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

After rupture of the membranes, the amniotic fluid is green. What does this suggest?

  1. AThe mother has an infection with group B streptococcus
  2. BThe fluid is normal at term
  3. CThere is bleeding from the placenta
  4. DThe fetus has passed meconium
2.Maternity & obstetric nursingHard

A woman in labour is receiving oxytocin. The tracing now shows recurrent late decelerations. Which action should the nurse take first?

  1. AStop the oxytocin infusion
  2. BHelp her lie flat on her back
  3. CDocument the pattern and reassess in 30 minutes
  4. DIncrease the oxytocin rate to speed up the birth
3.Dosage calculationsMedium
024681010 mL

A child weighing 18 kg is prescribed 4 mg/kg of a drug. The stock solution contains 40 mg/mL. Draw up the dose: what volume V do you give?

18 kg4 mg/kg40 mg/mL
V = mL
4.Dosage calculationsHard
100 mg/5 mLV = ? mL

A child weighing 12 kg is prescribed 10 mg/kg per dose of an oral suspension that contains 100 mg in 5 mL. What volume V do you give?

12 kg10 mg/kg100 mg/5 mL
V = mL
5.IV infusion ratesMedium
500 mL60 gtt/mL5 h? gtt/min

Infuse 500 mL over 5 hours with a giving set of 60 gtt/mL. Find the drip rate R in drops per minute.

500 mL5 h60 gtt/mL
R = gtt/min
6.IV infusion ratesHard
200 mg100 mL5 mL/h? mg/h

A bag contains 200 mg of a drug in 100 mL and runs at 5 mL/h. How many milligrams per hour D does the patient receive?

200 mg/100 mL5 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: D · The fetus has passed meconium

Why this is the answer

Green fluid means meconium was passed in the uterus. It is more common after term and can occur with fetal stress, so the fetal heart rate is watched closely and the team prepares for the birth.

Answer

D · The fetus has passed meconium
2.Maternity & obstetric nursing

Answer: A · Stop the oxytocin infusion

Why this is the answer

Stopping the oxytocin reduces contraction-related loss of placental flow. Other steps follow at once: a lateral position, an IV fluid bolus as ordered, checking maternal blood pressure and notifying the provider. Waiting or lying supine makes the hypoxia worse.

Answer

A · Stop the oxytocin infusion
3.Dosage calculations

Answer: V = 1.8 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 = 4·18 = 72 mg

Volume

V = 72/40 = 1.8 mL

On the syringe

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

Answer

V = 1.8 mL
4.Dosage calculations

Answer: V = 6 mL

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 from weight

10·12 = 120 mg

Volume

V = (120/100)·5 = 6 mL

Answer

V = 6 mL
5.IV infusion rates

Answer: R = 100 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

5·60 = 300 min

Drip rate

R = 500·60/300 = 100 gtt/min

Answer

R = 100 gtt/min
6.IV infusion rates

Answer: D = 10 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

200/100 = 2 mg/mL

Dose rate

D = 2·5 = 10 mg/h

Answer

D = 10 mg/h

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