Impacted Fetal Head
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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