Fetal distress

1. Fetal distress Ob & Gy Department, First Hospital, Xi’an Jiao Tong University SHU WANG

2.   Definition Fetal distress is the term commonly used to describe fetal hypoxia. It is a clinical diagnosis made by indirect methods and should be defined as: Hypoxia that may result in fetal damage or death if not reversed or the fetus delivered immediately. It includes acute distress and chronic distress.

3. Etiology of fetal distress • Maternal: • poor placental perfusion • hypovolaemia • hypotension • myometrial hypertonus • prolonged labor • excess oxytocin

4. fetal: • cord compression • oligohydramnios • entanglement • prolapse • pre-existing hypoxia or growth retardation • infection • cardiac

5. Mechanism of fetal distress • There are potentially limitless causes for fetal distress but several key mechanisms are usually involved. Contractions reduce temporarily placental blood flow and can compress the umbilical cord. If a women is in labor longer then this can cause fetal distress via the above mechanism．Acute distress can be a result of placental abruption, prolapse of the umbilical cord (especially with breech presentations), hypertonic uterine states and the use of oxytocin. Hypotension can be caused by either epidural anesthesia or the supine position, which reduces inferior vena cava return of blood to the heart. The decreased blood flow in hypotension can be a cause of fetal distress.

6. Signs and symptoms Acute fetal distress

7. Cardiotocography signs :increased or decreased fetal heart (tachycardia and bradycardia), especially during and after a contraction decreased varibility in the fetal heart rate．Abnormal fetal heart rate (less than 120 or more than 180 beats per minute). A normal fetal heart rate may slow during a contraction but usually recovers to normal as soon as the uterus relaxes. A very slow fetal heart rate in the absence of contractions or persisting after contractions is suggestive of fetal distress. 

8. A rapid fetal heart rate may be a response to maternal fever, drugs causing rapid maternal heart rate, hypertension or amnionitis. In the absence of a rapid maternal heart rate, a rapid fetal heart rate should be considered a sign of fetal distress． • For a diagnosis of fetal distress to be made, one or more of the following must be present: • 1) Persistent severe variable deceleration. • 2) Persistent and non-remediable late declarations. • 3) Persistent severe bradycardia.

9. amniotic fluid is contaminated by meconium. There are 3 degrees about contaminated. • Io means slight contamination.The color of the amniotic fluid is slight green • IIo suggests mild contamination. Color of the amniotic fluid is dark green • IIIo suggests severe contamination. color of the amniotic fluid is dark yellow. • If the amniotic fluid is severely contamination, it suggests the fetal distress, it must be managed as soon as possible.

10. Decreased fetal movement felt by the mother • biochemical signs, assessed by collecting a small sample of baby's blood from a scalp prick through the open cervix in labor：fetal acidosis elevated fetal blood lactate levels indicating the baby has a lactic ．A fetal scalp pH of less than 7.2 , Po2>60mmHg suggests fetal distress．

11. Chronic fetal distress

12. Decreased or disappear fetal movement: less than 10 times per 12 hours is regarded as decreased. With the first effect of hypoxia, the fetal movement is increased; if the hypoxia persists, the fetal movement is decreased, and may disappear. If the fetal movement lost, the fetal heart beat will be disappearing within 24 hours. Cautions: Dangerous for the fetus if the fetal movement disappear. Management immediately!!

13. Abnormal cardiotocography signs: • slow fetal heart rate(<120bpm) or rapid fetal heart rate (>180bpm) last more than 10 min in the absence of contractions is suggestive of fetal distress; • the fetal heart rate is more than 160bpm , especially above 180bpm, it suggests early hypoxia, unless the maternal heart rate is faster.

14. FHR is slower than 120bpm, typically less than 100bpm. It is very danger for fetus． • the fetal heart rate normally show continuous minor variations, with a range of about 5 bpm ,loss of base line variability implies that the cardiac reflexes are impaired, either from the effect of hypoxia or of drugs such as valium. It may be serious;

15. Early deceleration: with each contraction the rate often slows, but it returns to normal soon after removal of the stress • The early deceleration in the heart rate start within30 seconds of the onset of the contraction and return rapidly to the baseline rate. It is not of serious significance as a rule and indicate that while the fetus is undergoing some stress the cardiac control mechanisms are responding normally.

