Ultrasound in obstetrics 1.Introduction 2.Definiation 3.Equipments use in ultrasound 4.How ultrasound works 5.Indication of obstetric ultrasound 6.Finding in the first trimester scan 7.Mid trimester ultrasound 8.third trimester scanning 9.Thanku

2.  The development of ultrasound has
dramatically altered obstetric management.
 It forms an important tool to detect
congenital fetal anomalies, assess gestation
maturity and guide invasive diagnostic and
therapeutic obstetric procedures and
measures blood flow.

3.  It is a sound wave beyond the audible range
of frequency greater than 2MHZ (cycles per
second). The SONAR stands for "Sound ,
Navigations and Ranging“.
 The clinical applications of ultrasound in
obstetrics was introduced and popularized
by IanDonald in Glasgow in 1958.

5.  1. Transducer:- Is a device that converts
variations in a physical quantity, such as
pressure or brightness, into an electrical
signal, or vice versa.
 2. Video display terminal:-It display the
inner structure of body that is received by the
recover in the form of signal.

6.  3. Frequency range:- Ultrasound
frequencies in diagnostic radiology rang-
e from 2 MHz to approximately 15 MHz.

7.  Sound emitted at high pitch does travels in a
more or less straight line.
 At a low pitch it spreads out. Sound that is
produced at a very high pitch is therefore
transmitted in a narrow beam which is produced
by a type of reducer. The transducer trans-form
electrical energy to sound and back again.
 When the transducers placed on the body, a
sound wave passes into the body and en-
counters a structure; a fraction of the sound is
reflected back.

8.  The amount of sound from each organ varies
according to the type of tissues encountered:
 1. Strong echo's give bright white dots. For
e.g. Bones
 2. Weaker echo’s give various shades of
grey according to strength.
 3 Fluid filled areas cause no refection and
give rise to a black image

9.  It can be divided into fetal ,uteroplacental and maternal.
 1. Fetal :-
 a. Diagnosis of pregnancy.
 b. Assessment of gestational age.
 c. Diagnosis of multiple pregnancy
 d. Diagnosis of IUFD.
 e. Detection of anomaly.
 F Assessment of growth (IUGR).
 g. Assessment of wellbeing.
 h. Diagnosis of presentation.
 i. Diagnosis of ectopic pregnancy.

10. 2. Uteroplacental:
 a. Localization of placenta (placenta previa).
 b. Diagnosis of abruption placenta.
 c. Diagnosis of molar pregnancy.
 d. Diagnosis of uterine malformations.
 e. Assessment of liquor volume.
 f. Uterine size either < or > dates.
 g. Diagnosis of cervical incompetence.

11.  3. Maternal:
a. Pelvic mass diagnosis and follow up.
b. As an adjunct to obstetric intervention.
c. Amniocentesis.
d. Chorion villous sampling.
e. Cordocentesis.
f. Fetoscopy.
g. Intrauterine fetal therapy (transfusion)

12.  1. Fetus: Fetus can be generally well
visualized satisfactorily after7 complete week
of gestation. The scan done should be able
to in form the following:
 a. Regular fetal heart pulsation.
 b. Measurement of CRL.
 c. Fetal activity

13. 2. Amniotic cavity: It measures about 10mm
at 5 weeks and 15mmat 6 and 7 weeks of
pregnancy.
3. Trophoblastic layer of placenta: The site
where the trophoblasts seems to be
localizing to form the placenta is important in
the first trimester in woman in whom a
chorion villus sampling is indicated on
medical grounds.

14.  Advantages:
 1. Estimation of gestational age in most
accurate 4- 5 days, provided the crowm lump
length can be measured.
 2. Evaluation of any adrenal pathology is
easiest at this stage of pregnancy.

15.  Disadvantages:
 1. Satisfactory evaluation of the fetal
structure is not feasible.
 2. Fetal number may show a change on
subsequent scanning lateron.
 3. Placental location may appear to change
as pregnancy progress because of
differential growth rates at different parts the
uterus.

16.  Findings:
 1. Fetal growth: Is calculated on the basis
of an accurate gestational age and is
expressed in percentiles. Normal fetal weight
is between 10th and 90th percentiles. Weight
less than 10 percentileis considered as small
for gestational age and more than
90thpercentile is large for gestational age.

17.  2. Fetal heart: Four chamber view of heart and
evaluation of out-flow track are done for
screening of congenital heart diseases.
 3. Fetal gender identification: It is confirmed
by detection of testes within the scrotum in the
third trimester.
 4. Placenta and umbilical cord: It is discoid
shape. Placental thickness is 30mm. Placental
thickness if more than 45mm at any period is
considered abnormal.

18. 1. Amniotic fluid:
a. Decreased: Oligohydramnious is diagnosed
when there is no amniotic fluid pocket of 1.0
cm in size in two perpendicular plane
b. Excessive: Hydramnious is diagnosed when
the largest single pocket is 8.0 cm in two
perpendicular planes.

19.  2. Viability of the fetus:
 a. Heart pulsation.
 b. Fetal limb movements.
 3. Placenta:
 a. Location, Fundal, Anterior, Lateral,
Posterior, Low lying.
 b. Abruption, presence of retro placental clot.