndrome.
Assess for thrombocytopenia.
Coagulation laboratory studies
Elevations of the prothrombin time (PT), activated partial thromboplastin time (aPTT), and international normalized ratio (INR) can indicate a present or developing coagulopathy.
Electrolyte levels
Check for complicating electrolyte derangements such as a hypocalcemia, hypokalemia, and hypomagnesemia. Use this first set as a baseline for comparison during and after fluid and/or blood resuscitation.
BUN/creatinine levels
These measurements can be helpful in identifying renal failure as a complication of shock. If the BUN level rises during or after resuscitation with blood products, consider red blood cell hemolysis as a complication.
Type and crossmatch
Begin the process of finding appropriately matched blood for resuscitation in the event that it is needed.
Fibrinogen level
Levels are normally elevated to 300-600 mg/dL in pregnancy. Normal or low values raise concerns for a consumptive coagulopathy.
Liver function tests (LFTs), amylase, lipase
These studies can be helpful in considering other abdominal pathology, such as HELLP syndrome, if there is abdominal pain in addition to, or instead of, uterine tenderness.
Lactate level
Consider ordering this if the initial electrolyte study shows an anion gap or septic or hypovolemic shock is suspected as a concomitant diagnosis.
Imaging Studies
Studies to be considered with vaginal bleeding and decreasing red blood cell counts in the postpartum patient include ultrasonography (U/S), computed tomography (CT), or magnetic resonance imaging (MRI).
Ultrasonography is a fast and helpful modality for imaging pelvic structures and should be the first-line study for pelvic pathology.
Ultrasonography
In a hemodynamically unstable patient, a bedside ultrasonography can be performed by an experienced emergency medicine provider as an extension of the physical examination. In general, a dedicated pelvic ultrasonography (transabdominal and/or transvaginal) is helpful in identifying large retained placental fragments, hematomas, or other intrauterine abnormalities. Retained placenta and hematoma can look ultrasonographically identical. Using a Doppler ultrasound to look for vascularity can help to differential between the two, with clots being avascular and retained placenta often receiving persistent blood flow from the uterus.
The abdominal views of the focused assessment with sonography in trauma (FAST) examination are helpful in identifying fluid within the peritoneum that may be the result of hemorrhage. This study is designed to identify intra-abdominal and pericardial fluid that requires early operative intervention in trauma patients. However, the abdominal views are useful in any patient with suspected intra-abdominal free fluid. These include views of the right upper quadrant (RUQ)/Morison's pouch area (the most dependent area of a supine patient's peritoneal cavity), the left upper quadrant (LUQ) spleno-renal recess, and views of the pelvis (sagittal and coronal views of the uterus and pouch of Douglas). This study can detect 250-500 mL of fluid in the peritoneum, but it is a poor study for identifying retroperitoneal or paravaginal hemorrhage (extra-peritoneal bleeding).
Ultrasonography cannot reliably differentiate between blood, urine, or ascites; however, in the setting of suspected hemorrhage, any fluid in the abdomen should prompt further investigation.
More stable patients can have their abdominal and/or pelvic ultrasonography confirmed with an official study performed by a radiologist.
Computed tomography
In the event that ultrasonography is not diagnostic, CT is a helpful follow-up study. This may also be the first-line study when a pelvic hematoma or abscess is suspected, which may be missed with a sonogram. The traditional teaching is that pelvic CT is a less than ideal study for pelvic structures, due to artifact from the surrounding pelvic bones that reduces the image quality. However, this is generally not the case with modern multidetector CT studies. When enhanced with intravenous (I+) and intra-intestinal (O/R+...either oral or rectal contrast), CT can detail pelvic hematomas, cesarean delivery wound dehiscence, and retained placental tissue.
Magnetic resonance imaging
MRI is a time consuming study that is rarely performed from the ED in these patients. It can be helpful in delineating tissue planes to determine if a fluid collection (hematoma or abscess) is intrauterine or extrauterine when this is not clear from ultrasonography or CT. It can also help to distinguish a placenta accreta from simple retained products of conception.
Limited literature is available on abdominopelvic imaging in postpartum hemorrhage since the presentation of significant bleeding prompts rapid resuscitation and immediate intervention based on the clinical picture rather than documented imaging. Nonetheless, all 3 imaging modalities can assist in the evaluation of a bleeding source, but ultrasonography is usually sufficient for emergent situations.
