Female patients with lower abdominal pain presenting to the emergency department or acute care clinic may represent a diagnostic challenge. Faced with a large differential diagnosis (Table 14-1), their clinical work-up is often time and resource consuming. Bedside ultrasound is the diagnostic imaging modality of choice for the majority of cases. It provides real-time information that expedites patient care and disposition.
Table 14-1. Differential Diagnosis of Lower Abdominal Pain in Female Patients ||Download (.pdf)
Table 14-1. Differential Diagnosis of Lower Abdominal Pain in Female Patients
Inflammatory bowel disease
Irritable bowel syndrome
Pelvic inflammatory disease
Hemorrhagic functional cysts
Imaging the pelvis is a crucial step in the evaluation of women with lower abdominal pain or pelvic pain. Accurate management is predicated on choosing the most effective diagnostic tool. Four diagnostic modalities are available for evaluating the pelvis: laparoscopy, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasonography. Several clinical entities will be considered with regard to the advantages and disadvantages of each modality.
While CT is used routinely for the preoperative evaluation of masses that are suspicious for malignancy, it is generally considered a second-line imaging modality to ultrasound in the evaluation of pelvic pain. The advantage of CT is the ability to image the full extent of a large adnexal lesion that cannot be visualized in its entirety with sonography alone. Another advantage of CT is its usefulness in diagnosing gastrointestinal entities, such as appendicitis and diverticulitis. A major disadvantage of CT is the cost involved in obtaining these readings. CT is not portable and is not immediately available at the bedside for serial examinations. Patients must be transported to the radiology suite, which expends personnel resources. CT exposes patients to radiation; if IV contrast is used, nephrotoxicity or severe allergies are potential side effects.
Although MRI is also considered a second-line imaging modality, it has several advantages over CT and ultrasound. MRI does not expose the patient to radiation and provides more detailed information for the detection of subtle tissue differentiation of pelvic organs. MRI has better tissue resolution than ultrasound, and is therefore more accurate in diagnosing pelvic inflammatory disease (PID) and pelvic masses. A 1999 study compared MRI with endovaginal ultrasound for the diagnosis of laparoscopy-proven PID. Of the 21 patients proven to have PID, MRI diagnosed 20 (95%) patients while endovaginal ultrasound correctly diagnosed 17 (81%) patients.1 Many of the same disadvantages of CT—cost, availability, lack of portability—apply to MRI as well.
While laparoscopy remains the gold standard for the diagnosis of PID and pelvic masses, its use may not be readily available or justified in screening patients with vague symptoms. Laparoscopy is invasive, costly, time-consuming, results in scarring, and requires the small but ...