Pocket ObGyn – Routine Prenatal Visits

Dec 8, 2019 admin PHỤ KHOA, SẢN KHOA 0

Pocket ObGyn – Routine Prenatal Visits

Common Obstetric Terms

  • Gravidity: Number of times a woman has been pregnant (including current Preg)
  • Parity: Preg outcomes, using TPAL 4 numbers indicating prior Term deliveries/Preterm deliveries/Abortions/Living children (eg, G3P1021). Deliv refers to a single event, not the number of births (ie, multiples count as 1 deliv event). Eg, G3P0112 = currently in 3rd preg, after 1 abortion & 1 preterm deliv of twins (both alive)

T = Term: ³37 w0d

P = Preterm: 20 w0d–36 w6d

A = Abortus: Spont or induced losses <20 w0d

L = Living: Living children at the time of the encounter

  • EDD: Initially determined from 1st day of Accurate dating is crucial for Preg mgmt. EDD is 280 d (±13 d; or 40 w) from LMP. Dating can be confirmed by US if menses are irreg, LMP uncertain, if conception occurred while on contraception, or if there is a size-dates discrep. US most accurate prior to 12 w & should be compared to LMP. Later sono dating less accurate (±2 w in 2nd trimester, ±3 w in 3rd trimester). US = LMP EDD if w/i:

4 d btw 6–9 w6d gest

7 d btw 10–13 w6d gest

10 d btw 14–20 w0d gest

  • Viability: ~24 w0d. Previable: <~24 w0d
  • Early term: 37 w0d–38 Full term: 39 w0d–40 w6d. Late term: 41 w0d–41 w6d
  • Post term: ³42 w0d, ­ stillbirth risk (JAMA 2013;309:2445)
  • Primigravida: 1st Preg
  • Nulliparous (nullip): No prior birth events (regardless of outcome)
  • Primiparous: Gave birth once (ie, >20 w, or once for “T + P” in TPAL system)
  • Multiparous: Gave birth more than once (parity does not include ABs)
  • Grand multipara: Woman who has delivered 5 or more times
  • NT: Thickness of nuchal fluid on 1st trimester sono, ­ in Down syn
  • Triple screen: uE3 + hCG + AFP to evaluate for Trisomy 21, Trisomy 18, NTDs
  • Quad screen: Triple screen + inhibin A
  • IUGR = <10%ile for gestational age
  • GLT (screening): 50 g oral gluc ® 1 h serum gluc
  • GTT: 100 g oral gluc after fasting ® 1, 2, 3 h post gluc
  • FH: FH-measurement from pubic bone to top of fundus correlates w/ GA after 20 w (20 w = umbilicus, add 1 cm/w after that). FH misses 30%
Summary of prenatal care by gestational age
GA General mgmt & special screening by approximate weeks GA
1st trimester (Weeks 0–14) Complete H&P w/ careful review of Ob-Gyn Hx, FHx, meds, nutrition, social history (SHx).

Determine EDD,Viability (US).

Social services (if high risk), social & DV screen.

Prenatal 1st visit labs (CBC, T&S, HBsAg, RPR, Rubella, HIV, ±Hgb electrophoresis, ±HCV, ±CF, HbA1c if suspect DM [or do early GLT], GC/CT, Pap, UA/C&S, PPD [or QuantiFERON])

Offer aneuploidy screening: NT @ 10–13 w, mat serum screening (1st trimester 10–13 w6d; 2nd trimester 15–22 w6d; or mat cell free fetal DNA). See Genetic Screening.

Visits every 4 w to check fetal heart tones.
2nd trimester (Weeks 14–28) 15–22 w6d: AFP, Quad screen, or 2nd part of integrated/sequential screen.

18–22 w: Sono for fetal anatomy, placentation, AFI, adnexae, CL. 25–28 w: 3rd trimester labs (GLT ® ±GTT, CBC, recheck RPR, T&S,

HIV if ­ risk). Rhogam for Rh negative.

Visits every 4 w for FH, fetal heart tones. Plan contraception & feeding.
3rd trimester (Weeks 28–42) 35–36 w: Perineal swab for GBS; clinic sono for presenting part; deliv planning & counseling; GC/CT rpt if high risk.

If CHTN, GHTN, DM, GDMA2, other high-risk factors: ±fetal testing

1–2´/w (BPP or NST starting 32–36 w, depending on problem). 25–33 w: Visits q4w to check for FH & fetal heart tones; 33–37 w: q2w;

37 w – deliv: Visits qw; induce after 41 w, or continue to 42 w0d w/ twice weekly NST/AFI for fetal assessment.

 

Considerations in Routine Prenatal Care

  • OB review of systems: Every encounter ask about VB, LOF, CTX, & FM, & other systems by complaint.

