Importance of intrapartum sonographic monitoring

1. ROLE OF INTRAPARTUM
ULTRASONOGRAPHY
(ISUOG)
DR BHAGYALAXMI GONAL
SENIOR RESIDENT GIMS GADAG

2. INTRODUCTION
• Extensive evidence over the last 30-35years has
demonstrated the value of ultrasound in prenatal fetal
assessment: antepartum sonography
• Over the last 10-15 years, recent studies suggest that
ultrasound may play a important role in the pre labor and
intrapartum period: intrapartum sonography

3. BASICS IN INTRAPARTUM SONOGRAPHY (IPS)

4. ISUOG INDICATIONS OF IPS
Slow progression to arrest of labour
Suspected foetal malpresentations like
occipitoposterior
Need to assess fetal head position before instrumental
delivery

5. INTRAPARTUM SONOGRAPHY
TRANS ABDOMINAL TRANSVAGINAL
Position Engagement
Position Progression Prediction
MACHINE : SIMPLE 2-D ultrasound machine with probe
frequency between 3.5-5.5 MHz

6. TECHNIQUE OF TAS
• Maternal position: Supine
• Transducer position: Transversely on suprapubic region of
maternal abdomen
• Images in sagittal and transverse planes
• Landmarks : foetal orbit, cerebellum.

8. TRANS PERINEAL USG
Technique :
• Position: lithotomy
• Transducer : place a covered transabdominal transducer
on the perinium in a mid sagittal position between the
labia below the symphysis pubis
• Landmarks: fetal orbits, cerebellum, midline cerebral echo.

9. OBJECTIVE VALUES OF IPS
Four practical measures that are measurable and
reproducible
AOP Angle of progression/ Angle od descent
HPD Head perinium distance
HD Head direction
MLA Mid line angle

10. ANGLE OF PROGRESSION (AOP)
It is measured in sagittal projection:
Is the angle between the long axis of symphysis
pubis and the line extending tangentially from its
most inferior edge to the foetal skull

12. AOP
• AOP at the ischial spines is 116 degrees.
• It is a very objective and constant indicator of descent
• AOP more than 120 degrees, there is increased probability
of spontaneous vaginal delivery

13. HEAD PERINIUM DISTANCE
• It is measured in frontal projection ( rather than
sagittal)
The HPD is defined as the shortest distance
from the outer bony limit of foetal skull to the
maternal perinium.

15. HPD
• HPD <40mm – chance of increased vaginal delivery
• When large caput can be confusing with the head
station
• While planning instrumental delivery

16. HEAD DIRECTION
Angle between the longest recognizable axis of
the foetal head and the long axis of the pubic
symphysis

18. MID LINE ANGLE (MLA)
It is defined as angle between the anteroposterior axis
of the maternal pelvis and midline of foetal brain visible
as a hyperechogenic line interposed between the two
cerebral hemispheres

20. MLA
• This parameter measured , similarly as HPD in frontal
projection
• It accurately reflects the position of the head in birth canal
• If instrumental delivery is considered in case of large caput
MLA plays a important role in identifying the position
• Change in the MLA value reflects the turns of foetal head
and progress of labor

21. IPS BEFORE INDUCTION OF LABOUR
For sonographic parameters predicts success of
induction:
- Pre induction cervical length < 20mm
- Position of the foetal occiput
- Posterior cervical angle <90 degree
- Perineum head distance < 40mm
The odds of CS increases by about 10% with
each increase of 1 mm in cervical length above
20mm

22. IPS IN THIRD STAGE OF LABOUR
Placenta not delivered after 30 minutes
TRAPPED PLACENTA
The myometrium is seen to
be thickened all around the
uterus and a clear
demarcation is often seen
between the placenta and
the myometrium
ADHEERENT PLACENTA
Myometrium will
thickened in all areas
except where the placenta
is attached where it will be
very thin or even invisible

23. IS IT IMPORTANT TO LEARN IPS?
A F BARBERA ET AL 2019,, MARGARET. R ET AL AND Y. EI. SAYED,,
Vaginal vs ultrasonographic
examination on foetal position 2004.
• Vaginal examination was
correct in 71.6% of the time
and ultrasound was correct in
92.0% of the time
• The angle of head descent
measured by trans perineal
sonography is objective,
accurate and reproducible in
assessing descent of the foetal
head during labor.

24. DOES IPS NEEDS SPECIAL EXPERIENCE?
• NO:
• Measurement of the angle of
progression on transperineal
ultrasound imaging is reliable
regardless of foetal head
station or clinician level of USG
experience.

25. IS IT EASY TO LEARN IPS?
• Learning and accuracy of the determination of fetal head
position in labour is easier and higher , respectively, with trans
abdominal sonography than with digital examination.
• This should encourage obstetricians to introduce clinical
ultrasound examination into their practice.

26. IS IT CONVENIENT TO THE PATIENT ?
YES: it takes < 5minutes to
perform
Yes it is better tolerable than
digital examination

27. DOES IPS HAS PREDICTIVE CLINICAL VALUE ?
YES
Favorable vaginal delivery when fetal head perinium
distance < 40mm and
Angle of progression > 120degree
2D OR 3D ultrasound have similar predictive value

28. CAN IT LOWER CS RATE ?
YES
By more objective use of instrumental delivery
By better assessment of progress of labour
By lowering the need for induction of labour

29. DOES IT REPLACE CLINICAL EXAMINATION?
NO
It just fine tunes the clinical examination,
It is superior in difficult cases

30. TAKE HOME MASSEGES
IPS Adds significant
importance to normal
labor and
instrumental delivery
IPS is essential but
NOT substitute to
clinical skills
The best predictor for
success of induction
is cervical length
measured by USG
The best predictor of
vaginal delivery is
AOP
IPS may decrease
the need of CS
The images stored
cab be used in case
of any medicolegal
issues in the future

31. THANK YOU…