The document discusses various diagnostic tests used in fetal monitoring including: 1. Non-stress tests (NST) which evaluate fetal heart rate patterns to assess oxygenation, neurological, and cardiac function. A reactive pattern indicates intact fetal well-being. 2. Biophysical profiles (BPP) which combine NST and ultrasound to assess fetal movements, tone, breathing and amniotic fluid in a standardized scoring system. 3. Doppler studies analyze umbilical and cerebral blood flow to identify compromised fetuses before problems occur. Reverse diastolic flow in the umbilical artery is ominous. 4. Amniocentesis tests amniotic fluid for genetic/infection screening or lung maturity

1. Diagnostic Tests Sandy Warner RNC-OB, MSN Carrie Hallett- Voss, RNFA

2. NST - Non Stress Test Evaluation of FHR pattern in the absence of regular contractions to determine fetal oxygenation, neurological and cardiac function

3. Non Stress Test (NST) NST became popular as primary surveillance in mid 1970’s due to simplicity and shorter testing Currently a reactive pattern is defined as 2 accelerations in 20 minutes that reach 15bpm or greater above BLFHR and lasts 15 seconds or greater

4. NST Definition Reactive NST indicates less than 1% chance of fetal death within 1 week unless there is a catastrophic event Accelerations may occur either spontaneously or in association with fetal movement NST done to determine the adequacy of fetal oxygenation and (CNS) autonomic function

5. Non Stress Test: Benefits to patient non-invasive easy, inexpensive, fast no known contraindications good screening test

6. Non Stress Test (NST) Accelerations indicate intact neurological functioning between the fetal CNS and the fetal heart Pathway may be disrupted by: Fetal sleep Fetal hypoxia Drugs (BTMS, ETOH, beta blockers, muscle relaxants, & CNS depressants) Congenital fetal anomalies

7. Non Stress Test (NST) 50% of fetuses will be reactive by 26-28 weeks 85% of fetuses will be reactive by 28-32 weeks KEYPOINT: Once fetus has had a reactive tracing (15 X 15) the same reactivity is expected in further NSTs.

8. Indications for NST for High Risk Conditions high risk for utero-placental insufficiency (smokers, HTN, diabetes, autoimmune disease) post dates motor vehicle accident (MVA) previous stillbirth IUGR decreased fetal movement isoimmunization if other tests suggest fetal compromise routine

9. Reactive Non Stress Test Arrows above from pushing the MARK button Indicating mother’s perception of fetal movement FM and Accelerations 15 X 15

10. NST Regimen 1986 study by Boehm showed that by increasing NST to 2 times a week, the corrected stillbirth rate dropped from 6.1 /1000 to 1.9/1000 after a reactive NST Twice a week for high risk (post dates, HTN, IUGR, IDDM) Once q week for other risk conditions If condition no longer exists, e.g. decreased fetal movement, continued testing is not required Same day evaluation for reporting of decreased fetal movement

11. Non Reactive NST Not necessarily an ominous sign, rather it does indicate the need for further testing. May be followed by a BPP or a CST If initially non-reactive, prolonging the period of evaluation usually allows a change in the fetal status and it becomes reactive Occurs more often in the preterm fetus < 32 weeks due to immature ANS

12. Non Reactive NST Non Reactive NST

13. NST Non reactive NST with good variability probably not an indication for delivery rather, could be related to fetal adaptation to stress Non Stress Test (NST)

14. Vibroaccoustic Stimulation (VAS) Artificial acoustic stimulation Done after 25 wks gestation when fetus can hear After 10 minutes of baseline and no accelerations, place the artificial larynx on the maternal abdomen over the fetal head

15. Vibroaccoustic Stimulation Provide 5-10 sec stimulation near fetal head, wait one minute If no acceleration repeat cycle for a total of three times if non-reactive after 40 minutes, proceed with further evaluation

16. Vibroaccoustic Stimulation Fetuses 28 weeks or greater respond to VAS with a consistent increase in heart rate. Observed changes are greater as term is approached. Can be used during version to get breech to move from midline spine to lateral spine Use to startle the fetus to release cord

17. Contraction Stress Test A method of observing the response of the FHR to the stress of uterine contractions A FHR response to 3 spontaneous or induced uterine contractions in 10 minutes may occur : Spontaneously Use of nipple stimulation Use of Pitocin The desired result: Negative CST (no late decelerations)

18. Interpretation: CST Negative : No late or significant variable decelerations are identified in response to 3 or more contractions lasting at least 40 seconds in a 10 minute window. Positive : Late decelerations are identified with 50% or more of contractions even if the contraction frequency is less than 3 in 10 minutes.

19. Interpretation: CST Suspicious : (Equivocal) inconsistent or occasional late decelerations with less than 50% of contractions. Repeat in 24 hrs. Tachysystole: Contractions closer than Q2min, or lasting longer than 90 sec, or > 5 contractions in 10 minutes. Repeat in 24 hrs . Unsatisfactory: the quality of the tracing is inadequate for interpretation or adequate uterine contractions were not achieved.

