Obstetrics Flashcards
Parity
of pregnancies that led to a birth beyond 20 weeks’ gestational age or an infant weighing > 500 g
Gravidity
of times a woman has been pregnant
Developmental age
of weeks and days since fertilization
Gestational age
of weeks and days measured from the 1st day of the LMP
Determinants of gestational age
- Fundal height
- Fetal heart tones (Doppler)
- Quickening
- Ultrasound
Fundal height measurement
Umbilicus - 20 weeks + 2-3 cm/weeks thereafter
Fetal heart tones (Doppler)
Typically 10 - 12 weeks
Quickening - appreciation of fetal movement
Usually heard 17 - 18 weeks
Ultrasound
- Measures fetal crown-rup length: 6 - 12 weeks
2. Measures biparietal diameter, femure length, and abdominal circumference: 13 weeks
Most reliable measurement of GA
Ultrasound
Quantitative B-hCG
- Diagnose and follow ectopic pregnancy
- Monitor trophoblastic disease
- Screen for fetal aneuploidy
B-hCG
- standard for diagnosing pregnancy
- produced by placenta
Rate of B-hCG production
- reaches peak, 100,000mIU/ml by 10 weeks’ GA
- decreases throughout 2nd trimester and levels off by 3rd trimester
Ultrasound
- used to confirm intrauterine prenancy
- gestational sac visible by 5 weeks GA
- B-hCG in range of 1000 - 1500 IU/ml
Renal changes during pregnancy
- Renal flow increases 25-50%
- GFR increases early then plateaus
Weight changes during normal pregnancy
- uterine weight increases from ~ 60 - 70 g to ~ 900 g - 1200g
Weight gain recommendations during pregnancy
- 1.0 - 1.5kg/mo
Weight gain guidelines by BMI
- undeweight: 12 - 18 kg
- acceptable: 11- 16 kg
- overweight: 7 - 11kg
- severely overweight: 7kg
Folic acid supplementation
decreases neural tube defects for ALL reproductive age woman
- 0.4mg/day
- 4 mg/day for women w/ hx of neural tube defets in prior pregnancies
CV changes during normal pregnancy
- HR gradually increases 20%
- BP gradually decreases by 10% by 34 wks, then increases to prepregnancy values
SV increases to maximum at 19 weeks then plateaus
CO rises rapidly by 20% then increases to addl 10% by 28 wk
Pulm changes during pregnancy
- RR remains unchanged
- TV increases by 30 - 40%
- Expiratory reserve gradually decreases
- Vital capacity unchanged
- Resp minute volume increases by 40%
Blood changes during normal pregnancy
- Blood volume increases by 50% in 2nd trimester
- Hct decreases slightly
- Fibrinogen increases
- Electrolytes remains unchanged
GI changes during normal pregnancy
- sphincter tone decreases
- gastric emptying time increases
Immunoglobulins that cross placenta
IgG
Organisms that can cross placenta (9)
- Toxoplasmosis
- Rubella
- HIV
- Parvovirus
- CMV
- Enterovirus
- Treponema pallidum
- Listeria monocytogenes
- Parvovirus B19
Prenatal Visits
Wks 0 - 28: every 4 wks
Wks 29 - 35: every 2 wks
Wks 36 - birth: every wk
Heme Prenatal Dx Testing: initial visit
- CBC, Rh factor, type and screen
Infectious Dz prenatal testing: initial visit
- UA and cx
- Rubella Ab titer
- HBsg
- RPR/VRDL
- Cervical gonorrhea and chlamydia
- PPD
- HIV
- Pap smear (to check for dysplasia)
- Consider HCV and varicella based on hx
Genetic testing during initial visist
- HbA1c
- Sickle cell screening
- Tay-Sachs disease
- Cystic fibrosis
Prenatal Dx Testing: 9-14 wks
- PAPP-A + nuchal transparency
- free B-hCG +/- chorionic villus sampling
