From the Guidelines
Diagnosing an extrauterine pregnancy (ectopic pregnancy) requires a combination of clinical assessment, laboratory tests, and imaging studies, with transvaginal ultrasound being the most useful method to evaluate the endometrium, early pregnancy, and adnexa 1. The diagnosis should be suspected in any woman of reproductive age with abdominal pain, vaginal bleeding, and a positive pregnancy test.
- The first step is to perform a quantitative serum human chorionic gonadotropin (hCG) test to confirm pregnancy,
- followed by transvaginal ultrasound when the hCG level is above 1,500-2,000 mIU/mL (the discriminatory zone) 1. If no intrauterine gestational sac is visible with hCG above this threshold, an ectopic pregnancy is likely.
- Serial hCG measurements showing abnormal rises (less than 53% increase over 48 hours) further support the diagnosis.
- Progesterone levels below 5 ng/mL may also suggest an abnormal pregnancy. In stable patients with inconclusive ultrasound findings, follow-up imaging and hCG testing are appropriate. For unstable patients with severe pain or signs of rupture (hypotension, tachycardia), immediate surgical intervention is necessary. Laparoscopy remains the definitive diagnostic method when imaging is inconclusive but clinical suspicion is high. Early diagnosis is crucial as ruptured ectopic pregnancies can cause life-threatening hemorrhage, making prompt recognition essential for reducing maternal morbidity and mortality. The Society of Radiologists in Ultrasound consensus conference recommendations provide a lexicon for first-trimester ultrasound, which helps in the diagnosis of extrauterine pregnancy 1. The location of a pregnancy is divided into normal, abnormal, and unknown, and the essential word in the definition of intrauterine pregnancy and ectopic pregnancy (EP) is implanted, which helps differentiate pregnancies that are temporarily located in the lower uterine segment 1. Transvaginal ultrasound has a high sensitivity and specificity for diagnosing ectopic pregnancy, with a positive likelihood ratio of 111 for the finding of adnexal mass without an intrauterine pregnancy on TVUS 1.
From the Research
Diagnosing Extrauterine Pregnancy
To diagnose an extrauterine pregnancy, also known as an ectopic pregnancy, several methods and tools can be utilized. The diagnosis often involves a combination of clinical presentation, laboratory tests, and imaging studies.
- Clinical Presentation: Ectopic pregnancy should be considered in any patient presenting early in pregnancy with vaginal bleeding or lower abdominal pain in whom intrauterine pregnancy has not yet been established 2.
- Laboratory Tests: Serial beta human chorionic gonadotropin (β-hCG) levels can be used to help diagnose ectopic pregnancy. Trends in these levels, particularly if they are not rising appropriately, can indicate an ectopic pregnancy 3, 2.
- Imaging Studies:
- Transvaginal Ultrasound: This is a critical tool in the diagnosis of ectopic pregnancy. It can directly visualize a yolk sac and/or embryo in the adnexa, which is definitive for ectopic pregnancy. However, most ectopic pregnancies do not reach this stage, and the diagnosis is often made based on the absence of an intrauterine pregnancy and the presence of other signs such as echogenic fluid in the cul-de-sac 4, 5, 6.
- Echogenic Fluid: The presence of echogenic fluid in the cul-de-sac is highly suggestive of ectopic pregnancy and correlates with hemoperitoneum at the time of surgery 5.
- Pregnancy of Unknown Location (PUL): This term is used when a woman with a positive pregnancy test has a transvaginal ultrasound that cannot determine the site of the pregnancy. While most women with PUL are subsequently diagnosed with a spontaneous abortion or viable intrauterine pregnancy, a significant percentage have an ectopic pregnancy. Strategies for managing PUL include expectant management, diagnostic dilation and curettage (D&C), and empiric methotrexate therapy 3.
- Diagnostic Criteria: The definitive diagnosis of ectopic pregnancy can be made with ultrasound visualization of a yolk sac and/or embryo in the adnexa. In the absence of these findings, the diagnosis is often based on a combination of clinical presentation, serial β-hCG levels, and ultrasound findings such as adnexal masses or free fluid in the pelvis 2, 4.