The diagnostic effectiveness of an initial transvaginal scan in detecting ectopic pregnancy.
BACKGROUND
To determine the effectiveness of an initial transvaginal ultrasound scan (TVS) in the detection of ectopic pregnancy in consecutive women attending an early pregnancy unit (EPU).


METHODS
This was a prospective observational study. Unselected women attending a dedicated EPU underwent a TVS. Women were classified as having an intrauterine pregnancy (IUP), ectopic pregnancy or pregnancy of unknown location (PUL). Women with a PUL were followed up until the final location of the pregnancy was determined. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) with 95% confidence intervals (CIs) for the initial TVS in the diagnosis of ectopic pregnancy were calculated.


RESULTS
During a one-year study period, 5318 consecutive women attended the EPU. Outcome data were available for 5240 (98.5%) women. Of these, the initial TVS showed an IUP in 4693 (89.6%) cases and an ectopic pregnancy in 91 (1.7%) cases. The remaining 456 (8.7%) women were classified as PUL, and of these 31 (6.8%) were subsequently found to have ectopic pregnancies. The overall sensitivity of the initial TVS in the diagnosis of ectopic pregnancy was 73.9% (95% CI: 65.1-81.6) with a specificity of 99.9% (95% CI: 99.8-100), a PPV of 96.7% (95% CI: 90.7-99.3) and an NPV of 99.4% (95% CI: 99.2-99.6).


CONCLUSIONS
In unselected women attending an EPU, pregnancy location can be diagnosed accurately in over 90% of all pregnancies and in 73.9% of ectopic pregnancies with a single TVS.
Kirk
Emma
E
Early Pregnancy and Gynaecological Ultrasound Unit, Department of Obstetrics and Gynaecology, St George's, University of London, Cranmer Terrace, London, UK. ejkirk@hotmail.co.uk
Papageorghiou
Aris T
AT
Condous
George
G
Tan
Linda
L
Bora
Shabana
S
Bourne
Tom
T
D006063:Chorionic Gonadotropin / Q000097:blood; D005260:Female; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D011271:Pregnancy, Ectopic / Q000175:diagnosis*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000295:instrumentation* / Q000379:methods*
D006063:Chorionic Gonadotropin