Underestimation of the duration of pregnancy can occur in the
case of a marked Hegar's sign. The cervix is firm, but the transition
of the cervix to the uterus is so soft that the inexperienced
examiner may take the cervix for a small uterus and fails to feel the
corpus, or he may consider this a tumour. To avoid this it is
advisable to start with an external abdominal examination to locate
the fundus.
If in an advanced pregnancy the fetus has died a long time ago
the uterus is much smaller. The correct diagnosis will be found if an
ultrasound scan is used. Evacuation should be done in a hospital
because of the risk of DIC. It is a clear medical indication anyway.
Van den Bergh examined a young lady with the uterus up to a hand broad above the umbilicus. He diagnosed her pregnancy to be about 29 weeks. The ultrasound showed triplets of 19 weeks. The operation bij the Finks technique took about 15 minutes. She left the clinic three hours after arriving there.
A patient came for
termination. On bimanual examination a pregnancy of about 13 weeks
was found. Shortly after dilation a macerated leg is pushed out of
the cervix together with some offensive brown fluid. On the size of
the leg a pregnancy oﾄ 25 weeks is estimated. Because of the danger
of DIC the patient was sent to a hospital where an oxytocin drip was
applied which eventually lead to the delivery of the dead fetus.
Examination should include the ovaries and tubes. They will only
be felt if they are enlarged. An ovarian tumour may be dense, a cyst
is elastic and painless. Occasionally a cyst bursts during
examination. This will generally not cause a problem but occasionally
it may (Chapter 12)
In some cases of ectopic (or: heterotopic-) pregnancy there is a history of
increasing abdominal pains. Most patients do not complain. If an
ectopic pregnancy is suspected the diagnosis should be ascertained by
ultrasound scan, or serial ß-hCG estimation. If this is not available
bimanual examination must be carried out very carefully, and a
pregnancy test must be done, which in certain cases is negative. An
ectopic generally is soft and painful when touched and may burst as a
result of the examination, leading to an intense pain and collapse.
In case of a (suspected) ectopic pregnancy the termination must not
be done because the procedure is useless and it may lead to rupture.
Only if there is no possibility to reach a proper diagnosis a
termination may be justified to confirm the diagnosis by examination
of the removed tissues. The aspect of the removed tissues in case of
an ectopic pregnancy is described in
Chapter 9 )
2. PREGNANCY TESTS
Pregnancy tests detect the presence of hCG in blood or urine. Most act by
the principle of antibody reaction with the Beta-chain of the hCG
molecule, some react with the alpha-chain. The latter also react with
LH which has an identical alpha-chain. In slide tests the test fluid
is brought together with urine and a suspension of latex particles.
The test fluid causes the particles to coagulate, except if this
reaction is inhibited by the presence of hCG in the urine. Thus the
test is positive if nothing happens and negative if coagulation
occurs. This may be a cause of misinterpretation since one expects
something to happen if the test is positive. Other causes are the
occurrence of very fine coagulation and the fact that LH is also
recognised, for instance during the menopause. Since irregular
periods are common during the menopause a false positive test may
lead to an unnecessary termination:
- The patient is fifty-two years and her gynaecologist declared
her pregnant because her test is positive. Although a case of a
ninety year old pregnant woman is described (Genesis 21), at the
age of fifty + pregnancies are rare. A fibroma is found and no
pregnancy. The next day she comes back: her gynaecologist insists
that she is pregnant, and he examined her much better than the
present physician because he also examined her breast. Again a
pregnancy can not be diagnosed, although the doctor does examine
her breasts as well. She goes to another doctor who does a
termination procedure. He can not aspirate any tissue but
perforates the uterus.
-
- Modern tests determine the presence of hCG according to the
principle of monoclonal antibody immunoassay. The presence of hCG
forms a coloured spot on the test area of the device, while a
coloured spot on the control area appears in all cases if the test is
carried out properly. Development of tests tend to an ever increasing
simplicity of execution. Some tests are simply done by sticking a
strip of paper in urine and watch the change of colour of a control
area which shows that the test is well performed, and a test area
which shows that the result is positive or negative. Similar tests
are available to predict ovulation by detecting LH.
-
- Todays tests are so sensitive that pregnancy can
be detected with great accuracy even before missing a period. Such
very sensitive tests have a certain risk of giving a false positive outcome.
revised spring 2010