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

A newborn baby girl has a small amount of blood-tinged vaginal discharge on day 3. What should the nurse tell the parents?

  1. AIt shows a urinary tract infection
  2. BIt means the baby has a bleeding disorder
  3. CIt is caused by maternal hormones
  4. DIt is a sign of sexual abuse
2.Maternity & obstetric nursingHard

A student nurse is caring for a newborn receiving phototherapy for jaundice. Which action requires correction?

  1. AChecking the baby's temperature and hydration regularly
  2. BCovering the baby's eyes with eye shields during phototherapy
  3. CRemoving the eye shields during feeds when the lights are off
  4. DApplying baby oil to the skin before the lights are switched on
3.Dosage calculationsMedium
15 kg2 mg/kg/day3× per dayD = ? mg

A patient weighs 15 kg. The prescribed dose is 2 mg/kg per day, given in 3 equal doses. How many milligrams D are given per dose?

15 kg2 mg/kg/day3× per day
D = mg
4.Dosage calculationsHard
43 kg154 cmBSA = √(h·w/3600)135 mg/m²D = ? mg

A patient is 154 cm tall and weighs 43 kg. The prescription is 135 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

154 cm43 kg135 mg/m²
D = mg
5.IV infusion ratesMedium
15 gtt/mL40 mL/h? gtt/min

An infusion is ordered at 40 mL/h, but no pump is available. It runs by gravity through a giving set of 15 gtt/mL. Find the drip rate R in drops per minute.

40 mL/h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
1 g500 mL? mL/h3 mg/min

A bag contains 1 g of a drug in 500 mL. The order is 3 mg per minute. At what rate R do you set the pump, in mL/h?

1 g/500 mL3 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: C · It is caused by maternal hormones

Why this is the answer

Pseudomenstruation is caused by withdrawal of maternal hormones after birth and resolves within days. Swollen breasts in either sex have the same cause.

Answer

C · It is caused by maternal hormones
2.Maternity & obstetric nursing

Answer: D · Applying baby oil to the skin before the lights are switched on

Why this is the answer

Oils and lotions can cause burns under phototherapy lights and should not be applied. Eye shields protect the retina, temperature and hydration are monitored because of increased fluid loss, and feeds are an opportunity for eye contact without the shields.

Answer

D · Applying baby oil to the skin before the lights are switched on
3.Dosage calculations

Answer: D = 10 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 = 30/3 = 10 mg

Answer

D = 10 mg
4.Dosage calculations

Answer: D = 183.1 mg

Body-surface-area dosing: many cytotoxic and some paediatric doses are prescribed per square metre of body surface area: dose (mg) = dose per m² × BSA (m²). The Mosteller formula estimates BSA = √(height (cm) × weight (kg)/3600).

Body surface area

BSA = √(154·43/3600) = √1.839 = 1.356 m²

Dose

D = 135·1.356 = 183.1 mg

Answer

D = 183.1 mg
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

40/60 = 0.6667 mL/min

Drip rate

R = 0.6667·15 = 10 gtt/min

Answer

R = 10 gtt/min
6.IV infusion rates

Answer: R = 90 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

1000 mg/500 mL = 2 mg/mL

Dose per hour

3·60 = 180 mg/h

Pump rate

R = 180/2 = 90 mL/h

Answer

R = 90 mL/h

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