16. Early deceleration

18. Variable deceleration: no consistent relationship with uterine contraction. It is sometimes caused by compression of the umbilical cord between the uterus and the fetal body, or because it is looped round some part of the fetus. Provided that it does not persist for more than a few minutes it may have little significance, but persistence for more than 15minutes would call for treatment．

21. The most serious pattern of heart rate changes is fetal bradycardia with loss of baseline variability and late decelerations. • decrease (defined as onset of deceleration to nadir =30 seconds) and return to baseline FHR associated with a uterine contraction. The deceleration is delayed in timing, with the nadir of the deceleration occurring after the peak on the contraction.

22. Late deceleration

24. Biophysical Profile： Amniotic Fluid Volume Normal = 2 Points; Non-Stress Test Result Positive = 2 Points; Fetal Breathing Movements Active = 2 Points; Fetal Extremity/Trunk Movements Active = 2 Point; Fetal Movements Active= 2 Point. If Biophysical Profile scores less than 4 suggest fetal distress • Placental Insufficiency: Low estriol levels , E3 in urine less than 10mg/24h．

25. Treatment for Fetal Distress • Reposition patient: left-side-lying position. • Administer oxygen by mask. • Perform vaginal examination to check for prolapsed cord. • Ensure that qualified personnel are in attendance for resuscitation and care of the newborn. • Note: each institution shall define in writing the term qualified personnel for resuscitation and care of the newborn.

26. Each of the following actions should be performed and documented prior to starting a Cesarean section for fetal distress: • Perform vaginal exam to rule out imminent vaginal delivery; • Initiate preoperative routines; • Monitor fetal heart tones (by continuous fetal monitoring or by auscultation) immediately prior to preparation of the abdomen;

27. Ensure that qualified personnel are in attendance for resuscitation and care of the newborn (each institution shall define in writing the term qualified personnel for resuscitation and care of the newborn). • Stop using oxytocin, because oxytocin can strengthen the contraction of uterine which affects the baby's heart rate.

28. Definitions must grasped • Baseline FHR: approximate mean FHR rounded to increments of 5 bpm during a 10-minute segment, excluding periodic or episodic changes, periods of marked FHR variability, and segments of the baseline that differ by >25 bpm. In any 10-minute window, the minimum baseline duration must be at least 2 minutes or the baseline for that period is indeterminate.

29. Baseline FHR variability-fluctuations in the baseline FHR =2 cycles per minute. These fluctuations are irregular in amplitude and frequency, and are visually quantitated as the amplitude of the peak to the trough in beats per minute as follows: amplitude range undetectable, absent FHR variability; amplitude range greater than undetectable but = 5 bpm, minimal FHR variability; amplitude range 6 bpm to 25 bpm, moderate FHR variability; amplitude range >25 bpm, marked FHR variability.

30. Bradycardia-a baseline FHR <110 bpm. • Tachycardia-a baseline FHR >160 bpm.

31. Early deceleration-a visually-apparent, gradual decrease (defined as onset of deceleration to nadir =30 seconds) and return to baseline FHR associated with a uterine contraction. The decrease is calculated from the most recently determined portion of the baseline. It is coincident in timing with the nadir of the deceleration occurring at the same time as the peak of the contraction. In most cases the onset, nadir, and recovery of the deceleration are coincident with the beginning, peak, and ending of the contraction, respectively.

32. Variable deceleration-a visually-apparent, abrupt decrease in FHR below the baseline. The decrease is calculated from the most recently determined portion of the baseline. The decrease in FHR below the baseline is =15 bpm, lasting =15 seconds and =2 minutes from onset to return to baseline.

33. Late deceleration-a visually-apparent, gradual decrease (defined as onset of deceleration to nadir =30 seconds) and return to baseline FHR associated with a uterine contraction. The decrease is calculated from the most recently determined portion of the baseline. The deceleration is delayed in timing, with the nadir of the deceleration occurring after the peak on the contraction.