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 at 28 weeks asks why her heart rate is higher than before pregnancy. Which response is accurate?

  1. AThe heart rate rises because blood pressure is much higher in pregnancy
  2. BA rise of about 10 to 15 beats per minute is normal in pregnancy
  3. CHeart rate normally falls in pregnancy, so this needs urgent review
  4. DA higher heart rate in pregnancy always points to heart disease
2.Maternity & obstetric nursingHard

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

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

A child weighing 30 kg is prescribed 2 mg/kg of a drug. The stock solution contains 20 mg/mL. Draw up the dose: what volume V do you give?

30 kg2 mg/kg20 mg/mL
V = mL
4.Dosage calculationsHard
25%stockV₁ = ? mL

You must prepare 100 mL of a 2% (w/v) solution from a 25% (w/v) stock solution. What volume of stock V₁ do you need?

C₁ = 25%C₂ = 2%V₂ = 100 mL
V₁ = mL
5.IV infusion ratesMedium
500 mL10 gtt/mL8 h? gtt/min

Infuse 500 mL over 8 hours with a giving set of 10 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

500 mL8 h10 gtt/mL
R = gtt/min
6.IV infusion ratesHard
100 mg100 mL5 mL/h? mg/h

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

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

3Solutions

1.Maternity & obstetric nursing

Answer: B · A rise of about 10 to 15 beats per minute is normal in pregnancy

Why this is the answer

Blood volume and cardiac output rise in pregnancy, and the resting heart rate typically increases by 10 to 15 beats per minute. Blood pressure usually falls slightly in the second trimester.

Answer

B · A rise of about 10 to 15 beats per minute is normal in pregnancy
2.Maternity & obstetric nursing

Answer: A · 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

A · 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 = 2·30 = 60 mg

Volume

V = 60/20 = 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: V₁ = 8 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 = 2·100/25 = 8 mL

Answer

V₁ = 8 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

8·60 = 480 min

Drip rate

R = 500·10/480 = 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 = 5 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

100/100 = 1 mg/mL

Dose rate

D = 1·5 = 5 mg/h

Answer

D = 5 mg/h

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