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

Parents ask where their newborn should sleep at night. Which advice reduces the risk of sudden infant death?

  1. AOn a sofa with a parent when the baby is unsettled
  2. BIn a separate cot or crib in the parents' room
  3. CIn the parents' bed, between the two adults
  4. DIn a separate bedroom from the first night
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 smells of ammonia
  3. CFluid that contains glucose on a urine dipstick
  4. DA nitrazine test that turns yellow, showing acidic fluid
3.Dosage calculationsMedium
25 kg25 mg/kg/day4× per dayD = ? mg

A patient weighs 25 kg. The prescribed dose is 25 mg/kg per day, given in 4 equal doses. How many milligrams D are given per dose?

25 kg25 mg/kg/day4× per day
D = mg
4.Dosage calculationsHard
69 kg171 cmBSA = √(h·w/3600)135 mg/m²D = ? mg

A patient is 171 cm tall and weighs 69 kg. The prescription is 135 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

171 cm69 kg135 mg/m²
D = mg
5.IV infusion ratesMedium
1500 mL10 gtt/mL6 h? gtt/min

Infuse 1500 mL over 6 hours with a giving set of 10 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1500 mL6 h10 gtt/mL
R = gtt/min
6.IV infusion ratesHard
1000 mg250 mL5 mL/h? mg/h

A bag contains 1000 mg of a drug in 250 mL and runs at 5 mL/h. How many milligrams per hour D does the patient receive?

1000 mg/250 mL5 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: B · In a separate cot or crib in the parents' room

Why this is the answer

Both US (AAP) and UK (NHS) guidance advise room-sharing without bed-sharing: the baby sleeps on the back in a cot or crib in the parents' room for at least the first 6 months. Sleeping with a baby on a sofa or armchair is especially dangerous.

Answer

B · In a separate cot or crib in the parents' room
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: D = 156.3 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.

Total per day

25·25 = 625 mg

Per dose

D = 625/4 = 156.3 mg

Answer

D = 156.3 mg
4.Dosage calculations

Answer: D = 244.4 mg

Body-surface-area dosing: many cytotoxic and some paediatric doses are prescribed per square metre of body surface area: dose (mg) = dose per m² × BSA (m²). The Mosteller formula estimates BSA = √(height (cm) × weight (kg)/3600).

Body surface area

BSA = √(171·69/3600) = √3.277 = 1.81 m²

Dose

D = 135·1.81 = 244.4 mg

Answer

D = 244.4 mg
5.IV infusion rates

Answer: R = 42 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

6·60 = 360 min

Drip rate

R = 1500·10/360 = 41.67 ≈ 42 gtt/min

Answer

R = 42 gtt/min

At the bedside you round to the nearest whole drop: 42 gtt/min.

6.IV infusion rates

Answer: D = 20 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

1000/250 = 4 mg/mL

Dose rate

D = 4·5 = 20 mg/h

Answer

D = 20 mg/h

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