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 preterm baby at 30 weeks has repeated pauses in breathing of more than 20 seconds. Which drug is commonly used?

  1. APhenobarbital
  2. BNaloxone hydrochloride
  3. CAtropine sulfate
  4. DCaffeine citrate
2.Maternity & obstetric nursingHard

Fluid leaking from the vagina is tested. Which result supports rupture of the membranes?

  1. AA nitrazine test that turns yellow, showing acidic fluid
  2. BA ferning pattern on a dried slide under the microscope
  3. CFluid that contains glucose on a urine dipstick
  4. DFluid that smells of ammonia
3.Dosage calculationsMedium
024681010 mL

A child weighing 16 kg is prescribed 7.5 mg/kg of a drug. The stock solution contains 40 mg/mL. Draw up the dose: what volume V do you give?

16 kg7.5 mg/kg40 mg/mL
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 455 micrograms. The ampoule contains 0.5 mg/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

455 mcg0.5 mg/mL
V = mL
5.IV infusion ratesMedium
V = ?60 gtt/mL60 gtt/min12 h

A drip runs at 60 gtt/min through a set of 60 gtt/mL. How many millilitres V does the patient receive in 12 hours?

60 gtt/min60 gtt/mL12 h
V = mL
6.IV infusion ratesHard
1320 mLleft? mL/h8 h left

1500 mL was ordered over 10 hours. After 2 hours you find that 1320 mL is still in the bag, and the order must still finish on time. By what percentage Δ must the original pump rate be increased?

1500 mL / 10 hafter 2 h: 1320 mL
Δ = %

3Solutions

1.Maternity & obstetric nursing

Answer: D · Caffeine citrate

Why this is the answer

Apnoea of prematurity results from an immature respiratory centre. Caffeine citrate stimulates breathing and reduces apnoea episodes. Gentle stimulation is used during an episode.

Answer

D · Caffeine citrate
2.Maternity & obstetric nursing

Answer: B · A ferning pattern on a dried slide under the microscope

Why this is the answer

Amniotic fluid forms a fern-like pattern when dried and turns nitrazine paper blue because it is alkaline. Vaginal secretions and urine are usually acidic. Blood, semen and infection can give false positives on nitrazine testing.

Answer

B · A ferning pattern on a dried slide under the microscope
3.Dosage calculations

Answer: V = 3 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 = 7.5·16 = 120 mg

Volume

V = 120/40 = 3 mL

On the syringe

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

Answer

V = 3 mL
4.Dosage calculations

Answer: V = 0.91 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 = 455/500 = 0.91 mL

Answer

V = 0.91 mL
5.IV infusion rates

Answer: V = 720 mL

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

60·60/60 = 60 mL/h

Volume

V = 60·12 = 720 mL

Answer

V = 720 mL
6.IV infusion rates

Answer: Δ = 10 %

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

1500/10 = 150 mL/h

New rate

R = 1320/8 = 165 mL/h

Percentage change

Δ = (165 − 150)/150·100% = 10%

Answer

Δ = 10%

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

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