Prenatal Dx Testing: 15 - 22 wks
- Maternal serum alpha fetoprotein (MSAFP) or
- Quad screen
+/- amniocentesis
Prenatal Dx Testing: 18-20 wks
Ultrasound for full anatomic screen
Prenatal Dx Testing: 24- 28 wks
1 hr glucose challenge test for gestational diabetes screen
Prenatal Dx Testing: 28 - 30 wks
RhoGAM for Rh- women (after antibody screen)
Prenatal Dx Testing: 35- 40 wks
Group B Strep cx (GBS)
- repeat CBC
Prenatal Dx Testing: 34 - 40 wks
- Cervical chlamydia and gonorrhea cx
- HIV
- RPR in high risk pts
Quad screening
- MSAFP
- Inhibin A
- Estriol
- B-hCG
Maternal serum alpha fetoprotein (MSAFP)
- produced by fetus and enters maternal circulation
- reported multiples of median (MoMs)
- measurement results depend on accurate gestational testing
- rarely tested alone, quad screening incr. sensitivity for chromosal abnormalities
Elevated MSAFP (> 2.5 MoMs) associated w/
- open neural tube defects (anencephaly, spina bifida)
- abdominal wall defects (gastrochisis, omphacele)
- multiple gestation
- incorrect gestational dating
- fetal death
Reduced MSAFP (< 0.5 MoM) is associated w/
- Trisomy 21 and 18
- Fetal demise
- Inaccurate gestational testing
Trisomy 18 via quad screening
- Still UNDERage at 18**
- decreased AFP
- decreased estriol
- decreased B-hCG
- decreased inhibin A
Trisomy 21 via quad screening
- 2 up and 2 down**
- decreased AFP, estrol
- increased B-hCG, inhibin A
Pregnancy-associated Plasma Protein A (PAPP-A)
- recommended at 9 - 14 wks
- PAPP-A + nuchal transparency + free B-hCG can detect 91% of Down’s syndrome and 95% of cases of trisomy 18
- screen of low risk pregnant women (< 35 y/o)
- available earlier than CVS and less invasive than CVS
CVS
- done at 10 - 12 wks
- transcervical or transabdominal aspiration of placenta
- geneticall diagnostic/ available at earlier GA
Diasadvantages of CVS
- Risk of fetal loss is 1%
- Cannot detect open neural tube defects
- Limb defects are associated w/ CVS < 9 wks
Amniocentesis
- done at 15 - 20 wks
- transabdominal aspiration of aminiotic fluid using U/S needle
- genetically diagnostic
Disadvantages of CVS
At risk for:
- premature of membranes (PROM)
- chorioamniocentesis
- fetal maternal hemorrhage
Indications for amniocentesis
- in women > 35 yrs of age at time of delivery
- conjuction with abnormal quad screen
- in Rh-sensitized pregnancy to obtain fetal blood type or detect fetal hemolysis
- to eval lung maturity via lecithin to sphingomyelin ratio > 2.5
- detect presence of phosphatidylglycerol (during 3rd trimester)
ToRCHES pathogens
- organisms that can cross placenta
- Taxoplasmosis
- Other (Parvovirus, Varicella, Listeria, TB, malaria)
- Rubella
- CMV
- Herpes Simplex Virus
- Syphillis
Spontaneous abortion (SAB)
- loss of product of conception (POC) prior to 20 wk of pregnancy
- more than 80% occur in 1st trimester
Major factors that contribute to SAB
- Chromosomal abnormalities
- Maternal factors
- Environmental factors
- Fetal factors
Chromosomal abnormalities in SAB
- factor in 50% of SABs in 1st trimester
Maternal factors in SAB
Dx of Spontaneous Abortions
Dx of spontaneous abortions
- decreased levels of B-hCG
- U/S can identify:
- gestational sac 5-6 wks from LMP
- fetal pole at 6 wks
- fetal cardiac activity at 6-7 wks
- gestational sac 5-6 wks from LMP
