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In the Name of God Obstetrics Study Guide 1 Mitra Ahmad Soltani 2008

In the Name of God Obstetrics Study Guide 1 Mitra Ahmad Soltani 2008. Med-ed-online.org. References. Pritchard JA, MacDonald PC, Gant NF. Williams Obstetrics. 22 nd ed. , NY: McGraw-Hill; 2005 Lyon D. Use of Vital Statistics in Obstetrics. emedicine. Dec 2007

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In the Name of God Obstetrics Study Guide 1 Mitra Ahmad Soltani 2008

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  1. In the Name of GodObstetrics Study Guide 1Mitra Ahmad Soltani2008 Med-ed-online.org

  2. References • Pritchard JA, MacDonald PC, Gant NF. Williams Obstetrics. 22nd ed. , NY: McGraw-Hill; 2005 • Lyon D. Use of Vital Statistics in Obstetrics. emedicine. Dec 2007 • RCOG. Electronic Fetal Monitoring. UK.2001

  3. Birth rate number of births 1000 population • It includes men in the population.

  4. Fertility Rate number of live births 1000 women aged 15-44 years • While a woman with 2 second-trimester miscarriages would be considered fertile, her deliveries would not be included in the fertility rate.

  5. Reproductive Mortality rate contraceptive use plus direct maternal deaths 100000 women

  6. Maternal Mortality Rate number of direct or indirect maternal deaths 100,000 live births • A condition in which both mother and fetus are lost would both increase the numerator (maternal death) and decrease the denominator (live birth).

  7. Infant Mortality Rate infants who die prior to their first birthday 1000 live Births • IMR is often one of the sentinel indicators used to evaluate a population's overall health and access to health care.

  8. Neonatal Mortality Rate losses between 0-28 d of life (inclusive) 1000 live births • This rate is often divided into early (first 7 d) and late (8-28 d) rates.

  9. Fetal Death rate (stillbirth rate) number of stillbirths 1000 infants (total Births) • Infants means “live and still” born.

  10. Perinatal Mortality Rate Fetal deaths+neonatal deaths 1000 total Births

  11. Still birth • Delivery after 20 weeks' EGA (and more than 500 g birthweight) in which the infant displays no sign of life (gasping, muscular activity, cardiac activity) is considered a stillbirth.

  12. Live Birth • Delivery after 20 weeks' EGA in which any activity is noted is classified as a live birth. This is a difficult definition, as the lower limit of reasonable viability currently remains around 23 weeks‘ GA. Thus, a spontaneous delivery at 21 weeks‘ GA with reflex motion but no ability to survive with or without intervention would nonetheless be considered a live birth.

  13. Abortion • The most common definition of an abortion is any loss of a fetus that is less than 20 weeks' completed gestational age (since last menstrual period) or that weighs less than 500 grams.

  14. Preterm Infants • Preterm infant is another arbitrary definition because a subtle gradient of maturity exists. Premature is defined as a delivery before 37 completed weeks' gestational age, although the vast majority of babies born after 35 weeks' EGA have uncomplicated perinatal courses.

  15. Postterm Infants • The generally accepted definition of a postterm pregnancy is one that progresses beyond 42 weeks' completed gestational age based on last menstrual period (LMP). In practice, many clinicians use a lower cutoff such as 41 weeks' EGA when LMP is certain.

  16. Uteroplacental blood flow 500 to 700 ml/min

  17. Pelvis Obstetrical conjugate: the shortest AP diameter of inlet, which is 1.5 to 2 cm lesser than the diagonal conjugate. • If diagonal conjugate is >11.5 cm (or OB conjugate >10 cm)we can assume the pelvis inlet is adequate. • If interspinous diameter >10 cm then midpelvis is assumed to be normal. • If biischial diameter of the outlet >8 cm then outlet is adequate. • When the lowermost portion of fetal head is at or below the ischial spines(it means BPD is passing the inlet) it is usually engaged. Exceptions occur when there is considerable molding, caput formation, or both.

  18. contractions Braxton Hicks: 1-Irregular 2-Unpredictable 3-Nonrhythmic 4-Painless False labor: 1-During The last week or two of gestation 2-Rhythmic 3- with discomfort

  19. When corpus luteum is removed before 10 weeks gestation • Amp 17-hydroxyprogesterone caproate, 150 mg IM

  20. Average weight gain during pregnancy is: • 12.5 kg(about 25-30 pounds)

  21. Nausea and vomiting in pregnancy • Commence between the first and second missed menstrual period and continue until about 14 weeks.

  22. 4 basic features of fetal heart rate • Variabilities • Accelerations • Decelerations • Baseline heart rate

  23. Varabilities definitions • Normal is 5-25 bpm • B-B or short Term V is varying intervals between successive heart beats . • Long Term v is irregular waves on the CTG 3-5 bpm.

  24. Factors affecting Baseline variability • Para-Sympathetic affects short term variability whilst Long Term is more Symp. • CNS ,Drugs reduce Variability • High gestation increases variability

  25. Accelerations • Accelerations are transient increase in FHR of 15 bpm or more lasting for 15 sec. • Absence of accelerations on an otherwise normal CTG remains un clear. As many as 90 percent of nonreactive tests are false positive. However: • absence of acceleration with decreased baseline oscillation of the fetal heart rate(variability)or the presence of late decelerations following spontaneous uterine contractions is consistently associated with uteroplacental insufficiency

  26. Decelerations • Decelerations are transient slowing of FHR below the baseline level of more than 15 bpm and lasting for 15 seconds Or more.

  27. Early deceleration • Begins on the onset of contraction and returns to baseline as the contraction ends. • Should not be disregarded if they appear early in labor or Antenatal.

