Negative pregnancy tests can be misleading, according to a recent report.
A severely dehydrated woman was admitted to hospital with vomiting and vaginal discharge. She had gone nine weeks without a menstrual period. A pregnancy test concluded that she was not pregnant, but a physical examination suggested otherwise. An ultrasound scan revealed that she was carrying triplets.
Say the doctors, high levels of human chorionic gonadotropin - common in multiple pregnancies - can inhibit the antigen-antibody reaction on which many pregnancy tests are based (J Obstet Gynaecol, 2002; 22: 442).