BUKOVINIAN STATE MEDICAL UNIVERSITY
“Approved”
on methodological meeting
of Department of Obstetrics and Gynecology
with course of Infant and Adolescent Gynecology
“___”______________________ 201_ year
protocol #
T.a.the Head of the department
Professor
________________ O.A. Andriyets
METHODOLOGICAL INSTRUCTION
for practical lesson
“Physiology of pregnancy. Perinatal care of fetus. Methods of examination of pregnant
women.”
MODULE 4: Obstetrics and gynecology
CONTEXT MODULE 8: Physiology of pregnancy, labor and puerperium
Subject: Obstetrics and Gynecology
6th year of studying
2nd medical faculty
Number of academic hours – 6
Methodological instruction developed by:
ass.prof. Andriy Berbets
Chernivtsi – 2010
Theme: Obstetrics Terminology. Methods of Examination of Pregnant Women. Assessment of
Fetal Well-being
Aim: to know obstetrics terminology, the methods of external and internal examination of
pregnant women. To be able to prescribe and assess of modern methods of diagnostics of fetal
well-being in obstetrics for in-term revealing of pathological changes in pregnant woman's
organism and fetal status; prescribe an adequate treatment to the pregnant women in the case of
fetal hypoxia.
Professional motivation: learning the methods of obstetrics examination of pregnant women is
necessary to diagnose and to estimate the given information. An appropriate interpretation of
fetal well-being tests in light of the natural course of any antenatal problem provides a firm base
on which decisions are made.
Basic level: Student must know:
1. Anatomic terminology in English and Latin
2. Methods of physical examination of patient.
3. The structure of fetal head (anatomy of the skull).
4. Conceptus, development.
5. Obstetric ultrasound examination and its assessment.
6. Fetal heart rate auscultation.
7. To prescribe an adequate therapy of fetal well-being impairment
STUDENTS’ INDEPENDENT STUDY PROGRAM
I. Objectives for Students' Independent Studies
You should prepare for the practical class using the existing textbooks and lectures. Special
attention should be paid to the following:
Obstetrical terminology. Methods of examination of pregnant women:
1. Definition of the obstetrics terms: attitude (habitus), presentation, position, variety (visus).
2. Definition of the terms: axis of fetus, axis of uterus, axis of pelvis.
3. Engagement (synclitic and asynclitic).
4. Auscultation of fetal heart sounds.
5. Vaginal examination.
6. Speculum examination.
7. Examination of abdomen (Leopold Maneuvers).
8. Ultrasonic assessment of the fetus.
Assessment of fetal well-being:
1. Obstetric ultrasound examination.
2. Investigation of discharge from breast glands on the gestational age of pregnancy.
3. Electronic fetal monitoring.
4. Biophysical profile of the fetus.
5. Test for revealing of amniotic fluid.
6. Functional diagnostic's tests.
7. Invasive methods of assessment of fetal status: cordocentesis, phetoscopy, amnioscopy,
amniocentesis.
Key words and phrases: habitus (attitude), lie, presentation, the position, variety, axis of fetus,
axis of uterus, axis of pelvis, synclitism and asynclitism, engagement; Leopold's Maneuvers,
speculum and vaginal examination. Assessment of fetal well-being, fetal hypoxia, biophysical
profile of fetus.
Summary
Obstetrical terminology
The attitude refers to the relationship of parts of the fetus to one another (fetal head is flexed on
fetal chest, thighs are flexed on fetal abdomen).
The lie of the fetus is the relationship of long axis of the fetus to the long axis of the uterus and
is either longitudinal or transverse. In longitudinal lie fetal and uterus axes corresponds. When
fetal and uterus axes cross at 45- degree angle - an oblique lie is formed. At transverse lie fetal
and uterus axes cross at 90- degree angle Longitudinal lies are present in over 99% of labor at
term.
The presentation indicates that portion of the fetus that overlies the pelvic inlet. Presenting part
is the portion of the fetus that descends first through the birth canal (lowest in the birth canal).
When the lie is longitudinal, the presenting part is either the head (cephalic) or breech.
The position refers to the relationship of definite part of the fetus to the right or left side of
maternal pelvis. With each presentation there may be two position, right or left. The occiput,
chin and sacrum are the determining points in vertex, face and breech presentation, respectively.
Variety (visus) - the relation of the given portion of the presenting part to the anterior and or
posterior portion of the mother's pelvis. Since there are two position, it foiiows that there must be
six varieties for each-presentation. The presenting part in any presentation may be either the left
and right occipital (LO,RO),left and right mental (LM,RM),and left and right sacral (LS,RS)
presentations. Since the presenting part in each of the two positions may be directed anteriorly,
or posteriorly.
