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

Why is indomethacin generally not used as a tocolytic after about 32 weeks?

  1. AIt can close the fetal ductus arteriosus too early
  2. BIt causes severe maternal hypertension
  3. CIt triggers maternal hypoglycaemia
  4. DIt stimulates stronger contractions late in pregnancy
2.Maternity & obstetric nursingHard

The nurse must deliver a baby before the provider arrives. As the head crowns, what should the nurse do?

  1. AAsk the woman to cross her legs tightly until help comes
  2. BPull firmly on the head to speed the birth
  3. CApply gentle pressure to the head to slow the birth
  4. DPush the head back to delay the birth
3.Dosage calculationsMedium
70 kg25 mg/kg/day3× per dayD = ? mg

A patient weighs 70 kg. The prescribed dose is 25 mg/kg per day, given in 3 equal doses. How many milligrams D are given per dose?

70 kg25 mg/kg/day3× per day
D = mg
4.Dosage calculationsHard
52 kg143 cmBSA = √(h·w/3600)75 mg/m²D = ? mg

A patient is 143 cm tall and weighs 52 kg. The prescription is 75 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

143 cm52 kg75 mg/m²
D = mg
5.IV infusion ratesMedium
500 mL15 gtt/mL4 h? gtt/min

Infuse 500 mL over 4 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

500 mL4 h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
600 mL15 gtt/mL28 gtt/mint = ? h

A drip runs at 28 gtt/min through a set of 15 gtt/mL. There are 600 mL left in the bag. How many hours t until it is empty? Round to one decimal place.

28 gtt/min15 gtt/mL600 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: A · It can close the fetal ductus arteriosus too early

Why this is the answer

Indomethacin inhibits prostaglandin synthesis. In the fetus this can cause premature closure of the ductus arteriosus and reduced fetal urine output with oligohydramnios, risks that increase with gestational age.

Answer

A · It can close the fetal ductus arteriosus too early
2.Maternity & obstetric nursing

Answer: C · Apply gentle pressure to the head to slow the birth

Why this is the answer

Gentle pressure on the fetal head, with the woman panting, slows birth and reduces perineal tearing and rapid pressure changes in the fetal skull. The nurse then checks for a nuchal cord and supports the baby's body.

Answer

C · Apply gentle pressure to the head to slow the birth
3.Dosage calculations

Answer: D = 583.3 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

25·70 = 1750 mg

Per dose

D = 1750/3 = 583.3 mg

Answer

D = 583.3 mg
4.Dosage calculations

Answer: D = 107.8 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 = √(143·52/3600) = √2.066 = 1.437 m²

Dose

D = 75·1.437 = 107.8 mg

Answer

D = 107.8 mg
5.IV infusion rates

Answer: R = 31 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

4·60 = 240 min

Drip rate

R = 500·15/240 = 31.25 ≈ 31 gtt/min

Answer

R = 31 gtt/min

At the bedside you round to the nearest whole drop: 31 gtt/min.

6.IV infusion rates

Answer: t = 5.4 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

28·60/15 = 112 mL/h

Time left

t = 600/112 = 5.357 ≈ 5.4 h

Answer

t = 5.4 h

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