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

When is the nuchal translucency scan for first-trimester screening usually performed?

  1. AAt about 11 to 14 weeks
  2. BAt about 18 to 22 weeks
  3. CAt about 6 to 8 weeks
  4. DAt about 28 to 32 weeks
2.Maternity & obstetric nursingHard

A newborn has cyanosis that improves when crying and worsens during feeding. Which condition should be suspected?

  1. AChoanal atresia
  2. BCongenital hip dysplasia
  3. COesophageal atresia
  4. DCleft lip only
3.Dosage calculationsMedium
5%2 mLm = ? mg

How many milligrams of drug m are in 2 mL of a 5% (w/v) solution?

5% w/v2 mL
m = mg
4.Dosage calculationsHard
10%stockV₁ = ? mL

You must prepare 1000 mL of a 0.5% (w/v) solution from a 10% (w/v) stock solution. What volume of stock V₁ do you need?

C₁ = 10%C₂ = 0.5%V₂ = 1000 mL
V₁ = mL
5.IV infusion ratesMedium
60 gtt/mL30 mL/h? gtt/min

An infusion is ordered at 30 mL/h, but no pump is available. It runs by gravity through a giving set of 60 gtt/mL. Find the drip rate R in drops per minute.

30 mL/h60 gtt/mL
R = gtt/min
6.IV infusion ratesHard
750 mL15 gtt/mL40 gtt/mint = ? h

A drip runs at 40 gtt/min through a set of 15 gtt/mL. There are 750 mL left in the bag. How many hours t until it is empty? Round to one decimal place.

40 gtt/min15 gtt/mL750 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: A · At about 11 to 14 weeks

Why this is the answer

Nuchal translucency is measured between about 11 and 14 weeks, often combined with blood markers. The detailed anatomy scan follows at about 18–22 weeks.

Answer

A · At about 11 to 14 weeks
2.Maternity & obstetric nursing

Answer: A · Choanal atresia

Why this is the answer

In choanal atresia, the nasal passages are blocked. Babies breathe through the mouth when crying, but become cyanotic when feeding or calm. A catheter cannot be passed through the nose.

Answer

A · Choanal atresia
3.Dosage calculations

Answer: m = 100 mg

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

5% = 5 g/100 mL = 50 mg/mL

Mass of drug

m = 50·2 = 100 mg

Answer

m = 100 mg
4.Dosage calculations

Answer: V₁ = 50 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 = 0.5·1000/10 = 50 mL

Answer

V₁ = 50 mL
5.IV infusion rates

Answer: R = 30 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

30/60 = 0.5 mL/min

Drip rate

R = 0.5·60 = 30 gtt/min

Answer

R = 30 gtt/min

With a microdrip set (60 gtt/mL), gtt/min equals mL/h.

6.IV infusion rates

Answer: t = 4.7 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.

Rate in mL/h

40·60/15 = 160 mL/h

Time left

t = 750/160 = 4.688 ≈ 4.7 h

Answer

t = 4.7 h

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