Engagement exists when the bi parietal diameter of the fetal head have passed the plane of the
pelvic inlet. If at the time of engagement, the sagittal suture is midway between the pubic
symphysis and the promontory of the sacrum in a transverse position, the head is said to be
synclitic. In the sagittal suture rides anteriorly or posteriorly, the fetal vertex is asynclitic
(anterior asynclitism, posterior asynclitism).
Examination of pregnant women
Abdominal palpation: Leopold's maneuvers.
The first maneuver: the examiner hands palpate the fundal area and distinguish which part of the
fetus occupies the fundus. Importance: estimation of gestational age of the pregnancy and fetal
lie.
The second maneuver is accomplished when hands are placed on either side of the abdomen to
determine on which side the fetal back lies. Importance: estimation of fetal lie, position, variety,
amount of amniotic fluid, fetal movement.
The third maneuver is done with a single examining hand placed just above the symphysis.
Importance: determination presentation and presenting part. The presented part is grasped
between the thumb and third finger.
The fourth maneuver is done with the examiner facing the patient's feet and placing both hands
on either side of the lower abdomen just above the inlet. Importance: determination of fetal head
station (relation of presenting part to the pelvic inlet).
Vaginal examination. In vaginal examination a doctor should examine vaginal walls; dilation,
effacement, consistency and position of the cervix; presence of amniotic fluid; fetal presentation
and position, pelvis also.
To determine presentation and position by vaginal examination, it is advisable to pursue a
definite routine that consists of three maneuvers as:
Two gloved fingers are introduced into vagina and carried up to the presenting part.
Differentiation of vertex, face and breech presentation is then readily accomplished.
If the vertex is presenting part, the examiner's fingers are introduced in the posterior aspect of the
vagina. The fingers are then swept over the fetal head toward the maternal symphysis. The
examiner's fingers must cross the sagittal suture, and its course is outlined, with small and large
fontanels at the opposite ends.
The positions of the two fontanels then are ascertained, ie, anterior and posterior.
Auscultation. In cephalic presentation, the point of maximal intensity of fetal heart sounds is
usually midway between the maternal umbilicus and the anterior-superior spine of her ilium.
Employing ultrasonography, the fetal head and body can be located usually without difficulty.
Ultrasonic dating of the pregnancy and an ultrasonic fetal survey to detect gross abnormalities
have been recommended in some clinics as a routine part of early prenatal care. Routine
ultrasonography is most cost -effective in patients in whom the date of the last menstrual period
is uncertain and in patients with a family history of congenital anomalies. Considerable
individuaHzation should be exercised in making the decision to order this evaluation. If
ultrasonography is performed, it is most informative between 18-20 weeks.
Structural defects that have been diagnosed with this technique include craniospinal
abnormalities ( e.g., anencephaly, hydrocephaly, spina bifida, microcephaly), gastrointestinal
anomalies ( e.g., omphalocele, gastroschisis), excretory system anomalies (e.g., renal agenesis,
renal dysplasia, urinar obstruction), skeletal dysplasia and congenital heart defects.
Endovaginal ultrasonography is used primarily in the first trirneste to establish fetal viability.
Assessment of fetal well-being
Assessment of fetal well-being includes maternal perception of fetal activity and several tests
using electronic fetal monitors and ultrasonography
Tests of fetal well-being have a wide range of uses, including the assessment f fetal status at a
particular time and the prediction of fetal status for varying time intervals, depending on the test
and the clinical situation.
An active fetus is generally a healthy fetus, so that quantification of fetal activity is a common
test of fetal well-being. If, for example, the mother detects more than four fetal movements while
lying comfortably and focusing on fetal activity for 1 hour, the fetus is considered to be healthy.
Techniques using electronic fetal monitoring and ultrasonography are most costly, but also
provide more specific information. The most common tests used are the nonstress test, the
contraction stress test (called the oxytocin challenge test if oxytocin is used), and the biophysical
profile.
The nonstress test (NST) measures the response of the fetal heart rate to fetal movement.
Interpretation of the nonstress test depends on whether the fetal heart rate accelerates in response
to fetal movement. A normal, or reactive, NST occurs when the fetal heart rate increases by at
least I5bpm over a period of 15 seconds following a fetal movement. Two such accelerations in a
20-minute span is considered reactive, or normal. The absence of these accelerations in response
to fetal movement is a nonreactive NST. A reactive NST is generally reassuring in the absence of
other indicators of fetal stress. Depending on the clinical situation , the test is repeated every 3 to
4 days or weekly. A nonreactive NST must be immediately followed with further assessment of
fetal well-being.
