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

Where is the fundus normally found about 12 hours after a vaginal birth?

  1. AFirm, in the midline, at about the level of the umbilicus
  2. BFirm and displaced to the far left side
  3. CSoft and two finger-widths above the xiphoid process
  4. DBelow the symphysis pubis and not palpable
2.Maternity & obstetric nursingHard

Monochorionic twins at 22 weeks show one twin with polyhydramnios and a large bladder and the other with almost no fluid. What condition is suspected?

  1. ATwin-to-twin transfusion syndrome
  2. BPlacenta praevia
  3. CGestational diabetes in one twin
  4. DRh isoimmunisation
3.Dosage calculationsMedium
1 g+ 3.4 mLV = ? mL

A vial contains 1 g of powder. The label says: add 3.4 mL of water for injection to give a total volume of 4 mL. The prescription is 250 mg. What volume V of the reconstituted solution do you give?

1 g+ 3.4 mL → 4 mL250 mg
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 8400 units of a drug that comes as 10000 units/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

8400 units10000 units/mL
V = mL
5.IV infusion ratesMedium
730 mLleft? mL/h5 h left

1000 mL was ordered over 8 hours. After 3 hours you find that 730 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?

1000 mL / 8 hafter 3 h: 730 mL
R = mL/h
6.IV infusion ratesHard
500 mg250 mL60 gtt/mL200 mg/h? gtt/min

500 mg of a drug is diluted in 250 mL and given by gravity through a set of 60 gtt/mL. The order is 200 mg per hour. Find the drip rate R in drops per minute.

500 mg/250 mL200 mg/h60 gtt/mL
R = gtt/min

3Solutions

1.Maternity & obstetric nursing

Answer: A · Firm, in the midline, at about the level of the umbilicus

Why this is the answer

The fundus rises to about the umbilicus within the first 12 hours, then descends about 1 cm (one finger-width) a day. It is usually no longer palpable above the symphysis by about 2 weeks.

Answer

A · Firm, in the midline, at about the level of the umbilicus
2.Maternity & obstetric nursing

Answer: A · Twin-to-twin transfusion syndrome

Why this is the answer

In monochorionic twins, unbalanced vascular connections can shunt blood from one twin to the other. The recipient becomes overloaded with polyhydramnios, while the donor has low fluid and growth restriction.

Answer

A · Twin-to-twin transfusion syndrome
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

1000 mg/4 mL = 250 mg/mL

Volume

V = 250/250 = 1 mL

Answer

V = 1 mL
4.Dosage calculations

Answer: V = 0.84 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 = 8400/10000 = 0.84 mL

On the syringe

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

Answer

V = 0.84 mL
5.IV infusion rates

Answer: R = 146 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

1000/8 = 125 mL/h

New rate

R = 730/5 = 146 mL/h

Answer

R = 146 mL/h

Many hospitals allow such an adjustment up to 25% without a new order; check local policy.

6.IV infusion rates

Answer: R = 100 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

500/250 = 2 mg/mL

Volume per hour

200/2 = 100 mL/h

Drip rate

R = 100·60/60 = 100 gtt/min

Answer

R = 100 gtt/min

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