Maternity Nursing: cram pack

Formula sheets, the key method steps for every topic and 6 practice problems, with full solutions at the back.

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1Formulas and methods

Maternity & obstetric nursing

Method

  1. Place the woman in time: weeks of pregnancy, stage of labour or day after birth, and decide what is normal at that point.
  2. Look for the patient in danger: the mother, the fetus or the newborn, or more than one of them.
  3. Link the finding to its cause: VEAL CHOP for decelerations, the four Ts for bleeding, BUBBLE-HE after birth.
  4. Choose the action that improves blood flow and oxygen first (side-lying, stopping oxytocin, fundal massage), then escalate.

Dosage calculations

Dose from strength
volume = dose / strength
Weight-based dose
dose = mg/kg × body weight
Tablets
number = dose / tablet strength
Units
1 g = 1000 mg, 1 mg = 1000 mcg

Method

  1. Convert the ordered dose and the stock strength to the same unit.
  2. Use desired over have times quantity: (D/H) × Q.
  3. For weight-based doses, multiply by the weight in kg first, then divide the daily dose by the number of doses.
  4. Estimate first and check that the answer is reasonable.

IV infusion rates

Pump rate
mL/h = volume (mL)/time (h)
Drip rate
drops/min = volume (mL) × drop factor / time (min)
Infusion time
time (h) = volume (mL)/rate (mL/h)

Method

  1. Pump rate in mL/h: volume divided by time in hours.
  2. Drip rate in drops/min: volume × drop factor divided by time in minutes.
  3. For time remaining: volume left divided by the rate.
  4. Round as the question or the equipment requires.

2Practice problems

1.Maternity & obstetric nursingMedium

Which placental hormone causes insulin resistance in the second half of pregnancy?

  1. AOxytocin
  2. BHuman chorionic gonadotrophin (hCG)
  3. CHuman placental lactogen (hPL)
  4. DRelaxin
2.Maternity & obstetric nursingHard

A woman at 34 weeks with type 1 diabetes has a blood glucose of 2.8 mmol/L (50 mg/dL), is sweating and shaky but is alert. What should the nurse do first?

  1. AGive her usual insulin dose
  2. BCheck the fetal heart rate before any treatment
  3. CGive fast-acting glucose by mouth and recheck
  4. DWait until her next meal
3.Dosage calculationsMedium
15 kg2 mg/kg/day2× per dayD = ? mg

A patient weighs 15 kg. The prescribed dose is 2 mg/kg per day, given in 2 equal doses. How many milligrams D are given per dose?

15 kg2 mg/kg/day2× per day
D = mg
4.Dosage calculationsHard
25%stockwater = ? mL

You must prepare 100 mL of a 1% (w/v) solution from a 25% (w/v) stock solution. How much water W must be added to the stock?

C₁ = 25%C₂ = 1%V₂ = 100 mL
W = mL
5.IV infusion ratesMedium
310 mLleft? mL/h5 h left

500 mL was ordered over 10 hours. After 5 hours you find that 310 mL is still in the bag, and the order must still finish on time. To what rate R in mL/h must the pump be reset?

500 mL / 10 hafter 5 h: 310 mL
R = mL/h
6.IV infusion ratesHard
4 g500 mL? mL/h0.5 mg/min

A bag contains 4 g of a drug in 500 mL. The order is 0.5 mg per minute. At what rate R do you set the pump, in mL/h?

4 g/500 mL0.5 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: C · Human placental lactogen (hPL)

Why this is the answer

Human placental lactogen, together with other placental hormones, reduces maternal insulin sensitivity so more glucose is available to the fetus. This is why gestational diabetes usually appears in the second half of pregnancy.

Answer

C · Human placental lactogen (hPL)
2.Maternity & obstetric nursing

Answer: C · Give fast-acting glucose by mouth and recheck

Why this is the answer

An alert patient with hypoglycaemia is given fast-acting oral carbohydrate, then glucose is rechecked after about 15 minutes and followed by a snack or meal. Treating the mother also protects the fetus.

Answer

C · Give fast-acting glucose by mouth and recheck
3.Dosage calculations

Answer: D = 15 mg

Dose calculation: the amount to give equals what is prescribed divided by what you have, times the quantity it comes in: amount = (desired dose/stock strength) × stock volume. Always keep the units the same (convert g to mg, mg to mcg first) and check that the answer is sensible.

Total per day

2·15 = 30 mg

Per dose

D = 30/2 = 15 mg

Answer

D = 15 mg
4.Dosage calculations

Answer: W = 96 mL

Solution strengths: a percentage strength is grams per 100 mL, so 1% = 1 g/100 mL = 10 mg/mL. A ratio strength 1:1000 means 1 g in 1000 mL = 1 mg/mL; 1:10 000 is 0.1 mg/mL. For a dilution the amount of drug stays the same: C₁·V₁ = C₂·V₂.

Volume of stock

V₁ = 1·100/25 = 4 mL

Water to add

W = 100 − 4 = 96 mL

Answer

W = 96 mL
5.IV infusion rates

Answer: R = 62 mL/h

Infusion rates: a pump is set in mL/h = volume/time in hours. A gravity drip is counted in drops per minute: gtt/min = volume (mL) × drop factor (gtt/mL)/time (min). The drop factor is printed on the tubing package: macrodrip sets deliver 10, 15 or 20 gtt/mL (blood sets often 10 gtt/mL in the US, 15 in the UK) and microdrip sets 60 gtt/mL. Always use the drop factor the question or package gives.

Original rate

500/10 = 50 mL/h

New rate

R = 310/5 = 62 mL/h

Answer

R = 62 mL/h

Many hospitals allow such an adjustment up to 25% without a new order; check local policy.

6.IV infusion rates

Answer: R = 3.75 mL/h

Dose-based infusions: concentration = amount of drug in the bag/bag volume. Pump rate (mL/h) = dose per hour/concentration, and dose per hour = mL/h × concentration. Convert per-minute doses to per-hour (× 60) and keep the mass units the same (1 g = 1000 mg, 1 mg = 1000 mcg).

Concentration

4000 mg/500 mL = 8 mg/mL

Dose per hour

0.5·60 = 30 mg/h

Pump rate

R = 30/8 = 3.75 mL/h

Answer

R = 3.75 mL/h

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