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

Obesity before pregnancy (BMI 40) most increases the risk of which pregnancy complication?

  1. ALow birth weight from overnutrition
  2. BGestational diabetes
  3. CHyperemesis gravidarum
  4. DPlacenta praevia only
2.Maternity & obstetric nursingHard

A non-stress test at 36 weeks shows no accelerations in 40 minutes. What is the most appropriate next step?

  1. ARecord the result as reactive and reassuring
  2. BFurther testing, such as a biophysical profile
  3. CSend her home and repeat the test in a month
  4. DImmediately start oxytocin to induce labour
3.Dosage calculationsMedium
1:10 000ampouleV = ? mL

A prefilled syringe of epinephrine (adrenaline) is labelled 1:10 000 (0.1 mg/mL). The prescription is 1 mg IV in cardiac arrest. What volume V do you give?

1:10 0001 mg
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 260 micrograms. The ampoule contains 1 mg/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

260 mcg1 mg/mL
V = mL
5.IV infusion ratesMedium
10 gtt/mL60 mL/h? gtt/min

An infusion is ordered at 60 mL/h, but no pump is available. It runs by gravity through a giving set of 10 gtt/mL. Find the drip rate R in drops per minute.

60 mL/h10 gtt/mL
R = gtt/min
6.IV infusion ratesHard
2 g500 mL? mL/h2 mg/min

A bag contains 2 g of a drug in 500 mL. The order is 2 mg per minute. At what rate R do you set the pump, in mL/h?

2 g/500 mL2 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: B · Gestational diabetes

Why this is the answer

Obesity raises the risks of gestational diabetes, pre-eclampsia, venous thromboembolism, macrosomia, caesarean birth and stillbirth. Early glucose testing and VTE risk assessment are often recommended.

Answer

B · Gestational diabetes
2.Maternity & obstetric nursing

Answer: B · Further testing, such as a biophysical profile

Why this is the answer

A non-reactive NST may reflect a fetal sleep cycle or drugs, but it can also indicate hypoxia. A biophysical profile or contraction stress test is used to clarify fetal wellbeing.

Answer

B · Further testing, such as a biophysical profile
3.Dosage calculations

Answer: V = 10 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.

Concentration

1:10 000 = 1 g/10000 mL = 0.1 mg/mL

Volume

V = 1/0.1 = 10 mL

Answer

V = 10 mL

US labels now state mg/mL (1 mg/mL = 1:1000; 0.1 mg/mL = 1:10 000). Never give 1 mg/mL epinephrine IV push.

4.Dosage calculations

Answer: V = 0.26 mL

Drawing up a dose: volume = (prescribed dose/stock strength) × stock volume. Convert to the same units first, then check that the volume fits the syringe and lands on one of its graduations.

Same units

1 mg/mL = 1000 mcg/mL

Volume

V = 260/1000 = 0.26 mL

Answer

V = 0.26 mL
5.IV infusion rates

Answer: R = 10 gtt/min

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.

Millilitres per minute

60/60 = 1 mL/min

Drip rate

R = 1·10 = 10 gtt/min

Answer

R = 10 gtt/min
6.IV infusion rates

Answer: R = 30 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

2000 mg/500 mL = 4 mg/mL

Dose per hour

2·60 = 120 mg/h

Pump rate

R = 120/4 = 30 mL/h

Answer

R = 30 mL/h

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