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

Carboprost, a prostaglandin used for postpartum haemorrhage, should be avoided in women with:

  1. AEpilepsy
  2. BHypertension
  3. CA previous caesarean birth
  4. DAsthma
2.Maternity & obstetric nursingHard

A woman has just been diagnosed with gestational diabetes at 26 weeks. What is the usual first step in management?

  1. AStop eating all carbohydrates
  2. BNutrition advice, physical activity and blood glucose monitoring, with medication if targets are not met
  3. CStart insulin or an oral sulfonylurea straight away for every woman, whatever her blood glucose readings show
  4. DNo follow-up is needed until after birth
3.Dosage calculationsMedium
70 kg10 mg/kgD = ? mg

A patient weighs 70 kg and is prescribed 10 mg/kg as a single dose. Find the dose D in mg.

70 kg10 mg/kg
D = mg
4.Dosage calculationsHard
10%stockwater = ? mL

You must prepare 500 mL of a 2% (w/v) solution from a 10% (w/v) stock solution. How much water W must be added to the stock?

C₁ = 10%C₂ = 2%V₂ = 500 mL
W = mL
5.IV infusion ratesMedium
V = ?15 gtt/mL25 gtt/min3 h

A drip runs at 25 gtt/min through a set of 15 gtt/mL. How many millilitres V does the patient receive in 3 hours?

25 gtt/min15 gtt/mL3 h
V = mL
6.IV infusion ratesHard
400 mg250 mL8 mL/h? mg/h

A bag contains 400 mg of a drug in 250 mL and runs at 8 mL/h. How many milligrams per hour D does the patient receive?

400 mg/250 mL8 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: D · Asthma

Why this is the answer

Carboprost can cause bronchospasm, so it is avoided in asthma. Methylergonovine is the uterotonic to avoid in hypertension.

Answer

D · Asthma
2.Maternity & obstetric nursing

Answer: B · Nutrition advice, physical activity and blood glucose monitoring, with medication if targets are not met

Why this is the answer

First-line management is medical nutrition therapy, activity and self-monitoring of glucose. If targets are not met, medication such as insulin is added. Glucose is tested again after birth because the risk of type 2 diabetes is raised.

Answer

B · Nutrition advice, physical activity and blood glucose monitoring, with medication if targets are not met
3.Dosage calculations

Answer: D = 700 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.

Dose

10·70 = 700 mg

Answer

D = 700 mg
4.Dosage calculations

Answer: W = 400 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 = 2·500/10 = 100 mL

Water to add

W = 500 − 100 = 400 mL

Answer

W = 400 mL
5.IV infusion rates

Answer: V = 300 mL

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.

Rate in mL/h

25·60/15 = 100 mL/h

Volume

V = 100·3 = 300 mL

Answer

V = 300 mL
6.IV infusion rates

Answer: D = 12.8 mg/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.

Concentration

400/250 = 1.6 mg/mL

Dose rate

D = 1.6·8 = 12.8 mg/h

Answer

D = 12.8 mg/h

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