Whereas the nonstress test evaluates the fetal heart rate response to fetal activity, the contraction
stress test (CST) measures the response of the fetal heart rate to the stress of a uterine
contraction. With uterine contraction, uteroplacental blood flow is temporary reduced. A healthy
fetus is able to compensate for this intermittent decreased blood flow, whereas a fetus who is
compromised is unable to do so, demonstrating abnormalities such as fetal heart rate
decelerations. If contractions are occurring spontaneously, the test is known as a contraction
stress test; if oxytocin infusion is required to elicit contractions,the test is called an oxytocin
challenge test (OCT). The normal fetal heart rate response to contractions is for the baseline fetal
heart rate to remain unchanged and for there to be no fetal heart rate decelerations.
The biophysical profile is a series of five assessments of fetal well-being, each of which is given
a score of 0 or 2. The parameters include a reactive nonstress test, the presence of fetal
movement of the body or limbs, the findings of fetal tone (flexed extremities as opposed to a
flaccid posture). And an adequate amount of amniotic fluid volume. Perinatal outcome can be
correlated with the score derived from these five parameters.
A score of 8 to 10 is considered normal, a score of 6 is equivocal requiring further evaluation,
and a score of 4 or less is abnormal, usually requiring immediate intervention
Table 1. Biophysical profile
Biophysical Score
Variable
Fetal
Norma 1 = 2
breathing
movements
(FBM)
Abnormal = 0
Gross body
movement
Fetal tone
Of muscles
Reactive
fetal heart
rate
Explanation
At least 1 FBM of at least 30 seconds duration in 30 minutes
No FBM of at least 30-seconds duration in 30 minutes
Normal = 2
At least 3 discrete body /limb movements in 1 30 minutes
Abnormal = 0
2 or less discrete body /limb movements in 30 minutes
Normal = 2
At least 1 episode of active extension with return to flexion of fetal
limbs/trunk or opening/closing of hand
Abnormal == 0 Either slow extension with return to partial flexion or movement of
limb in full extension or no fetal movement
Normal = 2
Reactive NST
Abnormal = 0
Nonreactive NST
Qualitative Normal = 2
amniotic
fluid volume
Abnormal = 0
At least 1 pocket of amniotic fluid at least 1 cm in two
perpendicular planes
No amniotic fluid or no pockets of fluid greater 1 than 1 cm in two
perpendicular planes
Antenatal Care.
Women and their husbands/partners have the right to be involved in all decisions regarding their
antenatal care. They need to be able to make informed decisions concerning where they will be
seen, who will undertake their care, which screening tests to have and where they plan to give
birth.Women must have access to evidence-based information in a format that they can
understand. Current evidence suggests that insufficient written information is available
especially at the beginning of pregnancy and that information provided can be misleading or
inaccurate. Written information is particularly important to help women understand the purpose
of screening tests and the options that areavailableand to adviseon lifestyleconside rations
including dietary recommendations. Available information needs to be provided at the first
contact and must takeinto account cultural and languagebarriers. Local services should
endeavour to provide information that is understandable to those whose first language is not
English and to those with physical, cognitive and sensory disabilities. Translators will be
required in clinics with an ethnic mix. Couples should also be offered the opportunity to attend
antenatal classes. Ideally such classes should discuss physiological and psychological changes
during pregnancy, fetal development, labor and childbirth and how to care for the newborn baby.
Evidence shows a greater acquisition of knowledge in women who have attended such classes
compared with those that have not.
LIFESTYLE CONCERNS
At an early stage in the pregnancy women require lifestyle advice, including information on diet
and food, work during pregnancy and social aspects, for example, smoking, alcohol, exercise and
sexual activity. Women should be advised of the benefits of eating a balanced diet such as plenty
of fruit and vegetables, starchy foods such as pasta, bread, rice and potatoes, protein, fibre and
dairy foods. They should be informed of foods that could put their fetus at risk. Listeriosis is
caused by the bacterium Listeria monocytogenes which can present with a mild, flu-like illness
but is associated with miscarriage, stillbirth and severe illness in the newborn. Contaminated
food is theusual sourceincluding unpasteurized milk, ripened soft cheeses and pate.
Toxoplasmosis contracted through contact with infected cat litter, or undercooked meat can lead
to permanent neurological and visual problems in the newborn if the mother contracts the
infection during pregnancy. (Salmonella food poisoning has not been shown to have adverse
fetal effects.) To reduce the risk, pregnant women should be advised to thoroughly wash all fruits
and vegetables before eating and to cook well all meats including ready-prepared chilledmeats.
