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 a positive home pregnancy test. How is this sign classified?

  1. AA presumptive sign of pregnancy
  2. BA positive sign of pregnancy
  3. CA probable sign of pregnancy
  4. DA diagnostic sign of pregnancy
2.Maternity & obstetric nursingHard

Which newborn finding requires immediate follow-up?

  1. ASmall white spots (milia) on the nose
  2. BGrunting, nasal flaring and chest retractions at 1 hour
  3. CMoulding of the head shape after a vaginal birth at term
  4. DAcrocyanosis at 2 hours
3.Dosage calculationsMedium
95 kgBSA = 1.91 m²135 mg/m²D = ? mg

A patient weighing 95 kg has a body surface area of 1.91 m². The prescription is 135 mg/m². Find the dose D in mg.

95 kgBSA = 1.91 m²135 mg/m²
D = mg
4.Dosage calculationsHard
120 mg/5 mLV = ? mL

A child weighing 10 kg is prescribed 5 mg/kg per dose of an oral suspension that contains 120 mg in 5 mL. What volume V do you give? Round to one decimal place.

10 kg5 mg/kg120 mg/5 mL
V = mL
5.IV infusion ratesMedium
500 mL10 gtt/mL8 h? gtt/min

Infuse 500 mL over 8 hours with a giving set of 10 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

500 mL8 h10 gtt/mL
R = gtt/min
6.IV infusion ratesHard
300 mL15 gtt/mL32 gtt/mint = ? h

A drip runs at 32 gtt/min through a set of 15 gtt/mL. There are 300 mL left in the bag. How many hours t until it is empty? Round to one decimal place.

32 gtt/min15 gtt/mL300 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: C · A probable sign of pregnancy

Why this is the answer

A positive hCG test is a probable sign, because hCG can also be raised by a molar pregnancy or some tumours. Only fetal heart activity, fetal movement felt by an examiner or visualisation of the fetus are positive signs.

Answer

C · A probable sign of pregnancy
2.Maternity & obstetric nursing

Answer: B · Grunting, nasal flaring and chest retractions at 1 hour

Why this is the answer

Grunting, flaring and retractions are signs of respiratory distress and need urgent assessment. Acrocyanosis, milia and moulding are common normal findings.

Answer

B · Grunting, nasal flaring and chest retractions at 1 hour
3.Dosage calculations

Answer: D = 257.8 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).

Dose

D = 135·1.91 = 257.8 mg

Answer

D = 257.8 mg
4.Dosage calculations

Answer: V = 2.1 mL

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 from weight

5·10 = 50 mg

Volume

V = (50/120)·5 = 2.083 ≈ 2.1 mL

Answer

V = 2.1 mL
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.

Time in minutes

8·60 = 480 min

Drip rate

R = 500·10/480 = 10.42 ≈ 10 gtt/min

Answer

R = 10 gtt/min

At the bedside you round to the nearest whole drop: 10 gtt/min.

6.IV infusion rates

Answer: t = 2.3 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

32·60/15 = 128 mL/h

Time left

t = 300/128 = 2.344 ≈ 2.3 h

Answer

t = 2.3 h

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