Impacted Fetal Head

Reading: From SASCOG’s Pearls of Exxcellence - Cesarean Delivery with Deeply Impacted Fetal Head 

Imagine the scenario: 

You are called to do an urgent C-section as an intern for a patient with arrest of second stage of labor. Per sign out, the patient has been pushing for almost three hours and the fetal station has never made it below +1. There is significant caput. What are some of the things you should be thinking about to hopefully make this C-section easier? 

How do I identify an impacted fetal head? 

• What it is: 

• There have been various definitions proposed - basically, most of the definitions center on having a fetal head becoming deeply engaged within the maternal pelvis resulting in difficult extraction 

• Complicates 1.5% of cesarean births and up to 25% of emergent cesarean births 

• Risk factors 

• Fetal malposition - ie. occiput posterior and occiput transverse positions

• OP positioning leads to a larger occipitofrontal diameter (11.5cm) passing through the pelvic outlet compared to OA (9.5 cm) 

• See more on this in our malposition and malpresentation episode!

• Prolonged second stage 

• Failed operative vaginal delivery 

• Basically, anything that can wedge the head into the pelvis 

• Identifying an impacted fetal head 

• There is not a 100% way of identifying that a fetal head will be impacted before you actually do the C-section and you reach down into the pelvis 

• However, you should suspect it if there are any of the above risk factors 

• Regarding fetal position: 

• Can be known by palpating the sutures

• In babies that are OP, the posterior fontanelle will be felt

  • This feels triangular, as it is formed by the junction of the sagittal and lamboidal sutures 

• This is in contrast to babies that are OA, where the anterior fontanelle can be felt (shaped like a diamond) 

• Other methods = using transabdominal ultrasonography to figure out position, as rate of error for digital vaginal exam can range from 30-65% depending on the study 

• An impacted fetal head is usually identified during the cesarean delivery: when you place a hand beneath the pubic bone to lift the fetal head, it is often difficult due to how low the head is.

• Possibly cannot get hand around the fetal head to elevate 

• Or it is difficult to elevate and flex the head due to position or how low the head is 

Why do we care about IFH? 

• What are risks to mom? 

• Other than it being really hard to elevate the head and delivering the baby, there are multiple risks to both mother and infant at this stage 

• Increased risk of: 

• Maternal hemorrhage 

• Hysterotomy extensions 

• Bladder injury 

• What are risks to baby? 

• Neonatal hypoxia 

• Traumatic injuries 

• Therefore, important to identify this and anticipate how to resolve IFH 

What should you do if there is a suspected impacted fetal head? 

• Let others know what you are thinking 

• Tell nursing staff, anesthesia, and neonatology 

• This way, everyone is prepared 

• Call for help if needed - if you need another team member to come in for assistance, it’s better to have them and not need them than if no one is there 

• Position the patient accordingly 

• We tend to favor positioning patient in a modified lithotomy position 

• Can either frog-leg 

• Or place in lithotomy, but bend legs down so that the hip joint is not flexed during the initial part of the case

• Can use yellow fin stirrups 

• Easy to then flex at the hip joint into dorsal lithotomy if needed  

• Place your hysterotomy accordingly 

• Especially if the patient has entered second stage, the lower uterine segment will be distended 

• Hysterotomy should be placed relatively high to avoid inadvertent entry through the cervix or vagina 

• Maneuvers to resolve IFH 

• Now that you have encountered an impacted fetal head and done all the right things up until now. How do you get the baby out? 

• Vaginal hand or “push” technique 

• Someone wears sterile gloves and inserts hand into vagina to elevate the fetal head 

• They do not remove the hand until the head has been disimpacted by the surgeon from above or if this method has failed 

• Breech delivery or “pull” technique 

• Another technique is to deliver breech

• Surgeon will extract feet from hysterotomy and proceeds to deliver the rest of the fetus 

• Studies in low-resource settings show that this technique resulted in decreased maternal hemorrhage, hysterotomy extensions, and infection when compared to the “push” technique  — comparison of different methods via systematic review and meta-analysis

• Extending your hysterotomy

• If extraction is still difficult, can proceed with extension of the hysterotomy either via a J or a T extension 

• These are done usually with two fingers beneath the area that you wish to extend to protect the baby, then cut the uterus with bandage scissors 

• Can lead to more bleeding and will result in longer repair, but may lead to increased 

• Devices 

• Fetal Disimpacting System or cephalic elevation device; Fetal Pillow

• Basically an inflatable device that is placed into the vagina that elevates the fetal head!

• One randomized controlled trial at BWH in Boston that showed that this device led to 23-second reduction from hysterotomy to delivery compared with other methods 

• Patients all received the device in the vagina, but were randomized to whether or not the device was inflated or not.

• Other techniques 

• Other techniques have been described, but not as well studied as the push or pull technique 

• One = shoulder-first method, where the shoulders are initially delivered through the hysterotomy, followed by traction placed on axilla to facilitate delivery of the body and subsequently the head (Patwardhan maneuver)

• Last thoughts 

• If an IFH occurs, and it is particularly difficult, especially if it leads to need for multiple maneuvers, remember to debrief! 

