2nd and 3rd Trimester Bleeding

• Placenta previa - when the placenta partially or totally covers the internal cervical os. Defined as edge of placenta <10 mm from internal cervical os 

  • Occurs approximately 4/1000 births, but varies world wide. Increased risk associated with history of previous placenta previa, previous C-section, and multiple gestation 

  • Approximately 90% of placenta previa identified on ultrasound <20 weeks → resolve before delivery 

  • Painless vaginal bleeding can occur up to 90% of persistent cases 

  • 10-20% of women present with uterine contractions, pain, and bleeding 

  • Why we care: can lead to catastrophic bleeding, need for transfusion, and delivery. Can lead to stillbirth  

• Placenta accreta spectrum 

  • Listen back to our PAS series from March with Drs. Shainker and Einerson: 

    • https://creogsovercoffee.com/notes/2021/3/7/placenta-accreta-part-i

    • https://creogsovercoffee.com/notes/2021/3/14/placenta-accreta-part-ii-management

  • What it is: abnormal trophoblastic invasion of part of or all of the placenta into the myometrium of the uterine wall 

  • Can be painful or painless bleeding 

  • Risk factors: previous cesarean section, placenta previa, unexplained elevation in MSAFP (but not a good predictor!) 

  • Why we care: can lead to catastrophic bleeding, need for transfusion, and delivery. Also may require hysterectomy. Usually may need delivery at tertiary care center 

• Vasa previa 

  • What it is: when fetal vessels run within the membranes over the internal os of the cervix 

  • Very rare. Has been quoted 1/2500 deliveries 

  • Painless bleeding usually 

  • Two types: 

    • Velamentous cord insertion and fetal vessels that run freely within the amniotic membranes overlying the cervix or in close proximity of it (2 cm from os); usually pregnancies with low lying placenta or resolved placenta previas are at risk 

    • Succenturiate lobe or multilobe placenta and fetal vessels connectin both lobes course over or in close proximity of cervix (2 cm from os)   

  • Other risks: IVF 

  • Why we care: increased risk of fetal hemorrhage, exsanguination, and death 

• Placental abruption

  • What it is: Separation of the placenta from the inner wall of the uterus before birth 

  • Usually painful bleeding 

  • Incidence: 2-10/1000 births in the US 

  • Risk factors: hx of fabruption, cocaine use, tobacco use, hypertension, uterine abnormalities (ie. fibroids, bicornuate uterus) 

  • Why we care: can lead to catastrophic bleeding, need for transfusion, and delivery. Can lead to stillbirth. 

• Uterine rupture 

  • What it is: significant uterine disruption. Usually will occur along a previous uterine scar 

  • Very painful bleeding (pain is usually more significant than bleeding) 

  • Risk factors: previous uterine rupture, previous uterine scar, especially if a fundal or vertical scar (ie. cesarean delivery, myomectomy), induction, labor 

  • Why we care: very high incidence of morbidity and mortality for both mom and baby 

• Less dangerous causes:

  • Labor - “bloody show” with labor

  • Cervicitis 

    • Can be caused by infection (ie. BV, candida infection, trichomonas, chlamydia, gonorrhea) 

  • Cervical polyp 

  • Vaginal laceration 

Doing a Workup for Bleeding in the 2nd and 3rd Trimester

• History 

  • How much bleeding? (soaking through clothes? Passing clots?)

    • Passing tissue? 

    • Remember: just because someone has light bleeding does not mean that they don’t have something life-threatening for them or their fetus   

  • Is there pain? 

  • How long has the bleeding been happening? 

• Exam 

  • After your physical exam, do an abdominal and pelvic exam 

    • Lift the sheet: how fast is the patient bleeding? 

    • Abdominal exam: is there tenderness to palpation anywhere? Over the uterus? How pregnant does the patient appear to be (if no records?) 

      • Patients with rupture will be very tender to palpation 

      • Less likely to be tender to palpation with something like placenta or vasa previa 

    • Start with a speculum exam - if passing tissue, that should be sent to pathology 

      • Look for vaginal laceration, neoplasms, discharge, evidence of cervicitis, cervical polyps, fibroids, ectropion 

      • Send testing for cervicitis and vaginitis (ie. wet mount, as well as chlamydia/gonorrhea) 

    • Do not do a digital cervical exam without confirming where the placenta is located!

• Labs and Imaging 

  • Pregnancy test if not confirmed (just a urine pregnancy test!) 

  • Type and screen, CBC, coagulation profile

  • Putting the baby on the monitor 

    • Consider doing so if the fetus is viable 

    • Sometimes, the only way to tell if someone is abrupting or rupturing their uterus (other than having abdominal pain) is seeing non-reassuring fetal heart tracing 

    • Watch contraction pattern - can discern if someone is contracting with bleeding or now. Also, there may be evidence of abruption on monitor (small amplitude, frequent contractions) 

  • Ultrasound 

    • Usually, transabdominal is enough, but if you think that there is a placenta previa, placenta accreta, or vasa previa, you should do a transvaginal ultrasound 

    • Color and pulsed Doppler should be used to help in diagnosis 

    • Remember that placental abruption is a clinical diagnosis: you may not always see a blood clot or an area that appears “abrupted” on the placenta

    • Usually, placenta previa, placenta accreta, and vasa previa are diagnosed at the mid-trimester ultrasound and will require clinical follow-up 

Management 

• Depending on the amount of bleeding: 

  • Vital signs 

  • Two large bore IVs 

  • Resuscitation - fluids vs. blood products

• If there is less bleeding and you think you have more time:

