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 woman has painful haemorrhoids after a vaginal birth. Which measure is appropriate?

  1. ASitting on a hard surface for long periods
  2. BStraining hard to open the bowels
  3. CAvoiding all fluids to prevent loose stools
  4. DSitz baths, cold pads and stool softeners
2.Maternity & obstetric nursingHard

A newborn has excessive frothy saliva and chokes and turns blue with the first feed. What is the priority?

  1. APlace the baby on its back to sleep
  2. BGive the baby water instead of milk
  3. CContinue feeding more slowly
  4. DStop feeding and report it urgently
3.Dosage calculationsMedium
70 kg2 mg/kgD = ? mg

A patient weighs 70 kg and is prescribed 2 mg/kg as a single dose. Find the dose D in mg.

70 kg2 mg/kg
D = mg
4.Dosage calculationsHard
43 kg129 cmBSA = √(h·w/3600)25 mg/m²D = ? mg

A patient is 129 cm tall and weighs 43 kg. The prescription is 25 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

129 cm43 kg25 mg/m²
D = mg
5.IV infusion ratesMedium
1500 mL10 gtt/mL5 h? gtt/min

Infuse 1500 mL over 5 hours with a giving set of 10 gtt/mL. Find the drip rate R in drops per minute.

1500 mL5 h10 gtt/mL
R = gtt/min
6.IV infusion ratesHard
50 mg500 mL6 mL/h? mcg/min

An infusion of 50 mg in 500 mL runs at 6 mL/h. How many micrograms per minute D does the patient receive?

50 mg/500 mL6 mL/h
D = mcg/min

3Solutions

1.Maternity & obstetric nursing

Answer: D · Sitz baths, cold pads and stool softeners

Why this is the answer

Sitz baths, cold or witch hazel pads, topical treatments, fluids, fibre and stool softeners reduce pain and prevent constipation and straining.

Answer

D · Sitz baths, cold pads and stool softeners
2.Maternity & obstetric nursing

Answer: D · Stop feeding and report it urgently

Why this is the answer

Drooling and choking with feeds suggest oesophageal atresia with or without tracheo-oesophageal fistula. Feeding is stopped, the pouch is suctioned and the baby is kept upright while surgical review is arranged.

Answer

D · Stop feeding and report it urgently
3.Dosage calculations

Answer: D = 140 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

2·70 = 140 mg

Answer

D = 140 mg
4.Dosage calculations

Answer: D = 31.03 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 = √(129·43/3600) = √1.541 = 1.241 m²

Dose

D = 25·1.241 = 31.03 mg

Answer

D = 31.03 mg
5.IV infusion rates

Answer: R = 50 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.

Time in minutes

5·60 = 300 min

Drip rate

R = 1500·10/300 = 50 gtt/min

Answer

R = 50 gtt/min
6.IV infusion rates

Answer: D = 10 mcg/min

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

50000 mcg/500 mL = 100 mcg/mL

Dose per hour

6·100 = 600 mcg/h

Dose per minute

D = 600/60 = 10 mcg/min

Answer

D = 10 mcg/min

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