Physiologic Changes of Pregnancy: Part 2

10/08/2023
As part of our brief break for parental leave, we’re revisiting some of our most popular episodes! Today we’re revisiting Physiologic Changes of Pregnancy, part II.

---

We’re continuing “Fei and Nick’s Fabulous Adventure Through Pregnancy” today!

Need a refresher on all those lung volumes? So did we. There are a number of resources online to review them, however a nice quick video review can be found here.

These two episodes have covered a lot of ground on a lot of systems. We tried to come up with a quick-view table encompassing all of these changes. Let us know what you think!

View fullsize

Physiologic Changes of Pregnancy: Part 1

10/01/2023
As part of our brief break for parental leave, we’re revisiting some of our most popular episodes! Today we’re revisiting Physiologic Changes of Pregnancy - almost five years to the day since we released it! Check out our reprisal of part II next week with the all-encompassing table of changes.

---

As promised, our first episode on pregnancy! Join us on “Fei and Nick’s Fabulous Adventure Through Pregnancy!”

Today we tackled the changes of the immunologic and hematologic systems seen in pregnancy. There’s quite a bit of information there! If you feel like we’ve missed anything, feel free to reach out via email or social media.

Next week, we’ll release Part 2 and have some more resources ready for your studying!

Management of an Early Unlocated Pregnancy

Today we’re bringing back Dr. Erin Cleary one more time before she transitions to her new role as an MFM fellow at the Ohio State University! Dr. Cleary today talks with us on early pregnancy of unknown location - a common problem in the office or the emergency department/triage.

Women presenting to the ED with first trimester bleeding, pain, or both, have had a demonstrated prevalence rate of ectopic pregnancy up to 18% in some studies. Ruptured ectopic is a leading cause of pregnancy-related mortality in the first trimester, accounting for 2.7% of pregnancy-related deaths overall in 2011-2013. Proper identification and management of early, unlocated pregnancy is life-saving!

Dr. Cleary was kind enough to put together her high points from this episode for our blog post today:

H&P:

• Any patient with an unlocated pregnancy should be considered to have a potential ectopic pregnancy.

  • Women with prior ectopic, regardless of method of treatment, are at risk for ectopic in a subsequent pregnancy (three- to eightfold higher compared with other pregnant women).

  • If pregnancy is present while IUD is in place, risk of ectopic is 1 in 2 pregnancies for the levonorgestrel IUD and 1 in 16 pregnancies for the copper IUD.

  • Women with a history of PID have an approximately threefold increased risk of ectopic pregnancy

• Pelvic exam. THIS MUST BE DONE.

Beta-HCG

• The threshold for a positive qualitative β-hcg test is 20-50 milli-int units, depending on test. For quantitative serum tests, the threshold is 5-10 milli-int units, and 1-2 milli-int units, for ultrasensitive tests.

• The β-hcg concentration doubles every 29 to 53 hours during the first 30 days after implantation of a viable, intrauterine pregnancy.

• When ectopic pregnancy is on the differential, a qualitative test is not sufficient. A serum quantitative value is essential to:

  • 1. Interpret imaging (“discriminatory zone”)

  • 2. Have a baseline in the event the β-hcg must be trended

The Discriminatory Zone

• Definition: A concept that there is a quantitative β-hcg level above which the landmarks of a normal intrauterine pregnancy (yolk sac and embryo) should be visible on ultrasound.

  • Therefore, the absence of a gestational sac when β-hcg level is above the DZ is strongly suggestive of nonviable pregnancy, with 50-70% being ectopic.

• Pelvic ultrasound is the gold standard first line imaging modality in early pregnancy and for evaluation of suspected ectopic pregnancy

• Imaging results will fall into 1 of 5 main categories

  • IUP with normal adnexa. Normal pregnancy!

  • IUP with abnormal adnexa. Although rare, must evaluate for heterotopic pregnancy, or presence of both an intra and extra-uterine pregnancy.

  • No IUP, extra-uterine mass with YS/FP. Confirms ectopic pregnancy.

  • No IUP, adnexal mass without YS/FP. Suspicious for ectopic pregnancy

  • No IUP, normal adnexa. Differential includes normal but early IUP, failed IUP, or unidentified ectopic.

• A patient with a confirmed ectopic requires evaluation and counseling by an OBGYN to evaluate candidacy for medical or surgical evaluation.

Management:

• Expectant management: serial quantitative β-hcg level assessment ~q 48 hours, only for stable patients.

  • Scenario A: The β-hcg level rises appropriately (doubles approximately every 2 days).

  • Scenario B: The β-hcg level falls precipitously.

  • Scenario C: The β-hcg level neither rises appropriately nor drops precipitously. Now we should be MORE concerned about ectopic pregnancy, but abnormal IUP is also on the differential.

• Repeat pelvic imaging is very helpful

• Every patient who is stable and an appropriate candidate to trend β-hcg levels will eventually declare herself, with either a located IUP, a failed IUP/SAB, or a confirmed or presumed ectopic pregnancy.

We will cover ectopics for surgical and medical management in a future episode, so stay tuned!

Nausea and Vomiting of Early Pregnancy

On today’s episode, we discuss one of the most common ailments of early pregnancy, and recommendations for diagnosis and therapy. ACOG PB 189 (ACOG membership required) goes into all the details and makes for excellent further reading, and to learn all about that PUQE scale!

Probably the highest yield piece of information from PB 189 is the recommended therapy algorithm, which you’ll find below. For your practice, don’t forget about helpful adjunct therapies for acid reflux symptoms, like ranitidine or famotidine.

View fullsize

ACOG PB 189

Prenatal Genetic Screening and Testing

This topic can be a source of confusion and anxiety to many providers of OB care, and we hope that we can at least provide some of the basics in today’s episode. For in depth review, see ACOG PB 163 for screening tests, and PB 162 for prenatal testing (ACOG membership required).

One of the most useful and high yield tables on this subject is Table 2 from PB 163 (below). Knowing the differences between these tests, their components, and advantages/disadvantages can be useful for exams as well as your clinical practice.

PB 163 also reviews what the workup should be after a positive screen or after a sonographic finding of aneuploidy, which we did not cover in totality on today’s episode but may also be of use to you.

Just remember — are you screening, or are you testing?

View fullsize