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 congenital hypothyroidism included in newborn screening?

  1. AIt causes jaundice that cannot be treated
  2. BEarly treatment prevents brain damage
  3. CIt can only be treated before birth
  4. DIt causes hip dysplasia
2.Maternity & obstetric nursingHard

A woman at 12 weeks has light bleeding and mild cramping. The cervix is closed and fetal heart activity is seen on ultrasound. How is this classified?

  1. AMissed miscarriage
  2. BIncomplete miscarriage
  3. CThreatened miscarriage
  4. DInevitable miscarriage
3.Dosage calculationsMedium
80 kg5 mg/kgD = ? mg

A patient weighs 80 kg and is prescribed 5 mg/kg as a single dose. Find the dose D in mg.

80 kg5 mg/kg
D = mg
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 335 micrograms. The ampoule contains 0.5 mg/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

335 mcg0.5 mg/mL
V = mL
5.IV infusion ratesMedium
480 mLleft? mL/h5 h left

1000 mL was ordered over 12 hours. After 7 hours you find that 480 mL is still in the bag, and the order must still finish on time. To what rate R in mL/h must the pump be reset?

1000 mL / 12 hafter 7 h: 480 mL
R = mL/h
6.IV infusion ratesHard
200 mg50 mL10 mL/h? mg/h

A bag contains 200 mg of a drug in 50 mL and runs at 10 mL/h. How many milligrams per hour D does the patient receive?

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

3Solutions

1.Maternity & obstetric nursing

Answer: B · Early treatment prevents brain damage

Why this is the answer

Untreated congenital hypothyroidism causes poor growth and intellectual disability. Daily levothyroxine started in the first weeks allows normal development.

Answer

B · Early treatment prevents brain damage
2.Maternity & obstetric nursing

Answer: C · Threatened miscarriage

Why this is the answer

Bleeding with a closed cervix and a viable pregnancy is a threatened miscarriage; many continue normally. An open cervix means an inevitable or incomplete miscarriage, and a missed miscarriage has no fetal heart activity.

Answer

C · Threatened miscarriage
3.Dosage calculations

Answer: D = 400 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

5·80 = 400 mg

Answer

D = 400 mg
4.Dosage calculations

Answer: V = 0.67 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.

Same units

0.5 mg/mL = 500 mcg/mL

Volume

V = 335/500 = 0.67 mL

Answer

V = 0.67 mL
5.IV infusion rates

Answer: R = 96 mL/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.

Original rate

1000/12 = 83.33 mL/h

New rate

R = 480/5 = 96 mL/h

Answer

R = 96 mL/h

Many hospitals allow such an adjustment up to 25% without a new order; check local policy.

6.IV infusion rates

Answer: D = 40 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

200/50 = 4 mg/mL

Dose rate

D = 4·10 = 40 mg/h

Answer

D = 40 mg/h

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