Serum levels of smooth muscle heavy-chain myosin in patients with ectopic pregnancy.
OBJECTIVE
Previous studies have suggested that serum markers of smooth muscle destruction have utility in predicting ectopic pregnancy. Our goal was to determine whether a novel marker of muscle destruction, smooth muscle heavy-chain myosin (SMHC), is elevated in the serum of patients with ectopic pregnancy.


METHODS
We conducted a prospective cohort study, with consecutive enrollment, of all women in the first trimester of pregnancy who presented to our urban emergency department with complaints of lower abdominal pain with or without vaginal bleeding. Patients were excluded if there was a history of recent surgery or major trauma. Means were compared using 2-tailed Student's t test with P values less than.05 set for significance. Data analysis included calculation of receiver operating characteristic (ROC), 95% confidence intervals (CIs), and a regression model.


RESULTS
A total of 175 patients were enrolled; ectopic pregnancy was diagnosed in 29, and 146 had other diagnoses. Patients with ectopic pregnancy had a mean serum SMHC concentration of 2.53 ng/dL (95% CI 1.84 to 3.22), whereas those in the non-ectopic pregnancy group had a mean concentration of 1.41 ng/dL (95% CI 1.23 to 1.60; P <.0001). ROC analysis demonstrated an area under the curve of 0.72 (95% CI 0.65 to 0.79). Regression analysis to examine confounders in each group analyzed the effects of race, maternal age, estimated gestational age, and serum levels of human chorionic gonadotropin beta-subunit. Our analysis identified only a positive correlation between estimated gestational age and SMHC in the non-ectopic pregnancy group.


CONCLUSIONS
There is a statistically significant elevation of serum SMHC levels in tubal pregnancy, although our data suggest that the assay has limited clinical utility as a lone marker for ectopic pregnancy. Further investigation is needed to determine whether the assay has a role as an adjunct in the evaluation of suspected ectopic pregnancy.
Birkhahn
Robert H
RH
Department of Emergency Medicine, New York Methodist Hospital, Brooklyn, NY.
Gaeta
Theodore J
TJ
Department of Emergency Medicine, New York Methodist Hospital, Brooklyn, NY.
Suzuki
Toru
T
Third Department of Internal Medicine, University of Tokyo, Tokyo, Japan.
Katoh
Hirohisa
H
Third Department of Internal Medicine, University of Tokyo, Tokyo, Japan.
Nagai
Ryozo
R
Department of Internal Medicine, Gunma University, Gunma, Japan.
Bove
Joseph
J
Department of Emergency Medicine, New York Methodist Hospital, Brooklyn, NY.
D015746:Abdominal Pain / Q000175:diagnosis / Q000209:etiology; D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D016001:Confidence Intervals; D004636:Emergency Service, Hospital; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D009215:Myometrium / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000032:analysis / Q000097:blood*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011271:Pregnancy, Ectopic / Q000097:blood* / Q000150:complications / Q000175:diagnosis*; D011336:Probability; D011446:Prospective Studies; D012372:ROC Curve; D011863:Radioimmunoassay; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D014592:Uterine Hemorrhage / Q000175:diagnosis / Q000209:etiology
D018997:Chorionic Gonadotropin, beta Subunit, Human; D018995:Myosin Heavy Chains