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 woman on the antenatal unit should the nurse see first?

  1. AAt 30 weeks: mild ankle swelling in the evening
  2. BAt 28 weeks: due for routine anti-D
  3. CAt 38 weeks: irregular Braxton Hicks contractions
  4. DAt 34 weeks: severe headache, BP 164/110 mmHg
2.Maternity & obstetric nursingHard

A newborn's bilirubin is rising quickly at 30 hours despite phototherapy, and the baby is lethargic with an arched back and high-pitched cry. What does this suggest?

  1. AMild breast milk jaundice
  2. BA normal reaction to phototherapy
  3. CAcute bilirubin encephalopathy
  4. DNormal newborn reflexes
3.Dosage calculationsMedium
120 kgBSA = 2.09 m²135 mg/m²D = ? mg

A patient weighing 120 kg has a body surface area of 2.09 m². The prescription is 135 mg/m². Find the dose D in mg.

120 kgBSA = 2.09 m²135 mg/m²
D = mg
4.Dosage calculationsHard
38 kg141 cmBSA = √(h·w/3600)250 mg/m²D = ? mg

A patient is 141 cm tall and weighs 38 kg. The prescription is 250 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

141 cm38 kg250 mg/m²
D = mg
5.IV infusion ratesMedium
250 mL60 gtt/mL4 h? gtt/min

Infuse 250 mL over 4 hours with a giving set of 60 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

250 mL4 h60 gtt/mL
R = gtt/min
6.IV infusion ratesHard
450 mL20 gtt/mL20 gtt/mint = ? h

A drip runs at 20 gtt/min through a set of 20 gtt/mL. There are 450 mL left in the bag. How many hours t until it is empty?

20 gtt/min20 gtt/mL450 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: D · At 34 weeks: severe headache, BP 164/110 mmHg

Why this is the answer

Severe-range blood pressure with a headache suggests pre-eclampsia with severe features and a risk of eclampsia or stroke. The other women are stable.

Answer

D · At 34 weeks: severe headache, BP 164/110 mmHg
2.Maternity & obstetric nursing

Answer: C · Acute bilirubin encephalopathy

Why this is the answer

Lethargy, poor feeding, hypertonia with arching and a high-pitched cry are signs of acute bilirubin encephalopathy. An urgent exchange transfusion may be needed to prevent permanent kernicterus.

Answer

C · Acute bilirubin encephalopathy
3.Dosage calculations

Answer: D = 282.1 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).

Dose

D = 135·2.09 = 282.1 mg

Answer

D = 282.1 mg
4.Dosage calculations

Answer: D = 305 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 = √(141·38/3600) = √1.488 = 1.22 m²

Dose

D = 250·1.22 = 305 mg

Answer

D = 305 mg
5.IV infusion rates

Answer: R = 63 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 = 250·60/240 = 62.5 ≈ 63 gtt/min

Answer

R = 63 gtt/min

At the bedside you round to the nearest whole drop: 63 gtt/min.

6.IV infusion rates

Answer: t = 7.5 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

20·60/20 = 60 mL/h

Time left

t = 450/60 = 7.5 h

Answer

t = 7.5 h

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