Young female with abdominal pain

By Dainon Miles, MD
Edited by Hani I. Kuttab, MD

Clinical Case

A young female presented to the emergency department with acute-onset abdominal pain that started approximately one hour prior to arrival. She was in her normal state of health prior to developing the pain. Vital signs were normal; however, the patient displayed diffuse abdominal tenderness to palpation with mild rebound tenderness and voluntary guarding. Lab testing revealed an elevated white blood cell count and a lactic acid of 5.0 mmol/L. Urine pregnancy testing was negative. Given the severity of her pain, a CT scan of her abdomen and pelvis was ordered. However, the scanner is busy with multiple trauma patients and a stroke code and likely will not be available for another hour. A focused assessment with sonography in trauma (FAST) exam was performed for further evaluation (Figure 1 and 2).

**Figure 1.** FAST exam of the right upper quadrant, demonstrating free fluid noted at the tip of the liver.

**Figure 2.** FAST exam of the pelvis (sagittal view), demonstrating free fluid outside of the bladder.

Diagnosis

Ruptured hemorrhagic cyst. FAST exam performed revealed free fluid in the right upper quadrant, at the inferior tip of the liver, and in the pelvis, posterior to the bladder. The CT scan was canceled and the patient underwent a transvaginal ultrasound revealing a 4.5cm ovarian cyst. Gynecology was consulted and the patient was taken to the operating room for laparoscopy. Approximately one liter of hemoperitoneum was evacuated from the abdominal cavity.

Where are FAST exams most commonly positive?

Lobo et. al, performed a retrospective review of trauma patients with a recorded FAST exam to determine where free fluid most often collects in the abdominal cavity. This demonstrated that the caudal/inferior edge of the liver tip was the most sensitive location for the detection of free fluid. Figure 3 summarizes the key study findings (created by MadtownSono FAST expert Dr. Dana Resop) and depicts the likelihood of locating free fluid utilizing their data. Of note, 35% of the FAST exams performed in this study also located free fluid in the left upper quadrant— so don’t neglect looking closely in the other views! (1)

**Figure 3:** FAST exam “hot-spots” adapted from Lobo et. al. (2017). Figure created by FAST expert, Dr. Dana Resop.

Another study by O’Brien et al. looked more specifically at the left upper quadrant view in patients from two large urban emergency departments. They found that 32% of patients in this study had free fluid in the left upper quadrant, and 7% of all exams had isolated free fluid in this location. They emphasize the importance of visualizing the left paracolic gutter/inferior spleen tip. Fluid in the left upper quadrant view is most likely to occur in this area— approximately 84% of positive left upper quadrant FAST exams detected fluid here. (2)

Teaching point

Free fluid can collect in many different locations. A complete FAST exam should be thorough and visualize the various locations as outlined above. While the right upper quadrant, caudal/inferior edge of the liver is the most sensitive area, incomplete visualization of the left upper quadrant may miss ~7% (or more) of positive exams.

References

Lobo V, Hunter-Behrend M, Cullnan E, et al. Caudal Edge of the Liver in the Right Upper Quadrant (RUQ) View Is the Most Sensitive Area for Free Fluid on the FAST Exam. West J Emerg Med. 2017;18(2):270-280.
O’Brien K, Stolz U, Stolz L, et al. LUQ view and the FAST exam: helpful or a hindrance in the adult trauma patient?. Crit Ultrasound J. 2014;6(Suppl 1):A3.