Editing Ectopic pregnancy (section)

==== Pregnancy of unknown location ====

Pregnancy of unknown location (PUL) is the term used for a pregnancy where there is a positive pregnancy test but no pregnancy has been visualized using transvaginal ultrasonography.<ref name=kirk2013/> Specialized early pregnancy departments have estimated that between 8% and 10% of women attending for an ultrasound assessment in early pregnancy will be classified as having a PUL.<ref name=kirk2013/> The true nature of the pregnancy can be an ongoing viable intrauterine pregnancy, a failed pregnancy, an ectopic pregnancy or rarely a [[#Persisting PUL|persisting PUL]].<ref name=kirk2013/>

Because of frequent ambiguity on ultrasonography examinations, the following classification is proposed:<ref name=kirk2013/>

{| class="wikitable"
! Condition !! Criteria
|-
| Definite ectopic pregnancy || Extrauterine [[gestational sac]] with yolk sac or embryo (with or without cardiac activity).
|-
| Pregnancy of unknown location – probable ectopic pregnancy || Inhomogeneous adnexal mass or extrauterine sac-like structure.
|-
| "True" pregnancy of unknown location || No signs of intrauterine nor extrauterine pregnancy on transvaginal ultrasonography.
|-
| Pregnancy of unknown location – probable intrauterine pregnancy || Intrauterine gestational sac-like structure.
|-
| Definite intrauterine pregnancy || Intrauterine gestational sac with yolk sac or embryo (with or without cardiac activity).
|}

In women with a pregnancy of unknown location, between 6% and 20% have an ectopic pregnancy.<ref name=kirk2013/> In cases of pregnancy of unknown location and a history of heavy bleeding, it has been estimated that approximately 6% have an underlying ectopic pregnancy.<ref name=kirk2013/> Between 30% and 47% of women with pregnancy of unknown location are ultimately diagnosed with an ongoing intrauterine pregnancy, whereof the majority  (50–70%) will be found to have failing pregnancies where the location is never confirmed.<ref name=kirk2013/>

[[File:Histopathology of tubal pregnancy.jpg|thumb|[[Chorionic villus]] on [[histopathological examination]] of a tubal pregnancy]]
{{visible anchor|Persisting PUL}} is where the hCG level does not spontaneously decline and no intrauterine or ectopic pregnancy is identified on follow-up transvaginal ultrasonography.<ref name=kirk2013/> A persisting PUL is likely either a small ectopic pregnancy that has not been visualized, or a retained trophoblast in the endometrial cavity.<ref name=kirk2013/> Treatment should only be considered when a potentially viable intrauterine pregnancy has been definitively excluded.<ref name=kirk2013/> A ''treated persistent PUL'' is defined as one managed medically (generally with methotrexate) without confirmation of the location of the pregnancy, such as by ultrasound, laparoscopy, or uterine evacuation.<ref name=kirk2013/> A ''resolved persistent PUL'' is defined as serum hCG reaching a non-pregnant value (generally less than 5&nbsp;IU/L) after expectant management, or after uterine evacuation without evidence of [[chorionic villi]] on [[histopathological examination]].<ref name=kirk2013/> In contrast, a relatively low and unresolving level of serum hCG indicates the possibility of an hCG-secreting tumor.<ref name=kirk2013/>