  28. Late Decelerations • Are due to acute and chronic feto-placental vascular insufficiency. • Occurs after the peak and past the length of uterine contraction, often with slow return to the baseline. • Are precipitated by hypoxemia. • Associated with respiratory and metabolic acidosis.

  29. Variable deceleration • Inconsistent in configuration, No uniform temporal relationship to the onset of contraction, are variable and occur in isolation. • Worrisome when Rule of 60 is exceeded (i.e. decrease of 60 bpm,or rate of 60 bpm and longer than 60 sec) • Caused by cord compression of the umbilical cord

  30. Prolonged deceleration • Drop in FHR of 30 bpm or More lasting for at least 2 min • Is pathological when crosses 2 contractions i.e 3 mins.

  31. Prolonged Decelerations CAUSES • Cord prolapse. • Maternal hypertension • Uterine Hypertonia • Followed by a Vaginal Examination or Amniotomy or Spontaneous Rupture of Membranes with High Presenting part.

  32. Management of Prolonged Deceleration • Maternal position • IV fluids • Vaginal Exam to exclude cord prolapse • Assess BP • FBS if cervix is dilated and well applied to Presenting part

  33. Baseline tachycardia and Bradycardia • Uncomplicated baseline tachycardia 161-180 bpm or bradycardia 101-109 do not appear to be associated with poor neonatal outcome.

  34. Causes of baseline bradycardia • Postdates • Drugs • Idiopathic • Arrhythmias • Hypothermia • Cord compression

  35. Causes of Baseline Tachycardia • Asphyxia • Drugs • Prematurity • Maternal fever • Maternal thyrotoxicosis • Maternal Anxiety • Idiopathic

  36. Sinusoidal Pattern • Regular Oscillation of the Baseline long-term Variability resembling a Sine wave ,with no B-b Variability • Has fixed cycle of 3-5 p min. with amplitude of 5-15 bpm and above but not below the baseline. • Should be viewed with suspicion as poor outcome has been seen (eg Feto-maternal haemorrhage)

  37. Causes of Sinusoidal pattern • cord compression • hypovolemia • ascites • idiopathic(fetal thumb sucking) • Analgesics • Anaemia • Abruption

  38. Saltatory pattern • Seen During Fetal thumb sucking. • Could be associated with Hypoxia.

  39. Fetal Blood Sampling Why : -Persistent Abnormal CTG after reversible factors have been corrected, -Persistent late decels and 2 abnormal other features e.g baseline tachycardia or reduced B-B variability or just difficult to interpret the CTG when: -Rom, -PP accessible and well applied Cervix dilatation >= 3 -Left lateral maternal position -Sterile environment and good light and equipment -Good analgesia

  40. FBS-Cord PH • Fetal blood sampling is sampling from Arteries. • Normal value is 7.25-7.35 • Less than 7.20 shows significant asphyxia • Values between 7.2 and 7.24 need further evaluation • Low –normal PH should be repeated in 30 min • Less than 7.20 dicatates eminent delivery

  41. FBS- Lactate • FBS easier to interpret, difficult to perform • Anaerobic metabolism can lead to metabolic acidosis • Lactate levels more specific for degree of metabolic acidosis than Ph • Lactate rises quicker and takes longer to resolve than Ph.

  42. FBS Contraindications • Fetal Premature < 34 weeks Active Herpes Known HIV, Hep B,C positive Thrombocytopenia • Maternal Unfavourable Cervix Mobile Presenting Part Malpresentation(face etc) Abnormal placental hemorrhage Sepsis

  43. FBS-Sampling errors • Should be done Between decelerations • Excess pressure on PP reduces perfusion • Should not be done on the caput

  44. Points to remember • NST: Favorable: Increase15 bpm for 15 seconds within 20 min of beginning the test (before 32 wks of GA we consider 10bpm lasting 10 seconds) • BPP: Pregnancy termination for: • reduced AF • Gestational age over 36 weeks • Score of 2 Repeating the BPP test for: • Score below 6 + less than 36 weeks gestation/ low Bishop/ L/S>2

  45. Points to remember • Positive OCT: 50% or more of uterine contractions accompany FHR decelerations • Variable deceleration: occurs >= three times in a 20 min interval with FHR drop to 70 bpm • Persistent deceleration: more than 30 bpm reduction in a 2-10 min interval • Bradycardia: more than 30 bpm reduction of FHR in more than 10 min

  46. +OCT: late decelerations following 50% or more of contractions • 3 or more contractions • Lasting at least 40 seconds • In a 10-min period • By either spontaneous contractions or: • 0.5 mU/min oxytocin • Doubled every 20 minutes Hyperstimulation: frequency more than every 2 min or lasting longer than 90 seconds

  47. Points to remember in BPP scoring:score two, otherwise zero 1-Tone: 1 2-Respiration: 1 of 30 sec 3-AF: 1pocket more than 2 cm 4-NST: 2 of 15 bpm of 15 sec in a 20 min strip 5-Movement: 3 in 30 min

  48. Nonreassuring CTG patterns • Fetal tachycardia • Fetal bradycardia • Saltatory variability • Variable decelerations associated with a nonreassuring pattern • Late decelerations with preserved beat-to-beat variability

  49. Ominous CTG patterns • Persistent late decelerations with loss of beat-to-beat variability • Nonreassuring variable decelerations associated with loss of beat-to-beat variability • Prolonged severe bradycardia • Sinusoidal pattern • Confirmed loss of beat-to-beat variability not associated with fetal quiescence, medications or severe prematurity.

  50. Diagnosis of ROM • Conclusive: pooling of AF in the posterior fornix • Nitrazine paper test: A PH above 6.5 is consistent with ROM(false positive with blood semen, vaginosis),(false negative with minimal fluid)

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