Women who have not had a baby with spina bifida, should be advised to takefolic acid, 400
mg/day, from pre-conception until 12 weeks of gestation to reduce the chance of fetal neural
tube defects (NTDs). A recent study has failed to show the efficacy of this strategy in analysing
population incidence of NTD. This is suggested to relate to inadequate pre-conceptual taking of
folate and/or poor compliance. Suggestions of adding folate to certain foods, for example, flour
to ensure population compliance remain debatable. Current evidence does not support routine
iron supplementation for all pregnant women and can be associated with some unpleasant side
effects such as constipation. However, any woman who shows evidence of iron deficiency must
be encouraged to take iron therapy prior to the onset of labour or any excess blood loss at
delivery will increase maternal morbidity. The intake of vitamin A (liver and liver products)
should be limited in pregnancy to approximately 700 mg/day because of fetal teratogenicity.
Because alcohol passes freely across the placenta, women should be advised not to drink
excessively during pregnancy. Current evidence suggests that there is no harm in drinking 1–2
units of alcohol per week. Binge drinking and continuous heavy drinking causes the fetal alcohol
syndrome, characterized by low birthweight, a specific facies, and intellectual and behavioural
difficulties later in life.
Approximately 27% of women are smokers at the time of birth of their baby. Smoking is
significantly associated with a number of adverse outcomes in pregnancy including an increased
risk of perinatal mortality, placental abruption, preterm delivery, preterm premature rupture of
the membranes, placenta praevia, low birthweight, etc. While there is evidence to suggest that
smoking may decrease the incidence of pre-eclampsia this must be balanced against the far
greater number of negative associations. Although there is mixed evidence for the effectiveness
of smoking cessation programmes, women should be encouraged to partake. Pregnant women
who are unableto stop smoking should be informed of the benefits of reducing the number of
cigarettes they smoke. A 50% reduction can significantly reduce the fetal nicotine concentration
and is associated with an increase in the birthweight. Women who use recreational drugs must be
advised to stop or be directed to rehabilitation programmes. Evidence shows adverse effects on
the fetus and its subsequent development. Continuing moderate exercise in pregnancy or regular
sexual intercourse does not appear to be associated with any adverse outcomes. Certain physical
activity should be avoided such as contact sports which may cause unexpected abdominal
trauma. Scuba diving should also be avoided because of the risk of fetal decompression disease
and an increased risk of birth defects. Physically demanding work, particularly those jobs with
prolonged periods of standing may be associated with poorer outcomes such as preterm birth,
hypertension and pre-eclampsia and small-for-gestational-age babies but the evidence is weak
and employment per se has not been associated with increased risks in pregnancy. Women
require information regarding their employment rights in pregnancy and health-care
professionals need to be aware of the current legislation. Help for the socially disadvantaged and
single mothers must be organized and ideally a one-to-one midwife allocated to support these
women. The midwife should be able to liaise with other social services to ensure the best
environment for the mother and her newborn child. Similar individual help is needed for
pregnant teenagers and midwife programmes need to provide appropriate support for these
vulnerable mothers.
Common symptoms in pregnancy. Ethical aspects
It is common for pregnant women to experience unpleasant symptoms in pregnancy caused by
the normal physiological changes. However, these symptoms can be quite debilitating and lead
to anxiety. It is important that healthcare professionals are aware of such symptoms, can advise
appropriate treatment and know when to initiate further investigations. Extreme tiredness is one
of the first symptoms of pregnancy and affects almost all women. It lasts for approximately 12–
14 weeks then resolves in the majority.
Nausea and vomiting in pregnancy is one of the commonest early symptoms. While it is thought
that this may be caused by rising levels of human chorionic gonalotropin (hCG) the evidence for
this is conflicting. Hyperemesis gavidarum, where fluid and electrolyte imbalance and nutritional
deficiency occur, is far less common complicating approximately 3.5/1000 deliveries. Nausea
and vomiting in pregnancy varies in severity but usually presents within 8 weeks of the last
menstrual period. Cessation of symptoms is reported by most by about 16 weeks. Various nonmedical treatments have been advocated including ginger, vitamins B6 and B12, and P6
acupressure. There is evidence for the effectiveness of each of these but concerns about the
safety of vitamin B6 (pyridoxine) remains and there is limited data on the safety of vitamin B12
(cyanocobalamin).
