Indeterminate Ultrasounds in First Trimester Pregnancies
Article: Tayal, V.S. et. al. Outcome of Patients with an Indeterminate Emergency Department First-Trimester Pelvic Ultrasound to Rule Out Ectopic Pregnancy. Acad. Emerg. Med. 2004. 11(9) 912-17.
Overview: First trimester pelvic ultrasounds are common practices in the emergency department, with a significant portion of these scans ending in an indeterminant pregnancy diagnosis. This study followed these indeterminate pregnancies to determine the final outcome of the pregnancy and compared them to outcomes of determined pregnancies on initial emergency department visit.
Methods: The study is a prospective observational cohort study of first trimester patients who presented to a regional urban emergency department with abdominal pain, pelvic pain, or vaginal bleeding and underwent pelvic ultrasounds. Pelvic ultrasounds, trans-abdominal or trans-vaginal, examined the uterus in transverse and sagittal planes, as well as the adnexa and cul-de-sac. Initial scans were classified as intrauterine pregnancy (IUP), embryonic demise, ectopic pregnancy, molar pregnancy, or indeterminate pregnancy. IUP was defined as a fundal gestational sac with yolk sac or fetal pole. Ectopic pregnancy was defined as a fetal pole, yolk sac in gestational sac, or chorionic ring outside the fundus of the uterus. Embryonic demise was defined as gestational sac >10mm without a yolk sac, a gestational sac >18mm without fetal pole, or a fetal pole >5mm without cardiac activity.
The main measure of the study was the final diagnoses of the initially indeterminate pelvic ultrasounds. The study gathered this information from review of patient records, obstetric ultrasound reports, operative reports, clinic records, and pathology reports. A final diagnosis of IUP was determined by appropriately rising levels, findings on follow up pelvic ultrasound, or subsequent hospital notes indicating IUP. Ectopic pregnancy was determined by operative findings, empiric treatment with methotrexate, or absence of embryonic villi on biopsy. Patients with ectopic pregnancy were further classified into medical management with methotrexate, surgical treatment, or expectant management. Miscarriage was assigned by falling ß-hCG without intervention or ultrasound findings of clean endometrial stripe after documented IUP.
Results: A total of 1,490 patients with confirmed pregnancies were stratified over 13 months, with 300 patients (20%) being classified as indeterminate pelvic ultrasounds. 1,037 (70%) were classified as IUP, 127 (8%) as embryonic demise, 24 (2%) as ectopic pregnancies, and 2 (<1%) as molar pregnancy. Non IUP pregnancies were referred for obstetric consultation, with most being followed via serial quant ß-hCG and clinic follow-up. Out of the 24 ectopic pregnancies, 20 (83%) had operative management and 4 (17%) had expectant management.
Outcomes for the 300 initial indeterminate pelvic ultrasounds were 88 (29%) IUP, 158 (53%) embryonic demise, 44 (15%) ectopic pregnancy, and 10 (3%) unknown. Of the 44 ectopic pregnancies, 16 (36%) had operative management, 25 (57%) had medical management methotrexate, and 3 (7%) had expectant management. The ß-hCG value on first presentation did not significantly differ among the final diagnoses (p=0.748). There was a significant difference (P<0.01) in the treatment of ectopic pregnancy on initial presentation and indeterminate pregnancies determined to be ectopic, with the former being operatively treated at a higher rate.
Discussion: Overall, the indeterminate pelvic ultrasounds did not result in a viable pregnancy at a higher rate than most initial presentations for pelvic ultrasound. The authors proposed that the rigorous criteria for definitive ectopic pregnancy and a “unwritten pressure” to classify findings as indeterminate when clear ectopic pregnancy cannot be established could contribute to this increased rate. This finding was emphasized by the authors due to its impact on counseling patients whose first trimester pelvic ultrasounds are classified as indeterminate. The results of this study suggest that these patients may need to be counseled on their higher risk of nonviable pregnancy. The difference in treatment of ectopic pregnancies between the initial group and the indeterminate group was thought to be a result of ectopic pregnancies on initial presentation having a higher likelihood of instability. A limitation of this analysis is the small sample size of ectopic pregnancies diagnosed on initial pelvic ultrasound and warrants further exploration.
Takeaway: Pregnancies classified as indeterminate on initial pelvic ultrasound resulted in a nonviable pregnancy at a significantly higher rate than nonviable pregnancies found on initial presentation. This finding could impact how physicians counsel patients with indeterminate results on pelvic ultrasound in the first trimester.
Post by Neena Kashyap, MS4