• Both with the team - what happened, what went well, what could have been improved, and take home points 

• For full description of how to debrief, check out our episode on debriefing!

• Talk to the patient 

• Often, this can be traumatic for both the provider and the patient 

• The baby may need to go the NICU, there may need to be a hysterotomy extension 

• Discuss what occurred with the patient and if maneuvers resulted in certain complications 

• Discuss extensions, baby going to NICU

• Discuss if need for future C-section if T incision has occurred 

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.

The Standardized Cesarean Section

Back in June 2019, we did an episode on The Evidence-Based Cesarean Section. Back then, we talked a bit about incision types, infection practices, and some in surgical technique. In the November 2020 Green Journal, two of our podcast guests - Dr. Josh Dalhke and Dr. Jeff Sperling, in addition to their coauthors - make the case for standardizing cesarean delivery technique.

The text is definitely worth a read, as it’s a succinct review of the most current literature. Some of the practices you may employ already; others you may be surprised by! We talk a bit more with these two authors about the recommendations, what was most surprising, and what things are to come.

This checklist comes from the article, and is definitely worth discussing at your institutions. We’ll let the podcast speak for itself otherwise.

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Dahlke et. al, O&G, Nov. 2020 — hyperlink above

Preventing the Primary Cesarean, Part II

We’re re-visiting an old episode of ours on preventing the primary cesarean, with some more and differently focused information. We heard some great feedback from our last episode so we’re incorporating some of that here! This time around, we want to focus some more on how to promote normal labor and physiological birth! 

Let’s start off with talking about shared decision-making. This is a framework for taking situations with various individuals with different sets of knowledge, belief systems, and priorities and coming together to form a mutually satisfying plan to get everyone where they want to go. ACOG CO 587 reviews this in part, stating SDM can increase patient engagement and reduce risk with resultant improved outcomes, satisfaction, and treatment adherence.

Shared decision making can take the form of a variety of tools in prenatal care and on the labor floor:

1. Partograms - allowing patients to see where they are in their labor course compared to others.

2. Birth plans - providers and patients can come together early in their course of the pregnancy to identify patient goals and desires for their labor. Also allows recognition of some goals/desires may not be feasible due to the patient’s individual risk factors, pregnancy complications, etc. 

3. Patient education resources - we love www.birthtools.org, but there’s a number that exist (and some probably specific to your institution) that can help set expectations for the birthing process.

In identifying a patient’s desires in labor, one of the most common questions has to do with analgesia. Prental care is an excellent time to discuss both pharmacologic and non-pharmacologic options for coping. While epidurals are common in the USA, continuous labor support is another option for coping and also has been shown to reduce cesarean rates in trials. It can take on many forms, and be administered by anyone a laboring person trusts:

1. Physical support - positioning, use of touch, application of cold and heat and control of environment.

2. Emotional support - being present with the laboring woman, use of distraction.

3. Instructional/informational support - assistance with relaxation and breathing, using effective communication techniques.

4. Advocacy labor support - building trust, providing security and giving laboring women control.

Nutrition and hydration during labor is another common sticking point. It is very common for nutritional deprivation at NPO or clear liquid diets to occur in labor. This is for ostensibly, a good reason: fear of aspiration of stomach contents in the event for need for general anesthesia, or for vomiting due to decreased GI motility. However, a Cochrane review demonstrated no statistical difference in maternal or newborn outcomes related to type of birth or Apgar scores at five minutes. Nutritional deprivation provided no benefit or harm, and so evidence does not support nutritional deprivation. This review further stated that nutritional deprivation can cause maternal distress, unbalanced nutritional status, and increased pain in labor.

What about our original fear of aspiration? Current studies don’t show that nutritional deprivation ensure low stomach residue or acidity. When combined with decreased use of general anesthesia in modern obstetrics, concern for aspiration risk does not provide sound basis for implementation of withholding food or fluid from women in labor.

Next, let’s review the benefits of collaborative care models:

Labor is a team sport that contains the woman, her support person/people, her nurse, and provider (midwife/obstetrician/family practitioner). It shares the workload for this 24 hour in house care, providing a variety of perspectives on the case, in a mutually respectful environment. Now certainly, there are challenges to what sounds so harmonious: interdisciplinary mistrust, inconsistent communication, variable skill sets, scheduling logistics, hospital structure, to name a few. However, we know that this is evidence based! Studies where there have been 24 hour laborists and strip review and collaboration have led to significant decrease in NTSV rate. Why does it work? Well, it likely promotes consideration of alternative options, with experts of multiple perspectives and skill level.

Lastly, systems-based and structural design challenges may also contribute to cesarean. This work is nascent, but check out the awesome work by the folks at Ariadne Labs’ Delivery Decisions Initiative to learn more.