Constipation complicates approximately one-third of pregnancies usually decreasing in severity
with advancing gestation. It is thought to be related in part to poor dietary fibre intake and
reduction in gut motility caused by rising levels of progesterone. Diet modification with bran and
wheat fibre supplementation helps, as well as increasing daily fluid intake. Heartburn is also a
common symptom in pregnancy, but unlike constipation, occurs more frequently as the
pregnancy progresses. It is estimated to complicate one-fifth of pregnancies in the first trimester
rising to three quarters by the third trimester. It is due to the increasing pressure caused by the
enlarging uterus combined with the hormonal changes that lead to gastro-oesophageal reflux. It
is important to distinguish this symptom from the epigastric pain associated with pre-eclampsia
which will usually be associated with hypertension and proteinuria. Symptoms can be improved
by simple lifestyle modifications such as maintaining an upright posture especially after meals,
lying propped up in bed, eating small frequent meals and avoiding fatty foods. Antacids
(especially Gaviscon®), H2 receptor antagonists and proton-pump inhibitors are all effective,
although it is recommended that the latter be used only when other treatments have failed
because of its unproven safety in pregnancy.
Haemorrhoids are experienced by 1 in 10 women in the last trimester of pregnancy. There is
little evidence for either the beneficial effects of topical creams in pregnancy or indeed their
safety. Diet modification may help and in extreme circumstances surgical treatment considered
although this is unusual since the haemorrhoids often resolve after delivery.
Varicose veins occur frequently in pregnancy. They do not cause harm and while compression
stockings may help symptoms they unfortunately do not prevent varicose veins from appearing.
The nature of physiological vaginal discharge changes in pregnancy. If, however, it becomes
itchy, malodorous or is associated with pain on micturition, it may be due to underlying infection
such as trichomoniasis, bacterial vaginosis or candidiasis. Appropriateinve stigations and
treatment should be instigated.
Screening for maternal complications
ANAEMIA
Maternal iron requirements increase in pregnancy because of the demands of the developing
fetus, the formation of the placenta and the increase in the maternal red cell mass. With an
increase in the maternal plasma volume of up to 50% there is a physiological drop in the
haemoglobin (Hb) concentration during pregnancy. It is generally recommended that an Hb level
below 11 g/dl up to 12 weeks’ gestation or less than 10.5 g/dl at 28 weeks signifies anaemia and
warrants further investigation. A low Hb (8.5–10.5 g/dl) may be associated with preterm labour
and low birthweight. Routine screening should be performed at the booking visit and at 28 weeks
gestation. While there are many causes of anaemia including thalassaemia and sickle cell
disease, iron deficiency remains the commonest. Serum ferritin is the best way of assessing
maternal iron stores and if found to be low iron supplementation should be considered. Routine
iron supplementation in women with a normal Hb in pregnancy has not been shown to improve
maternal or fetal outcome and is currently not recommended.
BLOOD GROUPS
Identifying the maternal blood group and screening for the presence of atypical antibodies is
important in the prevention of haemolytic disease, particularly from rhesus alloimmunization.
Routine antibody screening should take place at booking in all women and again at 28
weeks’ gestation in those who did not have antibodies at booking. Detection of atypical
antibodies should prompt referral to a specialist fetal medicine unit. In the population, 15%
of women are RhD negative and should be offered anti-D prophylaxis after potentially
sensitizing events (such as amniocentesis or antepartum haemorrhage) and routinely at 28 and 34
weeks’ gestation.
INFECTION Maternal blood should be taken early in pregnancy and with consent screened for
hepatitis B, HIV, rubella and syphilis. Identification of women who are hepatitis B carriers can
lead to a 95% reduction in mother to infant transmission following postnatal administration of
vaccineand immunoglobulin to thebaby . Women who are HIV positive can be offered treatment
with antiretroviral drugs which, when combined with delivery by Caesarean section and
avoidance of breast feeding, can reduce the maternal transmission rates from approximately 25
to 1%. Such women need to be managed by appropriate specialist teams. Rubella screening aims
to detect those women who are susceptible to the virus allowing postnatal vaccination to protect
future pregnancies. All women who are rubella non-immune must be counselled to avoid contact
with any infected person and if inadvertently she does, she must report the event to her midwife
or doctor. Serial antibody levels will determine whether infection has occurred. Vaccination
during pregnancy is contraindicated because the vaccine may be teratogenic. Untreated syphilis
is associated with congenital syphilis, neonatal death, stillbirth and preterm delivery.
Following positive screening for syphilis, testing of a second specimen is required for
confirmation. Interpretation of results can be difficult and referral to specialist
genitourinary medicine clinics is recommended. Current evidence does not support the routine
screening for cytomegalovirus, hepatitis C or toxoplasmosis. Asymptomatic bacteriuria occurs in
approximately 2– 5% of pregnant women and when untreated is associated with pyelonephritis
and preterm labour. Appropriate treatment will reduce the risk of preterm birth. Screening should
be offered early in pregnancy by midstream urine culture.