  • Blood type and Rh status - administer Rhogam if it is indicated 

  • Management otherwise depends on reason for bleeding - will discuss briefly some of the more dangerous things 

• Placenta previa:

  • Usually will trigger an admission for monitoring 

  • If preterm, usually recommend steroids, and if <32 weeks, can discuss magnesium for CP prophylaxis 

  • Pending the stability of mom and fetus, may require emergent delivery via cesarean section 

  • Certain locations may have a “threshold” for prolonged admission - ie. three strikes = three bleeds and admission for the rest of pregnancy 

  • If otherwise stable, can usually be delivered between 36w0d - 37w6d via c-section

  • Usually can have vaginal delivery if >2 cm from os, but some institutions may discuss if >1 cm 

• Placenta accreta spectrum:

  • Will usually also trigger an admission for monitoring, and can also lead to emergent delivery + hysterectomy pending stability 

  • Steroids and mag if indicated 

  • If stable, recommend delivery between 34w0d-35w6d, and usually this will be done at tertiary care center with multi-disciplinary team 

• Vasa previa:

  • There is usually a lower threshold for bleeding and contraction in vasa previa because the bleeding could come from the fetus 

  • While an adult human has 5-6L of blood, a fetus has much less. A term fetus+placenta can have up to 500mL of blood (baby may have 250-300cc). Usually describe to patients in measurements of a soda can (355 mL). 

  • For this reason, many places will hospitalize vasa previa between 28-34w0d and monitor 

  • Recommend delivery between 34w0d-37w0d pending stability of mom and baby 

Placenta Accreta Part II: Management

After last week’s initial episode, we talk through some pearls for management. Keeping it simple today:

• Antenatal care considerations:

  • Pelvic rest, avoid travel - don’t get into a bad situation!

  • Prenatal care is fairly routine.

  • Hospitalization practices will vary by region and level of resources — i.e., admission for proximity. Bleeding should prompt admission, likely until delivery.

  • Sweet spot for delivery typically between 34-35’6 weeks, though some centers pushing towards 36+ weeks.

    • However, as Dr. Einerson mentions, the worst thing you can do is end up in an emergent delivery scenario with these patients!

  • Don’t forget about using late preterm steroids!

• Cesarean hysterectomy tips:

  • Collins 2019 paper on evidence-based management. Don’t deliver too late!

  • Multidisciplinary / interdisciplinary care leads to less morbidity.

  • Ureteral stents: if you need them to identify ureters to safely perform surgery.

  • Some tips from our guests:

    • Approach through VML skin incision, though Maylard / Cherney incisions are also reasonable. Fundal hysterotomy (typically) to avoid messing with the placenta.

    • Decrease blood flow before addressing the bladder - they often take the uterine vessels before developing the bladder.

    • Arterial catheters such as the REBOA are to be used in experimental settings only, and are associated with serious complications.

    • If bleeding - the most experienced operators need to be there.

    • Bipolar vessel sealing devices (such as LigaSure) are helpful!

• Conservative management?

  • To be done only on an experimental basis at this time! Reasonable to examine in a trial for a number of reasons.

  • Methotrexate does NOT work for retained placenta — MTX kills rapidly dividing cells, not stagnant cells left behind.

• Patient resources / advocacy:

  • Check out the National Accreta Foundation as a great patient advocacy resource.

Placenta Accreta Part I - Pathophysiology, Diagnosis, and Imaging

Today we welcome two special guests to the podcast — Dr. Scott Shainker, who is an assistant professor at Beth Israel Deaconess in Boston, MA, and Dr. Brett Einerson, who is an assistant professor at the University of Utah in Salt Lake City, UT. Both Dr. Shainker and Dr. Einerson are experts in the world of placenta accreta spectrum, with numerous publications, guideline papers, and advocacy efforts to their names. We did a two part series with them on PAS. This first episode, we focus on pathology, diagnosis, and imaging. Next week, we’ll get into management and future directions.

For further reading, check out ACOG’s Obstetric Care Consensus on PAS.

PAS has traditionally been thought of as an “invasive” disease, but that thinking is evolving to think of PAS as a disease of uterine dehiscence. The loss of the uterine decidua due to prior uterine scarring (i.e., due to surgery) brings about abnormal attachment and a “superhighway of vascularity,” thus that when delivery comes, the placenta fails to separate normally. Uterine muscle dehiscence likely accounts for the degree of invasiveness. It’s likely that cesarean scar pregnancies are a precursor to PAS.

https://resident360.nejm.org/clinical-pearls/placenta-accreta-spectrum

The PAS diagnosis and terminology is also changing, from the traditional accreta / increta / percreta divide seen above, to a FIGO staging system with both surgical and pathologic criteria. You can review those here.

We review some of the risk factors, but far and away the biggest is a combination of a prior cesarean and placenta previa. Dr. Shainker mentions Dr. Robert Silver’s landmark paper on this - the percentages are worth committing to memory. Other risk factors include other types of uterine surgery like abdominal myomectomy; IVF and ART; and potentially dilation and curettage, though that is controversial.

Imaging is great in research capacities with high sensitivity (approaching 90+%), but only 50% of patients with accreta know about it before delivery. So the real world sensitivity is very poor. Risk factors should raise suspicion primarily, and the use of imaging help guide your preoperative suspicion. SMFM has now published a consensus on ultrasound diagnosis, which is the gold standard. More data should hopefully improve the real-world detection rates for PAS.