Young Age and Low Number of Prior Pregnancies Identified as Risk Factors for Misdiagnosis of Interstitial Ectopic Pregnancy
Interstitial ectopic pregnancy (IEP) is a rare form of ectopic pregnancy that occurs when a fertilized egg implants in or near the junction of the fallopian tube and uterus. While it constitutes only 2-4% of all ectopic pregnancies, its mortality rate is seven times higher due to risk of rupture with catastrophic bleeding. Since early diagnosis and treatment are crucial to prevent complications and preserve fertility, IEP is a serious condition that requires prompt medical attention.
In one of the largest studies to date on diagnosing IEP, researchers at Boston University Chobanian & Avedisian School of Medicine found that younger women and women with fewer prior pregnancies are more likely to have an incorrect initial diagnosis of IEP.
Wendy Kuohung, MD“The rarity of the condition makes it challenging to identify the percentage of patients who are misdiagnosed for IEP at initial imaging scans,” says corresponding author Wendy Kuohung, MD, associate professor of obstetrics & gynecology at the school. “While advances in imaging technology in the past few decades have improved IEP outcomes, they continue to be misdiagnosed at high rates,” she adds.
In an effort to identify factors that contribute to misdiagnosis, the researchers performed a retrospective chart review of women who presented at a tertiary academic medical center with suspected or confirmed IEP during a seven-year period. While IEP was correctly flagged as an abnormal pregnancy requiring further monitoring in 85% of the cases, the rate of accurately diagnosing IEP on radiologic imaging at initial presentation was only 45%. Factors associated with missed diagnosis included younger age and gravidity—the total number of times a woman has been pregnant.
According to the researchers, risk factors for ectopic pregnancy have been extensively studied and include a history of ectopic pregnancy and tubal surgery, infertility and utilization of in-vitro fertilization and medications to stimulate ovulation, smoking, and sexually transmitted infections and pelvic inflammatory disease. “To our knowledge, patient characteristics such as age and gravidity contributing to IEP misdiagnosis on radiologic imaging has not been previously reported. What may explain these findings is that anecdotally, younger patients with fewer prior pregnancies don’t tolerate invasive pelvic imaging as well as older patients, possibly affecting the accuracy of the study. It is an area that requires further research,” adds Kuohung.
Kuohung believes awareness of these risk factors by both radiologists and gynecologists may lead to heightened awareness of IEP and improved accuracy of transvaginal ultrasound screening.
These findings appear online in the journal Emergency Radiology.