HYPERTENSIVE DISEASE Chronic hypertension pre-dates pregnancy or appears in the first
20 weeks whereas pregnancy-induced hypertension develops in the pregnancy, resolves after
delivery and is not associated with proteinuria. Pre-eclampsia defines hypertension that is
associated with proteinuria occurring after 20 weeks and resolving after birth. Preeclampsia occurs in 2–10% of pregnancies and is associated with both maternal and neonatal
morbidity and mortality. Risk factors include nulliparity, age of 40 years and above, family
history of pre-eclampsia, history of pre-eclampsia in a prior pregnancy, a body mass index
greater than 35, multiple pregnancy and pre-existing diabetes or hypertension. Hypertension is
often an early sign that pre-dates the development of serious maternal and fetal disease
and should be assessed regularly in pregnancy. There is little evidence as to how frequently
blood pressure should be checked and so it is important to identify risk factors for pre-eclampsia
early in pregnancy. In the absence of these, blood pressure and urine analysis for protein should
be measured at each routine antenatal visit and mothers should be warned of the advanced
symptoms of pre-eclampsia (frontal headache, epigastric pain, vomiting and visual
disturbances).
GESTATIONAL DIABETES Currently there is little agreement as to the definition
of gestational diabetes, whether we should routinely screen for it and how to diagnoseand
manageit. Accordingly, it’s recommended that routine screening for gestational diabetes should
not be offered.
PSYCHIATRIC ILLNESS The importance of psychiatric conditions related to pregnancy was
highlighted in the most recent Confidential Enquiry into Maternal and Child Health. At
booking, details of a significant history of psychiatric illness should be established and at-risk
women referred for specialist psychiatric assessment during the pregnancy.
PLACENTA PRAEVIA In approximately 1.5% of women the placenta will cover the os on the
20-week scan but by delivery, only 0.14% will have placenta praevia. Only those women whose
placenta covers the os in the second trimester should be offered a scan at 36 weeks to check the
position. If this is not clear on transabdominal scan, a transvaginal scan should be performed.
Screening for fetal complications
CONFIRMATION OF FETAL VIABILITY All women should be offered a ‘dating’ scan. This
is best performed between 10 and 13 weeks’ gestation and the crown–rump length measured
when the fetus is in a neutral position (i.e. not curled up or hyperextended). Current evidence
shows that the estimated day of delivery predicted by ultrasound at this gestation will reduce the
need for induction of labour at 41 weeks when compared with theduedatepr edicted by thelast
menstrual period. In addition, a dating scan will improvether eliability of serumscreening for
Down’s syndrome, diagnose multiple pregnancy and allow accurate determination of
chorionicity and diagnose up to 80% of major fetal abnormalities. Women who present after 14
weeks’ gestation should be offered a dating scan by ultrasound assessment of the biparietal
diameter or head circumference.
SCREENING FOR DOWN’S SYNDROME Current recommendations are that Down’s
screening programmes should detect 60% of affected cases for a 5% false positive rate. These
performance measures should be age standardized and based on a cut-off of 1/250 at term.
There are numerous screening strategies at the present time using either first trimester
ultrasound markers (nuchal translucency) or maternal (alpha-fetoprotein, oestriol, free-beta hCG,
inhibin-A and pregnancy associated plasma protein A) in either the first or second trimester.
Some programmes use a combination of both serum and ultrasound markers. To achieve the
targets, it is likely that combination screening will be required. Because screening for Down’s
syndrome is a complex issue, health-care professionals must have a clear understanding of the
options available to their patients. Unbiased, evidence-based information must be given to
thewoman at thebe ginning of thepr egnancy so that she has time to consider whether to opt for
screening and theopportunity to clarify any areas of confusion before the deadline for the test
passes. Following a ‘screen positive’ result the woman needs careful counselling to explain the
test result does not mean the fetus has Down’s syndrome and to explain the options for further
testing by either chorion villus sampling or amniocentesis.Apositive screen test does not mean
further testing is mandatory. Likewise, a woman with a ‘screen negative’ result must understand
thefe tus may still haveDown’s syndrome.
