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 woman 4 hours after birth has severe perineal pain and pressure. Her fundus is firm, lochia is normal, and her heart rate is rising. What should the nurse suspect?

  1. AA vulvar or vaginal haematoma
  2. BA urinary tract infection
  3. CNormal afterpains
  4. DUterine atony
2.Maternity & obstetric nursingHard

A newborn's bilirubin is rising quickly at 30 hours despite phototherapy, and the baby is lethargic with an arched back and high-pitched cry. What does this suggest?

  1. AA normal reaction to phototherapy
  2. BAcute bilirubin encephalopathy
  3. CNormal newborn reflexes
  4. DMild breast milk jaundice
3.Dosage calculationsMedium
1:10 000ampouleV = ? mL

A prefilled syringe of epinephrine (adrenaline) is labelled 1:10 000 (0.1 mg/mL). The prescription is 1 mg IV in cardiac arrest. What volume V do you give?

1:10 0001 mg
V = mL
4.Dosage calculationsHard
40 mg/1 mLV = ? mL

A child weighing 8 kg is prescribed 10 mg/kg per dose of an oral suspension that contains 40 mg in 1 mL. What volume V do you give?

8 kg10 mg/kg40 mg/1 mL
V = mL
5.IV infusion ratesMedium
500 mL15 gtt/mL12 h? gtt/min

Infuse 500 mL over 12 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

500 mL12 h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
500 mg50 mL20 mL/h? mg/h

A bag contains 500 mg of a drug in 50 mL and runs at 20 mL/h. How many milligrams per hour D does the patient receive?

500 mg/50 mL20 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: A · A vulvar or vaginal haematoma

Why this is the answer

A haematoma causes severe pain and pressure out of proportion to the birth, often with a firm uterus and normal lochia. Signs of hidden blood loss such as tachycardia must be reported.

Answer

A · A vulvar or vaginal haematoma
2.Maternity & obstetric nursing

Answer: B · Acute bilirubin encephalopathy

Why this is the answer

Lethargy, poor feeding, hypertonia with arching and a high-pitched cry are signs of acute bilirubin encephalopathy. An urgent exchange transfusion may be needed to prevent permanent kernicterus.

Answer

B · Acute bilirubin encephalopathy
3.Dosage calculations

Answer: V = 10 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.

Concentration

1:10 000 = 1 g/10000 mL = 0.1 mg/mL

Volume

V = 1/0.1 = 10 mL

Answer

V = 10 mL

US labels now state mg/mL (1 mg/mL = 1:1000; 0.1 mg/mL = 1:10 000). Never give 1 mg/mL epinephrine IV push.

4.Dosage calculations

Answer: V = 2 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

10·8 = 80 mg

Volume

V = (80/40)·1 = 2 mL

Answer

V = 2 mL
5.IV infusion rates

Answer: R = 10 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

12·60 = 720 min

Drip rate

R = 500·15/720 = 10.42 ≈ 10 gtt/min

Answer

R = 10 gtt/min

At the bedside you round to the nearest whole drop: 10 gtt/min.

6.IV infusion rates

Answer: D = 200 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

500/50 = 10 mg/mL

Dose rate

D = 10·20 = 200 mg/h

Answer

D = 200 mg/h

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