Fetal defects: ACEis
- fetal renal tubular dysplasia and neonatal renal failure
- oligohydramnios
- intrauterine growth restriction (IUGR)
- lack of cranial ossification
Alcohol: fetal defects
- Fetal alcohol syndrome (growth restriction before and after birth)
- Mental retardation
- Midfacial hypoplasia
- Renal and cardiac defects
- Consumption of > 6 wks per day is associated w/ 40% risk of FAS
Androgens: fetal defect
- virilization of females
- advanced genital development in males
Carbamazepine
- neural tube defects
- fingernail hypoplasia
- microcephaly
- developmental delay
- IUGR
Cocaine: fetal defects
- Bowel atresias
- Congenital malformations of the heart, limbs, face, and GU tract
- Microcephaly
- IUGR
- Cerebral infarctions
Diethylstilbestrol (DES): fetal defects
- Clear cell adenoma of vagina or cervix
- Vaginal adenosis
- Abnormalities of cervix and uterus or testes
- Possible infertility
Lead: fetal defects
- increased risk of SAB
- stillbirths
Lithium: fetal defects
Congenital heart disease (Ebstein’s anomaly)
Methotrexate: fetal defects
increased SAB rate
Organic mercury: fetal defects
Cerebral atrophy Microcephaly Mental retardation Spasticity Seizures Blindness
Phenytoin: fetal defects
- IUGR
- Mental retardation
- Microcephaly
- Dysmorphic craniofacial features
- Cardiac defects
- Fingernail hypoplasia
Radiation: fetal defects
- Microcephaly
- Mental retardation
- Medical diagnostic radiation delivering < 0.05 Gy to the fetus has no diagnostic risk
Streptomycin and kanamycin: fetal defects
- Hearing loss
- CN VIII damage
Tetracycline: fetal defects
- Permanent yellow-brown discoloration of deciduous teeth
- Hypoplasia of tooth enamel
Thalidomide: fetal defects
- Bilateral limb deficiencies
- Anotia and microtia
- Cardiac and GI abnormalities
Trimethadone and paramethadone: fetal defects
- Cleft lip palate
- Cardiac defects
- Microcephaly
- Mental retardation
Valproic acid: fetal defects
- Neural tube defects (spina bifida)
- Minor craniofacial defects
Vitamin A derivatives: fetal defects
- increased SAB rate
- Microtia
- Thymic agenesis
- CV defects
- Craniofacial dysmorphism
- Microphthalmia
- Cleft lip or cleft palate
- Mental retardation
Warfarin: fetal defects
** wages WAR on the fetus**
- Natal hypoplasia and stippled bone epiphyses
- Developmental delay
- IUGR
- Ophthalmologic abnormalities
Toxoplasmosis: transmission
- transplacental
- primary infxn via consumption of raw meat or contact w/ cat feces
Toxplasmosis: Sx and Dx
Sx: - hydrocephalus - intracranial calcifications - chorioretinitis - ring enhancing lesions on MRI Dx: - serum testing
Toxoplasmosis: Dx and Tx
Dx: serologic testing
Tx: pyrimethamine + sulfadiazine
Toxoplasmosis: Prevention
- Avoid exposure to cat feces during pregnancy
- Spiramycin prophylaxis for 3rd trimester
Rubella: Transmission
- transplacental in the 1st trimester
Rubella: Sx
- purpuric “blueberry muffin”rash
- cataracts
- mental retardation
- hearing loss
- patent ductus arteriosus (PDA)
Rubella: Dx and Tx
Dx: serologic testing
Tx: symptomatic
Rubella: prevention
- immunize before pregnancy
- vaccinate the mother after delivery if serologic titers remain negative
CMV: transmission
- primarily transplacental
CMV: Sx
- petechial rash
- periventricular calcifications