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 statement describes the "4 Ts" causes of postpartum haemorrhage?

  1. ATemperature, tachycardia, tears and time
  2. BTone, tachycardia, transfusion and tissue
  3. CTrauma, tension, temperature and thrombosis
  4. DTone, trauma, tissue and thrombin
2.Maternity & obstetric nursingHard

A non-stress test at 36 weeks shows no accelerations in 40 minutes. What is the most appropriate next step?

  1. ARecord the result as reactive and reassuring
  2. BFurther testing, such as a biophysical profile
  3. CImmediately start oxytocin to induce labour
  4. DSend her home and repeat the test in a month
3.Dosage calculationsMedium
12 kg10 mg/kgD = ? mg

A patient weighs 12 kg and is prescribed 10 mg/kg as a single dose. Find the dose D in mg.

12 kg10 mg/kg
D = mg
4.Dosage calculationsHard
63 kg147 cmBSA = √(h·w/3600)135 mg/m²D = ? mg

A patient is 147 cm tall and weighs 63 kg. The prescription is 135 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

147 cm63 kg135 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
400 mL20 gtt/mL25 gtt/mint = ? h

A drip runs at 25 gtt/min through a set of 20 gtt/mL. There are 400 mL left in the bag. How many hours t until it is empty? Round to one decimal place.

25 gtt/min20 gtt/mL400 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: D · Tone, trauma, tissue and thrombin

Why this is the answer

The 4 Ts are tone (atony), trauma (tears, haematomas, rupture), tissue (retained placenta or clots) and thrombin (clotting disorders). Tone is the most common cause.

Answer

D · Tone, trauma, tissue and thrombin
2.Maternity & obstetric nursing

Answer: B · Further testing, such as a biophysical profile

Why this is the answer

A non-reactive NST may reflect a fetal sleep cycle or drugs, but it can also indicate hypoxia. A biophysical profile or contraction stress test is used to clarify fetal wellbeing.

Answer

B · Further testing, such as a biophysical profile
3.Dosage calculations

Answer: D = 120 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

10·12 = 120 mg

Answer

D = 120 mg
4.Dosage calculations

Answer: D = 216.5 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 = √(147·63/3600) = √2.572 = 1.604 m²

Dose

D = 135·1.604 = 216.5 mg

Answer

D = 216.5 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 = 5.3 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

25·60/20 = 75 mL/h

Time left

t = 400/75 = 5.333 ≈ 5.3 h

Answer

t = 5.3 h

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