By the time the sac has reached a large enough size for the ectopic to
rupture, NORMALLY the urinary beta-HCG is easily detectable. However, the
test is not sensitive enough to be safe on its own as a rule-out:
Hemorrhagic shock from a ruptured ectopic pregnancy in a patient with a
negative urine pregnancy test result.
Kalinski MA, Guss DA.
Department of Emergency Medicine, University of California-San Diego Medical
Center, San Diego, CA, USA. [log in to unmask]
Ectopic pregnancy has been increasing in frequency over the past 2 decades.
The sudden rupture of a fallopian tube caused by ectopic pregnancy can lead
to hemorrhagic shock and death if not diagnosed and treated in a timely
fashion. The emergency physician is often the health professional that is
called on to make the diagnosis and coordinate timely and effective
intervention. The first step in the diagnosis of ectopic pregnancy is
demonstration of pregnancy by means of a rapidly performed and sensitive
qualitative urine test for the beta-subunit of human chorionic gonadotropin
(beta-hCG). A negative urine pregnancy test result will generally be used to
exclude ectopic pregnancy from further consideration. The following is a
report of a patient presenting to an emergency department with hypovolemic
shock in conjunction with 2 negative urine beta-hCG analysis results and a
quantitative serum beta-hCG level of 7 mIU/mL, a value less than the lower
limit of detection for the highly sensitive qualitative urine and serum
tests. This case report demonstrates the importance of further consideration
of the diagnosis of ectopic pregnancy in the setting of a negative urine
pregnancy test result.
Best wishes
Rowley.
-----Original Message-----
From: Accident and Emergency Academic List
[mailto:[log in to unmask]] On Behalf Of John Butler
Sent: 16 July 2005 20:55
To: [log in to unmask]
Subject: Re: Urine pregnancy tests
I have worked in departments which routinely use urinary pregnancy tests to
rule out pregnancy ( and therefore an ectopic pregnancy) in women presenting
to A&E with PV bleeding. If people are going to use urinary Bhcg tests as a
SnOUT for possible ectopic pregnancy, then it is important to know the
limitations of this diagnostic test.
Best wishes,
John Butler
----- Original Message -----
From: "Rowley Cottingham" <[log in to unmask]>
To: "John Butler" <[log in to unmask]>
Sent: Saturday, July 16, 2005 9:11 AM
Subject: Re: Urine pregnancy tests
Urine pregnancy tests are known to be less reliable than serum - that is not
news at all. The sensitivity can be increased and hence your confidence in
the result improved by using an early morning urine sample.
Best wishes
Rowley.
-----Original Message-----
From: Accident and Emergency Academic List
[mailto:[log in to unmask]] On Behalf Of Adrian Fogarty
Sent: 15 July 2005 23:57
To: [log in to unmask]
Subject: Re: Urine pregnancy tests
Double reading won't prevent sampling/collection errors.
AF
----- Original Message -----
From: "Ray" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, July 15, 2005 11:27 PM
Subject: Re: Urine pregnancy tests
> The link is to an incomplete BET.
>
> Over the years I can only remember one problem with a pregnancy test
> and that was "pilot error" so the tests are double read by 2 staff
> now.
>
> Ray McGlone
> Lancaster
>
> ----- Original Message -----
> From: "John Butler" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Friday, July 15, 2005 7:27 PM
> Subject: Re: Urine pregnancy tests
>
>
>> Hello Peter,
>>
>> One of our students has just completed a BET looking at this
>> question. There is reasonable evidence that serum is more sensitive
>> than urine Bhcg.
>> See below
>> http://www.bestbets.org/cgi-bin/bets.pl?record=00936
>>
>> John Butler
>>
>> ----- Original Message -----
>> From: "Peter Cutting" <[log in to unmask]>
>> To: "John Butler" <[log in to unmask]>
>> Sent: Thursday, July 14, 2005 4:40 PM
>> Subject: Re: Urine pregnancy tests
>>
>>
>> I'm sad to say that seeing 350 pts a day means they dont stay at the
>> back of a shelf for very long! (obviously they dont all get pregnancy
>> tests though......... even those with X X)
>> All were in date
>> Peter
>>
>>>>> [log in to unmask] 11:20:20 14/07/2005 >>>
>> Peter Cutting wrote:
>>
>>>Anyone else having any false negatives with the urinary preg tests?
>>>We are investigating a couple in our dept and apparently our gynae
>>>team are looking at it too after they have had some.
>>>
>>>As part of our review we discoverd that the strips we use clearly say
>>>in the manufacturers leaflet that they must not be called a negative
>>>result before 5 minutes. There is a question mark that we may not
>>>have been doing this with every strip.
>>>
>>>There are also quality control issues. Do any of you subject your
>>>strips to reference samples? ( again the manufacturers recommend that
>>>you do) and if so who does it?
>>>
>>>Our Near Pt Testing bods are getting interested in external quality
>>>assessment schemes like NEQAS or WEQAS ( http://www.ukneqas.org.uk/
>>>). Anyone doing that?
>>>
>>>Cheers
>>>Peter
>>>
>>>_____________________________________________________________________
>>>___
>>>Doctors.net.uk e-mail is protected from spam and viruses
>>>
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>>>
>>>
>>>
>>>
>>>
>>>
>> Remember they go out of date relatively quickly too if left in the
>> back of a cupboard.
>>
>> Another cause for false negatives.
>>
>> Andy Webster
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