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

What does the acronym HELLP stand for?

  1. AHaemolysis, elevated liver enzymes, low platelets
  2. BHyperglycaemia, elevated lactate, low potassium
  3. CHypertension, elevated lipids, low protein
  4. DHaemorrhage, eclampsia, low pressure
2.Maternity & obstetric nursingHard

One hour after a vaginal birth, the fundus is firm at the umbilicus, but there is a steady trickle of bright red blood. What is the most likely cause?

  1. AA tear of the cervix, vagina or perineum
  2. BA full bladder
  3. CNormal lochia rubra
  4. DUterine atony with blood pooling in the uterus
3.Dosage calculationsMedium
2 g+ 7.4 mLV = ? mL

A vial contains 2 g of powder. The label says: add 7.4 mL of water for injection to give a total volume of 8 mL. The prescription is 250 mg. What volume V of the reconstituted solution do you give?

2 g+ 7.4 mL → 8 mL250 mg
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 300 units of a drug that comes as 1000 units/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

300 units1000 units/mL
V = mL
5.IV infusion ratesMedium
640 mLleft? mL/h2 h left

1500 mL was ordered over 6 hours. After 4 hours you find that 640 mL is still in the bag, and the order must still finish on time. To what rate R in mL/h must the pump be reset?

1500 mL / 6 hafter 4 h: 640 mL
R = mL/h
6.IV infusion ratesHard
100 mg100 mL60 gtt/mL40 mg/h? gtt/min

100 mg of a drug is diluted in 100 mL and given by gravity through a set of 60 gtt/mL. The order is 40 mg per hour. Find the drip rate R in drops per minute.

100 mg/100 mL40 mg/h60 gtt/mL
R = gtt/min

3Solutions

1.Maternity & obstetric nursing

Answer: A · Haemolysis, elevated liver enzymes, low platelets

Why this is the answer

HELLP syndrome is a serious complication of pre-eclampsia. Right upper quadrant or epigastric pain, nausea and malaise are typical, and blood pressure is not always very high.

Answer

A · Haemolysis, elevated liver enzymes, low platelets
2.Maternity & obstetric nursing

Answer: A · A tear of the cervix, vagina or perineum

Why this is the answer

Continuous bright red bleeding with a firm uterus suggests trauma (laceration), which needs inspection and repair. Atony would make the uterus soft, and normal lochia does not flow in a steady stream.

Answer

A · A tear of the cervix, vagina or perineum
3.Dosage calculations

Answer: V = 1 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.

Concentration after mixing

2000 mg/8 mL = 250 mg/mL

Volume

V = 250/250 = 1 mL

Answer

V = 1 mL
4.Dosage calculations

Answer: V = 0.3 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.

Volume

V = 300/1000 = 0.3 mL

On the syringe

On this 1 mL syringe every small line is 0.01 mL.

Answer

V = 0.3 mL
5.IV infusion rates

Answer: R = 320 mL/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.

Original rate

1500/6 = 250 mL/h

New rate

R = 640/2 = 320 mL/h

Answer

R = 320 mL/h

This is more than a 25% increase: most hospitals require you to contact the prescriber instead of catching up, and to assess the patient for fluid overload.

6.IV infusion rates

Answer: R = 40 gtt/min

Dose-based infusions: concentration = amount of drug in the bag/bag volume. Pump rate (mL/h) = dose per hour/concentration, and dose per hour = mL/h × concentration. Convert per-minute doses to per-hour (× 60) and keep the mass units the same (1 g = 1000 mg, 1 mg = 1000 mcg).

Concentration

100/100 = 1 mg/mL

Volume per hour

40/1 = 40 mL/h

Drip rate

R = 40·60/60 = 40 gtt/min

Answer

R = 40 gtt/min

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