SCREENING FOR STRUCTURAL ABNORMALITIES The identification of fetal structural
abnormalities allows the opportunity for in utero therapy, planning for delivery, for example,
when the fetus has major congenital heart disease, parental preparation and the option of
termination of pregnancy should a severe problem be diagnosed. Major structural anomalies are
present in about 3% of fetuses screened at 20 weeks’ gestation. Detection rates vary depending
on the system examined, skill of the operator, time allowed for the scan and quality of
theultrasound equipment. Follow-up data is important to audit the quality of the service. Women
must appreciate the limitations of such scans. Local detection rates of various anomalies such as
spina bifida, heart disease, facial clefting and thelikeshould bemadeavailable.
Written information should be given to women early in pregnancy explaining thenatureand
purposeof such scans highlighting conditions that are not detected such as cerebral palsy and
many genetic conditions. It is important to appreciate that the fetal anomaly scan is a screening
test which women should opt for rather than have as a routine part of antenatal care without
appropriate counseling.
SCREENING FOR FETAL WELL-BEING Each antenatal clinic attendance allows the
opportunity to screen for fetal well-being. Auscultation for the fetal heart will confirm that the
fetus is alive and can usually be detected from about 14 weeks of gestation. While hearing the
fetal heart may be reassuring there is no evidence of a clinical or predictive value. Likewise there
is no evidenceto support theuseof routinecar diotocography in uncomplicated pregnancies.
Physical examination of the abdomen by inspection and palpation will identify approximately
30% of small-for-gestational-age fetuses. Measurement of the symphysio-fundal height in
centimetres starting at the uterine fundus and ending on thefixe d point of thesymphysis pubis
has a sensitivity and specificity of approximately 27 and 88%, respectively, although serial
measurements may improve accuracy. Customized growth charts make adjustments for maternal
height, weight, ethnicity and parity. Their use increases the antenatal detection of small-forgestational age fetuses and result in fewer unnecessary hospital admissions. While the evidence
for the benefits of plotting serial symphysio-fundal height measurements is limited, it is
recommended that women are offered estimation of fetal size at each antenatal visit and when
there is concern, referred for formal ultrasound assessment. Traditionally, women have been
advised to note the frequency of fetal movements in the third trimester. Although the
evidence does not support formal counting of fetal movements to reduce the incidence of late
fetal death, women who notice a reduction of fetal movements should contact their local hospital
for further advice.
Key points of pharmacotherapy and teratogenic factors
1 Severe congenital malformations (including those birth defects that cause death,
hospitalization, and mental retardation, and those that necessitate significant or repeated surgical
procedures, are disfiguring, or interfere with physical performance) occur in 3% of all births.
2 Only a small percentage of birth defects are due to prescribed drugs, chemicals, and physical
agents. Even when a drug is listed as a teratogen, it has to be administered during the sensitive
period of development for that drug, and above the threshold dose for producing teratogenesis.
Environmental causes account for approximately 10% of human birth malformations, and fewer
than 1% of all human malformations are related to prescription drug exposure, chemicals, or
radiation.
3 The etiology of congenital malformations can be divided into three categories: unknown (65–
75%), genetic (15–25%), and environmental (10%).
4 Reproductive problems alarm the public, press, and some scientists, to a greater degree than
most other diseases.
5 Physicians must recognize the consequences of providing erroneous reproductive risks to
pregnant women exposed to drugs and chemicals during pregnancy, or of alleging that a child’s
malformations are caused by an environmental agent without performing a complete and
scholarly evaluation.
6 Labeling an environmental exposure as teratogenic is inappropriate unless one characterizes
the exposure with regard to the dose, route of exposure, and stage of pregnancy when the
exposure occurred.
7 The application of the basic scientific principles of teratology is extremely important in
evaluating studies on the reproductive effects of an environmental agent. These principles
include the following criteria: exposure to teratogens follows a toxicological dose–
response curve; the embryonic stage at which exposure occurs determines what effects (if any) a
teratogen has; most teratogens have a confined group of congenital malformations (syndrome of
agent’s effects) and; no teratogen can produce every type of malformation.
8 The risk of morphological anomalies or intrauterine death resulting from exposure to a
developmental toxicant varies depending on the dose and the embryonic or fetal stage at which
exposure occurs.
9 The threshold dose for an environmental toxicant is the dose below which the incidence of
death, malformation, growth retardation, or functional deficit is not greater than that of control
subjects. The severity and incidence of malformations produced by every exogenous agent that
has been appropriately studied have exhibited threshold phenomena during organogenesis.
10 Teratogens follow a threshold dose–response curve, whereas mutagens and carcinogens tend
to follow a stochastic dose–response curve.
11 Physiological alterations in pregnancy and the bioconversion of compounds can significantly
influence the teratogenic effects of drugs and chemicals by affecting absorption, body
distribution, active form(s), and excretion of the compound.
