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 with hypothyroidism becomes pregnant. What usually happens to her levothyroxine needs?

  1. AThey usually rise, so levels are checked early
  2. BThey stay the same, so no monitoring is needed
  3. CThey decrease to zero, so she stops the drug
  4. DShe switches to iodine tablets instead
2.Maternity & obstetric nursingHard

A woman 2 hours after birth asks for help to the bathroom. She had an epidural that is now off. What is the main safety concern?

  1. AReopening of the epidural site
  2. BLeg weakness or numbness causing a fall
  3. CIncreased lochia from walking
  4. DFainting from low blood glucose only
3.Dosage calculationsMedium
024681010 mL

A child weighing 6 kg is prescribed 4 mg/kg of a drug. The stock solution contains 20 mg/mL. Draw up the dose: what volume V do you give?

6 kg4 mg/kg20 mg/mL
V = mL
4.Dosage calculationsHard
45 kg125 cmBSA = √(h·w/3600)50 mg/m²D = ? mg

A patient is 125 cm tall and weighs 45 kg. The prescription is 50 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

125 cm45 kg50 mg/m²
D = mg
5.IV infusion ratesMedium
1000 mL15 gtt/mL8 h? gtt/min

Infuse 1000 mL over 8 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1000 mL8 h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
500 mg50 mL10 mL/h? mg/h

A bag contains 500 mg of a drug in 50 mL and runs at 10 mL/h. How many milligrams per hour D does the patient receive?

500 mg/50 mL10 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: A · They usually rise, so levels are checked early

Why this is the answer

Levothyroxine needs usually rise in pregnancy. Thyroid function is checked as soon as pregnancy is confirmed and regularly afterwards, because untreated hypothyroidism can affect fetal brain development.

Answer

A · They usually rise, so levels are checked early
2.Maternity & obstetric nursing

Answer: B · Leg weakness or numbness causing a fall

Why this is the answer

After an epidural, the nurse checks that leg sensation and strength have returned before she stands. Combined with orthostatic hypotension and blood loss, this makes the first walk a high fall risk.

Answer

B · Leg weakness or numbness causing a fall
3.Dosage calculations

Answer: V = 1.2 mL

Drawing up a dose: volume = (prescribed dose/stock strength) × stock volume. Convert to the same units first, then check that the volume fits the syringe and lands on one of its graduations.

Dose from body weight

D = 4·6 = 24 mg

Volume

V = 24/20 = 1.2 mL

On the syringe

On this 10 mL syringe every small line is 0.2 mL.

Answer

V = 1.2 mL
4.Dosage calculations

Answer: D = 62.5 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 = √(125·45/3600) = √1.563 = 1.25 m²

Dose

D = 50·1.25 = 62.5 mg

Answer

D = 62.5 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

8·60 = 480 min

Drip rate

R = 1000·15/480 = 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: D = 100 mg/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.

Concentration

500/50 = 10 mg/mL

Dose rate

D = 10·10 = 100 mg/h

Answer

D = 100 mg/h

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