A 39-year-old woman with three children has been using the progesterone-only pill for contraception for two years. She has not missed any pills but feels unmistakably pregnant. With this form of contraception, her periods are usually irregular but she has had no bleeding for eight weeks. She now has bleeding like a period and also mild constant pain in her right iliac fossa. A pregnancy test is positive. An ultrasound scan reveals an empty uterus with a thin endometrium and normal adnexae with no free fluid. Serum human chorionic gonadotrophin (hCG) level is 215 IU/l. Repeat serum hCG 48 hours later is 49 IU/l.
How can one distinguish an ectopic pregnancy from an early intrauterine pregnancy or from a complete miscarriage?
What treatment options are open to her once a diagnosis is made?
What advice should be given to women following a miscarriage?
Miscarriage is defined as the loss of an intrauterine pregnancy before viability (24 weeks), but most miscarriages occur in the first trimester. Clinicians should avoid using negative terminology such as 'pregnancy failure'. 'Abortion', an old medical term used to mean pregnancy loss, should not be used in this context. Miscarriage in the first trimester is very common, with approximately one in six clinical pregnancies ending in miscarriage.1
How can one distinguish an ectopic pregnancy from an early intrauterine pregnancy or from a miscarriage?
Using transvaginal ultrasound scanning (TVS), it is usually possible to detect an intrauterine pregnancy sac with a yolk sac from five weeks following the last normal menstrual period (Figure 26.1). If the gestational sac is greater than 20 mm in diameter, a fetal pole or a yolk sac should be visible. At six weeks, the fetal pole should be visible and a fetal heart can usually be detected. If the fetal pole is greater than 6 mm in length, a fetal heart should be visible. The absence of these signs at six weeks does not necessarily mean that the pregnancy is non-viable and a repeat scan is usually arranged for one week later. This has been termed a pregnancy of uncertain viability.
Early intrauterine pregnancy showing 'cygnet ring' (arrow).
Until a pregnancy is definitely seen within the uterus, doubt remains as to its location. This has been termed a pregnancy of unknown location. At this point, a single serum hCG measurement can be taken to estimate the likely size of the pregnancy. A pregnancy with serum hCG above approximately 1500–2000 IU/l should be visible within the uterus. In a healthy pregnancy, the serum level of hCG should increase by at least two-thirds every 48 hours from about five to eight weeks. Clearly, in a failing pregnancy of whatever location, hCG levels will remain static or fall. Ectopic ...