In this article, we'll cover GTPAL, which is how you classify a patient's pregnancies and births, how to estimate a patient's due date, and some important prenatal labs and diagnostics, including hCG, Rh factor, MSAFP and OGTT.
This series follows along with our Maternity Nursing Flashcards which are intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI, and NCLEX.
When you see this Cool Chicken, that indicates one of Cathy's silly mnemonics to help you remember. The Cool Chicken hints in these articles are just a taste of what's available across our Level Up RN Flashcards for nursing students!
Maternity Nursing - Flashcards
GTPAL
GTPAL is a measurement of the number of pregnancies and deliveries with different outcomes a patient has had. GTPAL stands for gravidity, term, preterm, abortion, and living.
Gravidity
Gravidity is a measure of the patient's total number of pregnancies, including their current pregnancy. The total Gravida number will include Term, Preterm, and Abortion.
Gravida terms
There are three terms used for gravida, which are nulligravida, primigravida, and multigravida.
Nulligravida
Nulligravida means a patient has never been pregnant.
Primigravida
If a patient is primigravida that means they are on their first pregnancy. In your nursing career, you may hear something like "oh, she's a primi," which means that patient has not had a baby before. This is not to be confused with preemie, which is a slang term for a baby born prematurely.
Multigravida
If a patient is multigravida that means they have been pregnant multiple times, so two or more times.
Term
The term number in GTPAL is how many full term births a patient has had, full term meaning delivered at 38 weeks or later.
Preterm
The preterm number in GTPAL is how many preterm births a patient has had, preterm meaning the number of births from viability (~20 weeks) to 37 weeks.
Abortion
Abortion is a general medical term meaning a pregnancy that has ended without a live birth, including induced (elective/therapeutic) abortions and spontaneous miscarriages. The abortion number in GTPAL is how many abortions total there have been.
As Meris notes in the video, to most people, the term abortion means induced abortion, so be cautious about the use of this term, especially around patients that have been through miscarriage or baby loss.
Living
The living number in GTPAL represents how many living children the patient currently has. This number is independent of the other numbers, but would not exceed the combined total of Term and Preterm.
To clarify the meaning of living, imagine a patient lives to 120 years old and outlives all of their children. They may be G5 but L0.
GTPAL example calculation
Imagine a patient who has had 2 term deliveries, 1 preterm delivery, 7 miscarriages, and has 2 living children.
- G = 10 (the patient's combined 2 term birth + 1 preterm birth + 7 miscarriages )
- T = 2 (the patient's 2 term births)
- P = 1 (the patient's 1 preterm births)
- A = 7 (the patient's 7 miscarriages)
- L = 2 (the patient's 2 living children)
To further clarify what GTPAL means and doesn't mean, notice that the patient had a total of 3 births, but only has 2 living children. This patient lost their child at some point, and based on the available data, the child may have died in infancy or died at age 20—we don't know.
Estimating due dates
When estimating a patient's due date, there are two methods you can follow. For both, you will start with the first day of the patient's last period.
Nagele's rule
Using Nagele's rule, you'll take the first day of the patient's last period, subtract 3 months, then add 1 week, then add one year.
Cathy's rule
Cathy's rule is a simplified version of Nagele's rule. You'll take the first day of the patient's last period, then add 9 months, then add 1 week.
Cathy's rule is the same as Nagele's, but the months calculation is condensed into one step. When Nagele has you subtract 3 months then add 12 months, it's the same thing as adding 9 months. Ostensibly, subtracting 3 and then adding 12 makes cross-year calculations easier, but many people find 9 months to be easiest.
Prenatal labs & diagnostics
The prenatal labs and diagnostics we'll cover here are hCG, Rh factor, MSAFP, and OGTT. In later videos, we'll cover diagnostics that are further along in the process, like an amniocentesis.
hCG
Human chorionic gonadotropin (hCG) is known as the pregnancy hormone, and it is what's detected in an over-the-counter pregnancy test. However, it's only a probable sign of pregnancy, not a positive one.
hCG may be low in cases of ectopic pregnancy and elevated in cases of molar pregnancy or multifetal pregnancy.
Rh factor
Rh factor is whether or not someone has Rh antigen in their blood. This text looks for maternal-fetal blood compatibility. In the Rh factor test, blood typing is done at the first prenatal visit to determine if the pregnant patient has Rh antigen on their red blood cells (is Rh-positive) or lacks the Rh antigen (is Rh-negative).
If an Rh-negative patient is pregnant with an Rh-positive baby, they are Rh incompatible, and the patient may develop antibodies to fight back against the Rh protein. Usually, this is not a problem on the first pregnancy. However, if left untreated, on the second pregnancy, the antibodies could cross the placenta and attack the baby's red blood cells, which is a process known as erythroblastosis fetalis.
Luckily, there is treatment available called Rhogam.
Erythroblastosis fetalis
Erythroblastosis fetalis is when a fetus's red blood cells are destroyed faster than they can be made, because maternal antibodies have crossed the placenta.
Rhogam
Rhogam, which is short for Rh immune globulin, is a medication that can be given to Rh-negative pregnant patients to help prevent them from developing antibodies against the Rh protein present in the blood of Rh-positive babies.
Rhogam is administered at 28 weeks and within 72 hours of delivery. Rhogam is also administered after any pelvic or abdominal trauma or vaginal bleeding, because these are occasions wherein the maternal blood may mix with the fetal blood.
MSAFP
Maternal serum alpha-fetoprotein (MSAFP) is a test for genetic abnormalities that is performed at 15 - 20 weeks gestation. High MSAFP may be indicative of neural tube defects. Decreased MSAFP may be indicative of Down syndrome.
MSAFP will be down for Down syndrome.
As Meris points out in the video, it's important to note that MSAFP being high or low is not diagnostic in and of itself, and further testing is needed to determine if neural tube defects or Down syndrome is present.
Oral glucose tolerance test (OGTT)
The oral glucose tolerance test is a screening for gestational diabetes.
The one-hour OGTT is done at 24 - 28 weeks, and no fasting is required. The patient drinks 50 g glucose solution, and if their glucose levels are greater than 140 mg/dL one hour later, they must follow up with a three-hour OGTT.
A three-hour OGTT requires the patient to fast beforehand. Blood sugar is checked at fasting. Then the patient consumes a 100 g glucose solution. Then their blood sugar levels are tested after one hour, after two hours, and after three hours. If two or more of their results exceed the threshold, the patient is diagnosed with gestational diabetes.
3 comments
Thanks for the explanations and answers it really helped a lot in my studies
Wow 🔥
Very clear explanations! Thanks!!