title: Ectopic pregnancy with undetectable serum and urine beta-hCG levels and detection of beta-hCG in the ectopic trophoblast by immunocytochemical evaluation.
abstract: BACKGROUND
  Ectopic pregnancies associated with negative urine or serum pregnancy test by radioimmunoassay usually demonstrate either nonviable trophoblast or absent production of beta-hCG by the ectopic pregnancy.
  
  
  METHODS
  We report a patient with intra-abdominal hemorrhage caused by a ruptured ampullary ectopic pregnancy who had undetectable serum and urine beta-hCG levels (less than 5 mIU/mL). Immunoperoxidase staining of the ectopic trophoblastic tissue obtained at surgery revealed both beta-hCG and placental alkaline phosphatase.
  
  
  CONCLUSIONS
  Negative serum and urine pregnancy tests can occur even though beta-hCG produced by the viable ectopic trophoblastic tissue can be demonstrated by immunoperoxidase staining.
authors.affiliation: Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas.
authors.forename: M L
authors.initials: ML
authors.lastname: Maccato
authors.forename: R
authors.initials: R
authors.lastname: Estrada
authors.forename: S
authors.initials: S
authors.lastname: Faro
mesh_terms: D000328:Adult; D006063:Chorionic Gonadotropin / Q000032:analysis*; D018997:Chorionic Gonadotropin, beta Subunit, Human; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000209:etiology; D006801:Humans; D007124:Immunoenzyme Techniques; D010446:Peptide Fragments / Q000032:analysis*; D011247:Pregnancy; D011258:Pregnancy Tests; D011274:Pregnancy, Tubal / Q000175:diagnosis*; D012422:Rupture, Spontaneous; D014327:Trophoblasts / Q000737:chemistry*
chemical_list: D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D010446:Peptide Fragments