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 substance in amniotic fluid is used to judge fetal lung maturity?

  1. AAlpha-fetoprotein, assessed by its level
  2. BBilirubin, assessed by its colour
  3. CSurfactant, assessed by the lecithin/sphingomyelin (L/S) ratio
  4. DGlucose, assessed by its concentration
2.Maternity & obstetric nursingHard

Which finding is a sign that the placenta is separating in the third stage of labour?

  1. ASudden severe abdominal pain
  2. BThe uterus becomes soft and wide
  3. CA gush of blood and lengthening of the cord
  4. DImmediate fall in maternal blood pressure
3.Dosage calculationsMedium
25 kg20 mg/kg/day4× per dayD = ? mg

A patient weighs 25 kg. The prescribed dose is 20 mg/kg per day, given in 4 equal doses. How many milligrams D are given per dose?

25 kg20 mg/kg/day4× per day
D = mg
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 2.72 mg. The ampoule contains 4000 micrograms per mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

2.72 mg4000 mcg/mL
V = mL
5.IV infusion ratesMedium
60 gtt/mL100 mL/h? gtt/min

An infusion is ordered at 100 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.

100 mL/h60 gtt/mL
R = gtt/min
6.IV infusion ratesHard
450 mL60 gtt/mL28 gtt/mint = ? h

A drip runs at 28 gtt/min through a set of 60 gtt/mL. There are 450 mL left in the bag. How many hours t until it is empty? Round to one decimal place.

28 gtt/min60 gtt/mL450 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: C · Surfactant, assessed by the lecithin/sphingomyelin (L/S) ratio

Why this is the answer

Surfactant reduces surface tension and keeps alveoli open. An L/S ratio of about 2:1 or more suggests the lungs are mature. Amniotic fluid testing for lung maturity is now rarely used in practice.

Answer

C · Surfactant, assessed by the lecithin/sphingomyelin (L/S) ratio
2.Maternity & obstetric nursing

Answer: C · A gush of blood and lengthening of the cord

Why this is the answer

Signs of placental separation include a gush of blood, lengthening of the cord at the vulva, and a uterus that rises and becomes firm and globular. Severe pain or collapse suggests a complication such as inversion.

Answer

C · A gush of blood and lengthening of the cord
3.Dosage calculations

Answer: D = 125 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

20·25 = 500 mg

Per dose

D = 500/4 = 125 mg

Answer

D = 125 mg
4.Dosage calculations

Answer: V = 0.68 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

2.72 mg = 2720 mcg

Volume

V = 2720/4000 = 0.68 mL

Answer

V = 0.68 mL
5.IV infusion rates

Answer: R = 100 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

100/60 = 1.667 mL/min

Drip rate

R = 1.667·60 = 100 gtt/min

Answer

R = 100 gtt/min

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

6.IV infusion rates

Answer: t = 16.1 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

28·60/60 = 28 mL/h

Time left

t = 450/28 = 16.07 ≈ 16.1 h

Answer

t = 16.1 h

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