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

Why is tight glucose control before conception important in women with pre-existing diabetes?

  1. AEarly hyperglycaemia raises the risk of birth defects
  2. BIt prevents the need for any monitoring during pregnancy
  3. CIt prevents the mother from developing pre-eclampsia
  4. DIt guarantees that the baby will be born at term
2.Maternity & obstetric nursingHard

A woman at 34 weeks was in a car crash. She has abdominal pain, a rigid tender uterus and only slight vaginal bleeding. Late decelerations appear. Which statement is most accurate?

  1. AA rigid uterus after abdominal trauma is an expected finding and needs no further action
  2. BThe findings are typical of normal labour
  3. CLittle visible bleeding means blood loss is minor
  4. DShe may have a concealed abruption with major blood loss despite little visible bleeding
3.Dosage calculationsMedium
109 kgBSA = 2.03 m²100 mg/m²D = ? mg

A patient weighing 109 kg has a body surface area of 2.03 m². The prescription is 100 mg/m². Find the dose D in mg.

109 kgBSA = 2.03 m²100 mg/m²
D = mg
4.Dosage calculationsHard
20k units1000 mL? mL/h1200 units/h

An infusion contains 20000 units of a drug in 1000 mL. The prescription is 1200 units per hour. At what rate R do you set the pump, in mL/h?

20000 units/1000 mL1200 units/h
R = mL/h
5.IV infusion ratesMedium
60 gtt/mL200 mL/h? gtt/min

An infusion is ordered at 200 mL/h, but no pump is available. It runs by gravity through a giving set of 60 gtt/mL. Find the drip rate R in drops per minute.

200 mL/h60 gtt/mL
R = gtt/min
6.IV infusion ratesHard
500 mg50 mL10 mL/h? mg/h

A bag contains 500 mg of a drug in 50 mL and runs at 10 mL/h. How many milligrams per hour D does the patient receive?

500 mg/50 mL10 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: A · Early hyperglycaemia raises the risk of birth defects

Why this is the answer

Hyperglycaemia during organogenesis increases the risk of heart, neural tube and other anomalies and of miscarriage. Good preconception control and high-dose folic acid lower this risk.

Answer

A · Early hyperglycaemia raises the risk of birth defects
2.Maternity & obstetric nursing

Answer: D · She may have a concealed abruption with major blood loss despite little visible bleeding

Why this is the answer

Placental abruption can bleed into the space behind the placenta. Pain, rigidity and fetal compromise with little visible blood suggest a concealed abruption, which is an emergency for mother and fetus.

Answer

D · She may have a concealed abruption with major blood loss despite little visible bleeding
3.Dosage calculations

Answer: D = 203 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).

Dose

D = 100·2.03 = 203 mg

Answer

D = 203 mg
4.Dosage calculations

Answer: R = 60 mL/h

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.

Concentration

20000/1000 = 20 units/mL

Pump rate

R = 1200/20 = 60 mL/h

Answer

R = 60 mL/h
5.IV infusion rates

Answer: R = 200 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.

Millilitres per minute

200/60 = 3.333 mL/min

Drip rate

R = 3.333·60 = 200 gtt/min

Answer

R = 200 gtt/min

With a microdrip set (60 gtt/mL), gtt/min equals mL/h.

6.IV infusion rates

Answer: D = 100 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 = 10·10 = 100 mg/h

Answer

D = 100 mg/h

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