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 breastfeeding mother has afterpains (cramping) during feeds on day 2. What explains this?

  1. AShe has a urinary tract infection
  2. BOxytocin released during breastfeeding makes the uterus contract
  3. CHer milk supply is too low
  4. DThe placenta has not been fully delivered and is still being expelled
2.Maternity & obstetric nursingHard

A fetal heart rate tracing shows absent baseline variability with recurrent late decelerations. How is this classified and what does it require?

  1. ACategory I: normal, routine care
  2. BA normal pattern during fetal sleep
  3. CCategory III: an abnormal tracing that needs prompt intervention and preparation for expedited birth
  4. DCategory II: an indeterminate tracing that only needs continued routine observation and documentation
3.Dosage calculationsMedium
15 kg15 mg/kgD = ? mg

A patient weighs 15 kg and is prescribed 15 mg/kg as a single dose. Find the dose D in mg.

15 kg15 mg/kg
D = mg
4.Dosage calculationsHard
50%stockV₁ = ? mL

You must prepare 250 mL of a 1% (w/v) solution from a 50% (w/v) stock solution. What volume of stock V₁ do you need?

C₁ = 50%C₂ = 1%V₂ = 250 mL
V₁ = mL
5.IV infusion ratesMedium
V = ?20 gtt/mL50 gtt/min4 h

A drip runs at 50 gtt/min through a set of 20 gtt/mL. How many millilitres V does the patient receive in 4 hours?

50 gtt/min20 gtt/mL4 h
V = mL
6.IV infusion ratesHard
400 mL60 gtt/mL25 gtt/mint = ? h

A drip runs at 25 gtt/min through a set of 60 gtt/mL. There are 400 mL left in the bag. How many hours t until it is empty?

25 gtt/min60 gtt/mL400 mL
t = h

3Solutions

1.Maternity & obstetric nursing

Answer: B · Oxytocin released during breastfeeding makes the uterus contract

Why this is the answer

Suckling releases oxytocin, which causes milk let-down and uterine contractions. Afterpains are normal and often stronger in women who have had several babies. Emptying the bladder and simple analgesia help.

Answer

B · Oxytocin released during breastfeeding makes the uterus contract
2.Maternity & obstetric nursing

Answer: C · Category III: an abnormal tracing that needs prompt intervention and preparation for expedited birth

Why this is the answer

In the three-tier system, absent variability with recurrent late or variable decelerations, or with bradycardia, is Category III. Intrauterine resuscitation starts at once, the team is called, and birth is expedited if the pattern does not resolve.

Answer

C · Category III: an abnormal tracing that needs prompt intervention and preparation for expedited birth
3.Dosage calculations

Answer: D = 225 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

15·15 = 225 mg

Answer

D = 225 mg
4.Dosage calculations

Answer: V₁ = 5 mL

Solution strengths: a percentage strength is grams per 100 mL, so 1% = 1 g/100 mL = 10 mg/mL. A ratio strength 1:1000 means 1 g in 1000 mL = 1 mg/mL; 1:10 000 is 0.1 mg/mL. For a dilution the amount of drug stays the same: C₁·V₁ = C₂·V₂.

Volume of stock

V₁ = 1·250/50 = 5 mL

Answer

V₁ = 5 mL
5.IV infusion rates

Answer: V = 600 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

50·60/20 = 150 mL/h

Volume

V = 150·4 = 600 mL

Answer

V = 600 mL
6.IV infusion rates

Answer: t = 16 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.

Rate in mL/h

25·60/60 = 25 mL/h

Time left

t = 400/25 = 16 h

Answer

t = 16 h

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