20. Limitations of CST 30% false positive == unnecessary premature intervention conduct in L+D or adjacent area more expensive, time consuming must observe after test until uterine activity has returned to baseline activity level

21. Tachysystole of uterus Too many UC. Rising resting tonus. Positive CST

22. Key Points for Contraction Stress Test CST now used less frequently Uterine contractions produce a reduction in blood flow to the intervillous spaces in the placenta A fetus with inadequate placental reserves demonstrates late decelerations in response to hypoxia

23. Ultrasound Developed in WWII with submarines Diagnostic use since 1950s Definition: transmission of sound waves to investigate an object (Kline-Fath & Bitters, 2007)

24. Ultrasound Advantages: Inexpensive Noninvasive High degree of patient acceptance Yields much information (Kline-Fath & Bitters, 2007)

25. Ultrasound Indications Estimation of fetal age Earlier U/S performed, more accurate Viability Evaluation of fetal growth Location of placenta Fetal presentation in 3 rd trimester or with multiples Anomalies Assessment of amniotic fluid volume

26. Ultrasound con’t Numerous studies show positive effect on maternal bonding with ultrasound experience 3D U/S especially helpful in facial anomalies Nuchal lucency and nasal bone Used in combination with maternal serum levels to assess for chromosomal abnormalities (Kline-Fath & Bitters, 2007)

27. Amniotic Fluid Index (AFI) AFI = amount of amniotic fluid measured in largest pocket in each quadrant ( sum of 4 quadrants) Normal = 9-10 cm Borderline = 5-8cm Oligohydramnios < 5cm Polyhydramnios > 25cm

28. Biophysical Profile (BPP) “Intrauterine Apgar Score” Combines ultrasound and NST Fetal activities observed result from complex processes that are controlled by the CNS Activities that are first to develop are last to disappear when asphyxia occurs

29. 1. Reactive NST (within 1 hour of ultrasound portion of test) 2. Amniotic Fluid: at least one deepest vertical pocket > 2cm 3. Movement- at least three episodes of gross body movement within a 30 minute period Five Parameters of Biophysical Profile

30. Five Parameters of Biophysical Profile 4. Tone- at least one episode of flexion and extension of an extremity within a 30 minute period 5. Fetal Breathing Motions- at least 30 seconds within a 30 minute period

31. Scoring the BPP 2 points for each of the criteria met 0 points if the criteria is not met reported as: 0/10, 2/10, 4/10, 6/10, 8/10, or 10/10

32. Interpretation of BPP Anytime a (DVP) deep vertical pocket ≤ 2cm, further evaluation is warranted score 8/10 (excluding oligo) or 10/10: normal score 6/10 : equivocal, repeat within 24 hours score 0/10, 2/10, 4/10: delivery is indicated

33. Keypoints A deteriorating fetus will lose in this order : -Reactivity -Fetal breathing movements -Tone -Movement

34. Grading the Placenta

35. Doppler Studies Definition: Non-invasive study of the blood flow in the fetus and the placenta Studies the blood flow of the umbilical cord More recently may use to look at blood flow in the cerebral artery

36. Keypoints of Doppler Flow Studies Doppler waveform analysis can allow identification of a jeopardized fetus before compromises occur. Umbilical artery observed for flow Ratio number used to measure flow 3.5 in normal, can also be intermittently absent or absent Reverse diastolic flow is ominous

37. More Keypoints of Doppler Flow Studies The change in frequency is called the “Doppler Shift” This shift is computer analyzed and displayed as a velocity waveform The frequency of the echoes changes during the systolic and diastolic components of the cardiac cycle

38. Amniocentesis Trans-abdominal needle aspiration of 10-20 ml of amniotic fluid for lab analysis Done under ultrasound Requires sterile technique and time out

39. Amniocentesis Indications: Genetic R/O infection Fetal lung maturity Assess for bilirubin with hemolytic incompatibility

40. Amniocentesis Timing: Early – performed between 11-14 wks Significantly higher pregnancy loss Post procedure fluid loss 2 nd trimester – performed between 15-20 wks Usually for genetic screening 3 rd trimester Usually for fetal lung maturity (Gilbert, 4 th edition, pg 93)

41. Amnioreduction Reduces amount of amniotic fluid around fetus Procedure like amniocentesis only with tubing to suction canister or stopcock Done to relieve maternal symptoms or with twin to twin transfusion syndrome

42. Amnioreduction

43. Fetal Vesicoamniotic Shunt Procedure done for bladder outlet obstruction Most common cause is a posterior urethral valve Predominantly in males Can cause bladder to lose tone Hydronephrosis Hydroureter Can lead to permanent damage if not treated by 20 weeks gestation

44. Fetal Vesicoamniotic Shunt

45. Fetal Vesicoamniotic Shunt - echotip needle in bladder

46. Fetal Vesicoamniotic Shunt – post shunt placement and decompression of bladder

47. Bilateral Hydronephrosis (enlarged kidneys)

48. Cordocentesis / Fetal Blood Transfusion Blood Transfusion for anemia How much blood is given? Graph is used correlating the hematocrit of donor blood to the hematocrit of the fetus to determine donor blood volume to be given

49. Cordocentesis / Fetal Blood Transfusion

50. Fetal MRI Superior soft tissue contrast test Does not use radiation Used for fetal brain, spinal deformities, lesions, masses Also can assess placental and cord malformations Also used to measure lung volume Research still continuing for PPROM pts (Kline-Fath & Bitters, 2007)

51. Fetal MRI Con’t Not recommended in first trimester (no documented studies on harm from heat or sound, but not recommended) Not used routinely, only after U/S not able to detect Contrast dye not recommended Informed consent (Kline-Fath & Bitters, 2007)

52. Fetal Echocardiogram Timing: between 18-22 weeks Indications: Family history congenital heart defects Maternal diabetes Drug exposure Teratogenic exposure Chromosomal abnormalities Non-immune hydrops Maternal PKU Fetal arrhythmias Queenan, Hobbins & Spong (4 th edition, 2007)

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