1st FM: 16–18 w if multiparous, 18–20 w if nulliparous

  • Physical: BP, weight (current & interval change), FHR, & FH at each Complete PE & pelvic exam at 1st prenatal visit.

FHR: Detected by Doppler at 10–12 w & by fetoscope at 18–20 w (w/ nml BMI)

  • Cervical exam: Assess dilation, effacement, station near term.
  • Psychosocial screening: Tobacco use, EtOH use, DV, nutrition, psychosocial situations, job-related risks & high-risk behaviors.

Tobacco: Encourage tobacco cessation each visit; ~50% of  quit smoking during or before their Preg. ~50% resume smoking w/i 1-y postpartum. A/w IUGR, low birth weight, placental abruption, placenta previa, PPROM, ectopic Preg, & peri- natal mortality. Children of smokers ­ asthma, colic, obesity, & SIDS. Counsel using 5 A’s strategy (Ask, Advise, Assess, Assist, Arrange). Nicotine replacement not well assessed, but likely safer than smoking. Bupropion & varenicline less used in Preg.

EtOH: No safe threshold a/w mental retardation, neurologic deficits, fetal EtOH syn (esp w/ chronic EtOH use; growth restriction, facial anomalies, & CNS deficits).

DV: Red flags include unwanted Preg, late presentation for PNC, substance abuse, poor weight gain, & multi somatic complaints.

  • GDM screening: 2-step approach w/ GLT then See Chap. 17. Perform btw 24 & 28 w. Opt out for extremely low risk considered (age <25, BMI <25, no FHx of DM, no personal h/o gluc intolerance, no h/o adverse obstetrical outcomes a/w DM, & not of an ethnic group w/ ­ risk DM).
  • Vaccines: See Chap. 1. Influenza vaccine recommended for all pregnant women. TDaP recommended for all in 3rd trimester (­ transplacental IgG immunity for neonate) or postpartum if >10 y since last (MMWR 2011;60:1424). Postpartum vax for rubella or varicella if nonimmune.
  • GBS screening at 35–37 w or if deliv anticipated (every Preg) (Obstet Gynecol 2011;117:1019). See 10. Swab lower vagina, introitus, & rectum. Cx valid for 5 w. For pts w/ sev PCN allergy (anaphylaxis, angioedema, respiratory distress, urticarial) ® request clindamycin & erythromycin sens testing.

Physiologic Changes of Pregnancy

(Best Pract Res Clin Obstet Gynaecol 2008;(5):801)

  • Cardiovascular: ¯ SVR ® ­ BP ¯ early (~10% by 7–8 w) ® nadir at 24 w ® gradual ­ to term. Cardiac output ­ in 1st trimester ® peaks in 2nd trimester at 30–50% above nonpregnant values. See Chap. 12.
  • Respiratory: O2 consump ­30–50 mL/min (2/3 due to mat requirement, 1/3 for fetal). Tidal vol ­ to 500–700 mL (prepregnancy of 200 mL). Respiratory rate Minute ventilation ­ from 7.5–10.5 L/min. Functional residual capacity ¯ by 500 mL.Vital capacity unchanged. See Chap. 13.
  • Renal: Renal bld flow ­ 35–60%. Kidneys ~1 cm larger w/ ­ in bld vol; renal pelves, calyces, & ureters ­ in size in resp to GFR ­ 40–50%, peaks at 180 mL/min by the end of 1st trimester. See Chap. 14.
  • Gastrointestinal: Progesterone ® ¯ esoph sphincter tone ® Delayed gastric emptying & ­ intestinal transition time. Increased constip. See Chap. 15.
  • Hematologic: Plasma vol ­s 10% ­ by 7 w ® plateau at 32 w ~50% above nonpregnant ® dilutional anemia of Preg. Red cell mass ­ 18–25% secondary to ­ erythropoietin. Nml Preg Hgb 11–12 g/dL. WBC ­ in 1st trimester ® plateau at 30 w. Nml Preg WBC 5000–12000/mm3. Platelet count ¯ due to dilution &/or increased consump. Mild thrombocytopenia (100000–150000/mm3) seen in ~8% of pregnancies. Preg is a procoagulable state, predisposing to thromboembolisms w/ 4–6 fold ­ DVT. Factors VII,VIII, IX, X, & XII; fibrinogen; von Willebrand factor; antithrombin III; & prot C ­. Factor XI & prot S ¯. Prothrombin & Factor V are unchanged. See Chap. 16.
  • Endocrine: ­ hepatic production of thyroid-binding globulin ® ­ total Free T4 essentially unchanged (except for transient ­ from hCG’s thyrotropin-like activity in 1st trimester). TSH falls in 1st trimester, then normalizes. No real change in mat thyroid status. Pancr islet cells undergo hyperplasia ® ­ insulin secretion. Placental factors ¯ mat insulin sens. Pituitary ­ 135%, but no optic nerve compression. Prolactin levels peak at term. See Chap. 17.

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