12 Interpretation of dose–response relationships for teratogens must take into account the
active metabolites, when metabolites might be the proximate teratogen rather than the
administered drug or chemical, the duration of the exposure (chronic versus acute), and the fat
solubility of the agent.
13 The role that the placenta plays in drug pharmacokinetics involves transport, the presence
of receptors for a number of endogenous and xenobiotic compounds, and the bioconversion of
xenobiotics.
14 The genetic constitution of an individual is an important factor that affects the susceptibility
of a species to a drug or chemical.
15 Animal teratology studies are helpful in raising concerns about the reproductive effects of
drugs and chemicals, but negative animal studies do not guarantee that these agents are free from
reproductive effects.
16 Well-performed epidemiology studies represent the best methodology for determining the
human risk and the effects of environmental toxicants.
17 In vitro tests can be used to study the mechanisms of teratogenesis and embryogenesis, and
for preliminary screening procedures. However, in vitro studies cannot predict human
teratogenic risks at particular exposures without the benefit of data obtained from whole animal
studies and epidemiological studies.
18 The clinician must be cognizant of the fact that many patients believe that most congenital
malformations are caused by a drug or medication taken during pregnancy.
19 Ignoring the basic tenets of teratology appears to occur most commonly in the evaluation of
environmental exposures when the exposure was very low or unknown and the agent has been
reported to be teratogenic at a very high dose or maternally toxic dose.
20 The evaluation of the toxicity of drugs and chemicals should (when possible) use data
obtained from investigative approaches including: (1) epidemiological studies, (2) secular trend
analysis, (3) animal reproductive studies, (4) dose–response relationships, (5) mechanisms of
action (MOA) studies that pertain specifically to the agent and include receptor
affinity, cytotoxicity, genotoxicity, organ toxicity, and neurotoxicity, and (6) biological
plausibility
IL Tests and Assignments for Self — assessment.
Multiple Choice.
Choose the correct answer / statement:
1. The most common fetal lie found during early labor is: A - Oblique;
B - Transverse;
C - Vertex;
D ~ Longitudinal.
2. The most common fetal presentation found during early labor is: A - Oblique;
B - Transverse;
C - Vertex;
D - Longitudinal.
3. What is presentation?
A - Relationship of the fetal presenting part to the right and left side of the maternal pelvis;
B - Relationship of the long axis of the fetus with the uterine long axis;
C - Portion of the fetus lowest in the birth canal;
D - Part of the fetus that is most easily palpable on abdominal examination;
4. Leopold's maneuvers are used to establish all of the following except:
A - Fetal gender; B - Fetal lie; C - Fetal presentation; D - Fetal position; E - Fetal movement.
5. What do we identify carrying out the third Leopold's Maneuver?
A - part of the fetus which occupies the fundus of the uterus
B - fetal back;
C - the lie of the fetus;
D - the presenting part;
E - the position of the fetus.
Real - life situations to be solved:
6. While perfoming the first Leopold maneuver the physician palpates in fundal area irregular
and soft part; carrying out third maneuver determine round, firm and balloting part. What is the
presentation of the fetus?
7 While examining the abdomen of pregnant woman physician identifies the longitudinal lie of
the fetus, head presentation, left position
anterior variety.
Where is the best place for auscultation of the fetus heart sounds?
What is the normal fetal heart rate?
III. Answers to the Self- Assessment.
1. D. 2. C. 3. C. 4. A. 5.D. 6. Cephalic presentation. 7. Auscultation should perform on the
abdominal left side and lower the umbilicus. The normal heart rate of fetus is 120-140 beats per
minute.
Students must know:
1. Obstetrics terminology.
2. Examination of the abdomen ( Leopold's maneuvers).
3. Pelvic examination.
4. The landmarks of fetal skull, segments of fetus heard.
Students should be able:
1. To take history (anamnesis).
2. To perform objective examination of pregnant woman.
3. To perform Leopold's maneuver.
4. To identify the lie, position and presentation of the fetus.
5. To perform the auscultation, vaginal and speculum examination.
6. To estimate the given information.
References:
1. Danforth's Obstetrics and gynaecology. - Seventh edition.- 1994. - P. 289-304.
2. Obstetrics and gynaecology. Williams & Wilkins Waverly Company. - Thirdl Edition.- 1998.
- P. 118-130.
3. Basic Gynecology and Obstetrics. - Norman F. Gant7 F. Gary Cunningham, -j 1993. - P. 328397.
4. Obstetrics and gynecology. - Pamela S.Miles, William F.Rayburn, J.Christopher. Carey. Springer-Verlag New York, 1994. - P, 30-34.