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 baseline variability is considered moderate (normal)?

  1. AAn amplitude of 6 to 25 bpm
  2. BAn amplitude of 3 to 5 bpm
  3. CAn amplitude of more than 25 bpm
  4. DAn amplitude of 0 to 2 bpm
2.Maternity & obstetric nursingHard

A woman at 32 weeks with type 1 diabetes has nausea, vomiting, abdominal pain, rapid breathing and a glucose of 16 mmol/L (about 290 mg/dL). Which complication should be suspected?

  1. AHypoglycaemia
  2. BDiabetic ketoacidosis
  3. CHyperemesis gravidarum
  4. DNormal pregnancy nausea
3.Dosage calculationsMedium
12 kg2 mg/kg/day3× per dayD = ? mg

A patient weighs 12 kg. The prescribed dose is 2 mg/kg per day, given in 3 equal doses. How many milligrams D are given per dose?

12 kg2 mg/kg/day3× per day
D = mg
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 0.15 mg. The ampoule contains 1000 micrograms per mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

0.15 mg1000 mcg/mL
V = mL
5.IV infusion ratesMedium
320 mLleft? mL/h6 h left

500 mL was ordered over 10 hours. After 4 hours you find that 320 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?

500 mL / 10 hafter 4 h: 320 mL
R = mL/h
6.IV infusion ratesHard
400 mg100 mL10 mL/h? mg/h

A bag contains 400 mg of a drug in 100 mL and runs at 10 mL/h. How many milligrams per hour D does the patient receive?

400 mg/100 mL10 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: A · An amplitude of 6 to 25 bpm

Why this is the answer

Moderate variability (6–25 bpm) shows an oxygenated fetus with a functioning autonomic nervous system. Minimal (5 bpm or less) or absent variability can mean hypoxia, sleep or medication effects; more than 25 bpm is marked variability.

Answer

A · An amplitude of 6 to 25 bpm
2.Maternity & obstetric nursing

Answer: B · Diabetic ketoacidosis

Why this is the answer

Diabetic ketoacidosis can develop quickly in pregnancy, even at moderately raised glucose, and carries a high risk of fetal death. Ketones and blood gases are checked urgently, and fluids and insulin are started.

Answer

B · Diabetic ketoacidosis
3.Dosage calculations

Answer: D = 8 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.

Total per day

2·12 = 24 mg

Per dose

D = 24/3 = 8 mg

Answer

D = 8 mg
4.Dosage calculations

Answer: V = 0.15 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

0.15 mg = 150 mcg

Volume

V = 150/1000 = 0.15 mL

Answer

V = 0.15 mL
5.IV infusion rates

Answer: R = 53.33 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

500/10 = 50 mL/h

New rate

R = 320/6 = 53.33 mL/h

Answer

R = 53.33 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

400/100 = 4 mg/mL

Dose rate

D = 4·10 = 40 mg/h

Answer

D = 40 mg/h

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